1973 AC Model-70.


1973 AC Model-70 Front offide 3/4 profile

Where they are available full size versions of the images on this page can be accessed by clicking on them.


Links to other Invacar Resources on this website: The Invacar FAQPDF Scan of the Model 70 Workshop Manual.


An appropriate comment now would probably be "Now for something totally different..."

It's not great secret that I've always been a fan of and have owned quite a few oddball cars.  However this one hit even me as a complete curve ball.  Grab yourself a coffee and make yourself comfortable as I take you through the abridged version of the story where this car was turned from a mouldy hulk in a field back to the car you see above.


The usual reaction from people when they see this car is "What is it?"


It's an Invacar.  The immediate response then is "A what?" For anyone born later than the mid 80s likely something that you've never seen given that they disappeared in 2003.

The answer of what it is, is one which requires a little bit of a history lesson to answer properly, I honestly can't properly answer it in a couple of sentences.  It is worth noting though that this is very, very much the heavily abridged version of the history of the Invacar, fact checked to the best of my ability.  At some point down the line I may try to flesh this out a bit with a chronology of more of the actual models involved - but putting that together would be quite a project in its own right.

The origins of the Invacar date back to the 1940s, when Bert Greeves (yes, the Bert Greeves better known latterly of Greeves Motorcycles) constructed a vehicle for his cousin Derry Preston-Cobb who was completely paralysed save for having use of one arm.  While this used a lot of off-the-shelf motorcycle parts, the underlying chassis was a bespoke design from the start.  The photo below shows this vehicle, its creator and intended user looking quite pleased.

 

JPJ132 - The original Invacar, shown with Bert Greeves, the creator, and Derry Creston-Cobb, his cousin.

 

Source: Greeves Rider's Association Archive.

This image is believed to be from early 1942. 

Not unreasonable for him to look quite pleased.  You have to remember that this is a good forty years before anyone really started to make real steps towards making any public transport accessible. So prior to getting this machine he would have been almost entirely dependent on others for any transportation. 

While a few other companies had adapted existing vehicles for hand control, it was the bespoke nature of this design which allowed it to catch the attention of quite a few people and it didn't take Greeves long to realise there was a market out there for these vehicles.  They were also (as far as I am aware) the first company who from the outset specifically tailoring each vehicle the the needs of the intended user, and very much the first to offer a petrol powered machine which could be operated using only one hand.  While wartime meant that there was no chance initially to start building more vehicles than the original, they were quick to formally set up the company Invacar Ltd and to file patents for the design of the vehicle and specially designed control systems.

While a lot of people believe that Invacar rose up as an offshoot of Greeves Motorcycles, this isn't actually really true.  Instead it was the success of Invacar Ltd that came first and provided the solid foundation on which Bert Greeves was able to build his motorcycle division on.

The design you see above was pretty quickly refined into a production ready vehicle once wartime came to an end.

The key to the company really climbing to fame and becoming a household name though came in 1949 when Invacar Ltd won the government contract to supply the newly formed NHS with invalid carriages.  The moment they won that contract and showed they had the drive and ability to ramp up production to meet its requirements pretty much cemented their success over the next 25 years or so.

It's this success which resulted in their name becoming used pretty much universally to refer to any invalid carriage, just in the same way that Hoover is commonly used (in the UK at least) to refer to any vacuum cleaner, or Kleenex to refer to any brand of tissues.  While there were a plethora of companies involved, the common person on the street would refer to them all as "Invacars."

While the original vehicles were very basic by today's standards they really shouldn't be overlooked.  Part of the key to their success was the use of a bespoke frame but generally using tried and tested parts where possible, including the Villiers 9E through to 11E motorcycle engines.  They were never intended to be fast (the "special" alterations to Derry's example aside - he was well known for being something of a speed demon despite his physical limitations!), but were designed to provide adequate performance and good fuel economy.  40mph doesn't sound like much today but in the 40s/early 50s it was more than enough for most journeys the average user was likely to need to make.

The biggest change to come to the Villiers engined machines came in the 50s when enclosed cabins were brought in, providing users with far more useful weather protection.  Under the skin though they were still based around the same Villiers power unit, which was being asked to haul around an increasingly large body even though the chassis had been kept as light as was really practical.  Performance and handling were starting to look distinctly old fashioned as the 1960s got underway.  While they were a massive step forward compared to most things which had come before, it's still worth remembering that if you were riding a motorcycle with the same drive train that you would have had both of your hands AND both feet kept busy - and these vehicles were generally controlled with a single handed tiller plus separate gear shift.  They were quite a handful to drive (and I still very much hope to have a shot of one one day to see for myself).

The government didn't solely source vehicles from Invacar, other makers were involved too most notably being AC Cars.  While they're best known for their sports cars like the Ace and Cobra, AC had quite a bit of experience with producing small cars throughout the microcar boom of the 50s and 60s and had found the experience in that field transferred over well.  Though it's actually worth noting that the groundwork for what became the AC Petite was the AC All-Weather Invalid Tricycle...so their microcar credentials actually owe a lot to the invalid carriage market!

The increasingly archaic feeling design of invalid carriages across the board definitely wasn't something which had escaped the notice of the government.  In the mid 1960s (if anyone knows the exact date please feel free to let me know) they set out a number of design specifications for a replacement for the older vehicles, intended to bring the invalid carriage firmly into the present day and to make the cars far more useful.  This is really where AC came in.  The majority of the companies who provided invalid carriages were either (like Invacar Ltd) companies specialising solely in that field.  They saw that AC had a very useful mix of knowledge; having experience with the production of microcars, invalid carriages, and that while at a glance it may seem rather incompatible, the experience with their sports car production held a lot of principles which could prove useful, especially as the intention was for this to be much more car-like in many ways than the predecessors.  As such they were the company the government Invalid Vehicle Service approached with their specification, instructing them to design what at the time was essentially the ultimate invalid carriage.

Based around these specifications, what AC came up with was what we now know as the Model 70.

Superficially this looked very similar externally to the outgoing vehicles, as cosmetics really weren't high on the priority list so the existing bodywork was simply tweaked to fit the new car...no point spending money on something which wasn't important. While the cars didn't really look different, they were a completely new vehicle under the skin.

Out went the flimsy single backbone chassis, replaced with a sturdy platform design - helpfully demonstrated nicely by a photo taken of this one just after powder coating during a restoration.

 

A bare AC/Invacar Model 70 Chassis from underneath (front of the car is to frame right)

 

Note: This is a slightly later production example so has extra triangulation pieces visible right at frame left and the front outriggers are slightly beefed up compared to the earlier cars - the core design though never changed.

Out went the old Villiers two stroke engine, replaced with a four stroke two cylinder 500cc (well, 493cc to be precise) power plant sourced from the Austrian company Steyr-Puch, producing 19.3bhp. This allowed them to also ditch the motorbike style manual gearbox, replacing it with a CVT belt drive from Salsbury (now Comet) and a centrifugal clutch. Proper semi-trailing arm suspension on the rear and adjustable gas shock absorbers all round and a significantly wider rear track for stability rounded things off mechanically.

Inside the car provision was made for several different control schemes to account for different needs. "Out of the box" there were 56 possible control combinations available, with the factory being set up to make up bespoke configurations as required.

The standard layout used a set of motorcycle-like handlebars for steering (replacing the tiller used in earlier cars - though could still be specified if required for single-handed use), a twist-grip throttle, with braking provided by pressing the whole handlebar yoke downwards.

The "off-the-shelf" control options we know existed included:

[] Two-handed handlebars including brake and throttle.

[] Single handed tiller as above. Either left or right handed.

[] Steering wheel with hand controls for throttle and/or brake.

[] Absolutely normal steering wheel and foot controls.

These were clearly demonstrated in this period advertisement for the vehicles.

If anyone has a better quality scan of these I'd love to see it.  While these images are easy to find through web searches, they all seem to be copies of the same original poor quality image.  A decent scan would be really nice to see!

 

Incavar Model 70 Informational Brochure/Flier Page 1

 

Invacar Model 70 Informational Brochure/Flier Page 2


This meant that the cars were vastly easier to drive - the CVT meant that you had true "twist and go" ability, just like a modern moped. The Steyr-Puch engine providing performance that allowed the cars to keep up with the flow of normal traffic perfectly acceptably; cruising at 50-60mph being entirely doable-with a top speed reputedly of 82mph if you were brave enough and had a good enough set of earplugs. While it was still somewhat limited simply by the three wheeler setup and being a lightweight vehicle, the handling characteristics were far less wayward than the earlier cars and probably even more importantly, were far more predictable. By far the biggest handling vice I've found is a lack of straight line stability in the face of side winds, and there's really nothing to be done about that, it's just a fundamental limitation of such a lightweight vehicle.

