Maybe there is a problem with Summit's part numbers......Tim
81 U-Joints
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 1,058
Likes: 27
From: Eastern North Carolina
81 U-Joints
I have a 81 with a automatic transmission, I purchased some u-joints today to replace the ones on the drive shaft. The joints I bought were for a automatic but they are way too big. I took them back to the parts store and this time took a old one with me an was surprised to find out that the u-joints recommended for a car with a manual trans matched the size of my old ones. Did GM switch up on the u-joints sizes for a automatic sometime during the production year? Weird 
Racer
Joined: Nov 2008
Posts: 297
Likes: 3
U-joints
On my 80 C-3 automatic, all the u-joints were the same size (large) except for the rear driveshaft joint which was smaller (shorter). When I went to buy new joints, every parts place: Autozone, Advance, NAPA etc. had the wrong info in their computer. We finally just had to go to the shelf and start opening boxes and compare to the old ones. I think it is a common problem on 80 thru 82.
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Burning Brakes
Joined: Jul 2009
Posts: 1,132
Likes: 14
From: A town SC
From general research on these cars ive read that 81 back to im thinking 75 or so.
auto/1310 drive shaft 1310 half shafts
Man 1310 drive shaft 1330 halfshafts
Not sure about further back when big blocks come into play.
auto/1310 drive shaft 1310 half shafts
Man 1310 drive shaft 1330 halfshafts
Not sure about further back when big blocks come into play.
Le Mans Master
Joined: Oct 2000
Posts: 6,362
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From: Oak Harbor WA
Race Director
Joined: Jul 2004
Posts: 12,694
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From: Scottsdale Arizona
Raise the rear end and put axle stands under the frame allowing the wheels to turn freely
Put the tranny in neutral
use about 18 inches of extensions (3/8 drive is good) and use a 12 point socket (can't remember the size)
Undo the straps that hold the joints to the differential yoke and tranny output yoke
Struggle the driveshaft out
Lots of how-tos to explain how to replace the U-joint in the drive or half shafts. I'm a big fan of the cut off wheel method
Don't forget to put some locktite blue on the threads when you put it back together.
Drifting
Joined: Jul 2009
Posts: 1,532
Likes: 14
From: Dallas-Fort Worth TX
Mine drive shaft and the half shafts were different size. I installed spicer. Do a search for a distributor in your area. They will have the correct info and size. I ran into the same BS with the local part stores not knowing what to use.
Le Mans Master
Joined: Aug 2006
Posts: 7,419
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
I had the same problem spicer drive shaft were 5-625X and half shafts were 5-627X. I got mine at a truck parts company.
Drifting
Joined: Jul 2009
Posts: 1,532
Likes: 14
From: Dallas-Fort Worth TX
Exactly............ I went to a truck parts store as well. Big trucks. They had spicer advertisment posters and banners all over the place. Nothing but mechanics there buying parts for there shops. I thought for sure they would flip me off when I told them what I was looking for. But he went to the back and got em. Had the Trans shop press them in.
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 1,058
Likes: 27
From: Eastern North Carolina
Well, I think its all figured out now, won't know for sure until I pull the half shafts. I guess the best thing to do is compare the new ones to your old ones before you buy them.
Thanks Everyone........Tim
Thanks Everyone........Tim
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 1,058
Likes: 27
From: Eastern North Carolina
CA is right, if you add enough extensions to your wrench you can reach the pinion yoke through the tunnel. My screw on the pinion yoke were two different sizes 1/4 inch 12-point and I'm sorry I can not remember the other size. If I get a chance I'll check and get back to you....Tim
Le Mans Master
Joined: Aug 2006
Posts: 7,419
Likes: 1,555
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
One more think.
You can change the drive shaft 'U' joints on the drive shaft yourself but to do the half shafts you should bolt them together or get this tool or have a shop that has it do it for you as you can bend the half shafts and render them useless.
I have no stock or fincial interest in www.volvette.com but they are the only place I've seen this tool sold.
Part # TL30.
I have no stock or fincial interest in www.volvette.com but they are the only place I've seen this tool sold.
Part # TL30.
Last edited by Peterbuilt; Feb 12, 2010 at 01:12 AM.
