Rear Diff Rebuild Questions (1 Viewer)

[kazanski]

Hi all - I was able to rebuild my from differential thanks help from the board, and now I am on to the rear so figured I would reach out for some help to make sure I am going down the right path.

Specs:
- 1997 LC
- 150K miles
- factory e-lockers
- Stock height

I have been chasing a grinding on deceleration (I know it is a common thing around here), but I am a glutton for punishment. I rebuilt the front diff and that didn't solve it, so I am on the rear, and then most likely the transfer case and a part-time 4x4 kit to top it all off. Anyway, I don't do any hardcore crawling or offroading, but I do want to use it for extended road-trips and back country camping so I want it reliable.

I have the rear diff removed, stripped down, and cleaned and I am getting set to reassemble and reinstall. Based on my research I had a few things I am concerned with that I thought I would put out the community before I go through hassle of assembly and installation, just to find that I need to take it all apart again. Based on the shape of the bearings and the backlash, I am fairly certain that the rear is the culprit of some of my "grinding" noises.

1. First thing I noticed what the Locker was not functioning properly and locker fork/gear looked like it may have been rubbing or in contact with the locker mechanism at all times. The color of the gear is rainbow, which I am assuming is from high amount of heat from the rubbing. May be paranoia, but figured I would ask here if this is normal.
2. Second item is the condition of the pinion. It is pretty clear from the about of backlash and the condition of it that the bearings were starting to wear. but the face of the pinion gears is mirrored quite a bit, which I am assuming is from excessive contact with the ring gear and not a good thing. I was hoping to reuse the ring and pinion, but again wanted to see if I am setting myself up for failure here.
3. I have started seating races in the case and I noticed the that outer pinion bearing that came with the kit that I ordered doesn't match the one that came off of it, which also doesn't match what I think the OEM spec was. The kit that I received has a Koyo 30306JR, the bearing I pulled was marked 30306DJR, can anyone confirm the correct rear pinion bearing part number (w/ factory e-locker)? Is there anything I am missing with this? The only difference I can tell from Koyo site is that the 30306JR race is 2mm thicker than the one that came off of it, but all other bearing dimensions are equal. This causes the race to sit 2mm higher and not flush with the case machining, which I am not sure matters much.

Thanks in advance for info, pictures are below (and any other comments/opinions welcome from what you see based on the pics)

Locker discoloration:

Pinion condition:

Bearing race depth:

 

[kazanski]

Adding/editing original post to be more specific. Initially was worried about outer pinion bearing part numbers and now I am looking at the inner bearing part numbers and looks like the same issue. This is a kit from Cruier Teq that looks like it came from Sierra Gear, so not sure if this normal. The stock bearing numbers are still available (referenced Zuk here: Toyota bearing cross reference - http://www.gearinstalls.com/bearing.htm) so it is interesting that they subbed out other bearings instead of just including the original spec… I should have read Zuk again and listened to him instead of buying a kit.

 

[JoeCova]

I just rebuilt my rear diff today with 4.88s and an ARB.



1. I don’t know since I have ARBs.

2. The mirror polish is from REM/shot peening the gears at the factory. Lots of benefits to this that you can look up on your own but it’s not something to worry about. What was your backlash?

3. The 30306JR bearing will technically work but the chief difference is the bearing taper. The 30306JR is very shallow compared to the 30306DJR. I opted not to use the bearing that came with the kit and instead ordered a new OEM rear outer pinion bearing which is 30306DJR. The 30306JR will fail at some point due to this lack of taper.

All other bearings in my kit were the same as OEM.

Below are pics that compare. You may not be able to remove the race if the 30306JR because of how shallow it is if you ever needed to service it again.

 

[kazanski]

I just rebuilt my rear diff today with 4.88s and an ARB.

1. I don’t know since I have ARBs.

2. The mirror polish is from REM/shot peening the gears at the factory. Lots of benefits to this that you can look up on your own but it’s not something to worry about. What was your backlash?

3. The 30306JR bearing will technically work but the chief difference is the bearing taper. The 30306JR is very shallow compared to the 30306DJR. I opted not to use the bearing that came with the kit and instead ordered a new OEM rear outer pinion bearing which is 30306DJR. The 30306JR will fail at some point due to this lack of taper.

All other bearings in my kit were the same as OEM.

Below are pics that compare. You may not be able to remove the race if the 30306JR because of how shallow it is if you ever needed to service it again

thanks for the reply, answers/notes below:

2. This makes sense, thanks for the info. As usual I meant to measure before and instead just started tearing things apart, but based on the feel test from recently doing the front there was a lot more play.

