After a front end rebuild I took my 66 convertible to an alignment shop to have the front end aligned. Before disassembling the front end originally, I noticed an unusually large number of shims at the right front upper rear control arm stud location. It was shimmed as far out as the threaded stud would allow and still be able to intall a lock washer and nut. At the time I thought it was a product of old bushings and worn ball joints. After replacing the ball joints and bushings the alignment shop had the same problem after the rebuild. He said he couldn't meet the recommended caster spec at the right front wheel. There is only one shim at the front stud and as many as will fit at the rear stud and that only gives me -1 degrees of caster at the right front. The left front can be aligned just fine. He aligned both to -1 degree of caster but I have to manually steer out of turns. Has anyone had a similar problem and if so, what is the solution? Is something bent? Everything went together very easily and appears straight (frame, control arms...). What measurements can I make to find the problem part? Thanks in advance.

 

If you walk around and look at the underhood of a bunch of C2 and C3 cars at a car show you will see just about every imaginable combination of shimming possible. I guess that's a combination of mass production and almost 40 years of wear. But yours seems to be an extreme case. I bet neg one degree of caster steers pretty wierd. They make special offset bushings that will allow bringing the alighnment in some, but I'm not sure it would be much improvement in this case. I would suspect something has been bent somewhere, although if neither the alighnment shop and the rebuild shop noticed anything amiss, it must not be too obvious. I would check your frame over for cracks around the front spring pocket closely. I would also look for any sign that the lower control arm mount, that is welded to the underside of the front crossmember, has had any welding work done on it or looks askew compared to the other side. When I rebuilt my car I found I had a bent spindle when I tried to put new brake pads on and found the rotor wasn't centered between the caliper. The new pad would not go in on one side - something to check. You don't say if your car has any accident history. If it took a hit in the right front it may not be straight anymore. If you can't turn anything up you may just have to find a frame shop familiar with these cars, and have them check it out and see what the deal is. Good luck.

 

I believe offset cross shafts are for camber and not caster. YOu really want positive caster.
I want 5 degrees positive on my C3 so I just pulled the upper arms, a jack under the lower is suficient to hold the spring.
Anyway you can pull the one A arm and move the hole for the through studs 1/4 inch. I slotted mine. If you have a friend with a mill the assembled arm can be put in the mill and it only takes a few minutes with a 3/8th cutter to slot the hole to 7/16 wide
Slot it 1/4 inch towards the front so the arm can be reinstalled to the rear. This doesn't affect camber just gives you about 3 extra degrees of positive caster.
To fill in the rest of the old slot cut a bolt in half and slide half in the unused part of the slot , The washer and nut hold it in place.
The A arm doesn't need to be disassembled to do this.
I know it works. I make custom cross shafts in different offsets for camber and relocated caster holes.