Pinion Seal Adventure - Bad Superseded Part (1 Viewer)

[EricG]

The other day, when I went to replace my rear brake pads, I found oil *everywhere* under the back of the truck. Complete mess. Seems to be the pinion seal. I dumped a quart of gear oil into the diff and it didn't fill it. I just got back from about a 3000 mile road trip in the truck. No noise, but I have no idea how low it's been for how long

Picked up the new seal (90311-38047) and nut (90179-22016 - DON'T BUY THIS, more in a bit) parts at the Toyota dealership yesterday, and went at it today.

Everything came apart fine. But the oil looks bad. Water contamination? Last time I was through water up to the hubs would have been December 2022.

The nut holding the companion flange (which are still available from Toyota for about $240 - I asked) is staked to the shaft, so should be replaced.

I pulled the oil slinger out and looked at the bearing. Seems ok, but you can't see much. I'm guessing that, based on the oil level and the condition of the oil, its days are probably numbered

I found a piece of pipe the right size to tack up a quick seal driver and got that in, put the flange back on. And then the problem. The new pinion nut was clearly not going to thread onto the shaft far enough to stake it. The flange was definitely fully seated. So I compared the new nut (center) with the old nut (left)

The new nut is clearly much taller, flanged, etc. The height that you need to stake it at is in the hex part of the nut. Clearly not going to happen.

So, my quick project is not going to be quick after all - Murphy always gets a vote. Back to the dealership to see if they gave me the wrong part.

The guy at the parts counter double checks the part number, and checks across years (my axles are out of a newer truck). The part number is right - but it superseded the original part at some point. But it clearly won't work and the original part is no longer available. He admired the problem, but couldn't offer any solution.

So, I headed south to Red Line Land Cruisers (Parts, Service - Toyota FJ40, FJ55, FJ60, FJ62, FJ80 - https://redlinelandcruisers.com) to see if they'd run into this and how they handled it. Justin took me back into their parts inventory and found me a solution! Part number 90179-22005 MANUAL TRANSMISSION OUTPUT SHAFT REAR SET. I believe it's from an FJ-60. That's the not on the right in the picture above. It's identical height as the original. The hex part is bigger - took a 1.25" socket, vs 1.1875" for the original (I don't have metric sockets that big, but those fit well).

Put everything back together, and refilled with fresh gear oil. Given how that looked, maybe I'll change it out again in a few hundred miles. But I suspect the damage is done. We'll see.

I did inspect my breather - everything looks intact. I have it extended up behind the fuel fill. I pulled the filter off the end - which is completely caked with mud & dirt - and blew it out while the pinion was apart. I guess my working theory is that on my long road trip, the diff oil got hot enough to boil off the water. The breather filter was to clogged to do its job, so it pushed out the pinion seal instead.

Hope that helps someone. Huge shout out to Justin at Red Line for getting me back on track!

 

[JoeCova]

The old nut had a washer...the new nut removes the need for the washer....

If your old pinion was staked without a washer or could not use the original washer and thus the new nut I would question if your drive flange is fully seated.

Did you retorque the pinion nut to 181 ft lbs?

 

[EricG]

The old nut had a washer...the new nut removes the need for the washer....

I looked at that - it would still be to tall.

 

[JoeCova]

I looked at that - it would still be to tall.

So where did your OEM washer go? I updated my previous comment, did you torque to 181?

 

[EricG]

So where did your OEM washer go? I updated my previous comment, did you torque to 181?

I used the OEM washer with the 90179-22005 part.
Where do you get the "181" torque number from? FSM (pg SA-80) has a process for setting bearing pre-load, but as far as I can tell, the 3rd member has to be removed to do it. I counted the turns taking the original nut off, and put the new one back the same number of turns, as I've seen described a few places. Which you can't really do if you leave the washer off and use the new nut.

 

[JoeCova]

I used the OEM washer with the 90179-22005 part.
Where do you get the "181" torque number from? FSM (pg SA-80) has a process for setting bearing pre-load, but as far as I can tell, the 3rd member has to be removed to do it. I counted the turns taking the original nut off, and put the new one back the same number of turns, as I've seen described a few places. Which you can't really do if you leave the washer off and use the new nut.

SA-104 for On-vehicle Repair and SA-132 for Removal and Assembly both state 181 ft-lbs prior to checking pinion bearing preload.

The whole point of the crush sleeve is to provide press-like resistance to the outer pinion bearing so it doesnt spin on the pinion and burn out while also providing torque resistance to the pinion nut so it doesnt come loose.

Counting turns may or may not work, I would def check preload.

Also this is the part number I got when looking up the rear pinion nut? Toyota 90179-22011? I know most of the master gear install kits replace this with a flanged nut.

 

[EricG]

SA-104 for On-vehicle Repair and SA-132 for Removal and Assembly both state 181 ft-lbs prior to checking pinion bearing preload.

The whole point of the crush sleeve is to provide press-like resistance to the outer pinion bearing so it doesnt spin on the pinion and burn out while also providing torque resistance to the pinion nut so it doesnt come loose.

Counting turns may or may not work, I would def check preload.

Also this is the part number I got when looking up the rear pinion nut? Toyota 90179-22011? I know most of the master gear install kits replace this with a flanged nut.

Ok, I guess I didn't read far enough - didn't see that section. Thanks, I'll take a look at it. Maybe I'll be re-doing this job
I had to lean hard on a big ratchet to get close to the turns, but I doubt it was anywhere close to 181 ft pounds.

 

[JoeCova]

Ok, I guess I didn't read far enough - didn't see that section. Thanks, I'll take a look at it. Maybe I'll be re-doing this job
I had to lean hard on a big ratchet to get close to the turns, but I doubt it was anywhere close to 181 ft pounds.

I just rebuilt both my front and rear diffs so I had the FSM memorized. Fingers crossed you are good to go.

 

[bhsdriller]

Could be fine. I did mine the same way as the OP and it's been good, going on ~6 years

 

[Rifleman]

EricG, Just as an FYI anytime you play in water, and the depth of that water goes over the hubs for any length of time you should plan on doing a oil change on your diffs, The reason i say that, oil seals are made to keep oil in, not to keep water out when you submerge those seals,​

Remember the only thing applying pressure on that lip seal to keep oil in, and water out is a very small and weak garter spring, once you submerge that seal you now have water pressure trying to force it's way pass that garter spring, and the deeper you go the more water pressure you get,​

I use to work on heavy duty US military trucks (M923 series of trucks) that could ford 6 feet of water, (with a snorkel even deeper water) but they were set up with an on board air system that would pressurize the front and rear axle housings, transfer case, transmission, and engine with low pressure air (around 3 to 5 PSI) to keep that water pressure from forcing it's way passed all those rubber lip seals,​

Even with this system in place we would still do a complete fluid change on all of those systems as soon as we reached a field maintenance depot to remove any water that got pass those seals,​