Drivetrain clunk???

[JPLT1]

Ihave had a clunk in my drivetrain for some time now. Hasnt gotten any worse and hasnt gotten any better. The car runs fine with no problems. The u joints have been changed, driveshaft u joint have been changed, new ring and pinion in the rear end too, and the clunk is still there. When I take off from a stop under normal acceleration it will clunk going into second gear and nothing else. When I take off from a slow roll or turn a corner and accelerate it clunks. I have heard on other forums that his is normal. I cant imagine that this is normal. Does anyone have any ideas as to what this may be? Thanks for the help.

 

[68Roadster]

JPLT1,
I too have this problem on my 68.
Heres what I have been told so far:

1) The rubber bushing that secures the diff to the crossmember is loose or worn out....

2) The rear end fluid has been changed and the GM additive has not been put back into the diff...

3) The trailing arm front bushings are bad or the shims are missing and they are loose.....

4) Possible wheel bearing side load discrepancy...

I feel your pain bro......been driving me nuts for 6 years.....I can smell a rear end rebuild on the horizon for me.....only way I'll be happy and secure....

Lotsa Luck!

Cee

 

[JPLT1]

Thanks, I will add this to my notes of things to look at next time I have it up in the air. Hopefully that will be soon when my headers get here.

 

[68Roadster]

Sweeeet lookin ride.......like the Black Sheep logo too!

Let us know what ya find out.....

 

[JPLT1]

I will. I know the fluid and additive are in the rear end. Hopefully I can find a bushing or shim that is missing or wornout. Cross my fingers.

 

[vader86]

I would take a look at the bearings.

 

[78SilvAnniv]

Not much experience...

...but here is what I went through. I don't think your clunk is 'normal'.

First thing that comes to mind are u-joints and bushings, but you have addressed these. U-joints will also make a squeaky, squealy sound. I don't know about worn bushings, mine haven't made any noise.

I had clunks, and then it progressed to moaning and groaning in fits and starts as the pieces grabbed and slipped against each other when taking off from a stop or turning a corner at low speeds.
This was a direct result of worn side yokes. Because of this condition, we also replaced the rear end.

I think the clunk, if it were from the drivetrain proper, would occur at initial load, not only second gear. I think the suggestion to narrow the search down to the suspension components, body and frame mounts and shims is good advice.
Good luck with your search.
Heidi

 

[Mad-Mic]

does it do it when you step on the gas from say 40 mph in 4th gear?

mine does this sometimes as well. i was told with all the u joints in these cars it will do it. it's not bad but seems to be after i let off the gas and i put load back on the drive train. not like flooring it just tapping the gas. at first i thought it was a transmission mount cause this has happened to me before in my 82 Z/28. if it don't do it under "race" conditions i think you are fine then. if it does it like i said at around 40 mph in 4th gear slightly tapping on the gas then it is natural occurance in these cars. mine has never done this under "race" conditions like from a dead stop upon a launch.

hope this helps

 

[ggsteiny]

Drive train clunk

Don't forget to check the motor mounts,a bade one can cause a clunk sound from engine movement if defective. save the wave.

 

[JPLT1]

I dont think it is the motor mounts as the motor dosent do anything funny upon revving it. Also the sound definitly comes from the back of the car.

 

[compyelc4]

JPLT1 and Mad-Mic:

I have a 95 auto, with 20K. Always babied. My clunk is similar to Mad-Mic's. Have had it since showroom. Never worse, never better. Hear/feel it mostly when easing up on accelerator and then loading her back up as when slowing down to turn corner then giving her gas coming out of the turn.

I can "punch" her at any speed, even off the line and no clunk.

I was getting ready to replace all those components you did JPLT1, but I guess I'd be wasting my money huh?

I think I'm going to leave her alone. Actually, I had a similar thing in my '96 Monte Carlo SS, except the clunk occurred when I shifted into drive from park. Sounded identical though. GM said that was drive shaft slop. They revalved the transmission so she eased into gear a little less harsh and than solved THAT problem. Probably not related though.

Ted

 

[JPLT1]

Thats exactly what happens. It has been there as long as I have owned the car. 3 years now. Im still going to investigate the problem though, it just dosent seem right or normal.

 

[68Roadster]

This sounds like one wicked problem with no fix in sight....
Mine tends to happen when I load up the car one way...
Heres the scenario....
Run thru the gears pretty good, make a right or left hand turn and pull up to a stoplight......ease her back into first gear, let the clutch out and hear a double clunk as she starts to roll out.....the weird thing is I can feel it in the seat of my pants......it's almost like the whole *ss end shifts......this will only happen after I load the car up one way or the other by turning.
Wheels are tight, u-joint are new because of this problem, diff is full with oil/additive and trailing arms are tight shim wise. Guess the bushings could be shot but seem OK.
Another weird thing is the tires on the rear don't sit in the wheel wells the same......one sits out farther than the other, about 1 inch.
I'm about one season (spring) of yanking the whole rear end out to try and remedy this problem......

Cee

 

[compyelc4]

JPLT1,

I've been all over the internet with this problem. No cure yet. Let's stay in touch. I just joined a vette club and plan to do mucho outings this coming year. I'll let some expert out there give her a test drive and diagnose the darn thing. I'll let you know what I find out. You do the same.

Ted

 

[jmccloud]

clunk

I had a similar clunk (feel it in my .ss, going into second gear, sometimes rounding a turn and hitting a bump, sometimes just hitting a bump), but very intermittent and unpredictable. Got new tires and the dealer suggested checking the donut. It was flat. When aired up, the nut holding the spare cover went up several turns less. Clunk is gone. I think the previous owner had tightened the spare tire cover but hadn't checked the donut.

 

[vigman]

The other MYSTERY rear end KLUNK

Are the splines in the rear hubs shifting as they get worn.. My 88 does it.. and I have done EVERYTHING in the rear end.. except the yokes.. that go into the hubs... some people fix this by OVER tightening the yoke nuts.

With MIXED sucess!

Vig!

 

[swoosh]

I have a 96 than clunks ever so often. It doesn't bother me a bit.
If my vette wouldn't make any typical sounds of a CHEVY. I would wonder am i driving a LEXUS.

 

[Full Bull]

my 95 does likewise...particularly when I've slowed down for traffic...say to 5-10 mph...and then accelerate slowly...clunk. My mechanic says there's nothing wrong...just a quirk on that year's vette.... .????

 

[JPLT1]

Hey all, thanks for the responses. Sorry I havent checked back in a while. Well, I had my wheels off the other day to do some cleaning and noticed that all the bushings are rotted and appear to be collapsed. Im going to replace those next and will post back with the results. Probably wont be for a couple weeks though.