Differential Pinion -- no Preload. (1 Viewer)

[TractorDoc]

Working thru the rear axle of the '78 FJ40. Wanted to replace axle bearings, seals, install rear discs, etc. When removing the pinion flange and rear axles I noticed some play in the rear pinion -- more than I feel comfortable bolting back together or calling "good enough." There is about a half inch or so vertical travel on the pinion shaft in the housing -- tried to take pictures in the "down" and "up" positions.

Common sense tells me that the bearing closest to the cut gears on the pinion should not be able to move/cause this sort of issue (the bearing is intact/looks ok from the inside). The only thing I can come up with is the far bearing closest to the threaded end has moved toward the driveshaft. I know bearing preload is set withing a certain tolerance -- is there a way I can "press" the bearing down further onto the pinion (with a spacer under the nut while the nut is tightened down?) to achieve a more appropriate bearing placement or does that occur when I reinstall the drive flange for the propeller shafts?

Thanks for any help for the new guy -- I looked thru the archives but could not find this specific question.

 

[Tools R Us]

The bearing preload is set by the pinion nut clamping force, without it the pinion will flop around. Put it back together, torque and see what you have.

 

[TractorDoc]

Got it. That makes sense -- just didnt think the pinion would drop that much by taking the flange off -- but it is decades old with 75000+ miles on it. Ill tighten the nut up to the proper torque and see where I am at -- things did turn over smooth before taking the flange off!

Thanks again for the quick response. . . I will sleep better/stop worrying about it for the night.

 

[MScruiser]

The bearing preload is set by the pinion nut clamping force, without it the pinion will flop around. Put it back together, torque and see what you have.

This.

It also helps to remember the number of turns it took to remove the pinion nut; that way you can get pretty close to the correct preload when you put things back together.

 

[B y r o n]

Take a look at this information for a better understanding of what is involved. It's possible you need a new crush sleeve to get the proper preload on the pinion. If you have any question on the subject contact Zuk as he has been more than helpful in the past to get things right, at least for me and several others.

 

[shawnfj40]

You need to remove that outer bearing. If your pinion has a crush sleave on it, you need to toss it replace it with a new one. They are not reusable. The only other option would be to install the correct shims to set your preload. If you have shims now you are good to go and need only to torque the pinion nut to spec and your preload should be on the money.

 

[dare]

I had a similar issue in mine but worse, very common on Landcruisers. I was 3000kms from home so we cranked the pinion nut up and it went went from a very noisy, leaky mess to quiet, no play and almost leak free for about 6000kms until I pulled it out and put another diff in.

It's better to get rid of the crush spacer and run a solid pinion spacer. It's also common to run a little more preload than Toyota specify.

 

[TractorDoc]

I was not aware of the crush sleeve "option" -- my service manual did not show that component in the parts break down (Thank you Byron for the link to the pics/rebuild info). I suppose I can try to pop the outer cone bearing off to see what lies below it. Cars and tractors are different in this aspect -- I am used to setting pinion preload with shims behind a bearing cone.
If I have no crush sleeve I should be able to install the bearing, slinger, new oil seal, flange, and torque the nut down to the recommended 145-173 ft.lbs. to acquire the 8-11 in.lb. preload (with the used bearing) -- corrrect? I did not count the turns when I removed the old nut as I was replacing it with a new one anyway; I did not know how similar the two would be in terms of position.
Was there a year/model break where adjustment went from using shims to a crush sleeve?

Thanks again for all the replies -- Im learning more than I thought I would!

 

[Cruiserdrew]

I think the '78 is unique--but memory may be faulty on this point...

Fine spline pinion 4.11, and the pinion spacer is built into the pinion, and the pinion pre-load is set only with shims, thus no crush sleeve needed. It's a nice way to do this and I'm surprised Toyota stopped doing it that way.

But if it's that loose, the bearings may be worn out or close. I would bolt it together, but if the pre-load is still close to zero, you need a rebuild.

 

[shawnfj40]

Pinion preload is never built in. All of the early diffs used spacers and shims. I'm not sure when Toyota started using crush sleeves but they did. It's not hard to switch but it is time consuming. The sleeves are a cost cutting device and make setup simpler.

 

[TractorDoc]

Thought Id bring some closure to the topic that I started. I was able to extract the cone bearing from the threaded end of the pinion shaft and found a washer and shim setup that will determine the preload (no crush sleeve).

The bearing and cone looked to be in decent condition so back in it went with a coating of gear oil, slinger, and new oil seal (the original objective of taking everything apart). Slid the flange in and torqued the new nut down to 150 ft. lbs. I used the large pipe wrench in place of the SST that I did not have (nor took the time to make -- the wrench did the job).

No end play is present and the pinion turns the ring gear frim but smooth. Backlash is within spec and I applied some Prussian Blue to the ring gear teeth -- tooth contact between the pinion and ring gear looks to be appropriate (tried to take a picture -- could not get it to show up on the camera well enough to post).
Thank You again to everyone that contributed advice/information -- I really appreciate it!

 

[shawnfj40]

Sounds like everything worked out peachy! Congrats!