A while back I noticed a wetness from the pinion seal, I cleaned it somewhat and ordered a new National pinion seal 7044NA and a Ford pinion carrier O-ring (even though it's not leaking). I've checked the rear axle lube level, it's good so all I can say is it's been a long time leaking very slowly. It's a '77 F-150 with Ford 9" rear.

My plan is to first secure the truck on level ground with hubs locked and TC in 4wd, trans in Park ... so it can't roll and then undo the U-joint from the yoke and wrap tape around the joint caps and tie it up out of my way.

I'll clean the yoke, nut, pinion threads, etc (brakleen and brush) and mark them all (punch marks) for orientation and measure the exposed threads ... then loosen the pinion nut. Once loose, I'll pull the pinion carrier out (5 bolts) with all parts still in place (nut, yoke, washer, etc). Take the pinion carrier with shim(s) into my shop and there remove the nut, record parts, etc .... and put the new seal in place and loosely reassemble the pinion and yoke, etc. EXACTLY as they were While the carrier is out, I'll change rear axle lube too, what hasn't drained I'll use a pump and pump out.

I'll slip the pinion and it's carrier with same shims, new O-ring, back in place back into the hogshead snout, tighten those 5 bolts to spec. Then I'll tighten that pinion nut back to EXACTLY the same position on the pinion shaft end, same nut, same washers, put it back exactly the same. I'll add lock tite to pinion threads and stake the threads adjacent to the nut.

Lastly, I'll refill the axle lube and reattach the driveshaft via U-joint.

I thought about adding a drain, but there's really no need.

 

I personally would replace the crush sleeve or use a crush sleeve eliminator. This comes from my own personal negative experience with trying to index the nut and pinion and re-use it.

Also something to look for. My '76 (9") was leaking from what I thought was the pinion seal, but when I cleaned the diff and inspected the pinion support, I noticed that it was actually cracked around one of the 5 bolts. An unusual circumstance, but might be worth looking at while you are in there.

 

An old mechanic friend told me a seal shouldn't leak unless there is a loose bearing behind it. I watched him tighten the pinion nut on an 8.8 rear once, he said that usually stops the leak. It did. 8.8 started coming on 79 LTD's, he said they had to do it all the time. On a 9 inch he would probably look deeper as HB250 says.

 

I might would snug up just enough to eliminate excess slop if I detected any. I would not want to go too far as they don't relax.

 

Well, I don't believe my lying eyes. I bought 4 quarts of new rear end lube @18 per, crawled under there with tools, but first, before getting dirty, I checked the level. Appears to be good clean lube and a dip stick I made shows me it's pretty darn near full, maybe 1/4" below the fill plug. Anyway, it's plenty, but I did top it off to threads. I guess most of what I was seeing is just 47 years of accumulation? I'm gonna change it yet, replace the seal and O-ring too because I have them .... but it'll wait a bit.

 

I agree, crush sleeve should be replaced or better yet, eliminate it and use the kit that comes with shims and a spacer. I did this on mine and took a little bit of of setup and use of a 1/4" beam style torque wrench to confirm proper pre-load on the bearing without the seal installed. If I recall correctly you're looking for 10-15 inch pounds when you're rotating the pinion (disregard the initial higher reading due to inertia). Since you will have the carrier out anyway, it's pretty easy to do if you have the torque wrench. Nice thing about that mod, that if/when you need to swap pinion seals in the future, remove the yoke, spacer and shims, swap seal, put yoke back on with same shims and spacer, torque pinion nut and be on your way. You don't need to torque the pinion nut near as much either since you won't need to "crush" anything.