The Stovebolt Site Forums The Shop Area Engine Shop Pinion nut HELP.............

I have a sizeable leak at the front side of the rear end. Leaking from behind the yoke. I have obtained a new pinion oil seal and would like to put it in. I cant seem to budge that pinion nut. Also wondering if there is anything else I should know about this procedure, before I screw something up in my rear end. Anyone been here before? TIA, Tony

Had the same problem with my 55. Find a two jaw heavy duty puller and make sure that the jaws fit behind the yoke. Thats what worked on mine. The puller has flat arms with wide jaws.
After you get the yoke off, check yoke shaft for a groove, if there is one you'll need a "speedy sleeve" to give you a good sealing surface. HTH
Bob

I've been in your situation a few times. I've only ever been able to take the pinion nut off with an air impact gun. Once the nut is off, I remove the pinion flange to expose the seal and replace it. I realize the pinion nut is torqued down to set a pinion pre-load but I've got luck so far and haven't had any rearend gear problems with just tightening the nut back up with the same nut. KNOCK ON WOOD!!!

I have been fortunate as well. Large impact wrench and high air pressure then put it back on with the impact just not as tight. I offer this idea only if the impact wrench does not work, you might try heating the nut with a heat gun or torch. BE CAREFUL oil is flamable and you CAN do damage with excessive heat. Stay off the yoke and Pinion shaft. Just the nut (I realize it is a tight fit). If you haven't tried the Impact yet then don't try the torch. Good luck.

It looks like I'll have to scrounge up an impact, and a compressor while I'm at it. And have a puller handy for when I get that nut undone. Does anyone have any idea what the "pre load" torque spec might be? 46 panel, why put back on with impact but not as tight as it was?

If you can be sure and clean and oil the pinion threads before you wrench it off. I distroyed one on a 58 GMC 4x4 years ago while learning this proceedure.Then if you have a touque wrench, hold the yoke with a pipe wrench and get your proper force

just did one on my pick up if the yoke moves up and down or side ways it may need more than a seal. tighten it down to specs and see if all the play is out of the yoke.

Pinion pre-load is about 250 - 350 foot/pounds dependng who you talk to. This has already been done on your existing install. The loading (what you need to do after installing the seal) is about 25 inch/pounds.

Tony , if you have a '46 panel then you have a non standard diff with the open drive .
Lets assume it is a '55 pickup diff .
Donsz is correct with the original preload , BUT , the inch / pound load is for the rotation preload on the pinion bearings , not the nut torque.
Tighten the nut with care that you dont go tighter than it was originally.

Thanks Dusty - good catch.

Thanks for all the replies. I'm working on my '61 Apache right now. I sold my '46 3/4 ton this past August. I spent the day doing the R&R on the coil springs. Gonna get back to that pinion nut Monday evening.

Yachtcare, 2 reasons that I said that. First I didn't know what kind of vehicle. Second, and major reason is you might have an enormus impact with big power and I didn't want you to break something. I have a 1/2 inch drive impact and use max air pressure (about 110 cause thats what my compressor kicks off at). Never had trouble breaking one loose yet but there is always a first time. When reinstalling I just clean up the thread on the pinion and nut with some solvent (like carb cleaner) when it dries I put Locktite on the threads, start the nut and run it up as far as it will go (to insure no cross thread or damage) then I tighten it as tight as my impact will go and let it hammer a couple of seconds. My impact is not terribly powerful.

Thanks for the clarification. I went out and blocked up the yoke and tried giving it a few tugs with the breaker bar. I just about pulled the truck off the jackstands sideways. If it is indeed initially torqued to 250 or more ft lbs I wont be getting it loose anytime soon. I dont have a compressor, so of course no impact. And I really dont like the idea of heating my rearend to a rosy glow. I think I'll go shopping for a mobile welder or the like that may have a truck mounted compressor that can pay me a visit this week. In the meantime I'll get back to swapping in the OD tranny, and re bushing the trailing arms.

Tony , I don't have an impact gun either , so I got a piece of flat strap , about 1" x 1/8" , drilled 2 holes just the same as the 2 in the yoke , bolted the strap to the yoke and let the end of the strap touch the ground.
Then I got the 1/2 drive swimg bar , socket attached and on the pinion nut and used a small bottle jack to crank the nut undone .
Not so easy , but very achievable.
Maybe just a length of pipe on the swing bar if you have the space.

You don't need to re-torque the pinion nut as long as you mark it berfore you take it off. Use a center punch and mark the nut and stud. When you put it back together, re-align the marks.

Follow Dusty's method to loosen. I would use a big pipe wrench and cheater long enough to brace against the frame. And it won't hurt to heat the nut with a propane torch.