indy300

Guys/Gals, I need some ideas. During my runs at Putnam Park I had extreme wheel hop on some right hand turns. I had to lift to get it to stop. I asked a couple of guys at the track and they quickly eliminated wheel bearing problems. I have a 2001 coupe with the selectable suspension that was set on "sport" and apparently I have C6 Z06 sway bars on (28.5mm on rear). I am wondering if the rear sway bar is too stiff for my car?..

Does the masses have any ideas what could be causing wheel hop on the turns?

Thanks in advance.

robvuk

Was your active handling on? Did you modify the brakes? Do you make the appropriate changes to the FRONT swaybar as well?

indy300

The brakes are stock. The front sway bar is a thick one also. I tried turning active handling and traction control on/off and it still did it.

thanks.

robvuk

Maybe a bad right rear shock? Loss of shock control might show up that way. Very unusual but possible.

yellow01

What tires?

EMTs will hop even in corners. Never had it happen on the track, but occaisionally if I got on my '01 (had EMTs on it) too much in turns I wouldn't slide but it would hop.

indy300

I have stock EMT's. In the past I've had the back take a hop while going around the highway and there was a break in the road. But this is wheel hop like getting on it from a stand still. The hop that beats the rear up.

yellow01

Can't say for sure. I've had both of what you describe with the EMTs.

I'm not trying to convince you it's that, I really don't know.

What I can say for sure is I have had wheelhop - dropping the clutch kind and going around corners under power - with EMTs. Each time ti was the duh-duh-duh-duh constant hop that either ends with you letting off the gas or a trashed rear end...

I have NEVER had it, EVER when running on non runflats (specifically Kumho MXs) even when driving on the same roads and same driving habits.

Based on my experiences, and what you describe, I say tires. JMHO.

indy300

Thanks for your suggestion. You may be correct. If it IS the tires, I think it would be interesting. GM and Goodyear spent countless hours and money designing the right combination for the tires and rear suspension and I go past their limit my first time at the track .

After a couple of laps my rear tires were at about 37 to 39 psi. Maybe too much air for the rears?

indy300

Well, it is not the thick rear sway bar causing the wheel hop. I went back to my base suspension rear bar and it still does it. I have a deserted set of roads close by to test it

I checked the computer codes. I had history codes for "steering sensor rate malfunction" and "loss of communication with BCM". Do these mean anything to anyone?

I'm at a loss. I don't want to take it back to the track until it is fixed. I don't want to damage the car...

yellow01

Are they historical or current codes? Sometimes loss of comm can happen for who-knows-why.

Do you have the adjustable shocks? Maybe they're acting up? Have you tried different modes (if you have 'em)?

indy300

They are all historic codes. I have the adjustable shocks and I've tried different settings. NADA!

Thanks for the continued help.

Solofast

If you have both Z06 bars that isn't likely the problem. If you have only Z06 the rear bar it could be part of the problem, since that would tend to make the inside rear wheel lift more and could make it worse if you have a differential problem.

What I am thinking here is that if you have a problem with the limited slip diff, it could cause what you are seeing. If this is happening when the inside rear tire is unloaded and you are trying to accelerate it could be that your limited slip is unlimited (clutch pack worn out) and your inside rear tire is spinning, which could cause the hop. Just cornering with a bit of acceleration isn't going to cause hop, it will take some wheelspin to do make that happen, which can happen only with an open diff.

Chock the front wheels and jack up one rear tire. It is better to use a floor jack and align it with the car so that if the car moves the jack will roll and the car won't fall off the jack. Leave the car in netural and don't set the ebrake. Put a torque wrench on one of the lugs and try to tighten it, don't go over 100 ft lbs of torque. Determine where it breaks away. Somebody can chime in on what the torque spec is for diff breakaway torque, but if it isn't over 50 lbs I'm sure you have a problem... On older Camaros' it was around 100 pounds if I recall correctly...

It is possible that excessive use of the stability control could result in premature limited slip wear. What is happening in that case is that stability augmentation is kicking in and trying to help control the car. To do that it is activating one rear brake and letting you apply power with the other rear wheel. This will help rotate the car, but it is he!! on the differential clutch packs. I left the the car in the normal mode for one autocross run by accident and could feel the diff locking and unlocking. It wouldn't take much of that on the track to wear out the clutch pack...

If you find the breakaway torque is low you will have to get the diff clutches replaced..]

Let us know how it comes out...

indy300

Well I did what you suggested. Got the right rear tire in the air and tried to tighten a lug nut. At 100 ft-lb it didn't break loose. I assume thats good and bad I'm goin to make sure the diff is full of fluid now. Then....i have no idea...

Solofast

In looking at my post I should have put the caveat in there that you should be pulling so as to increase the torque on the wheel. That is, when the wheel is being torqued, the wrench is to the outside of the wheel. If it is to the inside, you aren't putting as much torque on the wheel.. But still if you have good clutches in the diff, maybe you have a shock or bushing issue or wheel bearing issue. I'm pretty much at a loss other than looking for things like leaking shocks or trying to find something loose...

yellow01

I wish you were local I'd let you put on my tires and take her for a spin and see if you still get it.

It's just my gut...

I know what you said about GM engineering the car well, but at the same time there are compromises... runflats are one of em.

You said on some right hand turns, was it always the same ones? Any small mid corner bumps or irregularities?

You said OEM runflats - are they the SAME tires since 2001? (sorry if this is a dumb question but some people don't put on the miles, I'm trying to understand how hard they are by now)

When you do find out what's doing it PLEASE post, I'm very curious to see this one through.

indy300

I don't know if the runflats are original. The car has 58K miles and the tire still have a lot of life left.

The wheel hop would always occur on the same right hand turns. The turns did not have any irregularities. The hop would occur as I got back on the gas.

As far as the shocks... they react well and normal when I push the rear of the car down. The shocks are clean and I don't see any fluid leaking out of them.

What is the test for wheel bearings? Some guys at the track pulled and shook the rear wheels (the car on the ground) and said it wasn't the bearings. What is a better test?

Thanks for everyone's help on this issue.

indy300

NEW DEVELOPMENT!!!

So I put the vette on jack stands to get under the rear to investigate my slow leaking differential and look for any wheel-hop related obvious clues. I'll refresh your brain: I get wheel hop when accelerating out of a RIGHT hand turn. Well, I found a bunch of "crud" covering the lower third of my right rear shock (F45 Selective Realtime Damping). The crud also covered the cable connector (electronic suspension control?) at the bottom of the shock. It looks like dirt and dust stuck to a "wet" surface. The crud was black and just a bit oily. The surface isn't currently wet, but was in the past. I saw no evidence of leaking brake fluid. The LEFT rear shock looked completely clean and dry.

So I assume this is evidence of a leaking shock, correct? Damn, I hate to fork out the money for a replacement F45 shock and that not cure my wheel hop problem.

yellow01

If it's only on the shock and not on the inside of the wheel then I'd say yes, sounds like a bad shock... although leaking externally is kinda wierd.

It could also be a bad cv boot, but that's grease and sprays everywhere inside the wheel.

I'd say pull the shock and compress it by hand and see if it even rebounds. I blew an OEM shock (not sure how), the car drove ok on the street but when I pulled the shock (for another reason) I could compress it and it simply never came back.

Glad you found some indication, even if it means you need to fix something.

indy300

Well, I pulled the right rear shock. I was able to compress it easily by hand and it did not extend back out. I think the case is solved!

Now I need decide on a replacement. I don't think I want to spend $400 for one shock. I may switch all four with non-F45 shocks.

ErnieN85

Bilstein sports & turn off the selective ride with a TECHII