One of the biggest things that's notable throughout is that thanks to a combination of a pretty thorough government specification (I'd love to see a copy of the actual documentation if it still exists anywhere) and AC taking a definite pride in their design is that the whole car is very much "designed up to a standard rather than down to a price."  For such a small car it is extremely robustly built, and equally was designed so that most day to day maintenance tasks are simple and quick for a workshop to attend to.  The rather flaky reliability record of the Villiers machines (not that they were inherently unreliable - but people's expectations from a vehicle were evolving and people were tending to travel further, so late 40s/early 50s reliability wouldn't be seen favourably in the late 60s) was something that was firmly addressed, the Model 70 generally being far more dependable.


Unfortunately as nothing was done to address or update the appearance of the car, they still carried a strong social stigma, clearly signalling to anyone that the user was someone who had a physical disability. This is something that the cars struggled with pretty much from the start right through until the closure of the scheme.

Appearance just wasn't something that the DHSS were interested in as part of the spec though, the bodywork was there purely to keep the weather out and the user in - and that's all down to how they treated the vehicles. They never even thought of them as cars, instead treating them much more like a prosthetic or glorified wheelchair. Which does admittedly make some degree of sense in a purely conceptual sense. It is after all a tool that the user used to move around. However it did mean that the social aspect to the cars never really came into the picture.

The first AC built Model 70s entered service in June 1971, initially just being built by AC, but with Invacar Ltd joining the lineup in November of the same year. The cars made by the two companies were both made to the same specification so were all but identical, just a couple of really minor detail differences being present due to differences in how the factories were set up.

The scheme generally ceased accepting new users in 1978 when the current Motability service was launched. This provides a leased standard car and provides for the necessary modifications to the vehicle for the user. The exception to this rule was for military personnel who had injuries which prevented the adaptation of a normal car being viable, as such it was possible for an Invacar to be provided through the War Service Pension Scheme through until 1983.

By 2003 these cars were really quite hopelessly outdated and a huge number of people would argue totally unfit for purpose. Especially from a safety stand point as the Invacar was designed basically before any real safety provision beyond a seatbelt was required. Though equally you could argue the same for a plethora of small cars from the same sort of era, I don't think I'd fancy being in a crash in an Isetta or a Peel any more than a Model 70. Contrary to a lot of beliefs, the Model 70 was in fact crash tested (with the results seen by those involved as quite favourable) - but the expectations in the early 70s obviously were rather different to those in 2022!

Publicly it was under the umbrella of road safety concerns though that the Government finally drew a line under the scheme, closing it with immediate effect at the end of the 2002-3 financial year*. At that point all remaining Invacars were recalled and were to be destroyed - along with truly vast stocks of spare parts.  Used vehicles weren't retained either - when an Invacar came off service it was always supposed to be destroyed - which is one of the reasons that so very few of the earlier Villiers based or electric cars survive - simply nobody really thought to preserve any at the time.

* There were a handful of stragglers that kept running for a little longer in special cases, but very few and for only a limited time.

There were a few reasons they did this, safety definitely was one, and not unjustifiably - especially when you keep in mind that the users of the cars were already disabled so likely more frail or likely to have difficulty getting clear of the vehicle in the event of an accident. Realistically though cost was a huge driver. The way the scheme was run meant that it was always necessary to keep a complete set of spares on hand for all types of vehicle that were out on lease to users and indeed spare vehicles in the case of a total loss accident. Plus there were then the staff needed to administer the scheme, mechanics and personnel to undertake the recovery work necessary if there was ever a breakdown. By 2003 there were allegedly a couple of hundred vehicles still in service on the scheme - a number which made the costs to keep it operating seem truly ridiculous.

It seems that there was pretty much a 50/50 split (this is based entirely on anecdotal evidence I fully admit) between the users at the end, between those who still had an Invacar because it simply wasn't possible for a conventional car to be adapted to suit their needs, and historic users who honestly just didn't want to "upgrade" to a standard car, because they liked their quirky little blue three wheeler. Irrespective of this though, as the vehicles were the property of the government the wishes of the users were pretty irrelevant. They were simply told that their vehicles were to be recalled rather than being asked.

That should have been the end of it. A handful of the cars were shipped off to museums around the country which had expressed interest in the social history side of their story, but the vast, vast majority were passed on to scrap dealers who were given a contract for disposal of the vehicles.

It should be noted that there were a tiny handful of these cars sold privately by AC and Invacar to end users which obviously weren't subject to the recall. We're talking tiny numbers though, probably less than 50 cars over the 1971-78 production run - I'm only personally aware of three that were still in circulation in 2003.

By all rights, this is where my car's story should have ended.

In the end more by luck than judgement a handful of the cars did escape the crusher. This was mainly because the relatively small amount of metal and large amounts of fibreglass in the construction meaning that (remembering how low scrap metal prices were back in 2003) the cost to properly dispose of the car actually exceeded the value of the contract given to the scrap merchants to dispose of the vehicles. Given their small size, this lead to a few here and there simply being forgotten about in the corners of sites. Especially as the government never really chased up the process once the vehicles had been handed over - even though the contracts did apparently state that the VIN plates of the destroyed vehicles should have been returned as proof that the vehicles had been destroyed.

Time continued to march onwards, the weeds and the other detritus which fills industrial yards built up around the little blue cars stuffed in the back of the site, and the cars were by and large forgotten about - both by the companies who were meant to have destroyed them and by the general public who by and large would never even have noted their passing.

Fourteen years passed with my car and around a dozen others forgotten about in a muddy field in rural Sussex. Had it not been for the land owner making a decision to clear the site as a whole, they may well still have been there today. It did look briefly like despite having dodged it on the first round and hiding for fourteen years* that TPA and the other cars in the field would finally end up in the crusher. That however never happened.

By this point in time public awareness of the Invacar was probably at about the lowest that it had ever been, and dropping further year on year. That was all about to change.

* TPA had actually been hiding for a little longer.  She was last taxed in Ministry service in September 2001 - so following the normal rules of the scheme, should have been sent for disposal back then, even before the mass cull started in 2003.
 



It was a grey, cold, drizzly day in February 2017 when Ian Seabrook (of Hub Nut fame) stood looking at the pair of cars he had agreed to buy, wondering quite what he had got himself into. As someone who had an affinity for cars which tend to fall into the oddball and unloved category he had jumped at the opportunity to pick up one of them hopefully for restoration when he heard about the plight of the vehicles in that field. After inspecting the cars on offer, he chose the best two of the bunch. TWC725K, hereby referred to as TWC - pronounced "Took" as W in Welsh is pronounced as "oo" in English, and TPA621M - my car. The intention was to restore TWC to a roadworthy state, one worthy of note as she was the oldest known surviving Invacar built Model 70, with TPA being used as a source of spares. While both cars were fundamentally complete mechanically, TWC had by far the best bodywork of the two. They had both been sitting in the field since around 2001 though so the mechanical and structural condition of the cars was a complete mystery at the time. A proper inspection was pretty much impossible given that the cars were on boggy ground, and didn't roll - TPA was missing at least one wheel.  TPA is the car to the right of the frame in the image below.

 

Invacars TWC725K and TPA621M in 2017 prior to rescue

 

Image provided by Ian Seabrook and used with permission.

It turns out that the chassis on these cars was VERY well rust proofed, and neither of these two cars has seen any real issues with structural corrosion, despite sitting in a field for the best part of a couple of decades, quite likely without even having wheels on for a good chunk of that. Most 70s British cars would have been a vaguely car-shaped pile of rust by that point.

Over the course of a few months, Ian worked on getting TWC back into a running and driving state, culminating in her journeying to the Festival of the Unexceptional under her own power all the way from Wales in 2018. The story of this mission and videos covering it can be found here: HubNut Blog: Project Invacar and on the HubNut YouTube Channel.

It's worth making a brief pause here to talk about legality as it's important and an area where there's a huge amount of misinformation floating around on the internet.

One of the biggest misconceptions and of repeated "facts" is that these cars were banned from the road back in 2003. This simply IS NOT true. The Ministry issued cars were all recalled and were registered as having been scrapped (which rendered them impossible to tax - therefore illegal to drive), but there was never anything signed into law which specifically banned them from the road. The administrative process of scrapping a car back in 2003 simply included ticking a single box on the V5C document and sending it into the DVLA, at which point a marker was added on the computer file for that car showing that it was for all intents and purposes, dead.  Obviously this didn't affect the tiny handful of privately owned examples which were able to continue being used as normal.

Thanks to a lot of hard work by the Invalid Carriage Register, the DVLA agreed a number of years ago that it would allow for the scrapped marker to be removed from any surviving cars provided evidence could be shown that the car did indeed exist and wasn't wearing a fabricated identity. This means that it's entirely possible to obtain a V5 document for the cars and for them to be properly taxed for use on the road resulting in them being treated as any other lightweight three wheeler from the period. There is no need to change anything else on the V5, though quite a few of them are missing details like the engine number, so it can't hurt to fill in any blanks while the opportunity is there. Likewise quite a few show 9999cc as the engine size (what the computer system defaulted to if no data was entered in that field) rather than the correct 493. There is NO need for any changes to things like "body type" or the likes.

