Clunking Noise

[Muddy]

I purchased a 1992 Corvette coupe (manual gearbox) about a couple months ago and have noticed a clucking noise (sound like a lug nut being dropped in to a wheel hub cover) when the car is under load. For example if I slowly reverse the car into my garage, which has about a 1.5” lip between the driveway and the garage floor, I have to put a load on the drive train (to get the tires over the lip) and I get this clunking noise (just one). If I then allow the car roll back out of the garage and try to slowly reverse the car back into the garage, the same way as previous, there is not any clunking noise. It is like something has moved and it is quite happy where it is. Now if I roll the car out of the garage again and accelerate in the forward direction a bit harder than usual I get the clunking noise (again just one). The clunking nose only happens under hard acceleration or load in both the forward and backwards direction. Has anyone experienced this problem?

I inspected the rear drive train assembly (it sound like it was coming from there) for loose mountings and joints but I suspect whatever is moving takes a large amount of force, at least more than I can give it.

I can always turn my radio up and the noise goes away!!

Cheers

Muddy

 

[evolution]

Sounds to me like a broken engine or tranny mount.

IMHO at least. I used to have a car that would do that under heavy load, ie. hard acceleration or brakestands

 

[jjones]

Had something similar going on and replaced 4 U joints (with Zerks) this week. Clunking is gone.

 

[Paul G]

I secong the u-joints. Time to give them a good inspection.

 

[Ken]

... only happens under hard acceleration or load in both the forward and backwards direction. Has anyone experienced this problem?

Yep! It wasn't the u-joints for me though. We're taking the precaution, as my project is being wrapped-up, to replace the wheel bearings. I was experiencing the very same thing -- only clunks (clicks in my case) when you initially load the drivetrain, no matter whether it's forward or reverse.

I have had people tell me that there was another shim (?) or washer (?) somewhere on the axles that weakens in the later model Vettes and that also causes the clunk or click sound.

Good luck. (and wish me luck as well )

 

[Muddy]

Hey Guys,

Thanks for the advice; it looks like I may have to replace the U joints. The vett will be off the road at the end of this month (I am having withdrawal symptoms even thing about it :cry) due to the new state (Texas) inspection that we into effect last month. You see my car was chipped when I bought it and there is no way it will pass the emissions the way it is set up, or so I have been told. I can use this time to look at the clunking problem and figure out how to unchip the car.

Where is the best place to get tires, my back two tires are almost like slicks.

Once again thanks for the advice guys, keep up the good work. I will let you know what the problem was.

Ken, good luck in getting your axial re-shimmed.

Cheers
Muddy

 

[jjones]

Sorry about the down time

Muddy
Yeah - I was out of service, too, for about a week but for the record, it wasn't a "guy" who mentioned u-joints! I'll forgive you.

Also - my car was running with a custom built Tommy Hill racing chip and breezed through Florida emissions every time (when we still had it) My recommendation - you should try to go through first before pulling the chip. Vette just might surprise you. Good luck. jj

 

[Muddy]

Sorry JJ,
It was a bit chauvinistic of me to take it for granted that only guys know about vetts.

I’ll put the car through the test as it stands, after I get new tires and at least I’ll have a month to get the car fixed before I am charged again.

You Gals and Guys are doing a great job.

Cheers
Muddy

 

[Ken]

Where is the best place to get tires, my back two tires are almost like slicks.

Sorry Muddy, I skipped over that part of your response yesterday. You DO know that we have the Tire Rack as an affiliate sponsor for the Corvette Action Center Community, don't you?

There are also many others listed in our Portal as well. Happy hunting.

 

[Muddy]

Hey Ken,

No I did not know Tire Rack is an affiliated sponsors for the Corvette Action Center Community, but I know now . Do we get any discount from them, it so, what would it be?



Cheers
Muddy

 

[vigman]

Shimmy....

On the shaft that mates to the wheel flange there is a factory shim. ( on the U joint side where the flange rests aganist the bearing)

This flange insures a TIGHT FIT between the BACK SIDE flange/ bearing/ front flange.

What will happen is if you replace your wheel bearing WITHOUT checking the runout.. your NEW bearing will get a LITTLE less life ( maybe 10k ish) because the load on the bearing race will not be centered SLIGHTLY.

So I shim when I re do...

and it is a dealer part.

Vig!