I removed the differential driveshaft yoke today and replaced it with the larger one my new driveshaft requires. When I went to my haynes manual to check the torque for the big nut, I discovered I was supposed to somehow measure the previous torque (???) and snug the nut back on just a little tighter??? TOO LATE! Now what do I do? I know very little about differentials, looks like it's time to learn!

Help, anyone?

-Roy

 

Thanks Gary, you are correct it is a '68 cast iron case differential. I'll try your procedure and see how it works out. Do you happen to have a differential schematic diagram you could post or E-mail me? Like I said, it really is high time I start learning a little more about this "black box".

-Roy

 

Gary this is a case for our solid spacers instead of crush sleeves. We can just retighten the pinion nut and call it good knowing the setup is the same.
I would do away with all crush sleeves in any rebuild.

 

He can't do that. He bought the transmission and yokes from me, and I sent him the pinion seal with the tranny. The 1350 pinion yoke requires a special seal.. The original style seal will leak like crazy!!

 

EEK! I'm glad you chimed in, Olivier, I still have the seal you sent, I bought a new one (original type) but haven't finished reassembly yet. I removed my old seal then put in the new one...guess I now have to remove the new one and re-use the one you sent or acquire a new one that will fit. Do you have a part number for me??

Norval, this delicate crush-sleeve that now is causing me problems will definitely be outta there if I end up doing a rebuild (or sooner if there is any way of swapping in a solid piece without removing the diff from the car? Probably way too much to hope for ). I'm on a deadline here, a good friend is taking his date to the prom in 3 weeks in the vette, so I need to get the transmission swap finished soon.

My new shop will be built this summer, and next winter I'll have time and space to take apart EVERYTHING I want to, including the engine. For now, as soon as I get the flywheel back from the Machine shop on Tuesday I want to start putting everything back together so I can drive!

 

Don't have a part number for the seal... The guys at Van Steel actually made this seal for me.

 

Van Steel actually made that seal for me.. I bought that 1350 yoke through them and they used the original seal because the manufactorer of the 1350 yoke didn't tell them that their yoke needs a special seal. The differential leaked like crazy with the stock type seal, so I went back to Van Steel.. They called the manufactorer and they told them that they don't make the seals for those yokes anymore.. so the guys at Van Steel made a seal for me.. The seal is only a year/ 3k miles old, so it should work fine for quite some time..

 

Just a little update: I followed the procedure Gary recommended, and the rear end seems to move freely without any noise or evidence of undue slop...of course the real test will be in this summer's driving.

I looked closely at the seal that Van Steel made up for the differential yoke, and it is essentially a stock seal with a tiny tension-type spring/band that encircles the OD of the rubber lip, effectively compressing the seal-lip diameter slightly to form a snugger seal against the yoke. The spring is easily removable, and I should be able to transfer it to a new seal should the need arise. We'll see if anything wants to leak once I take my first test drive!

 

What happened was they never told us we needed to change to a different seal when we went to the 1350 pinion yoke. They just sold us the yoke and sent us on our way. Kind of like buying a car and not getting the keys. Anyway, I called them up and I got a different seal for it. You can get the seal at any driveshaft or gear shop. I'm not sure of the number but it should be marked on the seal. If not than you need to call driveshaft shop and tell them that you are putting a 1350 pinion yoke on your diff. Tell them if you had the 1330 or 1310 yoke on it before. It only took me a day to get the correct one for Olivers car. Since you have a 68' if you have an auto than you had a 1330 pinion yoke. If it's a 4 spd than you have a 1310. This is also true for all 68-70 vettes.

 

I had a muncie 4-speed in before, which would be the 1310. I don't have a driveshaft shop around here (small town), but I will look and see if there is a part number on the seal Olivier sent for future reference. Thanks for clarifying that for me!

 

Dan, if I remember correctly, you weren't able to get the right seal on the same day and I had to get back to South Florida, so John machined another seal to make it work, but maybe my memory doesn't serve me right