The one peculiarity which seems to afflict all of the AC built cars is that the manufacturer is listed as "AC (ELECTRIC)" which we believe is due to a glitch from when the DVLA records were computerised back in the 1980s.  Likewise they never had the "Model" field populated.

The biggest challenge to be honest in getting one of these cars road legal is likely to be finding someone to provide insurance as they're such a rare car. Thankfully Hagerty weren't at all phased by such an oddball car and were able to provide me with cover no problem at all.

The question of ownership itself is worth mentioning while we're talking about legality. These cars were originally owned by the government - and indeed on the VIN plate it does clearly state "GOVERNMENT PROPERTY" in bold letters. So do we need to worry about someone coming along one day and claiming that they still have a claim to the cars? My take is that this is a clear no. As far as I'm concerned the government's claim to the cars ended when they handed them over to the scrap merchants for disposal. Any argument over whether the cars were properly handled from then on and whether the vehicles should ever have ended up in the hands of a third party I think is an argument for them and whoever was managing the contract for the disposal of the cars. However there was a clear transfer of ownership to the scrap merchant. It's also worth noting that the government department, the Invalid Vehicle Service ceased to exist entirely in 2004, and shortly afterwards all of the associated records were disposed of - so there literally is nobody TO come after them.



At several points during the restoration of TWC, Ian looks somewhat guiltily at TPA and notes that it's a shame that it's very unlikely that she would ever see the road again, only being fit as a spares source. Especially towards the end of the major work on TWC, by which point she had had the engine and gearbox removed due to problems with the original unit in TWC.  She was really looking rather sad by the end.

 

TPA621M awaiting rescue after helping revive TWC725K (in background)

 

TPA621M awaiting rescue after helping revive TWC725K

 

Both of the above images supplied by Ian Seabrook and used with permission.



This is where my part in the story really starts. Being intrigued by these little cars on seeing the story of TWC's revival I had picked up my own project car, KPL139P. While fundamentally mechanically sound that car had suffered major damage to the bodywork during a period where it apparently served as a tug on a static caravan park. I'm still curious to know how the car came to be there! During this period the entire front body section forward of the bulkhead, rear valance and both rear wheel tubs were completely removed. Large chunks of the wiring loom were also missing and there were a few areas where the chassis needed some structural repairs.  She was in quite a state.

 

AC Model 70 KPL139P Before restoration from the rear

 

The sheer amount of bodywork I was simply missing was far more obvious from the front!

 

AC Model 70 KPL139P before restoration from the front


When Ian was finished with TPA she was missing the whole drive train, but otherwise - most importantly body-wise was at least for the most part complete...As such it was a golden opportunity for me to make one good car out of the two as far as I was concerned.  Despite KPL being devoid of her drivetrain and looking like this when she was trailered away from my house, she has since been restored would you believe!  In fact you remember that lovely brand new looking Model 70 chassis I showed a photo of further up this page?  That's from KPL in mid restoration!

 

AC Model 70 KPL139P off to a new home, and against all odds, to be restored


So I made the trip over into Wales to collect TPA, brought her home (it's really quite handy having a car which you can fit in the back of a normal sized van!).

 

Yes, an Invacar will fit quite comfortably in the back of a normal long wheelbase Transit van

 

Though admittedly, the loading process would have been rather easier if I had remembered to take any ramps with me.  Never said I was the smartest.  Yes, this was exactly as precarious as it looks.

 

Loading a car, even a tiny one like this without ramps is an exercise in frustration, fear and pulled muscles.

 

Despite the loading process being slightly more exciting than planned, she was soon safely on my driveway.  Well...garden.  The driveway was already fully subscribed, and KPL wasn't actually picked up until a few weeks after TPA arrived so the garage was still full.

 

Has there ever been a more unloved pair of vehicles parked together in motoring history?

 

It was then a relatively simple matter for me to set about transplanting the running gear from KPL into TPA. It didn't take long before I had a car which would run and move under it's own power.


The recommissioning process to be honest was pretty simple. I was really quite lucky The single biggest hurdle was sourcing a replacement fuel tank as the original had rusted out due to a design flaw - there's a lip around the top of the tank which traps water there.  Meaning that most of them look like this by now.

 

AC/Invacar Model 70 fuel tanks regularly rust out because that lip traps water on the top

 

After 1976 the tank construction was changed so that the lip was at the sides rather than top/bottom which made later tanks at least somewhat less prone to this.  While there's only one hole visible in that photo, there's a hole in the back side of it that you could fit your hand through and the whole thing was paper thin.  It was completely useless other than to act as a template.

After hunting around for a while I eventually had an aluminium one made up using the old tank as a template by Fusion Fabs.  New and old side by side when I picked the new tank up.  I think the one on the left looks like it will work rather better!

 

New AC Model 70 fuel tank made by Fusion Fabs

 

Other than that it was mainly just a matter of freeing up rusted linkages, replacing brake lines, wheel cylinders (they're shared with the Reliant Kitten so readily available) and fitting a nice fresh set of tyres.

 

New tyres fitted to the wheels ready for fitment to TPA

 

I've made a concession to making my life easy here.  Being a 1973 car, TPA would originally have been running on 12" wheels, that change having taken place during 1974-5.  However there really isn't a huge choice of tyres in the correct sizes these days, especially at a reasonable cost.  However as 10" wheels and 145SR10 tyres is a size shared with the classic Mini (and indeed that's where the wheels are shared with) there are a fairly decent selection of tyres available in this size.  I chose these because they were readily available from several outlets at a decent price, and I don't imagine that a 400kg 20bhp three wheeler is exactly going to be pushing the limits of the tyres.  I was very pleased with how in period the tread pattern looks though, you really could believe they were original to the car.  Additionally the 10" wheels use far higher profile tyres, so provide a bit better isolation from imperfections in the road surface (the actual rolling radius between the 10" and 12" tyres isn't huge), which given the state of the roads around here and my back not being in the best of shape I was likely to appreciate.

Bodywork wise there was a bit more to be done.

While in a lot better shape than KPL TPA was in need of quite a bit of bodywork attention.

The entire rear valance/bumper moulding was missing below the slam panel for the engine cover.  The engine cover was also split in two - though I took the easy way out there, using the intact one from KPL. 

 

Damage to rear bodywork below the engine cover slam panel

 

Similarly there were large chunks missing out of both front corners, the car obviously having hit something at the front.  It's impossible to say if this happened in service or after retirement.

 

Impact damage to nearside front of bodywork

 

The nearside was probably the worst as the crack runs all the way up past the indicator.

At least on the offside the damage was mostly contained to the bit that was outright not there any more.

 

Impact damage to front offside of bodywork

 

The leading edge of the roof had obviously also taken an impact at some point, doing a good job of "peeling" off the drip rail over the door.  Sorting this was high on my list as I had visions of me taking my eye out while walking past the car.

 

Impact damage to roof and drip rail

 

The drip rail was simply transferred over from KPL, though the fibreglass work was going to need more thought.  Especially as I was going into this with zero prior experience of working with fibreglass.

The ideal solution here would have been to pull moulds off the bodywork of a good car - however this wasn't something I had access to at the time so I was going to have to come up with another solution.  What I ended up doing at the back was making up the rough shape of the valance in cardboard, then using that to support the fibreglass as I built it up, peeling the card out once it had set.  I really didn't want to leave anything like that behind given how close it sits to the exhaust.  Self adhesive aluminium tape has also been added to the back of the panel to help reflect the heat away from the panel as much as possible.  The result was far from perfect, but did the job and didn't look too bad from ten paces, which was about the best I was hoping for really.

 

Rebuilt rear valance

 

The front corners required a little more thought.  Being a more three dimensional shape I really struggled to get a usable profile out of cardboard.  So I got a bit more inventive.  I made a cardboard baffle to sit behind the panel, then entombed the area I wanted to recreate in expanding foam.  I was able to then whittle this back to recreate the profile I was after, shown here in progress.

 

Working on creating a buck to rebuild the corner over

 

The end result was never going to win any awards, but was a bit step forward compared to a huge hole.

 

TPA621M showing the reconstructed nearside front corner

 

The surface finish was also diabolical.  I've found the paint on this car to be incredibly difficult to sand away, it's got a really odd almost rubbery consistency and seems to clog any abrasives almost immediately.  Given my expectation has always been to get a professional to address some of the cosmetics down the line though, getting it so it's all actually there, free of sharp edges and vaguely one colour was my basic target, which I think I achieved.

The doors were in a poor way too.  The offside one had clearly taken quite a thump at some point which had badly split the outer skin, and the bolt holes for the handle had pulled through.  The locking mechanism was completely seized up on this side too.

 

Damage to the offside door skin and handle area

 

Superficially the nearside door looked to be in better shape, though this wasn't actually true.  This one had issues with the inner and outer parts of the moulding splitting apart meaning the whole thing had near zero structural integrity - and was also missing the door handle.

