Front diff pinion seal replacement (1 Viewer)

[l3n0x]

Hello!

Does anyone know about a guide on doing this job (on the vehicle)?

I can see some for 80's, but not for 100's. Is it that rare to happen? My truck has 170k miles on it (if we can believe that), and the front pinion is leaking

I suppose the only way to do it is to mark and reuse the nut and hope you get the preload right or else bearings will fail & the diff will need a rebuild? If it wasn't only 1.5q or so, I'd be topping it up in this case (instead of rebuilding), but a couple tenth of quarts can leak out so fast & run something dry.

It's not the breather.. that's clear.

 

[bwell]

Agh, that's not even that bad!!

You can buy a new pinion nut. But your correct on the pinion preload with the factory crush sleeve/spacer. Hypothetically you might be able be able to get the backlash set back to where it is currently but you run the risk of crushing the factory pinion spacer more.

When and if you tackle this job, only buy a new pinion seal that is from Toyota. I rebuilt my front differential about 3 1/2 years ago, and my pinion seal started leaking about 5 months ago(doesn't drip any where just residual like yours appears to be). But I used a solid spacer for the pinion, so just a matter of taking the time to replace the pinion seal. Make sure you index the front prop shaft to the companion flange when you do the job with a paint marker or metal punch so that you can get it lined back up the way it was previously installed.

 

[l3n0x]

Agh, that's not even that bad!!

You can buy a new pinion nut. But your correct on the pinion preload with the factory crush sleeve/spacer. Hypothetically you might be able be able to get the backlash set back to where it is currently but you run the risk of crushing the factory pinion spacer more.

When and if you tackle this job, only buy a new pinion seal that is from Toyota. I rebuilt my front differential about 3 1/2 years ago, and my pinion seal started leaking about 5 months ago(doesn't drip any where just residual like yours appears to be). But I used a solid spacer for the pinion, so just a matter of taking the time to replace the pinion seal. Make sure you index the front prop shaft to the companion flange when you do the job with a paint marker or metal punch so that you can get it lined back up the way it was previously installed.

Thanks! I already have the seal - Toyota of course. I'm now debating what is better... Leaking out 0.1quarts every 300 miles and refilling accordingly - might be able to run the diff a couple 10k's more, but it will get odd fast. Or doing the seal which might wreck the bearings if I don't get the preload back where it was - which I think is almost impossible to do.
I could get a new diff for ~$1800 if I manage to kill it either way, which is not good but not that bad.

 

[bentonrover]

Took me about a hour. I used car ramps. Mark the stake nut position with a marker. Unstake it. I needed a impact to break it. Then counted the turns. Pretty straight forward really. I reused the nut( yeah yeah). It was still in good shape. Counted the turns. Lined back up and all good. Mine blew cause of the breather was rust frozen. Took out both axle seals as well. Mine was really leaking. Like big drips all over. Good luck

 

[l3n0x]

Took me about a hour. I used car ramps. Mark the stake nut position with a marker. Unstake it. I needed a impact to break it. Then counted the turns. Pretty straight forward really. I reused the nut( yeah yeah). It was still in good shape. Counted the turns. Lined back up and all good. Mine blew cause of the breather was rust frozen. Took out both axle seals as well. Mine was really leaking. Like big drips all over. Good luckView attachment 2034950

Awesome! Thank you! I need a couple more success stories like this)

 

[slacker24-7]

I’ve replaced several pinion seals (but never on a 100 ) as bentonrover describes and I’ve never had a issue .

 

[l3n0x]

I wonder how I’m gonna reuse this nut?

 

[l3n0x]

Does anyone know if I have to fabricate a tool to hold the flange, or can I just undo the nut as-is without breaking anything in the diff/CV's?

 

[l3n0x]

I think I can try and transfer the markings to a new nut really. It won't be dead spot on ofc, but could be pretty close. I don't know if thats good enough?

Also I'm not sure about buying a new flange - in case the old ones is scored. Would that throw off the preload totally?

 

[suprarx7nut]

Does anyone know if I have to fabricate a tool to hold the flange, or can I just undo the nut as-is without breaking anything in the diff/CV's?

I think I can try and transfer the markings to a new nut really. It won't be dead spot on ofc, but could be pretty close. I don't know if thats good enough?

Also I'm not sure about buying a new flange - in case the old ones is scored. Would that throw off the preload totally?

No need to hold the flange. Car in park, wheels chocked, breaker bar that thing loose.

I think the key to successfull re-installation is just getting slightly more compression that you had previously. The acceptable range is wide. if you can loosen the current nut just barely, then use a torque wrench at the min spec value and tighten. Look at your match marks. Are they lined up yet? If not, increase torque on the wrench 10 ft-lbs and try again. Are they lined up now? If not, raise torque again and repeat until you get to the previous nut position. That will tell you roughly how much torque was present. Now you can remove the nut, and install a new one with just barely more torque. 5-10 ft-lbs. That should give you similar compression on that spacer plus a tiny bit. In theory, that should keep you safe enough to not prematurely kill the diff without having to rebuild it.

FWIW, I tried replacing the seal in car and failed. My new seal leaked worse than before. I remove the diff from the vehicle entirely and replaced all three seals. I reinstalled and it's now leak free. It can really tough to apply force normal to the seal when it's in the vehicle.

I would also strongly recommend a new companion flange. The companion flange surface is just as important as the seal. A new seal will not seal against a worn out (grooved) companion flange.

 

[l3n0x]

You know what i think right now after this last post? I’ll just leave it as is, and if it outlives the other failing parts of the car without destructing itself or leaking way more, I’ll might give it a proper rebuild.

 

[l3n0x]

Okay, afterall I've decided to jump into this.

Bought new flange, seal, and nut.

Now at re-assembly I have a problem. With everything in place the new nut, when snugged (and by that I mean 150Nm-110ft/lb) up is about 45degrees short where the old nut was..

I have removed the new nut and tried to reinstall the old nut (in case my marking where not correct when I transfered them to the new nut), but same story.. Could it be that the new pinion is a tad longer?

How do I set the preload now?

 

[l3n0x]

Okay so this is what I’ve ended up with.

The red mark is what counts. And it’s still a tad before than where it was. (??)

This is already very tight (like 240Nm), I couldn’t do anymore. This way it takes around 7Nm to spin the pinion (with one wheel off the ground and the other one on the ground, half-shafts connected). I know this doesn’t mean anything, but by feel it’s maybe a bit on the tight side. We’ll see how it turns out...

I think in the end the diff has to come apart eitherway (leak if I’ve left it or too tight or not tight enough), so at least I tried...

New vs. Old

Bright Red paint mark

 

[l3n0x]

I wonder if I’ve staked the nut enough...

 

[Wilsil]

Did you get it right in the end?