1980 Differential Question
Thread Starter
Heel & Toe
Joined: Jan 2009
Posts: 19
Likes: 0
From: Cincinnati OH
1980 Differential Question
I am in the process of rebuilding the rear suspension on my '80 and have gotten to the point of tear down of the differential. It is a 3.07 and while driving it is very quiet. I want to keep it that way. My '72 whinned like my kids. I just pulled the case apart and everything looks great. The car only has 85k miles on it. I am tempted to just replace the seals and gasket and bolt it back together after sprucing it up. Is there something I need to be looking at closer? This is as the name implies a car I intend to just use for a cruiser. I do however intend to boost the HP by installing true-dual exhaust and some minor engine mods next year.
Le Mans Master
Joined: Apr 2001
Posts: 5,000
Likes: 1
From: Minneapolis, Mn USA
Check your center crosspin for wear from the yoke ends. This, combined with yoke end wear, will determine your end play on these. The 80-82 center pin used was made softer (as compared to older iron unit pins) by GM to keep the rear end noise to a minimum. They are also difficult to find these days. Toms was making aftermarket pins but I think has stopped.
Check your yoke ends for mushrooming. Your yokes will not come out of the carrier if the ends are mushroomed.
Check the posi dog ears for wear-deformation. Should look the same on both sides.
I had a forum member sell me a "20K mile" differential that had wear on this crosspin, which upon further inspection, turned out to have been a rebuild that had parts installed incorrectly. Turned out to be a core and thats about it.
Check your yoke ends for mushrooming. Your yokes will not come out of the carrier if the ends are mushroomed.
Check the posi dog ears for wear-deformation. Should look the same on both sides.
I had a forum member sell me a "20K mile" differential that had wear on this crosspin, which upon further inspection, turned out to have been a rebuild that had parts installed incorrectly. Turned out to be a core and thats about it.
Thread Starter
Heel & Toe
Joined: Jan 2009
Posts: 19
Likes: 0
From: Cincinnati OH
Not good news!
Upon closer inspection it looks like the center pin is worn and the yoke ends are mushroomed. Not what I wanted to see. Typical GM quality. Why would they not harden both of those? I did look at Tom's website and they look to have what I need to rebuild if I can get it apart. Any idea how to get the mushroomed yokes out?
Le Mans Master
Joined: Apr 2001
Posts: 5,000
Likes: 1
From: Minneapolis, Mn USA
You can get a grinder in there and grind down the ends of the yokes. This will lead to debris, yoke metal and grinding wheel, being introduced into the carrier.
At that point, a full clean-up would be recommended. In order to properly do that, you should take that assembly apart. Since you've done that, you may as well rebuild the entire rear end and reset your backlash. You having fun yet!!
If you havent done this before or dont have the proper tools, pressess, etc, I'd recommend taking it to a Vette rear end specialist in your area. It is money well spent.
I can also recommend a fellow by the name of Paul Walter of Northside Corvette in Mpls area for 80-82 rear ends. He has a good pedigree going back to Motion Chev.
Brent.
At that point, a full clean-up would be recommended. In order to properly do that, you should take that assembly apart. Since you've done that, you may as well rebuild the entire rear end and reset your backlash. You having fun yet!!
If you havent done this before or dont have the proper tools, pressess, etc, I'd recommend taking it to a Vette rear end specialist in your area. It is money well spent.
I can also recommend a fellow by the name of Paul Walter of Northside Corvette in Mpls area for 80-82 rear ends. He has a good pedigree going back to Motion Chev.
Brent.
Drifting
Joined: Jul 1999
Posts: 1,542
Likes: 43
From: Plano TX
my 80 had mushroomed yokes also. I used a thin flat punch and a cheap but hardened long flat screw driver. Hit them with a hammer to clean out the yoke slots. Was worked much better than a grinder. Make sure you waer safety glasses just in case.
Did this at 33K mikes on the car. 90K miles later and the pin is still not warn so not sure what happened to the first one.
Did this at 33K mikes on the car. 90K miles later and the pin is still not warn so not sure what happened to the first one.
Thread Starter
Heel & Toe
Joined: Jan 2009
Posts: 19
Likes: 0
From: Cincinnati OH
Thanks for the advice
I appreciate the feedback. I was wondering if I could just use a fabricated punch shaped like the spline slot but that wouldn't address the high spots on the top of the spline tooth. I am not afraid of using my Dremel to grind it down. The debris isn't a problem as I work for a company that makes industrial cleaning machines and we have machines in our lab. DaveL82 where did you get your center crosspin? Did you replace the yokes and were the pin and yokes hardened.
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Thread Starter
Heel & Toe
Joined: Jan 2009
Posts: 19
Likes: 0
From: Cincinnati OH
I was lucky!
I removed the snap rings and the yokes pulled right out. If I can get these pictures to down load I would like some comments on the parts. The yoke ends looks pretty chewed up and the center pin also looks kinda chewed up.
