Project V8 Sunbeam Rapier Fastback: Part 8

Follow our progress as we take a 1973 Sunbeam Rapier Fastback and inject it with some power by adding a Rover V8 engine, and restomodding the entire car.

Another six months have flown past, and I’m still only getting to Hawera once a month to work on our project car, so time feels like it stands still at times.

Regardless, we are making decent progress. Here’s what’s been happening since our last update in January.

Project V8 Sunbeam Rapier Fastback: Electric Power Steering

After all the previous work on our electric power steering, it was time to get this moving along and finished to the point of being ready for LVV certification.

We housed a bearing holder in the firewall to support the steering shaft universals. We’ve also located the Toyota Wish power steering mounts to the A-pillars of the car and bolted it in, so this part of the project is looking pretty well done.

We’ve also made up a mount that goes to the firewall to help locate the unit from above. It’s all looking excellent – safe, strong and solid. We have high hopes that since we’ve effectively lifted the entire electric power steering system from a Wish and installed it in the Rapier, our LVV certification should be quite straight forward. We’ve allowed for the torque of the electric motor, and then some.

Project V8 Sunbeam Rapier Fastback: Gearbox mounting

We have had many thoughts around how to mount our Toyota gearbox; making up new plates (again) and also create new rails for them to bolt to. You might remember that the gearbox mount for the Rapier gearbox actually has the holes in exactly the right place for the Toyota gearbox cross member from a Corona, but the mount itself is 100mm too far forward of the gearbox and the whole thing is a massive ‘transmission hoop’ that goes up and over the transmission tunnel.

Then someone suggested we unpick the spot welds from another Rapier’s transmission hoop and locate in the right place for the Toyota gearbox. Brilliant! This will be incredibly strong, and the gearbox will bolt straight in, without us having to design and make anything.

I found the front clip from another Rapier and set to work with a grinder, cutting the floor out. Then it was out with a drill to remove the spot welds from the hoop. I’d like to say this was easy, but it was not. But in the end and after too long, we had our Rapier transmission hoop ready to go into the project car.

While I was away from Hawera, our friendly panel beater got that hoop into the car and has finished modifying the transmission tunnel to clear the gear shifter. The gearbox is now bolted to the new mount, meaning no more strops to hold the gearbox up, another milestone moment.

Project V8 Sunbeam Rapier Fastback: Engine mounts

With the gearbox located front/rear, it was time to check the drive line to make sure it aligns with the Rapier drive line. We want it to match up perfectly so we will not get any shudders or anything out of line. After checking the height of the rear of the gearbox in a standard Rapier, we found that our Toyota gearbox is 13mm too low, and the front of the Rover V8 18mm too low.

This process took a lot of time and so much measuring and rechecking, but we are confident of our results. We can put an alloy spacer under the gearbox mount easily enough and still have plenty of clearance to the transmission tunnel.

Lifting the engine should be simple enough; even though we’ve already had our engine mounts made up, we can use them as a pattern to create new ones that have the engine mount bolt holes 18mm higher. The bonus of this is that it will give us more sump clearance, something we have been short on up until now.

Project V8 Sunbeam Rapier Fastback: Rear disc brakes

We’ve spent so much time trying to figure out how to get disc brakes on our Hilux diff, along with a handbrake system that will work for us. Embarrassingly, it wasn’t until someone came along and had a look and said, “why don’t you just use a Hilux disc conversion?”. Honestly, I had no idea they existed, and we are kicking ourselves that we hadn’t even thought about this approach. 

A quick Google shows them for sale at a fair whack of cash, but a check on Facebook Marketplace also shows a guy an hour away from Hawera who is selling the adapter plates only, for $100. Since we only need the adaptor plates, I shoot off and buy them. They are perfect, meaning we have a lot more options around mounting callipers to the new adaptor plates, complete with a handbrake.

We read that the front callipers off a 1988 Subaru Leone will fit and these will have a cable-type handbrake system, since Subarus of that year still had the handbrake working the front wheels. But finding these callipers proved too hard, and so we started looking at Corolla rear callipers, again with the handbrake operated by the calliper, and not an internal drum-brake system that used on bigger Toyotas. We did get some of these Corolla callipers, but they are very small and would still require some work to make them fit.

In the end, a decision was made to fit Wilwood brakes all around the car. They make callipers that have a built-in handbrake, and we know they have them for many, many makes and models. 