 

While the nearside door looked better, it also had plenty of issues

 

My solution here was to make one complete set of doors out of two knackered ones.  The fibreglass sections of the doors from KPL were generally serviceable.

 

Frankendoor creation in progress

 

However the metal window frame had rusted through - so I had to take that bit off of TPA's original doors - which involved drilling out some of the hardest screws I think I have ever encountered.  It really shouldn't have, but separating the two window frames from the doors took me the best part of a whole afternoon.

 

I have no idea what the screws holding this together were made out of - it was like trying to drill through adamantium...

 

However after a certain amount of swearing (and being very careful not to drop the window glass!) I successfully had created a pair of doors which actually worked.

 

One pair of reassembled doors

 

The nearside one has obviously had the same issue with the door handle pulling through the fibreglass so a metal plate has been riveted in place behind it.  This seems a perfectly solid solution though so I see no reason to disturb that at this time.

The door seals were all hanging off (or missing).  These were simply glued in place at the factory, so I did the same.

 

Sticking the door seals back in place

 

Or rather I tried to.  After trying several different adhesives, none of which took to the bodywork properly I wound up drilling some holes and pinning it in place at several points with screws.  I do have a full new set of door seals to be fitted at some point, at which point I will try some Sikaflex PU adhesive (basically the stuff car windscreens are bonded in with), as if that won't do it nothing will.



I was exceptionally lucky in mechanical terms I think. The engine from KPL has always been a sweet little power unit, and aside from needing to replace the CVT pulleys due to tarnishing from years open to the weather I've not had to do much beyond a good service, cleaning up the carb and flushing some sludge out of the crankcase.  I was very glad that I had chosen to clean the oil pickup strainer shortly after I had run the engine for a few miles on the road though as it had collected quite a bit of sludge.

 

Sludge collecting on the oil pickup strainer

 

I have dropped this every other oil change since and am glad to report that since this first time there has been precisely zero slime found, so I reckon it was largely just down to oil degradation and moisture ingress from the long period of disuse.

I did have some intermittent issues with the fuel pump.  Initially I had issues with it weeping from the cover.  Well initially initially when I first got the engine running back on KPL the pushrod was also seized up, but a bit of exercise sorted that.  However even with the gasket under the cover replaced I still had problems with it drawing air in (visible as bubbles passing through the fuel filter).  I wasted quite a bit of time chasing this and never really came to a firm diagnosis of the cause of the problem with this pump.

 

A slightly troublesome fuel pump

 

Full rebuild kits for this pump aren't massively expensive, but at the time I couldn't find anywhere which seemed to have them in stock and would ship to the UK for sane amounts.  An alternative solution then presented itself when a friend offered me an electric pump to try out to see if that solved my issues - and would help point an accusing finger at the mechanical pump if so.

Suffice to say it did.  I quite quickly made the decision to stick with the electric pump, the reasons being twofold.  Firstly is that it allows me more flexibility with regards to routing the fuel lines.  The mechanical pump sits pretty much directly above the nearside exhaust downpipe, which I really don't like.  Using the electric pump means that I can route the fuel line into the engine bay keeping it a decent distance away from the hottest components like the exhaust.  It also should be a little more resilient (especially with the rerouted lines) to issues with vapour lock that modern fuels are more prone to.  The ducted intake for the engine fan means that when the engine is running that the engine bay temperatures in this car are kept very low, but I imagine they spike massively shortly after the engine stops.

I have used A1 Marine grade (ISO7840) fuel lines throughout the car. I've had no end of problems with lines bought from motor factors over the last couple of years disintegrating after only a couple of months on the car, so have decided this is a worthwhile switch. A1 lines are resistant to just about anything short of direct nuclear assault so get away from the worries over virtually all pump fuels in the UK now containing a minimum of 5% ethanol dissolving my fuel system. Currently (June 2022) in my region Esso Supreme+ super unleaded is still ethanol free - but there's absolutely no guarantee as to how long that will remain the case. Plus I can't always say for certain that I'll be able to be that picky about where I fuel up, especially as the car has a pretty small 4 gallon tank.  Yes it's a little more expensive than normal automotive hose, but if bought from a reputable source should be a truly fit and forget solution.

 

Note the ISO markings

 

Note the 10 bar working pressure...The couple of PSI our fuel pump delivers shouldn't be a challenge!

The first few trips out were very tentative, and I definitely found the first few miles driven in the car to present me with quite a large degree of sensory overload. It's not actually difficult to drive at all, but it's very different to a normal car, and the noise levels make it seem like there's an awful lot going on!

While TPA had lasted very well structurally, the original seat frame itself had rusted away quite badly where the backrest meets the base, and as such was basically scrap - or at the very least would need to be completely dismantled and rebuilt.

 

The original seat had rusted away badly

 

I think I handed this over with KPL in case it could be rebuilt or serve as a useful template.

As it happened, I had a driver's seat from a Series 2 Citroen Xantia sitting around in my garage.  I had always planned to make this into an office chair but had never gotten around to it.  In the off chance it could be made to fit I shoved it in the car...and discovered that the seat base literally slotted perfectly over the old support frame.  This meant that making adaptors to attach it was trivially simple.  This meant that the seat itself still retained all of the standard adjustment options to allow fine tuning of the driving position.

 

Could have been made to measure - Citroen Xantia seat fits perfectly

 

It's quite helpful that the seatbelt (unlike in most modern cars) is anchored to the chassis and body support frame rather than to the seat itself.  So it doesn't need to be massively strongly mounted as it would be in a modern car - it just needs to support your weight, not full crash loadings.

While fitting was very simple, getting the last couple of bolts in was quite fiddly - during which my husband captured a wonderfully flattering picture of me while I was working on it.  Thanks for that.

 

Not the most flattering picture of me really!

 

In all seriousness though, I think this image is actually quite useful as it does a decent job of showing how much floor space there actually is in the cabin, which is kind of tricky to convey in photographs sometimes.  For a single occupant it really is quite roomy.

The initial shakedown period went astonishingly smoothly all things considered.  We had a couple of issues with crud working itself loose within the carb itself and clogging the idle jet until I did what I should have done in the first place and just strip it down entirely and dump it in the ultrasonic cleaner, it took me a few attempts to get the free play set up properly in the brakes (just inexperience on my part there), and I established that there was something amiss with the brake master cylinder so that was replaced.  The only recurring issue I ran into was the pin holding the gear selector lever to the selector rod itself dropping out a couple of times.  I eventually managed to find a roll pin which could accept a cotter pin to retain it properly and this put an end to me reaching down to find the gear selector sitting on the floor no longer attached to the gearbox.

 

That gear selector should be standing perpendicular to the floor, not parallel.

 

While I kept it local for the first couple of months, I did try to use the car regularly.

Of course we made sure to commemorate the first visit to a petrol station, as far as we know since 2001.

 

TPA's first fuel station visit since 2001

 

Ever wanted to make a Mazda 2 look truly huge?

 

One of the first photos of TPA out and about actually having gone somewhere rather than just driving around in circles

 

One quite special thing which did happen while I was just starting the initial shakedown part of things was a visit from TWC.

 

TWC pays TPA a visit

 

As TPA was now (just about) roadworthy we were able to convoy to a nearby quiet car park to grab a few photos of the cars together.

 

TPA and TWC out and about together

 

TPA and TWC out and about together

 

The two of them out together though also allowed a very rare photo to be snapped from a following vehicle too - In mid 2019 seeing one Invacar on the road was a definite rarity - never mind two of them!

 

Invacars in convoy - image courtesy of Andy Freeman

 

This image courtesy of Andy Freeman - I'm struggling to find a link to a Flickr gallery or similar - if anyone has something useful I can put here please let me know!

While things went relatively smoothly in terms of mechanical recommissioning it was quite obvious though that the CVT side of things really wasn't happy.  This really wasn't a huge surprise given how long the system had been left completely open to the elements in KPL.  The pulley surfaces need to be very smooth for things to work properly, and I was pretty convinced that the secondary pulley wasn't moving smoothly either.  The sandpaper-like texture of the secondary pulley because of the surface rust was shredding the belt too in addition to causing a truly unnerving amount of vibration above 40mph.  These were really in need of replacement.

 

These pulleys were really past it due to their weather damage

 

With the secondary removed the extent of the rust pitting on the running surface is really obvious.

 

That's really had it

 

That running surface should have a satin smooth texture...not like 80-grit sandpaper which that felt like!

Additionally the fan attached to the back of it had partially disintegrated, most likely throwing everything out of balance, being another source of the very ominous feeling vibration I had above around 40mph.

 

The fan built into the back of the pulley had also failed

 

I did have a shot at cleaning this up, but realistically there was only one thing for it.

 

Nice new CVT pulleys

 

A new-old-stock set of CVT pulleys would do it!  The primary has a little aluminium oxide visible in the photos, but that cleaned straight off.  The secondary looks like a different setup, but it's just a different style and is fully interchangeable.  Doesn't that look better?

