tabbruzz

Need some opinions here. I have a problem with my 79 that I need to fix asap. Here's the deal- When the car gets hot after about 45 minutes of driving I start to hear a clunk, clunk, clunk from the rear end. While driving it feels like it's coming from the left, but the passanger claims it comes from the right. It happens as I'm braking and as soon as I let up on the brake to proceed. It happens 75% of the time once it starts. It also happens when turning AND going straight. It stops after about 3 or 4 clunk sounds. For some history the halfshft u-joints were just replaced, the pass wheel bearing was replaced, the brake pads are replaced. I did a test to see where the sound comes from. This is what I did- I had my wife drive forward and in reverse while I listened. When the clunk starts I flet the tire as its moving and felt the cluck equally on the driver and pass tire. It didn't do it every time. Now please can I have some input????? Thank you

Koz

It only happens when she's hot?

Here comes the obvious questions to get them out of the way for the guys who know what their talking about.. :D .. Do you have the diff. additive (2 bottles) along with the diff fluid in there.. Have you check your diff fluid? I'm guessing that a problem/clunking in the diff will vibrate it's way to the wheels. If it doesn't happen when she's cold then I wouldn't suspect wheel bearing or universal.. Have you tried draining and refilling the diff with clean fluid and addative.. Just to make sure you've done the easy stuff.. Good luck..

tabbruzz

I haven't checked the diff fluid, but already have plans to drain and refill it on Wednesday. It seems that bad fluid is usually a problem with sounds heard while turning. As my problem happens while turning or going straight, I really am skeptical that the fluid can fix the problem. Correct me if I'm wrong....

wcsinx

You are. It can. :lol: :thumbs: The fact that it only happens after it's warmed up would definitely seem to indicate the diff fluid. Don't forget the posi additive.

Eddie 70

Since you are going to be under the car, try checking the differential bushing. If it is worn it will give the clunking sound also.


[Modified by Eddie 70, 11:47 AM 7/7/2003]

TedH

I second both the fluid/additive and bushing suggestions. May also want to consider side yoke end-play if the lubricant or bushing are not the problem.

SmokedTires

:iagree: Could be the posi clutches sticking and releasing, the additive will help this. Also grab you rear tires at 3 & 9 o'clock and 6 and 12 o'clock and see if there is any play with either direction. Check the front of the trailing arms also to be sure the bushings/ shims are there keeping everything in place as they should.

Good luck :)

bigvette1

People may bark at this one, but it ihas resolved two problem rear ends in this house. I remove the rear cover, drain all fluid out, then flush it out with a can or two of brake cleaner sprayed into the rear end gears and clutch packs. Draining only does not get the sludge and chips out of the packs. Then fill "er" up with the 2 quarts of GM rear end lube and a bottle of the posi lube and drive it. Two times the clunks, growls, turning growls have been fixed.

tabbruzz

This is great guys---thanks for the responses. Anyway, I did grab the wheels from the 3 and 9 o'clock position and there is no movement. The 12 and 6 o'clock has very very little movement and about the same amount on each wheel. My friend checked the bushings and said they look fine, I will recheck..