Hey there guys,

This may be somewhat elementary to post this here, but I figured since the experts lerk here, I could get a more accurate response.

Here's the rundown. I bought a C5 recently, had F45 suspension with Z06 sway bars. The car was pretty darty, and the rear felt like one shock worked and the other was bad because the car would wobble over bumps(not normal for a C5). The guy had the car aligned just before I bought it. He said the rear tires were wearing wrong and he didn't like it.

So I replaced the shocks with Z06 shocks.(all four F45 shocks were completely shot). That seemed to pretty much fix everything. The car was still a little darty, but it wasn't bad. Well, because I don't autocross, the ride was really more stiff than I wanted to deal with since the roads around here are not good. So I changed back to a base suspension(shocks and sways. left the stock springs alone). Well, now, the wobbling in the rear is back and so is the darting(although not as much). Now I know this isn't normal because my previous C5 with the base suspension didn't do this.

Here is my theory and I just want confirmation:

When he had the car, the shocks were so bad, the car looked lowered even though it wasn't. Well, he got the car aligned in this state. When I got the Z06 shocks, it alleviated the wobbling because of the stiffness, but going back to a softer setup has caused this condition to reappear... SO, after all that, does it sound like the rear alignment is off?

Thanks for the help and sorry for the long winded explanation!
Daniel

 

The alignment shouldn't cause a wobble. It sounds to me like you've got a broken part or two in the rear end, or possibly a very worn hub, tie rod end, etc. It's hard to say, but these cars don't wobble unless something is seriously wrong.

Check over all the nuts and bolts back there and look at all the suspension parts. Make sure to examine the hubs and wheels too. If nothing else, just take it to your local trusted mechanic and have him do a thorough check of the whole car and see what's up.

 

If it was something pretty serious, wouldn't it still be noticeable with the stiffer shocks?

 

Maybe, but they may be masking something like a worn/broken spring too. It could be 100 things, but these cars don't wobble unless something is really screwed up. Pull the wheels and rotors off (so you can see the hubs) and start checking...

 

I would check the mounting points for the upper rear control arms. There was a problem in the early years of the C5 with broken welds on these mounts.
Bill

 

ok thanks! What should I look for when I pull the rotor? Should there not be any play in the hub?

 

I don't have my Helms manual with me, but the amount of allowable play is very minimal - seems like it's .005 or thereabouts. If you can physically feel movement, it's probably too much.

 

You normally check for play in the tie rod ends and the hubs with the wheels on. Just jack the thing up off the ground and pull on the botton of the tire...back and forth...then the top...then the front and back...etc. You shouldn't feel any play in the wheel. If you do, it means something is loose/broken/worn.

Once you check all those, then remove the wheels and the rotors and check the front and back of the hubs and make sure they're not broken. Mike S. found a broken hub while we were at Homestead this year, so it does happen. Always check them when you replace your rotors!!!!!!!!

 

All of the above, plus

Might check the Hub bearing bolts...we have found them to loosen up on a TT car and a T1 car... rare but did need a little extra torque,
PL @vansteel

 

Thanks guys. I will look at it and let you know what I find.