C1 leaking pinion seal

[Pat #25912]

I need to order a pinion seal and nut for my '59 but I think the pumpkin
maybe out of a passenger car. Cast numbers on the driver's side of the pumpkin are A292 over 3789812 and a sideways long thin P. Stamped on the pass side is A M 2 0 5. Any help identifying the pumpkin so I can order the right parts would be appreciated. Thanks again. Pat G.

[Mike M.]

Re: C1 leaking pinion seal

Pretty sure the pass and vet pinion seals same id and od. why not remove the seal and take it to local bearing and transmission supply house for a replacement. Make sure you don't overtighten or undertighten the flange nut.. mike

[Pat #25912]

Re: C1 leaking pinion seal

Thanks for the suggestion Mike. I plan to do this job on Sunday. The local GM dealer says he can have a seal and nut for me Satuday morning (for a '59 Corvette). I think you are right about them being the same as a pass car. Still, I wouldn't mind knowing what the pumpkin is from in case of future problems. Pat G.

[John M.]

Re: C1 leaking pinion seal

Pat,
I agree with Mike, just take to your local bearing house, or your FLAPS, and I am sure thay will have it, and probably cheaper then the GM dealer.
Don't forget to put some non-hardening sealer (ie, Permatex) on the splines of the pinion flange before installing. This will keep the lube from weeping out through the splines.

Regards, John McGraw

[Pat #25912]

Re: C1 pinion seal...not torqued

It seems that the big nut holding the drive flange was never torqued.
Expecting 150 to 190 ft lbs. of torque, I was surprised to find only maybe 20 to 30 ft lbs. So I torqued it to spec. Maybe I won't need to replace the seal. I will keep an eye on it.
Somebody "restored" this car about 3700 miles ago, I guess I shouldn't put the torque wrench away just yet.
Thanks for the tips. Pat G.

[Mike M.]

Re: C1 pinion seal...not torqued

Pat: if you torqued the flange nut 30 more foot/lbs, you have probably further crushed the CRUSH SLEEVE that regulates the pinion to ring gear position.If you did, you will have moved the pinion gear forewards and you will experience more rear end noise when running down the road. You may have to pull the third member and reset the pinion depth.Id you've not done it before, take to machine shop or speed shop. good luck, mike

[Dave Suesz]

A friend of mine does this for a living...

He uses a trick, when the pinion is not removed: Install a new seal, install the pinion flange, install a NEW nut, and torque to 125 ft-lb. Works every time. This may not be the right spec for a C1 pinion, I'm sure he could verify. The sleeve does not crush further, since it has already endured 125#-worth of torque. Using a new nut assures accuracy of the torque. The dimension from the pinion bearing races & gear to the ring gear does not change, since the position of the bearings is machined into the housing and shaft. The 125# torque preserves the accuracy of the bearing preload, which is pretty critical.

[Richard E.]

Re: C1 leaking pinion seal

Pat, John - FWIW, I recently got a new seal for my 62 from NAPA, P/N 17727, for $18. They tell me Chicago Rawhide supplies them. Regards, Dick

[John M.]

Re: C1 pinion seal...not torqued

Mike,
Unless my memory is really getting bad, crushing the sleeve any further will only increase the pinion bearing preload and will not change the relationship of the pinion to the ring gear. It is unlikely that he tightened it enough to even crush the sleeve any further. You have to have a good holding tool and a big breaker bar to put that much torque on it (or an impact wrench). If the flange turns easily, he probably did it no harm. Thankfully they finally did away with the crush sleeve and replaced it with hard shims to set the pre-load.

Regards, John McGraw

[Pat #25912]

Re: C1 pinion seal...not torqued

The flange still turns easy with one hand. It did turn a little easier
before I tighten it up. Service manual calls for 150 to 190 ft lbs. I torqued to 150. Didn't use an impact. I put a 3' pipe wrench on the flange with the handle stuck between the frame and leaf spring to hold it. Then tightened it with a 1/2" drive "click style" torque wrench. I'm sure there was only about
30 ft lbs torque before I started.

Is there any test I can do to check it without pulling the pumpkin?

Thanks for all the help. Pat G.

[Terry M.]

Don't use an impact for pinion nut

Pat,
I was glad to see you said you didn't use an impact wrench on the pinion nut. Besides the impossibility of getting an accurate torque using an impact, one runs the risk of bernelling the bearing races. That is, putting little bumps in the races where the rollers contact from the impact blows. That is a sure way to destroy the bearings.
C2 and C3 owners should not use an impact wrench on the pinion nut or the nut on the outer stub axles either, for the same reason.
All that said, I know some professional mechanics who routinely use an impact in these situations. All I can tell you is that I never would, nor would I take my car to them.
Terry

[Roy B.]

Re: C1 pinion Mike is RIGHT *NM*

[John M.]

Re: C1 pinion seal...not torqued

Pat,
There is a torque spec for what it should take to turn the flange on a properly pre-loaded pinion bearing. I do not have the spec right now, but it should be in the GM service manual. I gave mine away with my 60 when I sold it. I did not intend to, it was just in the trunk and I forgot to retrive it! On a C4 pinion the spec is 20-30 in/lbs of torque to turn the flange when properly pre-loaded, and I would think that this number would be fine for a C1.

Regards, John McGraw

[John M.]

P.S.

Pat,
I just found a spec for early GM rear ends from a differential manual, and they call for 15 in/lbs for used bearings and 25 in/lbs for new bearings. Keep in mind that this spec is for the pinion only and would need to be about doubled for the pinion and the carrier bearings. I would think that if the torque required to rotate the flange is less than 60 in/lbs or so, that you would be OK.

Regards, John McGraw

[Craig S.]

Re: C1 pinion seal...not torqued

For the C2 vintage rear ends, the rotating (not break away) torque is 16-20 inch pounds as viewed on the torque wrench while rotating. For used bearkings, cut this in half...Craig