U-joints for 1980 automatic
Thread Starter
Advanced
Joined: Jul 2003
Posts: 70
Likes: 0
From: Smithton il
U-joints for 1980 automatic
I am rebuilding the rear suspention and part of the job is replacing the U-joints on the half shafts and the drive shaft. I went to the local parts store and picked up the new joints. Have 5 of them installed and went to install the sixth one. Too big. It is the differential end of the drive shaft and it appears to be allot smaller. So I return to the parts store and they check the part number and it is the correct part for and 1980 automatic. So I tell them to look up the manual part number. Sure enough it is smaller. So my question is: Is the part stores parts database wrong, or do I have a differential from a manual car? The parts store indicates that both joints on the drive shaft should be the larger ones. For a manual they say that both joint should be the smaller ones. I have a small joint on one end and a larger joint on the other end. What is going on here?
Instructor
Joined: Sep 2003
Posts: 150
Likes: 0
From: Pecatonica IL
Re: U-joints for 1980 automatic (Jmccreary)
Not sure if the parts store is wrong, but I just finished the rebuild on my 80 and yours is correct. Without looking, I think the front of the differential is the smaller u-joint. The tranny end and halfshafts all take the larger ones.
Team Owner
Joined: Aug 2000
Posts: 21,453
Likes: 461
From: Massillon,Ohio USA
2020 C3 of the Year Finalist - Unmodified
Cruise-In VI Veteran
St. Jude Donor '08-'09-'10-'11-'12
Re: U-joints for 1980 automatic (c3-4me)
Not sure if the parts store is wrong, but I just finished the rebuild on my 80 and yours is correct. Without looking, I think the front of the differential is the smaller u-joint. The tranny end and halfshafts all take the larger ones.
Drifting
Joined: Jan 2001
Posts: 1,347
Likes: 4
From: Slidell La
Re: U-joints for 1980 automatic (Paul Borowski)
I found the auto flange on the pinion gear to be larger than the standard tranny diff. Sorry I don't remember the correct part number, haven't had a c3 in a while,, nassau blue C5
Instructor
Joined: Mar 2003
Posts: 235
Likes: 0
Re: U-joints for 1980 automatic (jimcork1)
I had the same problem on my 80. 5 were the same and one was different. I am not sure which one it was. I think possibly the u-joint on the front of the drive shaft. I think they would do this for clearance purposes. The front of the driveshaft comes very close to the cross member. I remember running into this problem at 2 different parts stores. I think they actually matched the joint I needed up to a 69 vette. Could have been something where they were using left over drivshafts from 79 and just changed the one end to match up to the new differential. just a thought though.
