Front Diff question

[Imagery]

I found that the oil seal was leaking or slinging oil so I checked the level to make sure it was still full. It just oozed out when I pulled the fill plug and really didn’t look to healthy so I decided to go ahead and drain and refill. When I pulled the drain plug, it had a good amount of shavings stuck to the magnet and the oil was very dark grey and almost looked like mud towards the end of the draining. Stuck my finger inside the fill hole and felt a sharp point on the outer part of the ring gear. May have to have it replaced but will get a local Differential shop to do the work and change the seal.

 

[FMC80]

That looks horrendous. What’s your question?

 

[BILT4ME]

You need to check your knuckles as well for birf soup. Odds are it has sucked them dry and drawn all the grease into the differential.

Clean out your differential housing vent system. Drill out the fitting so it can breathe and extend your line above the brake booster to avoid water intrusion.

 

[Imagery]

You need to check your knuckles as well for birf soup. Odds are it has sucked them dry and drawn all the grease into the differential.

Clean out your differential housing vent system. Drill out the fitting so it can breathe and extend your line above the brake booster to avoid water intrusion.

Well I guess my question was is that normal to look like that? But now after you said check birfs, that then explains why the oil was so thick and soupy. It must have sucked the birfs dry because it looked like a mix of birf grease and diff oil. Thanks for your help because I wasn’t sure what was happening.

 

[Grandlooser]

Wow, too many shavings man.

 

[FMC80]

Not normal brother.

 

[BILT4ME]

Well I guess my question was is that normal to look like that? But now after you said check birfs, that then explains why the oil was so thick and soupy. It must have sucked the birfs dry because it looked like a mix of birf grease and diff oil. Thanks for your help because I wasn’t sure what was happening.

Yeah, you're due for a front axle rebuild and possibly a differential rebuild as well.

That's too many shavings, and depending on what you found in there, could be worth a check up.

How many miles on it and what kind of service does it serve? (DD, trail, toy, it sits....)

Have you tried to tow anything in reverse?

 

[DiscoCam]

rip front diff....

 

[Imagery]

No not towed in reverse but did pull race car to Baja and back up from Cabo to Texas last April of 2019. Gears are 456 and now have 30k on them. I will check the rear which was also done same time but it won’t have the birf grease to deal with. The whole front end was done same time so it all has only 30k. I might pull the front shaft and engage the electronic diff lock and drive it 2wd till it can all be rebuilt. I don’t wheel hard and don’t get it in bad mud either, just dirt roads and logging roads when they aren’t to wet.

 

[BILT4ME]

No not towed in reverse but did pull race car to Baja and back up from Cabo to Texas last April of 2019. Gears are 456 and now have 30k on them. I will check the rear which was also done same time but it won’t have the birf grease to deal with. The whole front end was done same time so it all has only 30k. I might pull the front shaft and engage the electronic diff lock and drive it 2wd till it can all be rebuilt. I don’t wheel hard and don’t get it in bad mud either, just dirt roads and logging roads when they aren’t to wet.

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Ok, well, that makes a difference.

Did you do a break-in on the gears?

Has the oil been changed since the gears were installed? If not, then that's your break-in filings. I would change the oil, run it for about 1000 miles, and change it again to see how it looks.

Still need to do the breather and the birfs, though I think.

 

[Imagery]

Yes I put 500 miles on the gears for break-in and then fluid was changed. My breather hose from the axle has extension section and goes up to the frame, is probably stock location and the little valve is clear and moves up and down freely. I didn’t try blowing into fitting on axle to make sure nothing is blocking it but I will just to make sure. I pulled the inspection plug on top of the birf housing and put my finger in and felt grease and it was still of correct viscosity, at least there at the top. I put the grease gun in and pumped the same grease probably 50 pumps and it never squeezed back out so I really don’t know how much is in there.
when they do the front diff probably r&p replacement, don’t the birfs and axle shafts have to come out? I guess that would be the time to do everything but I’m not sure if this shop is familiar with the 80 front end. And I’m sure they won’t clean all the old grease off and do a good visual inspection, including the inner race and cage and bearing balls. I did all that once before about 16 years ago and just am not setup here to tackle that again but that’s probably the only way to be sure it’s done right and without shortcuts.

 

[Imagery]

I guess it might be a good idea to go ahead and pull the front driveshaft just to free up everything until I get it all figured out.

 

[BILT4ME]

I guess it might be a good idea to go ahead and pull the front driveshaft just to free up everything until I get it all figured out.

Pulling the front DS will make no difference, as it still gets pushed due to the drive flanges on the hubs. Unless you have lockout hubs or worn out drive flanges.

The stock fitting on the axle has a very small hole in it and I actually had to use a drill bit to clean out the port on mine. I wish now that I would have actually drilled the hole larger so the gear oil could drain back in.

What happens is the gear oil gets thickened by sucking in grease from the knuckles, then it causes it to be "overfilled" and then as it heats up, it pushes fluid up into the vent and the thick gear oil cannot drain back in. Then it clogs it up and there is constant mixing between the knuckles and the diff.

