arcticZ51

Just noticed this today- while driving through the center of town at low speeds when I hit some choppiness (sharp bumps) in the road I hear some sore of clunking/rattling from the rear of the car. I haven't picked up on it before as I don't hear it at higher speeds, or when I'm not driving down an enclosed road (businesses on either side) to amplify the sound.

My first guess was the exhaust bouncing around however after grabbing it and manually wiggling it in every direction it's completely quiet. The only other thing I can think of is something to do with the suspension. I read on here that my Z51 has rear grease fittings. I bought the car used a few months ago and I have yet to do an oil change (gauge still says 67%). I'll see if my mechanic can address this "grease fitting" at that time.

Meanwhile do you think this is the culprit? If so what IS this grease fitting for? If it is the culprit- is it reversible? Finally, has anyone else noticed the same on their car- and any ideas on what it could be that I haven't touched on?

Thanks in advance!

tlcj

Rear sway bar end links is my first guess.
Axle nuts torqed correctly is my second guess.
Do not think it wound be the diff lube issue since noise in straight line.
I have read some threads where the front sway links were bad but owner thought it was coming from the rear.

Full Metal Jacket

I had noises in the rear also but when going low low speeds and in reverese or 1st gear. typically backing out of parking space, drive way and other low speeds moving back and forth..

car drove great though.. Its a 2005 w/ 52k i dropped it off at Day Chevy, and they called back..

Diff needs fluid change under a service bulletin..

They did it all for 167.00!!!!! Car runs nice and tight now..

arcticZ51

Yeah my sound is definitely only evident when hitting bumps. I think the first reply regarding the sway-bar endlinks may be on to something.

S2K

It is the sways no question. I had this exact same issue on a number of occasions over the years. Once it actually was the front sways and the noise traveled such that it sounded like the rear. So when you get the sways checked also have them check the front. I went through the axle nut and the rear diff fluid before finally getting the problem correctly diagnosed. I'd bet money this is your problem.

arcticZ51

Excellent- thank you. So if it IS the sways- what is the solution?

tlcj

I assume this is the 2009 in your profile. Take it to the dealer and tell them to fix the clunk in the rear end. It should be covered under warranty. I believe there is a tsb on the subject, but I am not sure what years that covers.

arcticZ51

Do yo have a link to this TSB write up online? Thanks in advance!

Flat Broke

Rocks in hubcaps?

arcticZ51

I just got back from driving it again- honestly, it sounds less like a clunk and more like a metallic squeaking sound as I hit the bumps. ????

Ktzon

It may be the same problem that I had?

http://forums.corvetteforum.com/c6-c...r-service.html

arcticZ51

My gosh- I certainly hope not. Any news?

PS Do you only hear the noise when you hit bumps at lower speeds?

Ktzon

Yes, this is a problem that has been going on for years. I talked with Tadge Juechter (GM's Chief Corvette Engineer) at Carlisle 2 weeks ago about the problem. His' response was, GM knows about the problem and these cars shouldn't leave the factory with this issue.

There is a fix but it calls for your dealership to install stiffeners behind the seats.....I'll do the fix my self since I'm a Aerospace Engineer and deal with Oil canning issues and aircraft strengthening all the time. I don't have faith in turning the car over to my dealership for the fix.

Good Luck.

arcticZ51

I don't even know what "oil canning issues" are?! Does this affect 2010 Grandsports or a wider range of vehicles? Mine is a 2009 Z51.

Ktzon

Oil-canning-
A moderate deformation or buckling of sheet material, particularly common with flat sheet metal surfaces. Typically caused by uneven stresses at the fastening points. This terminology also refers to the popping sound made when pressure is applied to the deformed sheet forcing the deformation in the opposite direction.


Is what your hearing a metal "Popping sound" coming from the rear of the car? When your driving very slow over an un-even surface (Say a speed bump) the car will twist just enough to buckle the Aluminum sheet just behind the seats...thus Popping.

GM recommends the dealership take a hammer and pound the crap out of this, basically putting in dimples which will strengthen the Aluminum sheet. Something's wrong when a fix requires a hammer....

And yes, this problem is in the coupes, GS' and Z06's.

Vasta

I have the same problem when going over bumps in the road. To me it sounds more like a clunking noise. I've had my rear end fluid swapped, and I have a GHL cat-back system that seems tight. Next time I take it to the dealer, I'll have them take a look at the sway bar.

Gearhead Jim

They're not just pounding it with a hammer, they're doing a "percussion adjustment".

S2K

They will likely need to replace the end links. This is an easy job and will be covered under warranty. I am still betting big bucks that this is your issue.

mrtoner

Nope - loose lug nut fell out and is rolling around in the hubcap....

arcticZ51

Yeah I'm taking it for an oil change (not the dealer but my private mechanic). I'll have them take a good look at it while on the lift. Though if it's bad endlinks how will they be able to tell.

In other words I'm trying to avoid going to the dealer if I have to. I'm not necessarily as phobic as some about it but it doesn't make me feel all warm and fuzzy inside. Too many horror stories.