What is the best option; rebuild or replace rear diff? (16 Viewers)

[Kernal]

I drained the gear oil (Mobil 1 75W-90 with about 50K miles on it) from the rear diff today and checked the magnet. The gear oil still looked almost new and the magnet just had the usual amount of magnetic dust; no chunks, slivers or grit, just smooth black powder. Refilled the 3rd member with Wally World 85W-140 gear oil and the howl changed just slightly in tone/loudness, but definitely still present under load.

Anyone got an opinion on what a reasonable price would be for a used rear 3rd with unknown history like from a salvage yard??

 

[Kernal]

Update: After talking to a few differential rebuilders on the average it would cost somewhere around $800 +/- (add $250 for new ring and pinion), done local or sent out,---. So bit the bullet and went for a new/old stock Toyota 3rd member with actuator; just hoping that it is actually a new part. There were apparently three different part numbers over the years for the rear 3rd's in FZJ-80's but don't know when those numbers changed; the 3rd I've got coming is the middle part number of the three.

 

[jynx]

That will be a sweet score, I hope I comes thru. Is it loaded or just the housing? I bet you could sell yours and make most of your $$ back.

 

[Kernal]

It's supposed to be a complete 3rd; carrier, differential, and actuator as it comes from Toyota, the complete "chunk", never installed or so they said. If I had the time, tools, and another car (the 80 is now my daily driver) I might have tried to rebuild the old third myself and will likely rebuild it at some point in the future.

 

[Kernal]

Rear locker arrived

The rear 3rd showed up today. Only thing I noticed is they apparently removed the actuator motor and packed it separately for shipping?? It was my understanding that these came with the actuator installed so the shipper must have removed the actuator before packing it. The Toyota parts sticker on the original box has it as 41110-60350 then maybe more numbers which have been torn off. And another non-Toyota sticker has it as 41110-60351. I know they all work, just wondering which part I got i.e.: if there were changes or improvements to the -51 or -52. The actuator motor has numbers 41450-60042 and 8K10. Haven't pulled the 3rd out of it's wrapping yet.

 

[Tools R Us]

Nice, nothing like brandy new!

 

[TORTUS]

Is your diff an e-locker? It is a good idea to restore the carrier bearing preload when doing the job. The rear e-locked diff uses shims, all of the others are adjuster wheels. The rear full float unit is pretty easy to go in a day, don't even need to remove the wheels. The front is more work, pulling spindles, birfs, etc.

Zuk page on a rear '80 diff bearing replacement: gear install

That's my 3rd!! Zuk did great work!

 

[Kernal]

One thing I wondered about is whether or not the oil slinger for the front pinion bearing was redesigned later on in the production run of these 3rds. ZUK mentions on his web site that with high pinion 3rds lubrication of the front pinion bearing is/was a weak spot??

 

[jynx]

Man, that is dead sexy!

 

[Tools R Us]

One thing I wondered about is whether or not the oil slinger for the front pinion bearing was redesigned later on in the production run of these 3rds. ZUK mentions on his web site that with high pinion 3rds lubrication of the front pinion bearing is/was a weak spot??

That would only be an issue on a front diff and hasn't proven to be an issue. So no worries, run it.

 

[Kernal]

How to install the E-locker actuator into the differential?

With the actuator and diff separate as in the photos above what is the procedure for setting up the shift fork in relation to the dog clutch before installing the 3rd member into the axle housing? On page SA-86 #28 of the 96 FSM is states:

c. "install the actuator to the differential and match the shift fork hole"

then after cleaning the threads and using thread locker and tightening the shift fork bolt to 14 ft lbs:

g. "engage the sleeve with the dog clutch of the differential"

It isn't clear what is getting matched up with the shift fork hole and what position the shift fork shaft and the dog collar should be when you slide the shift fork into it; should everything be pulled toward the front of the 3rd member?

 

[drtyhry31]

Rear locker arrived

The rear 3rd showed up today. Only thing I noticed is they apparently removed the actuator motor and packed it separately for shipping?? It was my understanding that these came with the actuator installed so the shipper must have removed the actuator before packing it. The Toyota parts sticker on the original box has it as 41110-60350 then maybe more numbers which have been torn off. And another non-Toyota sticker has it as 41110-60351. I know they all work, just wondering which part I got i.e.: if there were changes or improvements to the -51 or -52. The actuator motor has numbers 41450-60042 and 8K10. Haven't pulled the 3rd out of it's wrapping yet.
View attachment 552671View attachment 552678

I know this is an old post but I've been looking through your post and replies to see if a new 3rd member got rid of the hum you were having under load. I'm having the same issue on my front diff. I can tap the gas real fast over and over and hear the hum directly connected to the throttle/ load and is louder than the motor from 45+ mph. As soon as I let off the gas, no noise while coasting. I removed the front drive shaft and the same noise is present in the back but it's very low and is probably just normal but as soon as the front shaft is put back in, the hum is back. Did you figure out what it was?

 

[Irish Reiver]

I also have this job on my todo list. The front pinion seal on my rear diff was leaking bad due to some dreadful corrosion. I just replaced the seal, cover and the flange which stopped the leak. I thought it was all good until i swapped out the old MT tires for some new BFG A/Ts. The huge reduction in road noise allowed me to hear the whine/hum of the pinion bearing. Saving this for cooler days in December.