1970 GTO Version 2.0

[andrewb70]

That's an interesting tidbit Andrew. I just had to go look at my car to see if the factory controll arms were offset. It looks like G-Bodies were centered.

Tom, I am not really sure why GM built the A-body arms the way they did. I was discussing this in detail with Ron S ($5000 mustang build) and he mentioned a few curious things. He does a lot of custom work and he has fixtures made to narrow a variety of rear ends. He was recalling a having to narrow a A-body 12 bolt rear end to be installed into a G-body. He mentioned how the position of the lower brackets on the 12 bolt were not exactly centered. I think it all has to do with having the pinion being in the proper position in the chassis and GM's desire to have equal length axles on the left and right sides. I don't know all this for a fact, it is just a theory.

In any case, the fact that my car has had a vibration since day one is very interesting. I have gone through 2 engines, 2 sets of tires, 2 different front spindles and brake packages, 2 rear ends and 3 different driveshafts. Everything seems to point to some sort of driveline misalignment issue. It is not a simple matter of pinion angles, because I have beat that issue to death. I think there is a lateral problem. The rear is offset to the side due to the control arms, that for sure. The other issue may be that my transmission output shaft and the pinion shaft may be out of parallel when viewed from the top (or bottom). This is an issue that few people think about. Once I am done with my classes I am going to install the transmission and really double check the position of everything.

Andrew