Front pinion seal replacement

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Joined
Apr 21, 2004
Threads
27
Messages
262
Location
Bainbridge Island
I am in need of replacing the front pinion seal. The question that I have is on the tightening of the pinion nut. Is the front preload on the pinion bearing adjustable with a crush sleeve between the bearings? or is it a setup of shims like the old FJ40's? The root of the question is how tight does it get torqued? I know about staking the nut good and tight, I will probably use locktite blue to keep it from backing off. I have done this on lots of other types of vehicles and older cruisers, so I am not that intimidated by the job itself.
 
I had to change the seal on my rear pinion. Yes that nut sets the preload as you describe. What I did was to remove the nut and replace the seal and then replace the nut back to it's original spot by lining up the stake marks and then staking it back down in it's original place. Probably not the ideal way of doing it but it seems fine after 6k.
 
What you need to do is check the backlash of the free play.
When you turn the pinion back and forth you feel some slop or free play. THat is what you need to measure before you remove the pinion nut.
With a dial guage inch/lb torque wrench you see how many inch/lbs there is. You are not turning the gears when you are measuring it.You can so this with the tires on the ground.
When you are replacing just the seal, you want the pinion nut to be a little tighter than it was before.

https://forum.ih8mud.com/showthread.php?t=18673&highlight=pinoin+seal
THis might help some
 
What I did was to remove the nut and replace the seal and then replace the nut back to it's original spot by lining up the stake marks and then staking it back down in it's original place. Probably not the ideal way of doing it but it seems fine after 6k.

I replaced my rear oil seal this evening and the above advice worked well. However, I made some mistakes and I'll pass the hindsight on.

I can think of three things I did that were good (not many, I know) (1) The first was to make some reference marks to relocate the position of the nut. With everything still tight, I took a Dremel (an engraver or scribe would work just as well) and placed aligned marks on the stake nut and the shaft to precisely locate how far the nut was threaded on (in case I ruined the stake nut and lost the reference). (2) Before breaking into the third member, I spent a good while twisting the companion flange by hand and getting "a feel" for how much preload should be on the backlash (I do not own an inch-lbf torque wrench) (3) When I ordered the oil seal from CDan, I got an extra stake nut, just in case.

Firstly, I tried a bunch of chisels and punches to "undo" the stake nut, but didn't have one of ideal width. So, I tried a screwdriver. I chose a cheap one as I was going to ruin it anyway; this was a mistake. I broke the brittle blade of the cheap screwdriver off in the crevice between the stake nut and the bed of the keyway. This added some time and I screwed up the stake nut so bad in the process of getting the screwdriver blade out that it was unusable; not what I had envisioned.

After replacing the oil seal (by the way, if you've done the birf job and have the 54mm hub socket, it works mildly well to press in the new seal), I used the origninal stake nut to push on the companion flange until the Dremeled marks aligned. At this point, everything is in it's original position, but I screwed up the stake nut so badly that I couldn't stake it. So, I removed the original stake nut and replaced it with the new one (by the way, the old stake nut sat on a separate plate washer; the new stake nut has a washer built-in; so, with the new stake nut, I didn't use the old washer), snugged it up against the companion flange and staked it down. Again, I spent some time twisting the companion flange by hand and it felt the same as it did before I messed with it.

So, I suppose the my advice would be to:
(A) Add some clear reference marks to realign the stake nut with the shaft.
(B) Take care in "unstaking" the nut so that it can be reused and find the proper tool to do so.
(C) Have an extra stake nut on hand just in case (they only cost about $3).

EDIT: My seal began to leak when I went to synthetic diff oil. It's had been slowly leaking for about two months and lost over a quart of oil in that time.
 
To undo the stake nut use an impact gun, makes it simple. I don't know how critical the preload is but mine is probably as off as yours. According to the FSM the crush spacer should never be reused, but?????
 
On a side note when you are in there check the flange that the seal goes around. It might not be the seal that is bad. The seal might have worked a groove into the flange and that is where it is leaking from. Check this or you might be having to do the job again really soon.
 
On a side note when you are in there check the flange that the seal goes around. It might not be the seal that is bad. The seal might have worked a groove into the flange and that is where it is leaking from. Check this or you might be having to do the job again really soon.

Good point. Yes, my flange had slightly detectable groove in it. I've heard that some folks will try to leave the oil seal a bit proud of its intended location so that the seal contacts the flange in a different spot and, hopefully, avoids the groove (I wasn't comfortable with this). Knowing that I have a groove, I would opt for an aftermarket oil seal next time (is it Man-a-fre that makes them?). Supposedly, they are a different thickness at the seal and would not be affected as much by the groove left by the Mr. T seal.
 
If you have gone that far, you should at least replace the flange if grooved. New aftermarket ones are $35. better than doing it again.

Good point. Yes, my flange had slightly detectable groove in it. I've heard that some folks will try to leave the oil seal a bit proud of its intended location so that the seal contacts the flange in a different spot and, hopefully, avoids the groove (I wasn't comfortable with this). Knowing that I have a groove, I would opt for an aftermarket oil seal next time (is it Man-a-fre that makes them?). Supposedly, they are a different thickness at the seal and would not be affected as much by the groove left by the Mr. T seal.
 

Users who are viewing this thread

Back
Top Bottom