My car is an 89 coupe with auto trans. I have a clunk that I believe is in my differential. I'm sure it's not the u-joints since they all have less than 5k miles on them. I'm equally sure it's not the rear wheel bearings since they both have less than 2k miles on them. The clunk is definately a heavy metalic sound and is coming from the rear. I've been hearing the clunk for some time and that's what prompted the u-joint change. It seems to get worse with time and miles. At first I only heard it when changing from drive to reverse and back. Now I also hear it when slowing for a stop or corner, or accelerating from stop or corner. Is this something a competent home mechanic can do himself or should I take it somewhere. Thanks.

 

Might try searching past posts, as there has been a lot of discussion on this lately. With all your new parts it could well be the rear end. I did have somewhat the same symptoms when the C-beam bolts were a tad loose.

 

While you are checking the "C" beam bolts, front and rear, try wiggling the pinion yoke. It should not move up & down, left & right, or in & out, at all. If it does, you have diff problems.

RACE ON!!!

 

I had similar clunk, very big clunk from rear end. It was the transmission! Somehow the clunk was transfered through the driveline. The tranny finally blewup, the new Level3 Raptor is in & clunk "Gone".

 

Always keep an open mind!!!! Just because you have new U joints and wheel bearings does not mean that there is nothing wrong with them. Put your car on a lift with the rear wheels free. Turn each wheel back and forth and watch the axle and the driveshaft. When I did this on my 87, I found the lost motion to be a worn left side spindle to bearing
spline and defective bearing.

 

I don't mean to highjack the tread but I also have the same symptoms and want to look into it during the winter.

I have a very similar clunk, but it doesn't' seem as audible as yours and its intermittent, it usually does it when I'm slowing down or when accelerating at a normal speed, from one stop sign to the next... just like yours. I'm also worried about the rear end and the tranny but they were both rebuilt about 3 and 4 years ago and I only put about 10000 Miles on it since the tranny was rebuilt.

I unbolted the C beam a wile back to change the main drive shaft U joints... and it seems like it started after doing this. I bolted them down with the impact and a wrench.... I'd be surprised if this was the problem but I guess I'll have to check it again.

CFI EFI, if wiggling the pinion yoke, up, down, left right, in, out... is all ok, but when you turn the yoke from left to right and there is a bit of play, is this normal?
I know it will turn with a lot of force and the wheels will turn, but what I'm asking is should there be a bit or play maybe 1/16 to 1/8 the of an inch only at the yoke itself when turning it from left to right?

jfb, you mentioned you found lost motion in the spindle to bearing spline and defective bearing. I know what a wheel bearing is... but I'm not sure about the spindle, is that the long metal bar with the tooths that inserts into the wheel bearing?
How was it defective exactly, were all the tooths warn out and it was wigling withing the wheel bearing hub? or was it something else?

Thanks for the help guys

 

It is hard to quantify and put into words. A certain amount of rotational play WILL be present. First, there is the necessary backlash between the ring gear and pinion, plus normal operating clearances in the diff parts. 1/16th to 1/8th, doesn't SOUND like it is excessive. Wait a second. You said 1/16th to 1/8th INCHES I was thinking of that, as that much of a turn. Definitly NOT a problem in inches. The splines he is referring to are those that egage the wheel bearing splines. That shaft is referred to as the spindle. It is the same shaft that holds the outer halfshaft u joint.

That brings to mind another possibility, though. That is the bearing where the diff, side output, yoke shaft, passes through the carrier housing.

RACE ON!!!

 

Just to make certain I understand, there are two of these bearings within the rear diff, one on the left and one on the right, and the only way to fix/replace them (if they are bad) is to pull out the diff ??

I'm asking all these questions because I'll be replacing the half shaft U joints this winter and I want to inspect every thing I can wile the half shaft are out.

The help is really appreciated CFI-EFI

 

Yes. They are the yoke shafts that the halfshaft inner u joints install into. The diff case, with ring gear, has to be removed from the carrier assembly, to change those bearings and seals. When you have the halfshafts out, reach up and check the side yokes for play. If they are sloppy, keep going and remove the carrier assembly. At this point, a contemplated ratio change, or diff rebearing and/or rebuild would be appropriate.

RACE ON!!!