 

Nice new CVT pulleys installed

 

This completely changed what she was like to drive!  Aside from getting rid of the horrendous vibration at speed, it freed up a lot of power and make the car feel much more willing. 

It wasn't until a year or so in that I suffered the first real mechanical failure. That was when the CVT belt snapped (which highlighted why there's a sturdy cage around the pulleys!). This was down to the belt I was using having been subject to years or poor storage conditions I think, as a replacement NOS example which had been stored properly restored normality, and indeed far smoother running than I had seen up until that point.  In hindsight, I really should have just fitted a new rather than unused but clearly poorly stored one when I installed those new pulleys - which would have saved me having to deal with the embarrassment of needing to be recovered home!

 

Always embarrassing as a classic car driver having to get recovered!

 

Also in hindsight, if I'd known how long it would have taken the recovery truck to get to me I would have just got a lift back to the house, picked up a spare belt and changed it at the side of the road.  It takes about fifteen minutes to do and really isn't difficult at all.  The belt which had failed definitely hadn't left any doubt in the fact that it had had it though.

 

No...No doubt that's had it!



Knowing that while we do have several new old stock belts on hand we know that the supply of the original Dayco 43-5639 belts is finite as they're no longer made, efforts were made to source a modern replacement. Some head scratching and searching through pages and pages of datasheets eventually unearthed the Dayco HP2020 - a current production belt used on a number of off road buggies, quads etc especially over in the USA, being OEM fitment on several Kawasaki vehicles. This belt was pretty much an exact match to the NOS ones we had so I ordered one up for testing. It turned out that buying one through Rock Auto and having it shipped over from the USA was far cheaper than buying one locally. That belt was fitted nearly 2000 miles ago at time of writing and so far it had performed flawlessly. I think it is very slightly heavier than the original belt, so it tends to drop the CVT into "fixed ratio overdrive" mode a fraction earlier, at 42 rather than 45mph as per the manual, but that's the only difference I've been able to detect.

This looks rather less aged than the one which can be seen to have failed above.

 

The Dayco HP2020 CVT belt is a suitable replacement



The first appearance of TPA at a reasonably sized event, and indeed the first time she ventured more than a mile or two from home was at the annual Stony Stratford Classic Car show in June 2019.

 

AC Model 70 TPA621M at the Stoney Stratford Summer Classic Car Show 2019

 

Barely a month later she travelled to the Festival of the Unexceptional 2019, a 26 mile drive - which having had the entire drive system apart the day before to replace the CVT pulleys felt like a very long run indeed! That was the point at which I realised that I really needed to make a sign with the most important details on it, as virtually everyone who passed by had to ask me what the car was.  It was the first real indication I had though of precisely how interesting a lot of people find this little car.

 

AC Model 70 TPA621M at Festival of the Unexceptional 2019

 

AC Model 70 TPA621M at Festival of the Unexceptional 2019

 

AC Model 70 TPA621M at Festival of the Unexceptional 2019


Since then we have covered well over 3000 miles together, with only one real period off the road following this happening in September 2019.

 

A broken wheel stud - no big problem, right?



A broken wheel stud. Not something which would generally be a big problem, however it turned out quite a significant headache in this case as the studs used were a bespoke part made for the Invacar.

Originally I had just assumed that they were press-fit studs the same as used on the Mini (which is whose parts bin the wheels and wheel nuts come from). Nope, these are screw in studs - however the section that screws into the hub is a 3/8" BSF thread, with the wheel end being 3/8" UNF - Not something you're going to find on the shelf anywhere. It also turned out be something that I couldn't find any machinist willing to make a few up for me. I'm assuming because of the safety critical nature of it and worries over liability if it were to snap while in service. This was particularly annoying as I really needed more than the one, as all of the studs on that wheel showed evidence of prior damage from being over-tightened. Since then we've come across this issue on several cars, having come to the conclusion that the original studs really are not very strong at all. My solution in the interim was to utilise bolts threading into the hub directly and appropriate conical washers to properly centre the wheel, though I was never really 100% happy with that solution.

"Why don't you just change the hub?" I hear you ask. Well...The hubs were also modified by the factory! The rear semi trailing arms and hubs are Fiat parts, a holdover from the original prototype Model 70 using a Fiat 500 power plant. The Fiat uses a different bolt pattern though, and wheel bolts rather than nuts. So the factory re-drilled the hub to the 4x4" pattern shared with the Mini, and fitted these oddball wheel studs. So replacing the whole hub means finding an appropriate Fiat item, and then getting a machinist to modify it to accept the appropriate studs - which my intention would have been to utilise standard Mini ones to save on future headaches. When I asked around for places to do this, the response I got was complete disinterest. Cue bashing of head against the nearest wall. If I'd known that would be an issue I wouldn't have bothered spending a couple of hundred quid on a new old stock Fiat hub! It turns out that later on in the production run it looks like Invacar/AC were able to source hubs made up to their spec, not sure whether this was directly from Fiat's OEM or another source. These also feature two half-moon shaped cut outs to make access to work on the brakes WAY less of a pain. However finding one of these isn't exactly easy in 2022 given they were last made probably in the 80s - and given that all the factory spares were supposed to have been scrapped back in 2003.

Helpfully a friend has recently offered to make me up a few replacement studs (which takes several hours EACH on manual equipment), AND a later style hub (albeit with one broken stud) looks to have turned up - so I might finally be able to get a line properly drawn under this issue at long last, after well over two years. While they're not planning to offer these on a wider basis due to the time involved in production and possible liability concerns, once we've confirmed that they fit properly, we WILL make sure that all the exact specifications are made available. It's not exactly difficult to make these if you've got a lathe and know how to use it, it's just really time consuming more than anything else due to the number of operations involved.


With this car being a fairly scruffy example throughout I didn't feel too guilty making a couple of concessions to comfort beyond the original specification. Fact of the matter being that this was a car that while not using exactly as a daily driver, I did fully intend to use beyond just bumbling along to the odd show.

I'm also treating this as something of an experiment, trying to decide what additions AC may have found it prudent to add if they had really wanted to market this car as a small car for personal transport rather than simply meeting a government contract specification.

In my opinion the single biggest shortcoming from a comfort perspective from the driver's seat in the Model 70 comes in the form of a complete and total lack of sound insulation or damping. It is VERY noisy at speed, the vast majority of that coming from the CVT pulleys which are pretty much right behind you. Engine noise itself is actually not too bad, mostly limited to some induction roar at higher engine speeds. Given that there is basically nothing soft in the cabin other than you, this results in almost painfully loud what essentially reverberates into white noise at any real speed.

What I have done is pretty simple, adding some carpet and trim to the cabin. This does a lot to help cut down on reverb, reducing overall noise levels quite markedly.  It also makes the cabin look and feel far less utilitarian. The next step of this will be to put some lining on the inside of the roof as well as I reckon that will make a huge difference to the overall noise levels in the cabin. There's also obviously no real isolation from road or wind noise, and both are very apparent at speed.  There's really not much to be done about either of those though.

Between the Citroen seat and the additional trim this cabin looks rather more inviting than the original setup I think!  Here's a before and after comparison - afraid I don't really have one with the original seat in place as it was swapped out so early on in proceedings.

 

AC Model 70 interior before the retrim

 

AC Model 70 interior after the initial retrim project was completed

 

AC Model 70 after the initial interior retrim project was completed

 

Really is surprising how much difference just changing the texture of a few surfaces can make to the feel of a space.

Some of you may have noticed the additional instrument pod that I've added down over my right knee.

 

Additional instrument pod added to AC Model 70

 

This just seemed to be a couple of instruments that were sensible to add, most notably a temperature gauge and a voltmeter.  The temperature gauge particularly as this wasn't a car which was really designed with long distance high speed cruising in mind so I really wanted to be sure that the temperature wasn't going to slowly creep up over time.  My gut feeling based on the size of the oil cooler was that it wouldn't be a problem - but I'd still rather know than not.  The temperature gauge reading up to 300C may come as something of a shock to those used to water cooled engines, but this is actually not an unreasonable scale for an air cooled engine - this is a direct reading of the cylinder head temperature.  So is always going to read higher than you'd expect looking at a "normal" temperature gauge for coolant or oil.  She usually seems to run right around the 150C range on the open road, the cooling system as I expected keeping up just fine.  The voltmeter is just useful to have in any vehicle which has an old school generator rather than an alternator, and has shown that the regulator in my case I think could do with a little adjustment as the cut in level is too high, meaning that it doesn't start charging until the engine revs are higher than they really should be.  The third slot is filled by a clock simply because that's something which the absence of in a cabin really bugs me!  I was quite pleased that I managed to find a reasonably well matched set of instruments there which didn't look too massively modern.  I know they're obviously newer than the car - but look like something which could have reasonably been added during its service life rather than some piece of plastic tat that someone has paid 1 for on eBay.

