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clunk clunk clunk (Read 207 times)
Jul 8th, 2018 at 6:36pm

mr._d   Offline
Newbie
1st Vette
Santa Fe Springs, California

Gender: male
Posts: 5
 
Hi guys,
New to the forum and to the Vette world. Purchased my Corvette about a month ago. Since then I have been reading up on all of your knowledge to help me with some of the issues I'm finding. You have helped me out already without even knowing it. For that, I say ...Thanks!!!!!
I am hearing and feeling a clunking noise at the differential area after driving it a mile or so. Going slow and even when backing up. Have changed the U-joints on the right half shaft hoping they were binding from being dry after sitting since 2006 non-op in a garage. Noticed a mark where to me looks like the U-bolt has made contact with the side of the differential at times. The U-bolts are evenly tightened down so am wondering what might be my issue inside the differential ? Appreciate your help guys
« Last Edit: Jul 14th, 2018 at 4:17pm by mr._d »  

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Reply #1 - Jul 9th, 2018 at 8:02am

68-73-77   Offline
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NCRS Member 68,73,77 Corvettes
Newark,Delaware

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Welcome to the forum, I would check the frt diff mount 1st...could be just worn out. Next check all the ujoints including the drive shaft. Last the diff gears which is not common. Could be the rear wheel bearings but they make a bad bearing sound.
Alan Smiley
 
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Reply #2 - Jul 9th, 2018 at 9:50am

69Shark   Offline
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ATTITUDE is the diff between
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69shark

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Welcome aboard!
Scott
 
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Reply #3 - Jul 9th, 2018 at 6:50pm

mr._d   Offline
Newbie
1st Vette
Santa Fe Springs, California

Gender: male
Posts: 5
 
Hey Alan thanks for your input. I went ahead and just ordered the front mount bushing. What better time to change the front mount bushing while I'm changing the u-joints on the drive shaft.

mr._d
 
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Reply #4 - Jul 10th, 2018 at 7:48am

Verde Andaluz   Offline
Junior Member
I Love my Corvette!
Tumwater, Washington

Gender: male
Posts: 33
**
 
Hi;  Welcome aboard.
I had the very same problem with my '75 vette when I first got her.
I did a lot of hit and misses trying to get it to quit clunking.
Finally I found a specialized Corvette Auto Shop near me that I was not even aware of.
They changed out my diff. oil and added new, plus an additive.  They then took it out in their parking lot and did quite a few "figure eights" and that fixed my problem.
Once in awhile, if the vette sits too long over winter months, come spring, I might get a little noise, but not hardly at all.  I just take it out and do the "figure eights" and that removes it right away.
Good luck.
Doug
 

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Reply #5 - Jul 14th, 2018 at 4:15pm

mr._d   Offline
Newbie
1st Vette
Santa Fe Springs, California

Gender: male
Posts: 5
 
Doug,
you hit the nail on the head. Changed the gear oil and additive in the differential. Did enough figure eights to make me feel that I was on an amusement ride. Driving the 2 mile trip home from work, Nothin. Smooth as can be. Had some serious doubts, but that's what all you corvetterans are for. Still have my list from Alan to finish up. Cant believe how sidetracked one gets under a car. Ended up pulling the spare tire carrier down and cleaned it in the (California approved) parts cleaner  Sad  No hurry right? Its what we love to do. Anyway, thanks again for everyone's help!!!
« Last Edit: Jul 14th, 2018 at 4:22pm by mr._d »  
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Reply #6 - Jul 15th, 2018 at 8:55am

Artsvettes   Offline
Global Moderator
New Jersey

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Posts: 3202
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That contact with the diff case is from the the stud on the U joint retainer. The only way that will happen is from ware on the stub axel and diff center pin. Quite common on the vette rear because of lack of hardness. What I believe happened is the u-joint strap was tightened down un evenly ausing one stud to stick out farther striking the case. The way to check how much clearance you have is remove the half shaft and pull and push on the stub. I think your oil change is only a temporay fix. Maybe when you tightened the u joint strap it is more even creating clearance.  I think
your fix is temporay...jack
 

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Reply #7 - Jul 15th, 2018 at 2:59pm

mr._d   Offline
Newbie
1st Vette
Santa Fe Springs, California

Gender: male
Posts: 5
 
Hey Jack, thanks for the good news. $$$….. I did pull & push the side yoke while I had the half shaft out. I would say it moved about a quarter inch. So I'm to assume dropping the differential for a rebuild, and will also be needing new side yokes as well?
Thanks, Jeff
 
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Reply #8 - Jul 15th, 2018 at 4:09pm

Artsvettes   Offline
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New Jersey

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Yeah, I'd say the yokes have mushroomed over, they will be a chore to remove. You won't know what else you will need until you open it up. Sometimes those yoke will wipe out the seal and score the case. Sorry to hit you with the bad news.....jack
 

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Reply #9 - Jul 15th, 2018 at 7:13pm

mr._d   Offline
Newbie
1st Vette
Santa Fe Springs, California

Gender: male
Posts: 5
 
Its easier to deal with something when you know what the problem is. I appreciate the help. Looks like its time to do some research on removing the differential.
Thanks again Jack
 
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Reply #10 - Jul 16th, 2018 at 1:29pm

68-73-77   Offline
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NCRS Member 68,73,77 Corvettes
Newark,Delaware

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If it's any consultation when I purchased my 68  16 yrs ago my rear made noises when I turned . So I took off the cover...what fun & looked over the inside ( no metal shavings or nicks on the gears)..everything looked ok so I buttoned it up.  Put in posi fluid I think 4 oz but it might have been 8oz then filled it with good gear oil. did the figure eights & haven't had a sound since.
Alan Smiley
 
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