Follow our progress as we take a 1973 Sunbeam Rapier Fastback and inject it with some power by adding a Rover V8 engine, and resto-modding the entire car.
Here’s what’s been happening since our last update in July last year.
Project V8 Sunbeam Rapier Fastback: Engine & gearbox mounts
We created our engine mounts a while ago, knowing that they might need to be changed again. We’re at that point in this project where we need to get the drive line to match that of the original Rapier Fastback, and that means lots of measuring and checking, and potentially altering our engine mounts to make sure everything lines up.
After checking the measurements in another Rapier Fastback, we find that the centre of the engine pulley hits a certain point on the front valance. We also check the distance between the transmission hoop on that Rapier Fastback, down to the centre of the output of the gearbox.
With those two measurements in hand, we see that the centre of our Rover V8 is 18mm too low, and the rear of the Toyota gearbox 13mm too low. We ended up putting some 18mm high nuts under the engine mounts, and recheck measurements. Perfect! Now we can get a 13mm rear alloy gearbox spacer made up, and get our engine mounts dropped by 18mm to get the engine to lift by the same amount.
Once those are done, our engine and gearbox will be their final resting places, and we can move on to getting a drive shaft made to suit, and tacking our engine mounts in place. We’ll still need to get these engine mounts approved, of course.
Project V8 Sunbeam Rapier Fastback: Rear disc brakes
We’d made progress on the rear end of our project car in the last article, and more has been made since. We’ve pressed new bearings onto the axles, and fitted new seals. However, the brakes are still our main focus. We need to make sure we have callipers with a cable mechanism for the handbrake. Another change for our Rapier is a move of the handbrake from the side of the car (next to the driver’s seat) to the middle of the car.
We picked up some Subaru Leone front brake callipers from Horopito Auto Wreckers (Smash Palace), as the Leone has the handbrake working the front wheels via a cable. We lathed out the middle slightly on our Toyota Estima discs so they would slip over the Hilux hub, and then looked at the Leone callipers. While the holes on the callipers don’t quite line up with our disc brake mounting plate, they are very close. But the Leone callipers are quite deep, and go below the depth of the disc. We could still use them, but they aren’t quite perfect.
We picked up some AE101 Corolla callipers, and they are starting to look like a better fit for the rear end. We’ve still got our Camry rear discs to play with and while they won’t fit over the Hilux hub, we could lathe out the centre slightly to test them out. This is next on our list. We’d love to go Wilwood brakes all around the car, but Wilwood do not make a brake calliper to fit discs of this size.

So, it was on to other options. We borrowed a rear brake calliper from a Toyota MR2, and it fitted perfectly – and those callipers have the cable-operated handbrake mechanism that we need. Pick-A-Part in Wellington was wrecking an MR2, and apparently it still had the rear brakes, so we headed there one weekend and removed them all, including all the handbrake cables.

In the last article in this series, we bought some Hilux disc brake adaptor plates, but due to Murphy’s Law, our MR2 callipers don’t work with the adaptor plates. So, we made up our own plates, and added a couple of spacers to the MR2 callipers, and that’s it – we have rear disc brakes. We still need to rebuild the callipers and probably replace the discs, but we have a working rear disc brake setup and that’s another job crossed off the long list.

Project V8 Sunbeam Rapier Fastback: Handbrake
If there’s one thing about English cars that’s a pain, it’s when they put the handbrake between the driver’s seat and the door. The seatbelt gets caught up on it, and it can interfere with getting in and out of the car.
From the outset of this project, I wanted to move the handbrake to the centre of the car. We’ve got our Toyota MR2 rear brake callipers that have provision for a cable-operated handbrake. Installing the handbrake itself was a piece of cake; we marked the transmission tunnel out and then cut the hole. Mounting the handbrake in the hole was one of the easiest parts of this project to date.
Of course, later, an extra layer of tunnel steel is to be spot welded inside the tunnel to reinforce the lever mounting area.
Then, onto the cables. Weirdly, the MR2’s handbrake cables are a lot longer than we needed, by about a metre. We’ll work on this another day.

Project V8 Sunbeam Rapier Fastback: Front struts
Since the last article, we’ve had the Rover SD1 stub axles altered slightly to suit the Hiace front hubs, while keeping within the NZCCM requirements. We’d ordered new inner seals to fit the outer diameter of the Hiace with the inner diameter of the Rover sealing surface of the stub axle. The bearings could not be sourced to allow this to be replicated, so we have machined two thin sleeves that apply with an interference fit on the Rover axles and a neat fit on the inside of the original Hiace bearings. An end washer was machined, the outside diameter of the Hiace washer with the inside diameter of the Rover, allowing the original the Rover retaining nut and split pin to be used. There has been no alteration to the Rover stub axles which will allow in the future replacement struts/stub axles to be fitted, and avoids any no-no of machining stub axles.
Using the Rover struts has provided a much better angle for camber control and much beefier stub axles than the Triumph. All other ball joints and steering arm mountings are identical to the Triumph struts.

