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My son purchased a ‘73 that we are beginning work on. The first order of business was to stop all the leaking going on. So the pinion seal was first, which is done thanks to all the great guidance here. My concern is how difficult the drive shaft was to remove, and am struggling getting it back on. There must be some tricks to making it easier. Putting new u-joints in also.
Any advice/suggestions would be appreciated.
I think I took mine out through the back. But I found things a lot easier if the rear tires are off the ground. This allows rotation of the shaft so you can get at the hardware.
Exhaust & parking brake cable were not an issue. But that is, the narrowest shaft tunnel I have ever seen.
But first, this is a great time to swap-out the snubber on the diffy.
If you haven't swapped-out the U-Joints yet, paint a white line reference mark on the shaft & yokes for original alignment and factory balancing.
Good idea on the snubber. As for the shaft, it’s very tight between the yokes with almost zero give at the tail shaft. I would think it should move a little forward to clear the rear yoke and drop down, but that’s not happening.
I heard some forum members disassembled the front yoke for removal out the front. I didn't have to on a '77 anyway.
I guess I was lucky coming out in one piece, aft. Then took it to a auto repair shop that had U-Joint installer tool. Really slick, 3 minutes later . . . . .
New Solid Spicers, labor was $30.
Keep at it, you will get it.
Last edited by HeadsU.P.; Sep 13, 2020 at 10:37 AM.
Keep D/S fully assembled. Insert the rear yoke end of the D/S just above and beside the differential. This will allow you to get the front end behind the trans tailshaft so you can insert the splined shaft into the trans. Now push forward until the rear U-joint clears and insert it into the differential yoke. You will need a rachet with 1 or 2 extensions on it to reach the diff yoke bolts for tightening.
(As above)
I put the yoke into the transmission and slide it all the way in (forward)
Slip the driveshaft over parking brake / seat belt cable and right up into place on the pinion yoke, hold it in place and slide the trans-yoke back to engage the u-joint, put both caps on the trans yoke finger tight and then using a 3/8 drive ratchet and 2 long extensions install the caps on the pinion end. there's a couple of places when turning the shaft around that you can see what's going on and I just use the wheels to rotate the differential for each bolt
Everyone thanks for the all replies and guidance (keep them coming). Going to order up the u- joints and give it a go later this week. Some good suggestions here to hopefully make it easier. And —- btw —- hats off to anyone who has replaced that pinion seal from the ground!! I have a lift and would not have attempted it without.
An extension with a wobble end for the socket will give you a few degrees of movement to make it easier to get the socket onto the screws and keep it there as there is little chance of having a straight line to them.
Have one of those "pointers" with a magnet on the end for when you drop a screw and it lands in a valley on a cross member and you have to retrieve - happened a couple times.
Have extra screws for when you can't retrieve one - hasn't happened yet, but will be putting in a new DS this weekend, so ...
If you're using a GM shop manual verify the torque values are correct. They were not in my '80 shop manual which I believe were the same as in earlier manuals. Here's a post from thread a couple years ago when I first did this job.
Actually, I just noticed something. Clearly there is an error in the table. Note that on one line it lists 28 N-m as 22 ft-lb and then on the next line it lists the lower metric value of 22 N-m as as a higher 30 ft-lb value. The correct conversions should be:
17 N-m to 13 ft-lb 28 N-m to 21 ft-lb 22 N-m to 16 ft-lb
The question then is which conversion is messed up, N-m to ft-lb or the reverse. My guess at this point is it's the N-m to ft-lb. I can believe the manual value should be the highest since on a 1980 the half shaft would have been a Spicer 1350 U-joint with a 5/16 bolt while the half shaft on an automatic used a 1330 and thus a 1/4" bolt, the same bolt as the drive shaft which used 1310's for both transmissions.
I guess since the bolt dominates the torque requirement and since the the 1310's and 30's use the same bolt I will stick with the lower torques. Of course, then the question becomes which is right, the 17 N-m or 15 ft-lb since they are not equivalent. Splitting the diffeence would be 14 ft-lb which happens to be an engineering recommendation for a 1/4-28 bolt, unplated and unlubed. As good a guess as an any. Chalk up one more error in the shop manual.