The single system in the cabin which could really do with some help is the heating/ventilation.  As is quite common on air cooled vehicles, air for the heating system is bled off from the engine cooling fan with heat provided by a heat exchanger built into the exhaust system.  The heat exchanger in this case actually seems to be pretty effective, the biggest limitation is simply that the amount of airflow is directly related to the engine speed.  So to actually get any really meaningful airflow particularly from the windscreen demister, you need to be driving at 40-50mph or above.  Not great when you're bumbling around town!  This is further frustrated by the fact that the demister blows downwards onto the windscreen (after all, it worked SO well in the Leyland National...).  The second huge limitation of this system is that it's a heater and a demister...that's it.  There is absolutely no provision for any form of forced air cooling.  The only option you have is to open a window.

My plan to attempt to address these issues will be to switch to an electrically powered blower rather than using engine cooling bleed air to feed the heater, I've just yet to find a suitable blower.  The cooling situation will probably be solved in a more old-school way, by adding a ventilation flap similar to that used on older Land Rovers and Citroen 2CVs, but tucked away under the dash on the front bulkhead.  With a vent down there and a window cracked open just a bit you should be able to get some decent airflow through the cabin to take the edge off on a warm day.



So what is it actually like to drive?

I have had to think about answering this one! Beyond "Interesting" anyway.

Having covered well north of 3000 miles in this car I'm very used to how she behaves now, and the whole experience is something I've become very comfortable with and feels natural.

Sitting in the driver's seat the view in front of you isn't particularly intimidating.

 

AC Model 70 dashboard layout

 

The instrument panel is simple enough, from the left we have:

[] Parking brake.
[] Windscreen washer pump.
[] Windscreen wiper switch.
[] Headlight switch.
[] Fuel gauge.
[] Four warning lights directly above the ignition switch.
[] The silver thing in the middle is a cabin light.
[] Speedometer.

The slot in the dash below the cabin light is where the early cars had the gear shift mounted, and the vast majority had had the gearshift moved to the floor mounted position by the late 1970s for safety reasons (so the driver wouldn't get impaled by it in an accident) unless it was specifically needed to be in that area for the user's needs.

[] The switch on the far right has been added by me, this will be for the heater blower when I fit it.

[] Attached to the left handlebar is a conventional indicator stalk, also incorporating a dim/dip control for the headlights and horn push.

[] The right hand side of the handlebars has a twist-grip style throttle fitted as you would find on most motorbikes.

[] On the floor to the right of the driver's seat is a gear selector - forward for forward, neutral in the middle, and backwards for reverse.

 

Control panel above the windscreen to the right



[] Above the windscreen on the right are three sliders controlling the windscreen demister, cabin heater and the engine choke control.

[] The three gauges below the dash on the right were added by me, and just seemed useful to have. I did my best to find something that didn't look too painfully modern, these dating from the early 80s I believe.

Funnily enough, the single thing which really took my brain a good few seconds to process the first couple of times I drove this car was the indicator stalk. My brain just expected a vehicle with handlebars to have motorcycle style thumb switch controls - having a normal car style stalk there just caused some serious cognitive dissonance initially. It works absolutely fine, it just felt really odd to me initially.


Actually driving really isn't difficult. It really is as simple as putting the gear selector into forward gear, releasing the handbrake and twisting the throttle and you're off. The throttle is quite responsive, and at town speeds she feels surprisingly nippy. While you're not going to outrun any modern traffic up to 40 mph or so, you're definitely not going to be unduly holding anybody up. Beyond that, you're definitely aware of the fact that you're driving a vehicle with 20 horsepower as acceleration is leisurely, but a fairly comfortable 60mph cruise is entirely doable. She's happiest around 55 though. 70mph on a major road is also achievable, though I generally reserve this for overtakes as the engine speed at that point is definitely getting towards the red line. I'm not totally sure if I fully believe the oft quoted 82mph maximum speed, but it doesn't seem all that outlandish. I can definitely vouch however for the fact that you do get some very confused looks from other road users when you go sailing past them in the overtaking lane on a dual carriageway or motorway. Well, you get very confused looks from other road users all the time - but particularly when you overtake them!

It's a car unusual enough that people do frequently take photographs of it while you're out and about - though obviously most are never shared so I never see them.  This was one that did pop up on Facebook though and I was given permission to share by the photographer.

 

AC Model 70 TPA621M out and about, phtographed here on the northbound A5 just outside Milton Keynes

 

Image courtesy of John Manyweathers on Facebook.

Handling is what I would describe as "acceptable." It's a tiny, relatively light weight three wheeler with very little weight up front. So long as you keep that in mind and treat it accordingly you're unlikely to get into trouble. Contrary to what a lot of people seem to believe, it won't actually tip over if you try to go around a corner north of 20mph. In fact I think if you were to throw it into a corner fast enough you would likely run out of grip and understeer rather than tip. Though the way the car will pitch if you push it faster than it's happy with makes it perfectly clear when you're pushing the limits so there's plenty of warning if you're being a bit too heavy handed.

I think video can probably give an idea of the driving experience pretty well - so here's a random onboard one I shot a while ago.  Few caveats: 1. I apologise for the audio quality, the microphone on that camera is awful.  2. I apologise for the camera shake - I've really not come up with a good way to mount one in that car yet so it always wobbles.

Also of note is that this was shot just after I had changed the CVT belt and there's a break in period of 50 miles where you have to keep below 50mph - so I was artificially limited to 50 when I recorded this.

Video Part 1.

 

Video Part 2.

The single biggest gripe from the handling department is just a lack of inherent straight line stability. There are a few reasons for this - the biggest of which is simply the fact that there is so little weight on the front wheel. This means that the car is particularly prone to getting pushed around by crosswinds, slipstream from other vehicles etc. It's quite unnerving to drive at any speed on a windy day - though you're not really likely to notice it much if you're just driving around town, which is what this car was really designed with in mind. The other major contributor to this is the very fact that it's a three wheeler - meaning the front wheel isn't positioned on the road where it tends to have been worn by other traffic. So you're always tending to have to fight against the camber of the road somewhat - especially if you're on a single track road. The final major factor is simply that the steering is very, very direct. I'd say if you were to directly compare it to a vehicle with a steering wheel you would be looking at probably somewhere around 3/4 of a turn lock to lock. So corrections to the vehicle's course when you're trying to drive straight require absolutely tiny steering inputs from the driver; it's very, very easy to end up overcorrecting and weaving down the road. That definitely took a bit of practice on my part. The other downside of the steering being so direct is that it means that it is really quite heavy, especially at low speeds, though this is just an inherent limitation of the control scheme. The travel of the handlebars is limited by the point at which the dashboard gets in the way, and reducing the gearing to make it lighter would result in an unacceptably large turning circle, so it's all a bit of a balancing act to find the best compromise. Again, this was really intended to be a city car, so a tendency to wander a little at higher speeds would be a reasonable trade off to keep the turning circle reasonably small.

The brakes work perfectly well compared to any car of the period. They're unassisted drums so a decently firm shove of the control is needed, but the response is very linear and there is plenty of braking power there if needed, more than enough to lock all the wheels if you were to absolutely stand on the brakes. In addition, thanks to how the CVT works you have quite a lot of engine braking available which is always helpful.

The braking system on this particular car though has seen one modification made, purely to address what in my mind was a shortcoming simply due to the age of the design, and that's that the braking system only used a single hydraulic circuit. This was very common practice in the early 1970s especially on smaller cars. In normal use this isn't a problem as it doesn't really behave any differently to what we're used to today. The issue however is that any failure of the hydraulic system would result in a complete loss of the braking system. Dual circuit brakes eliminate this by introducing a degree of redundancy - on most four wheeled cars having the front left and rear right wheels on one circuit and the front right and rear left on another - so a failure of any single hydraulic line while resulting in a very, very obvious reduction in efficacy of the brakes, doesn't leave you with no way to stop. A complete failure of the braking system is a terrifying enough prospect in any car, but in a tiny fibreglass box like this, doubly so given the limited crash protection. My solution was to swap the brake master cylinder for one from a Triumph Spitfire, with the front brake fed from one circuit and the rear pair from another. I originally had worries that the difference in functional capacity between the two circuits might cause issues with the brake balance, but testing has proved that not to be an issue. The braking effort provided still seems to be perfectly balanced with no tendency for the front wheel to lock up prematurely. In fact there really doesn't seem to be any appreciable difference in performance of the system, but I sleep somewhat easier knowing that there is something of a safety net there if something were to fail. A further future modification that I intend to add is a brake fluid level warning light, as there isn't one as standard. So it would be quite possible if a small leak were to develop during a trip not to realise it until you ran out of fluid - and therefore brakes. Just seems a warning light it's worth having.

This did require one small modification (in addition to the obvious additional plumbing) as the rest position of the piston in the Triumph cylinder is slightly different - shown in green on the image below.

 

Image highlighting the different rest positions of the master cylinder pistons relative to the mounting holes

 

Obviously the pushrods also needed to be swapped over.

Accounting for the different rest position of the piston was pretty simple, all that was needed was to drill a new hole in the yoke which actuates the pushrod slightly higher up and further forward.

