Project C4, 85 Corvette

[Steve85]

Some time ago at an autox (this was the first college solo I think)  i looked at on course pics and had a lot of positive camber in the rear around turns. First pic looks normal (driver rear) but second pic shows how positive it went when loaded up.






I got an alignment and used the VB&P specs for aggressive street which included going with offset bushings up front. (occasional casual autox) At rest, there is definite negative camber in the rear.

At my latest autox this weekend (MBCA at James Wood High School in Winchester), I decided it would be cool to get a shot of the rear suspension in action. Here it is below. I was very surprised to see the inboard mounts for the camber rods deflecting in/downward when turning. If you pause at the :32 mark, you can really see the deflection, the adjustment bolt is lower and more inward than the other side. That point on the course was a medium right hand turn after a straight, so it would load up the left pretty good.



It's hard to maintain camber when the mounting point is moving and the way it mounts there is no (or shouldn't be) pivot point. 

I tested the bolt tightness and it wasn't loose, but it wasn't as tight as it likely needs to be. I think this probably allowed just enough movement to make things worse over time. 

As suspected, the lower bolt hole has been worn and is now a bit slotted. You can see in the pic how much wider the bracket hole is than the hole the bolt goes through. It looks like it is offset, but as the photo was taken the left side of the bracket hole lined up properly with the diff mount such that the bolt could go through. 



I tightened the bolts and then went for a test drive to see if they would hold for now until I can get to a permanent solution. In the video, it looks like they holding for now. (And the rear definitely felt more stable)



I think the other contributing factor is that the bolts are not the factory original and while they are grade 8, they are "all thread". I believe this makes them just a bit skinnier than if they were a non-threaded shaft with threaded end (partial thread). Kind of what Dave was getting at and a great point! (I'll also look into the suggestion on the eccentric, these are actually VBP Smart Struts and you're right, really no need for the eccentric with the adjustable rod)

My solution will be to either get new brackets or have these welded to repair hole, order new flange headed partial thread bolts, and double check torque on installation. Then go back in after a few drives to make sure they aren't coming loose. 
Anywho, pretty cool to see the suspension in action (which was really the point of this shot to begin with ). It's amazing how much movement there is despite feeling so stiff.