Well here’s an update I’m not to glad to give - I did manage to get the drive shaft back in, but only with the caps off, and then carefully back on once positioned in the trans yoke. Still absolutely no room to move the trans yoke to get any kind of breathing room. The bad —— started out well on the test drive around the block a couple times, however, turning back in to the drive it made a very horrible sound in the rear end. Got it back on the lift, jacked it up, and as I as checking things out the rear passenger tire sags down to the lift runway. The side yoke is pulling out of the differential. I’m sure that sound was the last breath for the differential. Thinking back when I started the process, while the car was jacked up off the lift, I would have crank the jack I little to keep that same tire off the runway. Then I as thinking the the jack was settling, but that didn’t and doesn’t make any sense. I think that side yoke was creeping out before I started anything it just didn’t register. Or I blew the preload on the pinion. So I’m going to have to find a differential and start over. Sorry for being long winded!
Your differential may not be terminal. The side yokes have worn so badly that the C-clip which retains the passenger side yoke has come out. Yes the parts rattling around in the diff may have done serious damage but not for sure. Drop the diff and have a look inside. You certainly need new output yokes, but you may save the rest of the differential if you're lucky.
Well here’s an update I’m not to glad to give - I did manage to get the drive shaft back in, but only with the caps off, and then carefully back on once positioned in the trans yoke. Still absolutely no room to move the trans yoke to get any kind of breathing room. The bad —— started out well on the test drive around the block a couple times, however, turning back in to the drive it made a very horrible sound in the rear end. Got it back on the lift, jacked it up, and as I as checking things out the rear passenger tire sags down to the lift runway. The side yoke is pulling out of the differential. I’m sure that sound was the last breath for the differential. Thinking back when I started the process, while the car was jacked up off the lift, I would have crank the jack I little to keep that same tire off the runway. Then I as thinking the the jack was settling, but that didn’t and doesn’t make any sense. I think that side yoke was creeping out before I started anything it just didn’t register. Or I blew the preload on the pinion. So I’m going to have to find a differential and start over. Sorry for being long winded!
This latest development really sucks. But going back to your original problem, did you remove the front bolt on the pinion snubber bracket and swing it down and away to achieve more clearance?
Thanks again for all the replies. I did not try removing the snubber bolt, maybe that would have helped with the shaft. I’m still struggling with the fact I could not get the joints to clear the yokes with the caps on. I’m guessing another 1/4 - 1/2” is all it needed. Anyway, I have located another differential and shaft so I will be starting a new thread on the process/procedures for getting the differential out and back in!
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the hardest part is getting the top support free of the sombreros. Theres some youtube videos out there if you havent done it before. Just support the differential so it doesnt drop and injure you. Good luck
Well here’s an update I’m not to glad to give - I did manage to get the drive shaft back in, but only with the caps off, and then carefully back on once positioned in the trans yoke. Still absolutely no room to move the trans yoke to get any kind of breathing room. The bad —— started out well on the test drive around the block a couple times, however, turning back in to the drive it made a very horrible sound in the rear end. Got it back on the lift, jacked it up, and as I as checking things out the rear passenger tire sags down to the lift runway. The side yoke is pulling out of the differential. I’m sure that sound was the last breath for the differential. Thinking back when I started the process, while the car was jacked up off the lift, I would have crank the jack I little to keep that same tire off the runway. Then I as thinking the the jack was settling, but that didn’t and doesn’t make any sense. I think that side yoke was creeping out before I started anything it just didn’t register. Or I blew the preload on the pinion. So I’m going to have to find a differential and start over. Sorry for being long winded!
Hi everyone. I am ready to install the main driveshaft in my 76. I messed up and did not mark (or accidentially painted over the mark ) which end goes to the transmission and which goes to the differential. Mine has about a 1" by about .25" raised metal area on one end which I assume is a weight. Is there anyway to figure which end goes where at this point? Thanks
Drive Shaft remove/install
