Follow our progress as we take a 1973 Sunbeam Rapier Fastback and inject it with some power by adding a fuel-injected Rover V8 engine, and resto-modding the entire car.
Wow, our last update was in January of this year. So much and yet so little has happened. We’ve spent the entire year working on brakes and seats, and that’s pretty much it!
Here’s our update on those things, and a few other items we’ve crossed off the list as we get closer to going for LVV certification.
Project V8 Sunbeam Rapier Fastback: Engine & gearbox mounts
Last article, we had worked out that we needed a spacer under the gearbox mount, and we needed to lift our engine mounts to make the driveline line up with the same angle as the original drive train.
We’ve had these made, and although we have yet to tack our engine mounts in place (we’ll wait for LVV certifier approval first), our engine and transmission are now (finally!) sitting in their final resting place. This means we can move on to getting a driveshaft and hoop made, and putting our diff head into the housing.
Project V8 Sunbeam Rapier Fastback: Remote brake booster
Lots of progress has been made in this area, and we’re close to applying to get the remote brake booster certified.
We dumped the idea of a Ford Escort remote booster, and instead grabbed one of a Corolla. We’ve engineered a stainless steel rod to go from the pedal to master cylinder, and it works well. We installed a rose joint to ensure alignment, but have been told this is not a simple allowance, so will have to apply for a change of build plan consideration, or we’ll need to remove that. There is one more mount to be installed from the booster mount to the strut tower, to reduce any chance of flexing under braking.
Once this setup is certified, we can replace the Corolla booster and dual master with new ones, or just get the ones we have used rebuilt.
Project V8 Sunbeam Rapier Fastback: Bonnet clearance and fuel injection
While we were playing around with our ideas for a new remote brake booster, we decided to put an inlet manifold in place, and sit a Rover fuel injection unit on it, to check both clearances for our remote brake booster, and also the bonnet. While it looked like there was no way the bonnet would clear the EFI unit, we had about 20mm to spare, so no problems on that front. We may need to make a minor adjustment for sump clearance.
We are going to fit gas struts to the bonnets, and get rid of the “stick” and its mounting points on the radiator support.
Project V8 Sunbeam Rapier Fastback: E46 BMW M3 seats
We have spent far more time on getting our seats ready for certification than anything else during the year. This is because our seats are “fully stressed” – that means the seat belt is part of the seat, and we need to allow for a lot more stress in an accident situation.
But great progress has been made, and we are extremely close to getting the seat-up certified.
We have 100mm wide, 3mm thick plates under the car running from the front of the seat mount to the rearmost point of the floor pan. On top, we have 50mm wide, 3mm thick plates doing the same. There will be 12mm bolts coming down through the floor (currently 8mm) and 4mm thick box section steel as seat pedestals, to keep the seats level.
There’s also 3mm thick angle iron running across the front of the seats, so they tie into the chassis rails going across the car.
In designing all this, we had to make sure that the seats weren’t too far out, otherwise we could not get to the seat controls. It’s been an absolute mission, but LVV’s manual has been a great help in making sure we are doing things right.
So, still a bit of work to do on the seats, but we know what we need to do to (hopefully) in getting them certification standard.
Project V8 Sunbeam Rapier Fastback: Front brakes
We’ve left the front brakes for a while now, as we’ve concentrated on other parts of the build, but have been tinkering on the edges of what we can do.
Like the rear discs, the fronts are ventilated. We’ve got Rover SD1 struts, so we know Rover SD1 callipers will work, but they’d need to be for ventilated discs.
After a lot of hunting, it turned out a friend in Auckland had 4-pot Rover SD1 callipers sitting on his workbench. We grabbed those, knowing they weren’t for ventilated discs. Planning went on around making up some spacers, effectively splitting the calliper apart for the vented disc, and putting spacers in. After all, this all BMW and, as it turns out, Rover, does.
On a hunch, we go hunting on the internet and found you can buy a kit, complete with the spacers, longer pins, longer bolts and o-rings – all for $110. Seems like a bargain, and it instantly fixes our front brake dilemma.
We’re waiting on the spacers to arrive, then we can finish off the front brakes – except of course for putting new discs on, rebuilding the callipers etc.
We’re certainly aiming for 2026 to be the year the Rapier passes its LVV certification, so we can move on to the body and interior.
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I had 2 Rapiers and 1 New Humber Sceptre during the 1970ties, and as I purchased mine in 1972 I fell in love immediately. As a born Brit but living in Austria since the age of 8, I always was attracted to British Cars of that Era up the last one, my Rover 75 until 2012, all were every day cars.
Now I have a Rover Vitesse and a Triumph Stag as Classics.
Your Project is great, despite being a nightmare for any purist.
But as you wrote, the Rapier was an Exotic, in Austria perhaps even more as in NZ, a fortune as one could buy them very cheap . And one had a cabrio like feeling when driving with all windows down in hot weather, with no AC.
On the Rapier I learnt maintaining it myself. Purchased the original fully detailed Workshop manual, with all update pages included.
To your project car.
First I wondered why you installed all that tatty parts into a tatty looking, unpainted car, but after looking part 5 I understood.
First everything has to fit in place, then you will remove all the parts, restore them, finish your Fastback and then you will install all your shiny parts int a shiny looking car.
Looking forward until then.
Regards from Austria-
HI Roy
Thanks for the comments. You are right, we will get the whole car completed for mechanicals etc, get it certified, and then strip it and rebuild all the parts etc. It’s all part of the plan!
Love the Stag – definitely on the list of my dream cars to own.
Cheers
Fred