Building a GD427 Cobra Replica

Got the other oil seal and the thicker spacer in the mail today. As this new spacer is only 0.002″ thicker than the one I used to determine the endfloat and that one seemed to give an endfloat of something indistinguishable from zero, I carefully measured the endfloat with the new spacer (0.150″ thick).

Apparently my measurements weren’t that bad and I got a bit lucky. Measured endfloat now was 0.055 mm which corresponds to just a bit more than 0.002″. This is just above the minimum. Phew!

So, the all trial assembly to the complete rear end is now complete. What is left is the right-side camber shims (waiting for delivery) and measuring toe-in.

One thing I noticed was that there is some play on the left side of the output-shaft of the diff. That is, i can turn the brake-disc a bit without a corresponding movement of the input shaft. The right side has this as well, but much less. I’ll have to consult a jag expert to assess the limits on this. Mr. Haynes does only talk of excessive crownwheel to pinion backlash as the cause of a problem, but not how much of this backlash is allowed (maximally).

The one completed hub begs to be assembled. There are a number of steps involved to correctly complete this job. First is to create a level working environment. This is somewhat easy for me, as the car hoist I have is adjustable at the four corners. I already had the chassis levelled out, so the only thing needed was to check and fine tune it.

Next, I created a dummy shaft for the outer fulcrum, having a slightly smaller width as the hub. This simplifies assembling the hub to the wishbone considerably and makes sure the shims which are inside the fulcrum stay properly positioned.

The “hub—wishbone fit” was pretty much dead on. There are shims to make sure the hub is centred and to prevent bending the ends of the wishbone. I had bought a set of 8 or so but I could only fit (with considerable effort) one shim of 3 or 8 thou (cant remember). Not sure how critical this is.

Next up was setting up the lower wishbone having a 2″ downward slope over its length; presumably emulating the normal ride-height like that. Fitting shims between the drive-shaft and the brake-disc makes it easy to adjust the camber. The one-tenth of a degree negative camber should do just fine for now. I bet I need to revisit this once the car is completed and the proper ride-height is determined.

The big nut on the drive shaft needs to be torqued up (only to 75Nm apparently, which seems small for such a big boy). Doing that is somewhat awkward on just the hub, on the complete assembly however it is basically just a matter of ‘putting the thing on the handbrake’ and torque up the nut. Also the previously determined endfloat can be checked again now, which I will do tomorrow.

For the 4 inner lock nuts I’ve have fitted some temporary nuts for now; to be replaced with the metal-lock nuts once the whole assembly is attached to the chassis.

So, for the other side, I still need the inner oil seal and a set of shims to be able to complete it. They should arrive this week.

With a new inner oil seal delivered, completing one of the rear hubs was indeed a quick job. Pressing in the oil seal, but now making sure it was straight!

This completes one rear hub. To complete the other one I’m waiting on the (extra thick) spacer and another inner oil seal.

Got one inner oil seal delivered today out of the two ordered, so decided to quickly press that in the rear hub waiting for it. Too quickly it turned out; I pressed it in while it was not lining up exactly with the opening apparently because it bent.

So, out it came again and I’ll have to order a new one. No progress made today