Pinion Seal Replacement

[WarrenD]

I did try to search this topic and didn't find much. Some info from several years back, so maybe time for some current info!
Came back from a show and the pinion seal on the rear diff is leaking pretty bad. It needs to be changed. First off, what are my options? NOS leather, newer seals? Then the big question, how? I know the basics, I've been told to drill a few holes in the old seal, run bolts in and get a puller and pull. Is this the method the military used or is there a "special tool" that just clamps on and does the job?
I'm not really sure I want to tackle this and I'm also looking around for someone in the area whos is familiar enough with the M37 to do the job.
I have been told when it comes to the new seal, if it's the NOS one, to soak it overnight in neatsfoot oil before installing.
Finally, what weight gear lube should I be using and is there anything I should be wary of (I'm staying away from synthetic as it doesn't sound like a good idea for old seals)
Thanks,

[powerwagontim]

Hi Warren,
I would use the rubber seals. You will also want to get a speedi-sleeve to redo your yoke. Your description of removal works, but use large diameter sheetmetal screws threaded into the seal. They will likely move the seal a bit, then tear out, just move your hole and reinstall and try again. I usually put in 3 or 4, and pry a bit on one, then move to the next, and go around that way. Dont expect big things to happen all at once. I have also had ones be real stubborn and then it is time to get nasty, and essentially fold the seal in on itself with small cold chisel, being careful of the casting. There are no awards for the prettiest seal removed, so do what you need to do to get it out of there!
Tim

[WarrenD]

Thanks Tim. I haven't been able to find any info on a rubber seal, everyone I've talked with has the leather, either NOS or repro. From what I have seen, the rubber seal needs some sort of carrier to make up the size difference.
Is it ok to use a puller and push against the pinion shaft? I'd replaced the bolt (or nut or whatever holds the flange on) and push against that as long as it doesn't damage anything inside....
As for install, any hints? block of wood with hammer?

[powerwagontim]

Hi Warren,
You are correct that the modern seals need a carrier. I believe Charles sells one, and it wouldnt suprise me if John at Midwest Military also did.
If you have a puller that will grab the seal, I cant see you hamaging anything by pushing against the end of the pinion. I install mine with a big 1" drive socket I have that is a good match for the diameter. You could also check if a piece of PVC pipe might work. Other than that, yes, a wood block carefully worked around to insure you are getting it in straight will work.
Tim

[WarrenD]

I was thinking of rigging up something that I could screw into the old seal that I could get a puller onto. Ideally, I'd like to have a puller that just grabs the seal but it doesn't look there is enough room for that. I'd like to know how the military took them out back in the day but I suspect it was somewhat simplistic and involved more brute force than finesse.

[powerwagontim]

I have seen pictures of the puller, but they are not very clear. It seems to have very slender arms to get in between the pinion and the seal. Since we are not trying to save it, it does not really matter to have the "finesse" puller!
Tim

[vtdeucedriver]

Hey warren,
The Neatsfoot oil will work on the NOS seals just fine. The Book says for a couple of hours but I let mine soak for 2 days and then installed it. This was back in 98 and as you know the story, she did sit until I got it done and she is still nice and dry today!! When you get the old one out and I think I just used a small screwdriver and pryed it out evenly. Once its out, look at where the seal is riding and make sure there are is no scoring or pitting. If there is dress it out with some emry cloth if its light, if none at all, still run some emry or scotch brite to clean that surface good and put the new seal in. I know charles will come on and sing the praise of the rubber seals but hey.................the leather still works if properly prepped and installed. One other note, CHECK YOUR AXLE VENTS!!! make sure that they are not plugged. If thats the reason why the old seal started leaking then you may just blow the new one also.

[WarrenD]

Thanks Guys. Yes Jeff, I'm already planning on getting new axle vents. The front one seems free, but the rear is a little sticky. I have the TMs on CD up and running and just found the pinion seal section. I'd like one of those seal removal tools (41-R-2373-215)!! I have a leather seal and the Neatsfoot oil, Ed (my seller) gave me the procedure there. Soak it and then burnish the inside surface with a brass rod. Makes sense, the brass will transfer microscopically to the pores in the leather and provide a better wearing surface. I recall doing similar things with the trolleys from the turn of the century (1900 not this last one!).
Wondering if it's safe to use an impact gun on the flange nut (or bolt)?
I'm also going to check the flange, if it has pits, I have a sleeve coming that I can use.

[powerwagontim]

Warren,
I would use the sleeve regardless the condition of your yoke. The sleeve material is harder than the yoke, and will act as a better and smoother wear surface. The big complaint of the leather seals is that they are more abrasive, and will wear a groove into the yoke, allowing leakage. I have had good luck with leather seals used with sleeves.
Tim

[vtdeucedriver]

You should not need a impact, just a good socket and a very long braker bar. Definatly 1/2 in drive. I would also make sure you have a good torque wrench when you go back to tighten so its got the torque per the book.

[WarrenD]

Being that the axle is in the truck and I'm getting too old to limbo, I thought the impact gun would be easier to use than a longer breaker bar. My concern is more about damaging any internals. I think I have figured out how to make my own 41-W-3277-40 wrench which keeps the pinion from turning while you are removing the fastener.

[achiem37]

What I have done on my truck was to remove only the inner seal elements from the large seal assembly. Keep the outer ring in the housing and carefully pick out the dust seal then the rubber or leather inner seal. You'll find that the outer housing of the seal contains a pocket where the inner parts went. I will look up the modern seal size that fits into the pocket left from the old parts. Generally the outer diameter of the seal housing does'nt leak so why remove it if you don't have to. When you get the inner two parts out you'll see three stake marks in the bore of the seal housing . Carefully remove these with a dremel or such until they are smooth with the rest of the id. Then install a speedi sleeve on your yoke and drive in the new seals. I installed two seals one in front of the other for double protection. just be sure to lube the outer seal face as it may not see oil from the housing until the inner one leaks a bit. This little trick has worked great for me many times. i'll respond back with the seal numbers latter. Terry

[achiem37]

The seal numbers I used were CR# 18555 or 18565. The speedi sleeve is 99187. Both of the seals fit ok they just have different rubber compositions. I like the 18565 version and I think they are a little cheaper. These seals use a nitrile rubber material and is designed to replace an older leather style seal. The other material on the 18555 is polyacrylate and will work as well but is pricey. These are just some options for you.

[WarrenD]

Thanks I already have a leather seal so will soak it and use that. Sleeve is on order (on the way?) and I plan on using it regardless of the shaft condition. Ordered new axle vents today, so hopefully no issues there. I drained the diff and found smelly, brown milkshake, so water must have gotten in there. Guess the leaking seal saved the diff!

[Cal_Gary]

I did this job last year: If you chisel the old seal lip inward toward the pinion shaft (from the housing) it will loosen up a bit all the way around. Then just slide a good sized screwdriver sideways into the back edge of the seal and pry-it will usually turn right out. An impact won't hurt the pinion shaft-in fact, much easier to remove than the "breaker bar/cheater pipe/chock the wheels so it won't roll" drill. I got a rubber seal from VPW. I also needed a puller to remove the companion flange, and found a small steering wheel puller did the trick. I'll try to post some pictures tomorrow.
Also, I use standard GL 85w-90w in mine.
Gary