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1 clunk b4 full stop, 1 clunk top end of 2nd?

bem88

Member
Joined
Jul 26, 2007
Messages
5
Location
CO
Corvette
1988 coupe
Hello all: Well I can't find this, and nor can the mech. About 2 months ago my 88 started feeling a little mechanically rough in the back end - engine is fine - trans shifts nicely (auto)...and shortly after started to get a single clunk in the rear (maybe the left side) immediately before coming to a full stop, and again somewhere through 2nd - almost going into 3rd.

I had the rear half shaft U-joints swapped out and that reduced the roughness to about 30%, and intend to do the main shaft u-joints too. (Also will be changing the shocks - don't think they're doing much).

But the clunk is still there - it feels like something is shifting or rotating, rocking one way during braking, then back the other way under acceleration.

Now here's the thing - if I accelerate spiritedly I'll get the clunk in 2nd and then again before a full stop - but if I take it real easy I will not get the clunk in 2nd, and then also will not get it before the full stop. This is driving me bananas! I've looked all through the posts and this doesn't seem to appear! All nuts and bolts appear tight.
Any ideas? Thanks in advance.
 

gmjunkie

Well-known member
Joined
Nov 11, 2004
Messages
4,547
Location
Old Fort NC/Vero Beach FL
Corvette
03 Z-51,78 L82 Coupe
Hello all: Well I can't find this, and nor can the mech. About 2 months ago my 88 started feeling a little mechanically rough in the back end - engine is fine - trans shifts nicely (auto)...and shortly after started to get a single clunk in the rear (maybe the left side) immediately before coming to a full stop, and again somewhere through 2nd - almost going into 3rd.

I had the rear half shaft U-joints swapped out and that reduced the roughness to about 30%, and intend to do the main shaft u-joints too. (Also will be changing the shocks - don't think they're doing much).

But the clunk is still there - it feels like something is shifting or rotating, rocking one way during braking, then back the other way under acceleration.

Now here's the thing - if I accelerate spiritedly I'll get the clunk in 2nd and then again before a full stop - but if I take it real easy I will not get the clunk in 2nd, and then also will not get it before the full stop. This is driving me bananas! I've looked all through the posts and this doesn't seem to appear! All nuts and bolts appear tight.
Any ideas? Thanks in advance.
Wheel Bearings,Carrier Bearings,Pinion Bearing,Loose Yolk,Trailing Arm Bushings,Differential Mounting Bushings,Transmission Mount,Engine Mount, any or all could transfer a Clunk to the left rear!!;shrug:upthumbs
 

bem88

Member
Joined
Jul 26, 2007
Messages
5
Location
CO
Corvette
1988 coupe
Hi - thanks - at least you didn't say my transmission or diff!! Seriously - I took a look at what bushings I could - I do notice that the edges of the shocks bushes are showing signs of a little cracking - but all look structurally sound - I am thinking of a polyurethane kit though - might be a good thing. I bought the car a year ago and prior to that it had not had much use - I'm probably freeing up all the gremlins - it only has 63k miles on it. Thanks
 
R

roscoethug

Guest
I also have an '88 Auto with the same exact problem. Sounds like slop in the diff gears, but only when shifting from 2nd to 3rd. All other upshifts are quiet, but also the same noise when stopping and the trans is shifting back to 1st. I would love to know what needs fixing. Changing diff lube made no diff. (get it?)
 

G Winter

Well-known member
Joined
Aug 21, 2004
Messages
2,177
Location
NW Iowa
Corvette
1990 red convert 6 sp
Are you sure the C beam bolts are tight? I would check the torque on those four bolts. Remember it holds everything in the drive train in line.
 

muddywaters

Well-known member
Joined
Aug 25, 2002
Messages
765
Location
wilkes-barre,pa.usa
Corvette
1988 white 4+3 coupe 99 Torch Red 6spd. coupe
Wheel bearings, I thought I had slop in the rear end of my 88, changed out the wheel bearings (Timken) and it's like a new car,slop/clicking gone. And NO POLYURETHANE BUSHINGS, you WILL be sorry.
 
Last edited:
R

roscoethug

Guest
Thanks guys. Just got back from Carlisle where I spoke to some suspension and rear end gurus. They said to check the u-joints for "red dust" which would indicate they are beginning to fail., and do the same check for the bearings. They said u-joints are relatively cheap and easy to replace and a good starting point. I'll give it a shot and update the thread.
 

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