3. This is good to know, I assumed I could go with it but would rather go with OEM. I have the same issue with the inner pinion bearing, they provided the 30308JR instead of the 30308DJR which will most likely cause me issues with my pinion depth. I am not happy with having to order 2 additional bearings that amount to about half the cost of the kit, so I have a note into Cruiser Teq on it. They should either specify the part numbers on their site or let you know in the description it is not factory equivalent, but I am guessing they just take what they get from Sierra and roll with it. Never had any issues with their stuff before, including the front kit I just used.

Anyway, will see what response I get and go from there.

For future reference for those looking at this, 2 good references:
Zuk References: Toyota bearing cross reference - http://www.gearinstalls.com/bearing.htm

Post in thread 'Rear differential bearing symbols'
Rear differential bearing symbols - https://forum.ih8mud.com/threads/rear-differential-bearing-symbols.153899/post-2148485

 

[JoeCova]

thanks for the reply, answers/notes below:

2. This makes sense, thanks for the info. As usual I meant to measure before and instead just started tearing things apart, but based on the feel test from recently doing the front there was a lot more play.

3. This is good to know, I assumed I could go with it but would rather go with OEM. I have the same issue with the inner pinion bearing, they provided the 30308JR instead of the 30308DJR which will most likely cause me issues with my pinion depth. I am not happy with having to order 2 additional bearings that amount to about half the cost of the kit, so I have a note into Cruiser Teq on it. They should either specify the part numbers on their site or let you know in the description it is not factory equivalent, but I am guessing they just take what they get from Sierra and roll with it. Never had any issues with their stuff before, including the front kit I just used.

Anyway, will see what response I get and go from there.

For future reference for those looking at this, 2 good references:
Zuk References: Toyota bearing cross reference - http://www.gearinstalls.com/bearing.htm

Post in thread 'Rear differential bearing symbols'
Rear differential bearing symbols - https://forum.ih8mud.com/threads/rear-differential-bearing-symbols.153899/post-2148485

Here is a pic of my old pinion with the mirror shine as well. However the inner pinion bearing both OEM and in my kit were Koyo ST4090 which may just be due to locked vs non-locked.

Mine was a Yukon from ECGS but agree they should list the specific bearing numbers.

 

[kazanski]

Just to close things out, this was the response I got from Cruiser Outfitters:

The IKTOYLCBE kit you ordered is assembled by Sierra Gear/Axle by West Coast Differentials. They have used those same bearings in all of their 9.5" kits for many years, to date we've never had an issue with any of them outside of the initial comparison difference. Hope that clears things up.

So FYI to anyone looking to purchase the kit in the future. While I can appreciate that the bearings will "work" and they say no issues, also a bit disappointed that I am shelling out and extra $120 to order the factory spec on a kit that says its specifically for the 80. I guess I should have asked and done my research before buying.

 

[kazanski]

You were right about the race removal on these! It took me about 30-40min to remove the one I already installed because there is no lip to tap it out. If it weren't for this I may consider installing these and rolling with it, but not being able to get them out later is a concern.

Inside pinion. bearing comparison (old left v new right):

Outside pinion bearing comparison (Old right v new left):

 

[-Spike-]

Just to close things out, this was the response I got from Cruiser Outfitters:



So FYI to anyone looking to purchase the kit in the future. While I can appreciate that the bearings will "work" and they say no issues, also a bit disappointed that I am shelling out and extra $120 to order the factory spec on a kit that says its specifically for the 80. I guess I should have asked and done my research before buying.

I used the non-specced bearings provided by Sierra once, on a diff I had Zuk set up. Destroyed the diff in a couple of years. That failure is one of the first Zuk saw, and it brought the issue to his attention. FWIW, he replaced the bearings for free, which was way beyond what I expected. He won't install them now, and keeps a bunch of the correct bearings on the shelf.

 

[CharlieS]

As I recall, Zuk used a bunch of oem bearings in place of the ones that come in the common rebuild kits. He knows his stuff, so I'm inclined to follow his lead.

 

[JoeCova]

Just to close things out, this was the response I got from Cruiser Outfitters:



So FYI to anyone looking to purchase the kit in the future. While I can appreciate that the bearings will "work" and they say no issues, also a bit disappointed that I am shelling out and extra $120 to order the factory spec on a kit that says its specifically for the 80. I guess I should have asked and done my research before buying.

I’ll try to find a link but Zuk posted a page about how he basically hates the aftermarket bearings and they fail entirely too often to use them over the OEM style koyo bearing. 99% of the time when one fails it’s just replaced, no one reports back to sierra or whatever that that bearing sucks even if they did they just blame a bad install.