We started looking at Wilwood brakes and what sizes etc we need to fit the front and rear of the car. But on checking, Wilwood don’t actually make a rear calliper to fit our mount plates. So we go back to Plan A, and bought some Subaru Leone front callipers for our Hilux diff. The front callipers on the Leone have the handbrake mech built in, and should bolt straight onto our mounting plates. We’re now waiting for Horopito Auto Wreckers (Smash Palace) to remove them from the car so we can pick them up.

Project V8 Sunbeam Rapier Fastback: Front struts

With progress on the car’s rear end, it was time to (hopefully!) make some decisions on the front end. We can’t use the Triumph TR8 hubs, as we are moving to 5-stud wheels. One thought we’d had here was changing to a later-model Falcon hub to take advantage of that model’s 4-pot callipers and ventilated disc brakes; cheap to buy and easy to find added to the temptation. We borrowed a strut from a EA Falcon, but the stub axle was too long and too fat for us to do anything with, so that was crossed off the list.

The next idea was to look at a Rover SD1 strut; both the Triumph and Rover are English at least, and around the same era – perhaps we might get lucky here. It was off to another lock-up to remove a rusty front strut from an even rustier Rover SD1 V8. To put it in perspective, as I jacked up the front of the Rover, the front end lifted, but the rest of the car did not (in broke in half!). This one needs to go to the dump, it’s that bad. 

After much mucking about with rusty bolts, we got the strut out and headed back to the workshop. The top of the Rover strut went straight into the holes of the strut tower in the Rapier, so that was a great start. The Triumph lower ball joint bolted straight into the Rover strut, so another thing ticked off the list – as did the steering arm with the same spacings, retaining the original steering geometry.

But the hub doesn’t have the Toyota stud pattern we are after, and also the offset is far too much. After some more discussions with an external party, it was decided we’d go with Rover front struts but get some new hubs machined to reduce the offset and also to have a Toyota stud pattern. This will cost around $300 per side, but it means we can move on with the next stages of the project, knowing that this part is sorted.

But after some more thought on this, Toyota Hiace front hubs felt like they might fit. We measure the stub axle for the SD1 and then head to a Hiace parts car (van?) and pull the hub off. Measuring the stub axle, it’s 5mm thicker on the inside and 4mm thicker on the outside of the stub axle, so if we can get bearings to suit, this will bolt right onto the Rover SD1 struts. The Hiace hubs are narrower offset, which will mean that our front and rear track will end up being almost identical, if a little wider at the front (only millimetres out) – and that’s fine by us. We’ll hunt down new bearings and as long as we find some, then buy some Wilwood two-pot callipers for the front of the Rapier.

Of course being Hiace hubs, that means we get a matching stud pattern front to rear, so another item ticked off the list – as long as we can get some bearings to suit, so we can get the Rapier back on four wheels at last. It’s been a while!

Project V8 Sunbeam Rapier Fastback: Remote brake booster

While we’re making progress on the bigger parts of the project, we decided to start looking at the remote brake booster. We want to go to a dual-master brake system for safety, and this means having the brake booster forward of the strut tower as to allow room for the booster, such as they do in Ford Escorts and some BMWs, and no doubt other cars too.

We found an old 3 Series BMW parts car, and I started to remove the brake booster and all its fittings. The front of this 3 Series was gone, making access easy, or so I thought. Unfortunately, this model of 3 Series has bolts that feed through from the engine bay to inside the cabin, so the entire brake booster arm would have to come through from the inside. 

With a lot of yoga positioning and almost an hour under the dashboard, I got the whole thing out. It took 2.5 hours to actually get the whole job done, and we aren’t even sure this is the remote brake booster system we are going to use, but at least we have something to play with. I do not want to do this again.

As much as we would have loved it to happen, the BMW booster gives us ideas that this plan will work, but it’s not the right booster for our setup. During a trip to Horopito Auto Wreckers, Ted from the wrecking yard suggested that a Mk1 or Mk2 Ford Escort with a remote brake booster might work, and after looking at one, the Mk2 looks perfect. Horopito Auto Wreckers are going to remove it from the car for us, and we’ll pick that up along with the Subaru callipers.

That’s it for the moment; by Christmas (this year!), we will have the car back on its wheels and potentially with the engine and gearbox in place, diff finished as well as the front end, and all brakes done – including moving the handbrake to the centre of the car. We’ll aim to get more done, but the way this year is flying past, we’ll stick to realistic goals.

PART 1 HERE

PART 7 HERE

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