Eventually, we got both Hiace front hubs on the car, meaning we can get the car back on 4 wheels for the first time in a couple of years. It’s a milestone moment! We have adjustable suspension platforms to go onto the struts, so we can adjust the front height of the car oh-so easily. When we get our Rover front struts reconditioned, we’ll add the adjustable platforms at that point.
Now the front end (except brakes) is basically finished, we’ll leave it alone until it’s time to remove it all to get everything sandblasted and repainted, and also fit new seals and bushes everywhere.
Project V8 Sunbeam Rapier Fastback: Remote brake booster
Time to have a look at the Mk2 Ford Escort remote brake booster we would have liked to have used. We want to go dual-master on the Fastback, and that means we can’t use the existing pedal-box mount to achieve this. The strut tower just prevents changing the master cylinder, as the strut tower protrudes into the area of a potentially longer master cylinder.
Our intention is to design a simple extension of the mounting of the master cylinder and locate it forward enough to just clear the strut tower. This will be both a welded and pinned component, to ensure ‘belts and braces’ security that we have been utilising in any engineering changes. The extension is not that long, far shorter than the BMW or Escort that are similar, except we intend to incorporate a midway support for the pushrod that neither of those systems have, ensuring that distortion of the push rod can not occur. The pedal ratio will not be altered from standard, and obviously the extension will be mounted to the original master cylinder mounts and will be supported off the strut tower and the chassis.
Using a remote booster means we get the booster away from the cylinder heads and should be able to simply bolt on a dual master cylinder in front of the booster.
Surprisingly, the Escort’s system almost bolts into place, but it would mean having to modify the strut tower, and there’s no way we want to do that.

This does mean that the brake booster could be near the heads, but couldn’t confirm this as currently we only have the spare bare block in place, borrowed from a Hawera local. A quick call to the same person confirms he has a couple of spare heads and tappet covers we can borrow to make sure the booster will clear the heads.
Sitting the heads and tappet covers on also means we can check that the steering column will not foul the exhausts. For the first time, we have the motor looking more like a ‘real engine’, sitting there in the engine bay. It looks good.

The steering column is perfect and well away from anything, although we might borrow some Triumph TR8 extractors and slip them into place to see if they will clear the column. But that’s for another day.
For today, the brake booster looks fine where we want to put it. We can have it between the first and second cylinders on the right-hand bank, meaning it will be away from the exhaust ports but will still allow access to the spark plug. It’s a win for the day.
We’ll start working on the remote booster mounting setup another day, but at least we have a plan that could put us on the right track.
Project V8 Sunbeam Rapier Fastback: Front seats
It’s been a long time since we’ve worked on mounting our E46 BMW M3 seats, as we’ve been focused on getting the car back on 4 wheels. As a reminder, we’ve thrown out the standard – and terrible – factory seats, and are fitting some M3 seats that have built-in seat belts.
The Low Volume Vehicle Technical Association (LVVTA) calls these “fully-stressed seats” because the seat belts are built into the seat, meaning the seatbelt loads from restraining an occupant in an accident are taken entirely by the seat (and its mountings to the floor), rather than structural points in the vehicle’s sills and pillars. We need to follow the LVV Seat Anchorages Standard requirements around mounting fully-stressed seats in order to get the seats LVV certified.
We’ve played around with a few ideas for mounting our BMW seats. The front seat mounts are a walk in the park; right under the floor is a chassis rail going across the car, so we can use some 3mm angle iron to bolt the front of the seats directly to the chassis. That was easy.
But with fully-stressed seats in an accident, all the lifting force is on the rear of the seat, and we have no chassis rails going across the car at the rear of the seats, so we’ll need to do something else. In the end, a video call with an LVV Certifier meant we could move forward with mounting our seats. Basically, we are going to run 3mm thick steel plates under the car running back from the rear seat bolts to 400mm past the rearmost seat mount bolt. There will be corresponding steel plates inside the car, with bolts through the floor, connecting the two strips.
Installing those mounting plates under the car meant getting rid of the underseal, and that meant 2 hours with a heat gun and a scraper, with hot pieces of underseal falling onto my face, arms, hands, and often down my shirt. Those who have done this before will understand – this is not a fun job.
It’s not required, but we’ll also run steel plates down to the seats from the old seat belt mounting holes, purely to give the seats even more mounting strength.
Project V8 Sunbeam Rapier Fastback: Wheels
Another weekend’s work would focus on wheels; we need to decide what diameter rim we want, then work out the offset, and see what maximum widths we could run front and rear. For the rear, we’d also need to take some measurements to make sure the rim will clear the front face of the callipers and the leaf spring. At the front, we need to make sure the rim will clear the strut with room to spare, as well as being able to go lock to lock without hitting anything.

Deciding on rim design is the best and worst part of the project. At last, I get to check out some rim designs and go with whatever I think will work. On the other hand, what if I buy rims and they simply do not suit the car? Huge danger here, the rims can totally alter the car’s look.
Regardless, we have to push on. We managed to find 14, 15, 16, and 17” single wheels to fit to the car to check out rim diameters. I had always thought that 15” would be the maximum size, since often when seeing older cars with larger rims, it just doesn’t look right. But when the 17” was bolted on, it didn’t actually look too bad. But then, we put some 16” against the car, and they look perfect. So it’s 16” rims, around 9” wide on the front and 10” on the rear – with 15” as a backup option.


Then, someone found some 17” wire wheels to put on the car, just to have a look. I’ve mentioned before in a previous article that I absolutely love wire wheels, and were keen on them for our project car. But, I’m torn. Some days I love the look of them on the Fastback, other days not so much. I think in the end we’ll move to some deep-dish retro alloys – if we can find some. The hunt goes on for the perfect rims.
So for now, that’s where we are at. Much more to do, but we are at least going forward. In 2025, we aim to get all the modifications that need to be certified completed and ideally, all those mods LVV certified.
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