Rear-end clunk
Thread Starter
Racer
Joined: Feb 2000
Posts: 372
Likes: 1
From: Victoria British Columbia
Rear-end clunk
I have a clunk from the rear-end of my 87 auto when coming to a stop.GM manual says worn differential cross shaft in case causes this.It seems I've seen this discussed here and that it is considered "normal" by some.Am considering having the diff rebuilt but as this is the only symtom am not sure its needed.Opinions needed.Thanks
Instructor
Joined: Jul 2001
Posts: 219
Likes: 0
Re: Rear-end clunk (sailrmon)
Just finished doing this and what an education! I had a clunk usually from changing direction, ie going from reverse to forward. After getting many opinions including the worn side yolks (aka differential cross shafts), I ordered a bunch of parts and took it to the Man, Matt Lloyd, of Rome GA. What he discovered was that My side yokes were not worn at 125k miles. However, someone else had been in the Diff before to change clutch packs. They did not set it up correctly and the clutch pack was frozen. This caused the clunk. I had the new parts put in anyway and filled the whole thing up with synthetic gear lube and additive. Matt says I won't have to touch the dif again for 200k plus if at all.
Sometimes you can free up a stuck clutch pack by sucking out all the gear lube with a hand bleeder, flushing the diff two or three times with cheap gear lube than refilling with good stuff and fresh additive. Then, with the diff cold, do low speed figure 8's both left and right in the parking lot for a few minutes. Then drive a few miles to warm things up and repeat the figure 8's. If that doesn't do it, you may have to go in there. Special tools required. Matt did all the work for mine after I brought it to him for $250. If go that route, I have extra carrier shims (hard to get) and good used side yokes that I'll sell you cheap $$. :flag
Sometimes you can free up a stuck clutch pack by sucking out all the gear lube with a hand bleeder, flushing the diff two or three times with cheap gear lube than refilling with good stuff and fresh additive. Then, with the diff cold, do low speed figure 8's both left and right in the parking lot for a few minutes. Then drive a few miles to warm things up and repeat the figure 8's. If that doesn't do it, you may have to go in there. Special tools required. Matt did all the work for mine after I brought it to him for $250. If go that route, I have extra carrier shims (hard to get) and good used side yokes that I'll sell you cheap $$. :flag
Team Owner
Joined: Feb 1999
Posts: 37,190
Likes: 20
From: Trying to get back to Bokeelia, FLA-USA
St. Jude Donor '04-'05-'06, '15
Re: Rear-end clunk (LouisBarton)
Just finished doing this and what an education! I had a clunk usually from changing direction, ie going from reverse to forward. After getting many opinions including the worn side yolks (aka differential cross shafts), I ordered a bunch of parts and took it to the Man, Matt Lloyd, of Rome GA. What he discovered was that My side yokes were not worn at 125k miles. However, someone else had been in the Diff before to change clutch packs. They did not set it up correctly and the clutch pack was frozen. This caused the clunk. I had the new parts put in anyway and filled the whole thing up with synthetic gear lube and additive. Matt says I won't have to touch the dif again for 200k plus if at all.
Sometimes you can free up a stuck clutch pack by sucking out all the gear lube with a hand bleeder, flushing the diff two or three times with cheap gear lube than refilling with good stuff and fresh additive. Then, with the diff cold, do low speed figure 8's both left and right in the parking lot for a few minutes. Then drive a few miles to warm things up and repeat the figure 8's. If that doesn't do it, you may have to go in there. Special tools required. Matt did all the work for mine after I brought it to him for $250. If go that route, I have extra carrier shims (hard to get) and good used side yokes that I'll sell you cheap $$. :flag
Sometimes you can free up a stuck clutch pack by sucking out all the gear lube with a hand bleeder, flushing the diff two or three times with cheap gear lube than refilling with good stuff and fresh additive. Then, with the diff cold, do low speed figure 8's both left and right in the parking lot for a few minutes. Then drive a few miles to warm things up and repeat the figure 8's. If that doesn't do it, you may have to go in there. Special tools required. Matt did all the work for mine after I brought it to him for $250. If go that route, I have extra carrier shims (hard to get) and good used side yokes that I'll sell you cheap $$. :flag
i have the same issue with my 85..ive done the u-joints and rear wheel bearings...but i still have a wierd clunk when i shift from park to reverse or from park to drive and it only happens when cold....
did it sound like a cue ball hitting an eight ball....not so much a clunk but a "chunk"....
what you have sounds like what i have....also this started after i refilled the differential...
thanks for any input
Pro
Joined: Apr 1999
Posts: 740
Likes: 0
From: Chelmsford, MA USA
Re: Rear-end clunk (sailrmon)
I have the same clunk noise when I slow down with my '87 auto. I noticed though, if I place the shift
lever in {D} and slow down rather than in 3rd D, the clunk goes away. Does this happen with your '87 as well?
Bob
lever in {D} and slow down rather than in 3rd D, the clunk goes away. Does this happen with your '87 as well?
Bob
Instructor
Joined: Jul 2001
Posts: 219
Likes: 0
Re: Rear-end clunk (jd)
:yesnod: Did you replenish the limited slip additive? The GM stuff is actually better than you buy at the local auto shop. I also replaced all the u joints during this project though none had actually failed. It was one of those " now that its all apart, you might as well..." deals. I just got back from my first test drive and boy am I a happy camper! :D
