Need Help Troubleshooting a Noise

[Offbeat Octane]

Hi Everyone,
So last fall I noticed that at whenever i came to a stop i heard this not too lound clunk, promised myself I would spend the winter locating the source, and forgot about it. Just tonight i went out to check out something on the car, and in the process rocked my car side to side, and heard the clunk again, or something similar. I'm thinking maybe bushings? Not sure though, I'm doing the best to teach myself how to maintain this car, but i'll admit I'm still quite inexperenced with Vettes, and Mechanics in general. Any Help as always is much appreciated.

Chad

 

[Mac]

Chad, can you give a more accurate description of which area the clunk comes from? There are numerous things which can cause a clunking noise and some of them can mean you shouldn't drive until repairs are made.

-Mac

 

[Offbeat Octane]

Sorry, Rear of the car. other than that not sure. If thats too vague, Have someone rock the car while i try to find the sound tomorrow after work.

I'm going to need a second job for this car...

 

[Mac]

Corvettes have fully independent rear suspension which means there's a larger number of moving parts than a standard rear suspension... in other words, more things that can go clunk than others. Most of the time, it's easier to troubleshoot the rear suspension with the car on a lift but you can do it with a floor jack.

Basically, lift one rear corner like you were planning to change a tire. When the wheel is off the floor, grab the top edge of the tire and try to shake it in & out. Does it move? Does it clunk?? If not, work your way around the tire, doing the same thing- in & out.

If the tire check doesn't work, take the tire off and examine your shocks. They, too, can clunk! Stick your head underneath and examine the body mounts. A loose or rusted out body mount will clunk too.

If you don't find anything, move to the other side and repeat the procedures.

-Mac

 

[78SilvAnniv]

I'd also like to suggest checking your u-joints. There are 6 and any one of them could be the cause of your clunk.
Heidi

 

[BarryK]

also check the rear alignment shims, if any or all managed to come out it would allow movement of the trailing arm and cause a clunking sound, especially when going around a turn.......ask me how I know!

 

[GaryS]

Hi Everyone,
So last fall I noticed that at whenever i came to a stop i heard this not too lound clunk, promised myself I would spend the winter locating the source, and forgot about it. Just tonight i went out to check out something on the car, and in the process rocked my car side to side, and heard the clunk again, or something similar. I'm thinking maybe bushings? Not sure though, I'm doing the best to teach myself how to maintain this car, but i'll admit I'm still quite inexperenced with Vettes, and Mechanics in general. Any Help as always is much appreciated.

Chad

Noises or thunks that occur when starting out or stopping are often associated with a differential front bushing failure. This is about a $40 part and takes less than two hours to replace. It is a rubber bushing with a steel insert that is the forward mounting point for the nose of the differential. Very easy to replace, just a knuckle buster.

Noises that occur when moving the car from side to side can be the u joints or the axle, where it goes into the differential. Jack up one side of your car and support it on jack stands. Grab your tire at the 6 and 12 o'clock position and alternately push and pull at those two positions while you have someone watch the stub axles and see how much they move in and out at the differential.

Let us know what you find out.

Gary

 

[Offbeat Octane]

If it were the U-joints wouldn't I hear them while i was driving, not just stopping? I'll jack it up tomorrow, it's supposed to be nice, plus all my exams will be finished by then.
Thanks Everyone I'll let you know.

Chad

 

[Offbeat Octane]

It's not the u-joint's just checked, so to fix the differential bushings i need this part...
http://www.ecklers.com/product.asp?pf_id=A7153&dept_id=1861
How involved is it and what tools do i need?

Chad

 

[JOE BYRNE]

Welcome

Welcome to the never ending love affair. These cars can make you happy sad and mad sometimes all in one day. I have not had to change mine yet but it should not be to tough. Just make sure you have jack stands under her before you climb under. Make sure you soak the bolt with PB Blaster. Hardest part is the amount of room you are working in and the amount of skin you will loose in the process.

 

[78SilvAnniv]

If it were the U-joints wouldn't I hear them while i was driving, not just stopping?

You know, I was thinking about this as I read your above question (I've seen that you found it was not the u-joints) but I wanted to share my thought...

You are right about the u-joints making noise when driving (usually squeaking) and not only when stopping. I would like to point out that loose u-joints will make a "clunk" sound when FIRST put under initial load. This means it would clunk only when going from any neutral setting to any load gear. I do not think it would clunk when moving from a stop because it would still be under 'load' when stopped by the brake pedal...so this is why I feel my above suggestion for you to check u-joints was erronious. My bad.
Just something to file away in your brain somewhere...
Heidi

 

[purpleRac3r]

Ah, welcome to the world of independant suspension! Your differential front bushing isn't difficult; however, bear one thing in mind. If your is like mine was, the old bushing has compressed over the years, and the space between the differential bracket and the frame mount may be less than the thickenss of your new bushing. Not a big problem, but you may haave to apply a little judicous application of leverage to widen the gap enough to slip the new bushing in. Also, if you just remove the bracket from the differential and expect the bolt holes to align with the new bushing, you again may experience a touch of difficulty. You should be able to change it out within a couple of hours, even if you run into this problem. Good luck! Also check your shocks and shock mounts. Worn shocks and or loose mounts can cause some clunking noises. Can't hurt to check.

 

[Offbeat Octane]

Thanks Everyone, I'm printing all this out, and ordering the parts.
Soon as it warms up above 40 degrees i'll start on this. This isn't a huge deal though right? it's driveable till i fix it?

Thank You, Thank You!

Chad