tchapma1

A little info on the car, 02 Z06, stock suspension, lowered approximately 1/2" from stock, 21K miles, approximately 7 DE events. Running 18x10 fronts with 305/30/18 Hoosiers, and 17x12 rears with 335/35/17 Hoosiers. I get some slight rubbing on the inner fenderwells on the rear of the car with this setup on very high cornering loads (rubbing is more witness marks then a full on rub). I am a fairly aggressive driver with the car, so I'm not just putting around. I've got the noise with and without active handling on.

I was out at a DE this weekend and on high g right hand corners I was getting a kind of loud pop noise coming from what sounded to be the right rear of the car. I checked over the car after the session, everything looks good back there (no loose bolts, obviously bad bushings, or broken parts). The only thing that I couldn't figure out a way to check at the track (without some major disassembly) was a rear wheel bearing.

Anyone have any ideas on where I might want to start looking? Or possible causes? It does not appear to affect the car any, and did not seem to get worse as the weekend went on. Thanks in advance, I'd like to get it resolved before my next event.

davidfarmer

you should have a jack and a torx bit at the track, as those bearings can be tugged on to find out if they are bad or loose, just by jacking the car up. Tug side-to-side for tie rods ends, tug top/bottom for bearing.

Anyway, could be in the diff, but it would likely make noise at low speed as well. Could be a half-shaft, as the inside tire at droop could be at a weird angle. Make sure the sway bar hasn't slid to one side, and bumping the control arm.

I would try and get the noise to repeat on the street. If you can duplicate it, that would help isolate it.

BUT check the bearing first, both for wear and to have come loose

96CollectorSport

Do you think that it's marbles comming off the tires and hitting the wheel well?
At Road America around the carousel especially (long sweeping right hander) I will hear this loud thumping sound not in any particular pattern, I mentioned it to the guys after the session and they said it was just marbles being thrown up from the tires.

hisvett

The harder I push, the more it happens.

tchapma1

I've checked for play in the wheel bearings, and also for general looseness on the tie rods, etc. I can't find anything wrong in the suspension itself. I guess I should have said the only thing visually I hadn't checked was the bearings.

I don't notice the noise at low speeds, it's only in out on track in hard right handers. I will look at the sway bar, but I don't believe it is off center (or if it is, it's not by much).

I've tried a little to repeat the noise on the street, but I can't get it to occur. I'll try to get a video up of it in the next couple of days and see if that helps maybe...

tchapma1

At first that is what I thought as well, but the noise seems to happen at the same spots on track every lap. That leads me to think that it's probably not marbles coming off the tires. First session out my passenger thought it was that as well until it was doing it every lap in the same place.

Maybe the video will help.

Olitho

From my experience you should pull all your rotors and look at the hub flanges in the corner were they meet up with the spindle. Those can crack under repeated heavy loads and they make a popping/twanging noise when they begin to crack. I know first hand....


Oli

davidfarmer

and speaking of marbles, rock can get jammed on top of the calipers, and scrub the wheels.

I would also jack the car up, and sit the rear back down on the suspension. Put the car in gear, and just let it idle, spinning the rear tires (shut down TC). Listen to the diff and half-shafts for any clanking. OBVIOUSLY, be very carefull when running a car on stands, but it is usefull for things like this!

outnumbered

Check your axle nuts. Spec. on a C6 is 118 lbs.

Mine did the same thing last summer. The axle nuts were very loose.

Dan

davidfarmer

good catch, 118-ftlb on the C5 as well

MNCrystalRed2011

I have had this happen on my C5 too. I take the socket with me all the time now.

tchapma1

Thanks for the ideas guys, I'll check these out tomorrow night. Anyone know what size the axle nut is? 36mm I assume?

outnumbered

34 mm.

Good luck.

Dan

gonzalezfj

Actually... it's 33mm, but a 34 mm socket will work.

outnumbered

I was told in the C6 Z06 section it was 34. It does work. I hope it's ok.

I paid 42$ for a Snap-on Socket.

But I do love the best in tools.

QwickerRon

I suspect it's clutch chatter in rear end. Had the same problem after replacing pinion. Get "monkey milk" rear end lubricant at GM Dealer. It'll stop it. Matter of fact, there's a service bulletin on it.

Rob's 73

I have a poping noise from the rear and I have isolated it to the sway bar. If I jack up one front side of the car it will pop. If I jack up the same side it won't do it again. However if I jack up the other front side it will pop again. I can repeat the process over and over. I have held onto the sway bar while someone else jacks and I can feel the vibration when it pops. I also disconnected one end link and repeated the process and it doesn't pop. As soon as I reconnect the end link it will pop again.

I assumed it was sticking/binding on the bushings so I took them off and put a little grease on the inside of the bushing....no change.

Ideas? Car has 18K on it with less than a dozen track weekends.

The only time I hear it while driving is when I am going in a driveway or somewhere where a front corner of the car elevates before the rest of the car.

tchapma1

I've checked the torque on my axle nuts, and inspected the bearings as best I could I don't see any issues. No rocks in the calipers or anything like that. As before, everything looks good still...

ghoffman

ALso check the upper rear A-arm mounts. In some cases, the welds crack where the mounts are welded to the frame. It happend on our '01 T1 car, and made a squeaky clunky sound.

davidfarmer

welds-cracking.......that's scary!