Gearbox work is always fun - you’re only looking at replacing bearings which oddly is something I haven’t done on the upper and lower gear set shafts. I’ve only done bearings on the input (dual range), rear output and centre diff bearings. They’re easy to get to.
The front bearing should be relatively easy, that rear bearing will require a press no doubt. It’ll be easy to identify the offending bearing by spinning it
You should also read up on the torque specs for that upper gear set shaft so you know what you’re up for. Check out their special tools to hold the gears without damaging them, make them up to do the job.
At the end of the day you could have your cake and eat it too. Setup for the gearbox repair work but go get a replacement gearbox to swap in while you play doctor on your current box.
Ditch the paper gasket and use the same goo that you seal the front cases with. You only need a tiny smear of that stuff for it to do it’s job!
The hardest part of this job to me is setting the diff properly. I’d recommend marking the sun dials, back them off two or three times, write down how many turns out you did in relation to your two marks, this allows the front cases to boot and torque down properly without having the diff fight the cases.
If you’re going to replace the diff bearings throw the above out the window as you’ll need to set the backlash (from memory that’s the correct term, the other one is preload) anyway and that’s a whole other procedure to follow. I’ve back yarded mine and done it by feel, no problems (yet??).
Also a good time to replace all the seals - input, front diff, O ring on the sun dials, rear output shaft and the selector shaft seals.
It’s really interesting and satisfying pulling down a gearbox, fixing stuff and managing to put it all back together again - then be hyper vigilant with every little noise you hear once it’s back in the vehicle!
Some tips:
- get a copy of the WSM for your model, read up on what you’ll be doing, find the torque specs and bolt torque sequence diagrams
- use a cardboard panel to draw the gearbox outline on with all the bolt holes, number them in the torque sequence order (remove starting with last bolt number!) and place the respective bolt in the same location on the diagram (take note of which side of the gearbox the bolts come in from, I can’t remember which side without having a look)
- write out the different torque specs for the various bolts. This saves time once you’re in the thick of it! There are two different toque specs for different bolts on the front cases, the bolts around the diff have a higher torque than the others
- take photos as you go so you have a reference to fall back on if needed
- have some blocks of wood to help sit the box on its side so it won’t wobble around on the floor/bench (I highly recommend doing this work on a bench!)
- ensure all mating surfaces are cleaned properly before sealing the cases and rear housing. Use a residue free solvent as the final wipe down before applying the silicone
- have those torque specs handy for the sealing of the front cases, also have the two socket sizes ready to go
- it’s a good time to throw a front LSD in, just saying!! (Worth the effort in my book)
That turned out to be essay spec, I hope it’s given you some idea of what’s involved.
Cheers
Bennie