You can do a gear oil change quick and easy. Drain it and refill it. Do it again in 500-1000 miles and judge the condition.

Look at the balls on the knuckles. Where is the "grease line" on the ball. That's a good indication of the level on either side. Depending on the type of grease gun, 50 pumps to 200 pumps will get more grease in there than before.

If your gears aren't whining, grinding, or leaking, you're probably OK. Remember, you DS now turns 111% more per mile than it did before the gear change, so you have more pinion mileage than you did before (by about 11% comparatively.) This just means you need to shorten your PM schedule a bit.

Don't use compressed air to blow into the breather fitting because you don't want to blow out a seal internally and CAUSE a problem.

 

[Grandlooser]

Just get $1200 ready. Maybe you won't need it. But I bet something else on the truck does anyways.

 

[MUDZLLA]

still gets pushed due to the drive flanges on the hubs

OK help me out here. How is knuckle grease pushed into the differential from the drive flanges?

I agree on the breather fitting getting plugged when there is mixing of diff oil and birfield grease, but that's due to a failed inner seal. Or what am I missing?

 

[Cruiserdrew]

To me, the amount of filings and sludge looks pretty normal on new gears. If they are running quiet, I'd just do 2-3 quick succession gear oil changes and clean out the diff. You definitely need a knuckle rebuild to replace the seals. But don't panic, you may be fine, and it's worth a few gear oil swaps to find out.

 

[Imagery]

The grease line is the same on both sides but the right side is a little dryer than the left. The 4 nuts and cone washers order the knuckle were a little wet but not dripping or flying off in the wind. I went ahead and cleaned everything off so I can watch and see how it does from this point.
the grease gun I used does not put out much each handle squeeze. I actually didn’t count so it was probably less that 50 but I was just looking to see how close the level was to the top. It never started to squeeze back out so I didn’t pump it full. I don’t know if that plug is for filling as it probably doesn’t get the grease where it needs to be anyway. The birfs don’t make any noise even at full clock either way so hopefully they are Alright for the time being. I’ll run the fresh diff fluid about 500 miles or so and drain and see what it looks like. I’ll still get the diff shop to look at it and change out the pinion oil seal. But if they say the R&P are trashed, I will get them to replace them but I wonder if that will require them to take the axles and stubs out in which case they would be doing the birf rebuild. I would just first get the kit so I know it’s of best quality and not some cheap after market stuff. Then it’s still probably best that I do the birfs myself along with you guys here and I do have the FSM and those pages on birfs are already dirty and highlighted. It’s been 16 years since I did it so I will first have to order the kit and maybe bearings with races for birfs and wheels. I am also going to replace the brake drums and pads to the power stop hd so I guess I will be installing new races anyway. I ordered my parts from Cruiser Dan/American Toyota but not sure if he is still doing that. I guess you just want to do OEM for everything so I could order locally from dealership parts.

 

[Grandlooser]

To answer one of your questions, yes the outers and axle shafts need removal to take the diff out.

 

[FMC80]

The grease line is the same on both sides but the right side is a little dryer than the left. The 4 nuts and cone washers order the knuckle were a little wet but not dripping or flying off in the wind. I went ahead and cleaned everything off so I can watch and see how it does from this point.
the grease gun I used does not put out much each handle squeeze. I actually didn’t count so it was probably less that 50 but I was just looking to see how close the level was to the top. It never started to squeeze back out so I didn’t pump it full. I don’t know if that plug is for filling as it probably doesn’t get the grease where it needs to be anyway. The birfs don’t make any noise even at full clock either way so hopefully they are Alright for the time being. I’ll run the fresh diff fluid about 500 miles or so and drain and see what it looks like. I’ll still get the diff shop to look at it and change out the pinion oil seal. But if they say the R&P are trashed, I will get them to replace them but I wonder if that will require them to take the axles and stubs out in which case they would be doing the birf rebuild. I would just first get the kit so I know it’s of best quality and not some cheap after market stuff. Then it’s still probably best that I do the birfs myself along with you guys here and I do have the FSM and those pages on birfs are already dirty and highlighted. It’s been 16 years since I did it so I will first have to order the kit and maybe bearings with races for birfs and wheels. I am also going to replace the brake drums and pads to the power stop hd so I guess I will be installing new races anyway. I ordered my parts from Cruiser Dan/American Toyota but not sure if he is still doing that. I guess you just want to do OEM for everything so I could order locally from dealership parts.

Definitely all OEM. Dan is retired but lots of people have good things to say about https://toyotaparts.mcgeorgetoyota.com/
I don’t use them because shipping kills me. I use Genuine Toyota Parts - Wholesale Prices | Modern Toyota Parts - https://wholesaledirect.moderntoyota.com/
They have competitive prices and ship for a relatively competitive rate for where I am.
Also if you’re going with the knuckle kit, I’ve had excellent service through Cruiser Brothers, OEM Quality Parts & Accessories - https://cruiserbrothers.com/ I order their Mt Fuji kit and it has all OEM components to include Koyo bearings. They usually ship same day too.

 

[Pin_Head]

It could be normal depending on how long it has been since it was cleaned. I wouldn’t worry about it unless it is making noise.