The Stovebolt Site Forums The Parking Lot Tons 'o Fun Pinion seal changing procedure on a 49 3800

a few questions -

Looking at the shop manual I see a pinion nut, wash, flange and finally a retainer, holding the oil seal.

Throughout my forum search, I see mention of a crushed sleeve - but I don't see one in my assembly diagram, can anyone confirm?

Also, the replacement directions talk about oil seal and "packing" replacement. Can someone describe to me what this packing is?

And finally, does anyone have a part number for the seal should I not see one on the part I remove.

Any other gotcha's I should worry about?

Mark

I'm not much help on the specifics, but I do recall getting that pinion nut off was a real ordeal. Finally had to use a 3/4" drive deep socket and a cheater bar set on a floor jack. When I got it off, I realized the last person had used some kind of thread locker on it. If you have a hard time getting it off, you might try heating it up with a propane torch to soften any thread locker. I do remember I got my seal at O'Reilly's auto parts, but they had to order it.

It is pretty common to use a 3/4 impact gun to get the nut off. The new seals don't use packing. NAPA or Carquest should have the seal. They used that rearend style up to 1972.

Hy Bigtonka, the seal p/n is National 411330N, the "packing" is a felt, National 5M89. There is no crush sleeve, there is a special front bearing with one cup with opposite facing bearing surfaces, and two bearings and a specially sized spacer to give the proper preload when all the pieces are used together. The only "gotcha's" I can think of is, don't use the rear end with the tires on the ground to hold the pinion still for you while you torque the pinion nut, and especially don't use a big impact wrench to tighten it, this puts a lot of strain on the gear teeth and may break or crack some. You can make a rectangular plate to fit over the entire pinion flange and weld a piece of pipe to it that is long enough to reach the ground, or use a large pipe wrench with a piece of cheat pipe over the handle, hope that helps.

Thanks for the replies guys - but still a little bit confused about something...

RE: "3/4 impact gun" or "3/4" drive deep socket"

Are you referring to the drive? Because the pinion nut I have on my truck is bigger than 1". (I was looking for the nut size in another thread)

3B - the rig you described, its purpose is to hold the pinion while I use the impact on it correct? Such that I'm not working against the gears?

Hy Bigtonka, the guys were refering to the size of drive, not the size of the socket. You were correct in your assumption that the "rig" I described is used to hold the pinion, while you loosen it or tighten it.

If you look up the specs on the torque for that nut, you will see it is around 300 ft/lbs or more. That is why a big gun is used. Usually the impact socket for that size has walls thick enough that it won't fit in there. Then one gets into grinding the outside of a very expensive socket.

So Truckernix, if I cant use an impact socket, how do I remove it??


Or do you mean I don't use an impact, but a standard socket?

When I was trying to do this, I bought an expensive socket and then has to grind the outside to get it in there. It turned out that the only impact wrench I had at the time was electric and it wouldn't do the job. When I had it certified, I had the mechanic replace the seal. He told me that the seal surface had grooves and although he cleaned it up a bit, it still leaked. I bought a speedy sleeve and new seal and he installed them for me. It hasn't leaked a drop in 12000 miles.