Apocolipse

Hey all,

I measured the wheelbase setback on the C5 and it's about 3/16-1/4" greater passenger side vs driver side. Seems to be the upper control arm mount location is welded in the wrong spot. This will cause rear caster to be different.

Anyone else notice this? What is the tolerance on these cars?

Scooter70

Where are you measuring? The rear and/or front cradles could be off. It's typical to see the rear cradle aligned slightly to one side or the other enough that max rear camber is higher on one side than the other.

insertclevername

Street cars generally run more positive caster on the right to account for the crown on road (water runoff). This usually helps the car to track with only a slight drift to the right. All street cars should drift to the right, but not pull.

Get it on an alignment rack and the tech will tell you if you have a problem.

Apocolipse

Measuring from hub center to center distance. I've tried moving the cradle and it only changes about 1/16" at the wheel since the upper arm doesn't move.

Have also measured the upper control arm points to the bumper, as well as to a front reference point on the frame.

Seems the actual upper control arm mounts were welded in the wrong spot from the factory.

Bill Dearborn

Are there any indications of welding repairs around the rear UCAs? Back in the day there were some C5s that had broken welds at the rear UCAs and they had to be repaired in the field.

Here is a picture I pulled off the forum probably 15 or 16 years ago when I had my 97:



Those welds were done by NC robots with the mounts held in place by specific tools. I doubt they would have had such a large error in placement and welding of the UCA mounts in the factory. They were able to control things very close using that technology and if things had been that far out of alignment there would have been some sort of an alarm since they would have been welding to the frame without actually attaching the mount. 3/16 of an inch has been a ton of error in the NC and holding jig world going back decades.

Bill

Apocolipse

Hey Bill,

Thank you for the reply. One of the reasons that I was in there was to re-weld those locations you mentioned as a precaution since the frame is an early 98-99 which had the porous welds. This is where I started taking measurements and found it all out of whack. There is no indication of re-work at all. I also agree that it makes no sense to be off my that much with the jigs they used, hence my huge question mark around the entire situation.

Maybe if some people could measure their wheelbase simply comparing rim lips from side to side it would give an idea if this is just a crazy anomaly or something a bit more popular.