Pinion Seal Replacement- A Cautionary Tale...

[maineSS]

At some point in your PW experience, you'll be looking at a puddle of oil under the diff and wondering where it's coming from. The chances are about 99 in 100 it's coming from a leaking pinion seal, a grooved pinion yoke, or a combination of the two.

I recently replaced my pinion seal with the M-Series Rebuild seal retainer, and found it to be one of those experiences you wouldn't buy for a penny or sell for ten million dollars. Mine was a two week nightmare requiring the fabrication of several special tools and lots of pondering about how to proceed after yet another approach failed miserably.

I'm going to outline my proceedure so others can learn and avoid my mistakes. In my opinion, acess to a Mig welder is probably a must to get the seal out without a lot of extra disassembly.

Pic #1 shows the OEM seal retainer in place. It's a multi piece assembly made of very heavy sheet metal- you can absolutely forget about prying it out with a screwdriver, as even large ones will bend before collapsing the retainer walls. It's driven in sufficiently hard so that compression makes it very difficult to collapse the retainer inward- a crowbar would be needed, but it won't fit. Pic #2 shows the various retainer pieces. Pic #3 is the remains of the retainer center that holds the seal and felt- this needs to be cut out to even have a hope of
getting the retainer out without a welder. I didn't have a welder available so I had to cut the center out with a 3" holesaw. Continued...

[John S]

Oh yeah the caveman method. I have done a bunch of these . The first few went very smooth. I used screws and a slide hammer. Zip and it was out. Then I ran into some very stubborn ones. I beat and chiseld and beat somemore. Now I have a flanged ring that I mig to the seal and use a bearing puller. I made a sleeve to push against . I dont use the pinion to push against . Works well

[712edf]

My Rockwell sideloaders leak, but they have bolts around the pinion yoke. Not sure whats up with that.

Bucky

[maineSS]

I tried cutting thru the face of the retainer freehand with my 1/2" variable-speed drill, but couldn't keep it on track- it just kept skipping out. Since my holesaw arbor was center drilled for a 1/4" hole all the way thru, I had a pilot tool(pic #4) made up that attached to the pinion nut threads (3/4"x16). I used a 5 1/2" long grade 8 1/4" bolt. First the threaded part was cut off, then a piece of 1" cold rolled shaft was center drilled for a light interference fit about 1" deep, and the bolt pushed in. Next, the shaft was turned down to about 1 thou over the thread dia of a 3/4 x 16 fine thread nut. The shaft was cut off with a parting tool, leaving a 1/8" thick disc attached to the bolt, and then the end of the bolt was Tig welded. After that, the 3/4 x 16 nut was screwed onto a 3/4 x 16 bolt until there was 1/8" of thread left, and it was chucked up in the lathe. The bolt/disc piece was inserted into the tailstock chuck, moved up to the nut, and then pressed into place against the bolt end. The disc was then Tig welded into the nut. After a bit of straightening, I threaded it onto the pinion (pic # 5), and cut the center of the retainer out (pic #6). It required low speed and heavy effort on the part of the drill- had to stop 4-5 times to let the drill cool down, as it got quite hot. The slot in the side of the retainer was cut with a small cold chisel and drill during my exploratory work to see what I was getting into. Continued...

[maineSS]

The pilot took quite a licking, but kept on ticking till the job was done (pic #7)-it got slightly bent. Other tools didn't last so well. Pic # 8 shows the mini-slide hammer I started with after drilling & tapping 4 holes in the case- It got demolished after about 5 hits. Pic # 9 shows the remains of a 5/16" Allen wrench welded to a 1/4" bolt used as a hook attachment for a much larger slap hammer- the bolt bent repeatedly, and the allen wrench straightend out, while the case around the 4 holes bulged slightly. I cut the bolt head off to free up the hammer nut, as that attachment wasn't getting anywhere. Continued...