The original attachment point is shown as point A and the revised one as point B in the image below.

 

Image showing modification to brake actuator yoke

 

Being slightly closer to the edge isn't a worry here as the direction that force is applied is from right to left, so there shouldn't be any increased risk of failure.  This is one of those things where some people will have differing views, but mine is that I see whatever tiny risk there may be associated with drilling a new hole in a piece of thick steel as far lower than that of a potential hydraulic failure due to a wheel seal blowing out or a line rubbing through somewhere unseen.  Suffice to say, I'm not losing any sleep over it.  The other alternative would have been messing around seeing if I could find a slightly longer pushrod, though I'm happy with this setup.

Also on the subject of brakes, I've added an additional high intensity brake light.  The original tail lights aren't the best, especially if you're not absolutely spot on with the beam angle of the tiny reflectors.  So I picked up a generic 21W rear fog light as intended for use on trailers and such like...

 

Standard fog light bought to be used as additional brake light

 

...Which I then installed behind the engine air intake grill.

 

Hidden additional brake light installed behind air intake grill

 

It's significantly brighter than the standard brake lights, and being in a location you'd not normally be looking tends to draw the eye as well, so hopefully should be extremely conspicuous if you're following me and I brake, that's the whole idea.  It's essentially invisible when it's not lit though and you'd not spot it if you were not looking for it I think - so I'm going to call that a win.

The ride is quite bouncy, which isn't all that surprising given that you're looking at a car that weighs somewhere around 400kg and is running on 10" wheels. It's never going to ride like a Rolls-Royce. There is a decent amount of suspension travel though, and it's never felt quite as bone jarring to me as the ride in an actual Mini or many modern cars. The fact that anything and EVERYTHING around you rattles and squeaks though does tend to make it seem like the car is about to shake itself to pieces though when you do hit a pot hole.  Plus it's the classic three-wheeler problem if you do see a pot hole that's in your lane where you simply have no option but to chose if you hit it with the front wheel or one of the rear wheels.  Dodging them is harder than in a four wheel car - though this one does cheat a bit there by being so narrow.

On a nicely smooth road though (in this case a recently resurfaced bit of the M1) I was really astonished by how little vibration there is at speed. It's really obvious how good a job Steyr-Puch did at balancing that engine. I had expected there to be more inherent vibration from the CVT as well given the not inconsiderable weight of the belt and the rate at which it is spinning, but there really doesn't seem to be much.

Looking at the car and knowing that it's rear engined you could be forgiven for thinking that there might be a small luggage compartment up front. However there isn't. All that is hidden under that hatch is the fuel tank, brake master cylinder and the front wheel itself.  Later Model 70s did move the battery up front too, but on this one from 1973 it's still in the engine bay.

 

What's under the front service hatch of an AC Model 70

 

There is no separate luggage compartment at all, the only cargo space provided being a small shelf behind the seat.

 

Closer look at the parcel shelf behind the seat in a Model 70

 

Though the absence of any foot controls does mean that you can utilise the floor to carry cargo in ways that you simply can't in a normal car - and in fact I have on several occasions. While it does work, this doesn't make it an ideal car for the weekly family shop!  Especially if you have to stop in a hurry at which point everything will abruptly redistribute itself to the front of the vehicle.

Hasn't stopped me using it to do an (admittedly small) Costco run using this car though!

 

Practical?  Sure, you can fit a Costco run in it!

 

Yes, you can fit a Costco trip in an Invacar - though this was a very small one by our usual standards



Looking at it from a purely objective standpoint in 2022, it's a car with a lot of limitations. It's slow, noisy, unstable and completely lacking in any luxury equipment. However looking at it instead in the context in which it was designed back in the late60s/early 70s it really was quite well thought out. Testament to that is that even in 2003 there were still a couple of hundred of them in service.

While someone who is entirely used to modern cars would likely find it quite an alarming thing to drive, I very much enjoy the experience of driving an older car. As such I very rarely find that taking TPA out fails to put a smile on my face and have me take the longer way home. I just find it a lot of fun to drive, and it's absolutely a car which seems to put smiles on a lot of people's faces. For all I've heard a lot of derogatory comments about Invacars in general on the internet, thus far I've had very few negative comments from people in person. It's a subject about which there seem to be a huge number of armchair experts out there who have never actually set eyes on any of the cars in question. Folks in reality by and large just seem to be happy to see the car. It's surprising as well to find how many people that were around to see these cars in service upon seeing TPA suddenly realise that they haven't seen an Invacar in the best part of 20 years. Their disappearance really did seem to go completely unnoticed by the masses.


When I first started the process of reviving TPA I had pretty much expected this to be a weekend car that I'd trundle out to the occasional show in and use now and then for fun. The reality of it has seen the car used a good deal more than I had originally expected. I have been very pleasantly surprised by how well TPA does at the job of just being "a car" even in 2022. There have been plenty of occasions now where I've been out for a full day of running errands etc and got home having covered in the region of 150 miles in the day, without any more thought about it than if I was in a modern car. She just gets on with the job at hand - albeit rather noisily.

In terms of living with the car, it's so far been fairly painless. In general parts aren't particularly difficult to get hold of. The Steyr-Puch engine has quite a strong following, and as such there are several marque specialists who can supply the vast majority of parts, both in terms of normal consumables right up to what you would need to do a full rebuild. Most of the other mechanical and electrical components are pretty easy to find as they're all parts bin items from common suppliers. The tricky bit is often initially just figuring out what less obscure car they're shared with. The truly unique parts of the car as far as I am aware basically boil down to the actual driver controls (so the handlebar yoke itself), the dashboard, chassis, body shell, at least some of the glass, the gearbox (not the CVT - the bit used to select drive, neutral or reverse), fuel tank and the rear wheel hubs (which were modified by the factory on early cars, the later examples seem to have used a bespoke hub), and the exhaust silencer. Which compared to a lot of cars from 1973 which survive in pretty small numbers really isn't a bad list at all. With the exception of the aforementioned wheel stud debacle, the only part that I needed and couldn't source from anywhere was a fuel tank, hence my having one fabricated for me using the original tank as a template. Given the scarcity of original tanks I don't reckon that this actually ended up costing me all that much more.

The single consumable part which I can foresee being a moderate headache for owners as time goes on is the exhaust silencer. This is unique to the Invacar and is of quite elaborate construction as it contains a (surprisingly effective) heat exchanger for the cabin heater. While there usually seem to be one or two people who have a new old stock or usable second hand silencer for sale, they tend to be quite pricey and obviously this is a supply which is finite - eventually they're going to run out. When I get to a point of having to cross this bridge it is my intention to see if I can get a replacement made up in stainless steel. It won't be cheap though given the amount of work involved. With the potential for any internal leaks to force exhaust fumes into the heating system and therefore the cabin it isn't a job that you want to see rushed either.

 

Overview of an AC/Invacar Model 70 exhaust system.  The large ports at either end are the air duct connections for the cabin heater



One suggestion I've seen a couple of times is to adapt the system for an air cooled VW such as a Beetle. This is non trivial. On the VW the heat exchanger units for the heater are separate from the silencer, essentially built into what you would consider to be the exhaust manifold on most vehicles. The silencer is then just that, a silencer. Whereas on the Invacar everything is built into the silencer itself, with a very short down pipe running to it each side. It's my belief that given the amount of fabrication and modification you would need to do to make the VW bits fit that you would be just as well to make up a replacement to the original design. A 2CV system would be just as bad, as like the VW the heater box is built into the collectors rather than the silencer, and despite the engine layout being closer to the Steyr-Puch one, the exhaust takes a completely different route out the engine (going up and over the drive shafts before dropping downwards to the cross box, rather than straight down and out).


I had expected this to be an occasional use "toy" if I'm honest, I'm now homing in on having covered four thousand miles since I revived the car and can't really see that trend changing.
 

While a lot of people seemed to be happy to start going back to things towards the end of 2021, having lost several friends directly to COVID or complications arising from it I was taking quite a cautious approach (and still am), meaning that we were well into 2022 before I really started getting out to things beyond running errands I couldn't put off again.

May 2022 though I sort of see in my mind as TPA's "return" to the show scene, when I took her over to Birmingham for a convention I was attending. While the event, ConFuzzled wasn't in any way, shape or form car related, it is a big enough convention that it hosts its own small car show on one of the days. Having learned something from the couple of other events I'd taken the car to, and having to answer the same questions 349 times in the space of an hour I had made a very specific point of printing out a brief crib sheet on what the car was and an FAQ to stick in the window so I could take a look around. Which of course I promptly left sitting on the dining room table when I left the house. Yep, that sounds like me!

Being by and large a somewhat younger audience than at your average classic car show this was quite interesting. It meant that quite a large chunk of the people looking at the car (and being astonished by how tiny it was and the odd control setup) had never actually seen one when they were in service. They also were largely unaware of the history of the cars, and more to the point also unaware of the social stigma which historically used to be associated with them.  Here are a couple of photos from that event.

