Building a GD427 Cobra Replica

I am working towards a situation where i can fit wheels to the front temporarily, so the chassis can be positioned over the rear end, not unlike a wheelbarrow. After that I’ll want to fit temporary wheels to the back as well because the garage needs to be cleared out by the 20th of July. After we created the new floor, some cracks started to appear and I made an arrangement with the contractor for repairs this summer.

So, that means we’ll need to clear out the whole garage, again, and having some wheels on the chassis makes that a whole lot easier. Ideally I want to have the suspension set-up completely by that date, but we’ll see.

One thing I noticed at the front was that the damper bracket opening was a bit smaller than the one on the left. This is probably caused by the welding process which puts strain on the metal and causes it to bend. We’re talking 2 milimeters I think. With a piece of thread and two M12 nuts I carefully widened the bracket a bit, just enough to get proper clearance on the damper.

Moving to the front…

Apart from one bolt I’m missing for the front (the one I had got damaged somehow) I’m also going to need two pieces of brake pipe for connecting the flexible hose to the front calipers. Looking at most other GD builds and the pictures I have from GD, the routing often does not make sense to me, so I’ve experimented with some different configurations. Basically, there are 2 things to vary:

1. the positioning of the donor bracket (upside down / normal);
2. routing of the flexible brake hose, what I’ve called ‘north’ and ‘south’.

Positioning the bracket seemed to quickly lead to the ‘upside down’ solution for me (see also Simon’s post, although he reaches the opposite conclusion)

Next, the routing of the flexible brake hose. The ‘northbound’ routing seemed to work best for me. It does not come anywhere near any suspension part, neither in full bump, full droop and at both extremes of the steering.

I find that another advantage of the northbound route is that the routing of the fixed piping is greatly simplified, just needing a short piece with two bends, instead of routing it through the caliper openings.

It may of course be the case I’m missing something completely, as the setup with the upside down bracket and the northbound routing of the hose is basically different than everyone elses setup?

Looking at the last jobs for the rear end I tried replacing the straight grease nipples with 45° variants, but getting them properly positioned to the inside turned out to be quite a challenge. I’ll leave it on the backburner for now.

I double checked the torque on the drive shaft nu and got a helpful email from Terry about it too. Torqued it to 136Nm and put in the cotter pin.

The overview Terry sent me had torque numbers for the diff cover nuts as well, so out came the nord-lock washers again and the torque wrench. Probably not that important, but alas, looks nice at least.

Last job was deciding wether to fit the flimsy covers for the drive shafts. General consensus on the fora was a big no-no, so that made the decision a bit easier.

So, rear end done! All that’s left now is to fit it to the chassis. (Likely I’ll come up with new jobs for it soon, but my list is empty for now)

While the final castor setting is determined by personal preference after a test ride, the initial castor setting target is between 3 to 5 degrees. The first step is to determine the amount of shims which will not push the two parts of the upper wishbone together and won’t push them apart either.

Starting with the original 5 shims (although I think the original shims were of different thickness) turned out to be ok. I also started with the original setup of 3 shims to the front and 2 shims at the back. This gave me a 4.4° on the left side and 5.0° on the right side of the car.

Leaving the left side of the car alone, I moved all 3 shims to the back and that gave me 4.5° on the right side.

Should be close enough for now. The measurement is sort of ‘an estimate of what it should be’ at the moment. It does not really matter what the castor is (within reason obviously) as long as both sides are equal, we should be good to go. (Not that I have hands-on experience with this, it’s all theory for me still)

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