: Toyota Tech Guru's: Troy's rear diff diagnosis


AxleIke
05-21-2008, 11:31 PM
I want to double check my diagnosis of troy's rear diff as he asked me to look at it.

This was done with the rear wheels on the ground, and no rear drive shaft.

When I rotated the rear pinion flange, it move the normal amount of back lash, and then stopped. Upon further pressure, the pinion flange would move a little more, but in a wierd way, that is almost impossible to explain here.

So, I pulled the pinion flange off, and looked inside. No immediate destruction, but, when I grabbed the pinion, it was able to move side to side pretty good. I could see the bearing moving inside as well. The pinion did not shift down into the diff at all.

Is this a bad pinoin bearing or a bearing that has moved? Or something else?

I obviously understand that internet diagnosis is difficult, but any thoughts would be most helpful, especially thoughts that don't involve removing the rear diff.

RedRunnertc
05-22-2008, 02:05 AM
So, I pulled the pinion flange off, and looked inside. No immediate destruction, but, when I grabbed the pinion, it was able to move side to side pretty good. I could see the bearing moving inside as well. The pinion did not shift down into the diff at all.

Is this a bad pinoin bearing or a bearing that has moved? Or something else?


I don't recall - did the flange move when the bolt was on?

The reason I ask is that the bearing should move a little with no preload, right?

I don't recall what the pinion nut was torqued to, but I didn't have my good impact gun yet, so it might not have been enough trying to do it by hand.

Lysmachia
05-22-2008, 05:39 AM
That Impact Gun has been a godsend BTW....

/Godsend comment

I know Brian (TheFatKid) mentioned your rear U joint. I don't think he saw anything with the pinion when we swapped out your meats...

AxleIke
05-22-2008, 08:09 AM
I was thinking about it last night, and it totally could be the preload. Which is a good and bad thing. Good that your bearings are fine, bad that there seems to be something else wrong. Or maybe the preload was just off, and with a good tightening, it will be fine again.

Lysmachia
05-22-2008, 08:15 AM
Oh I see... getting Troy riled up when he's half way around the world... :D

:neener:

thefatkid
05-22-2008, 08:41 AM
Do you have a solid spacer? Why are you impacting the pinion nut?

The short answer is no, you should not have play with either condition. The bearings should have enough tension on the pinion to not come loose. The best thing to do now is......

remove the wheels and drums, check total preload. A guess without removing the axles and assuming your housing is not bent I would look for 10-15inlbs. The best solution would be to remove the diff for further/correct preload inspection.

RedRunnertc
05-22-2008, 09:06 AM
Do you have a solid spacer? Why are you impacting the pinion nut?

The short answer is no, you should not have play with either condition. The bearings should have enough tension on the pinion to not come loose. The best thing to do now is......

remove the wheels and drums, check total preload. A guess without removing the axles and assuming your housing is not bent I would look for 10-15inlbs. The best solution would be to remove the diff for further/correct preload inspection.

Yes, solid spacer.

By preload you mean how much torque it takes to spin the pinion, right?

thefatkid
05-22-2008, 09:14 AM
yea, that is preload. Do you guys have a rotational torque meter?

RedRunnertc
05-22-2008, 09:15 AM
yea, that is preload. Do you guys have a rotational torque meter?

Uh .... no

Lysmachia
05-22-2008, 09:46 AM
:doh:

And here I thought Ron was done with surgery.....

:banghead:

AxleIke
05-22-2008, 10:16 AM
Brian,

The impacting was to take the nut off. Not to put it on.

The preload was originally set with an in/lb torque wrench (when troy and I set up his gears a few months ago). It was set at 12 or so in/lbs. Tough to know for sure becasue the first mark on the torque wrench was 25 in/lbs.

The bearings look okay from a outside of diff inspection. By this I mean, they are not visiably chewed up or crappy like i've seen pics of some blown up diffs. Not sure if that matters or not.

thefatkid
05-22-2008, 10:21 AM
Doh! I though you guys had the stuff to build diffs. Anybody have a calibrated wrist up there?

I don't remember seeing anything wrong with the diff though. I did remember that a u-joint was loose. Was the pinion seal leaking? that might be a bad indication.

thefatkid
05-22-2008, 10:23 AM
Gotcha, it is hard to say. It has a solid spacer so hammer that nut on and check your preload. If it is too loose you know you have issues

AxleIke
05-22-2008, 10:55 AM
Pinion seal was leaking pretty badly.

RedRunnertc
05-23-2008, 01:58 AM
Pinion seal was leaking pretty badly.

I'm not entirely sure I got the pinion seal in there dead perfect to start with. I haven't had any issues with the fluid level though (I check it weekly)

thefatkid
05-24-2008, 09:03 AM
Well being that you just built the diff, I'd put a new pinion seal in it hammer a new nut on there with loctite and see what it does.

AxleIke
05-24-2008, 11:37 AM
The bearings were reused.

I think thats a great idea though. Give it a shot and see whats what.

RedRunnertc
05-24-2008, 12:33 PM
Pinion bearing was new.