 

TPA at the ConFuzzled 2022 MotorFurs event

 

TPA visits the ConFuzzled 2022 MotorFurs event

 

TPA visits the ConFuzzled 2022 MotorFurs event

 

TPA visits the ConFuzzled 2022 MotorFurs events

 

I would very happily have taken home the first generation XJ Cherokee as well, even if I'm not a great fan of the headlights - though I do understand the reason for fitting them given how poor the performance of the originals was!

 

TPA visits the ConFuzzled 2022 MotorFurs event

 

While this was an enthusiast gathering at a wider event rather than a formal show as such, there were some trinkets handed out to the owners of some of the most interesting vehicles, one of which it made me smile to receive.

 

Golden spanner award!

 

While it's just a little symbolic trinket rather than anything formal, it's the first time any of my cars has received any sort of recognition at an event other than conversations with passers by, so was fun.

I generally don't like sticking things in car windows, but decided that the window stickers that were handed out at this event were a worthy exception to the rule.  I can always take it off again if it bugs me!

 

TPA wearing her new window sticker

 

I DEFINITELY need to remember to take the information sign to put in the window next year though!

Back home safely after the event.  It was only about 60 miles each way and I've easily done more than that in a single day before, but it was the furthest I'd ever taken her in a straight line away from home and into another major population centre, so felt like quite an achievement.  We saw a little over 40mpg on fuel economy on the journey as well which confirmed my suspicions that the driving conditions in Milton Keynes were very much not helping things there.

I'm hoping that I'll feel more able to get her out to more actual shows and associated events as we move forward into 2023. Either way though, I fully intend to keep using the car on a regular basis. When it's not too windy anyway!


I do have an ideal in mind for a bigger adventure for TPA, though no real plan in place for when it might happen yet. The vast majority of surviving Invacars are in museums dotted around the country. My plan is to try to raise a bit of money for charity by doing a sponsored road trip over the course of a couple of weeks to visit every one of these cars in the UK (or at least every Model 70 depending on how many others there are too) with mine. Given that there's no small amount of logistical wrangling involved with that and I'm yet to feel fully comfortable with the COVID situation, it may well be a couple of years before we get to it - but it's something I would really like to do. While this was an idea which had been in the back of my mind ever since I picked the car up it wasn't until I'd covered a decent number of miles that I was convinced that the idea was really practical. Now I'm quite comfortable with covering reasonable distances though and am happy that I can keep up a pace that isn't going to make other road users absolutely miserable it seems rather more practical. If Alex Orchin can do Land's End to John o' Groats in a Peel P50, this should be a comparatively luxurious journey in a Model 70!

As and when any updates happen I will add them to this page as time allows. Not likely to be a much else this year though, as the weather is starting to turn she's likely to spend most of the next couple of months tucked away in the garage. I don't have any issue with using the car in less than clement weather, but having other vehicles on fleet with better weather proofing, heating and demisting equipment just make it seem more sensible. Not to mention the fact that vehicle lighting has come a long way since 1973.

If you see me out and about (usually in the Milton Keynes area) and have any questions about the car, please don't hesitate to say hello. I don't bite!
 

This brings us pretty much up to date with TPA, aside from a selection of photos below from her being out and about over the last couple of years.

Few general photos from July 2020, this was shortly after she returned to the road following the snapped wheel stud debacle and was the first time that the new number plates saw the light of day I think.

 

AC Model 70 TPA621M as she looked in July 2020

 

AC Model 70 TPA621M as she appeared in July 2020

 

AC Model 70 TPA621M as she appeared in July 2020

 

AC Model 70 TPA621M as she looked in July 2020

 

This must have been shortly before I added the external latches to stop the engine cover from rattling around and driving me mad (the lock on it is just a solid block of rust).

 

AC Model 70 TPA621M as she appeared in July 2020.

 

August 2020, parked up in Olney.  Using these diagonal spaces at the side of the street turned out to be a poor decision as reversing back out of them onto the busy road was an absolute nightmare.  Between the rear pillar being right in the way for my visibility and the lack of reversing lights meaning that nobody was likely to stop to let me out meant there was a fair wait before I could escape!

 

AC Model 70 TPA621M in Olney, Aug 2020

 

Looking very much at home parked up on street in Newport Pagnell in October 2020.

 

AC Model 70 TPA621M in Newport Pagnell in October 2020

 

December 2020, a pretty rare run out beyond the point where daylight had started to fade when I was dropping some things off at the post office in Neath Hill.

 

TPA621M out and about in December 2020

 

I always enjoy photos like this where you can pretty legitimately ask the question "When was this taken?" and there's very little to suggest it's recent or not.  This snap from New Bradwell was taken in early December 2020.

 

AC Model 70 TPA621M parked up in New Bradwell in December 2020

 

The following snaps were taken later on the same day.

 

AC Model 70 TPA621M in late afternoon, December 2020

 

This next one was my phone's wallpaper for a while.

 

AC Model 70 TPA621M parked up in New Bradwell, late afternoon Dec 2020

 

AC Model 70 TPA621M parked up in New Bradwell, late afternoon Dec 2020

 

AC Model 70 TPA621M parked up in New Bradwell late afternoon Dec 2020

 

In January 2021 blending in nicely as part of the street furniture as these cars once did in many cities.

 

AC Model 70 TPA621M in Bletchley, Jan 2021

 

February 2021, my full fleet as it was at that point in time.  I still find the contrast between TPA and the Jaguar amusing - likewise that on any given day I would honestly struggle to choose which to take out.  The Jag and Citroen have since moved on to new owners.

 

My vehicle fleet as it was in February 2021

 

Probably the most interesting thing to appear at the Bletchley Tesco grocery collection point in February 2021!

 

AC Model 70 TPA621M at Tesch Bletchley in February 2021

 

Within a few days of the last couple of photos, parked up next to Caldecotte Lake.

 

AC Model 70 TPA621M parked up by Caldecotte Lake, Feb 2021

 

AC Model 70 TPA621M parked up by Caldecotte Lake, Feb 2021

 

March 2021 parked up in Towcester Town Centre, making a VW Golf look massive.

 

AC Model 70 TPA621M in Towcester, March 21

 

I specifically remember taking this one in May 2021 at the Buckingham Tesco - don't let the photo fool you, there were some really nasty looking storm clouds juuuuust out of frame and the heavens opened a few minutes after I took the photo.

 

AC Model 70 TPA621M at Buckingham Tesco, May 2021

 

This was once a common sight at the side of roads around here, not so much in June 2021 when this was snapped in Towcester though.

 

AC Model 70 TPA621M in Towcester, June 2021

 

It's funny how small small cars don't seem these days...Bedford in Aug 2021.

 

Small cars, meet an actually small car.  AC Model 70 TPA621M, Bedford, August 2021

 

A very, very wet October afternoon in Bicester proves she's not just used as fair weather transport!

 

AC Model 70 TPA621M on a very wet October afternoon in Bicester

 

A couple of evening shots from down by Caldecotte Lake again from November 2021.

 

AC Model 70 TPA621M at dusk, Cadecotte Lake, November 2021

 

AC Model 70 TPA621M at dusk, Caldecotte Lake, November 2021

 

AC Model 70 TPA621M at dusk, Caldecotte Lake, November 2021

 

I took her along to the 5th December 2021 Milton Keynes Classic Car Club Breakfast Meeting.  Which was the first car gathering I think I'd been to since COVID arrived - it was enjoyable, if absolutely freezing.

 

AC Model 70 at the Dec 2021 Milton Keynes Classic Car Club Breakfast Meet

 

Took the opportunity to park up next to a friend's similarly diminutive little blue city car.

 

AC Model 70 TPA621M at the Dec 5th 2021 MKCCC Breakfast Meetup

 

She emerged from the winter hibernation properly in April 2022.  Not as though my cars are easy to spot from a distance or anything...

 

AC Model 70 TPA621M conspicious from a fair ways off, Apr 2022

 

AC Model 70 TPA621M.  I was going for a new phone background but didn't quite get the effect I was aiming for

 

A friend visited in September and had a quick shot of TPA.  It had been a long time since I'd seen one of these cars on the move from outside, so I'd forgotten quite how strange she looks on the road.

 

A rare photo of someone else driving TPA!

 

They had precisely as huge a grin on their face the whole time as I tend to though, so I guess I'm not entirely crazy!

Which I think brings us pretty much up to the current day...Updates will appear here as they happen (more or less!), and will hopefully be a bit more orderly than this page has been so far.  Suffice to say writing this one the best part of three years after the event has been quite the challenge and I know there are quite a few things I've glossed over or outright missed.  I will see what I can do to fill in a few of those blanks if I spot them down the line - but for now I've realised that I just need to call time on this page at some point and get it uploaded.



Should you have any comments, questions etc or personal stories regarding these cars that you would like to share please don't hesitate to drop me an E-mail.


Page Created: 15th December 2022.

Page last updated: 28th April 2023.


Back to the Automotive Index Page

Back to my Home Page