Removing the big diff nut

[Emit]

I'm in the process of doing the manual transmission refresh, nothing huge just replacing the roll pins and seals and a general cleaning/inspection. But I've hit some confusion:

I guess I need to remove the "differential screw adjustment assembly", (26 below) 103802 to change the seal or can I get to it from the back? I've seen that you may need the "special tool" and must mark its position so that the diff is has the same loading on reassembly, is there a way to knock it out without the tool? Any input appreciated as I don't want to mess this up :)

70869

[dmcman73]

I'm in the process of doing the manual transmission refresh, nothing huge just replacing the roll pins and seals and a general cleaning/inspection. But I've hit some confusion:

I guess I need to remove the "differential screw adjustment assembly", (26 below) 103802 to change the seal or can I get to it from the back? I've seen that you may need the "special tool" and must mark its position so that the diff is has the same loading on reassembly, is there a way to knock it out without the tool? Any input appreciated as I don't want to mess this up :)

70869

The passenger side doesn't have a diff nut and that has to be done on the transmission, you can do the drivers side with the diff nut while on the transmission as well.

Avoid taking that diff nut off, it sets the preload on the bearing and if you don't put it back exactly where it was (counting how many turns to remove and matching to thread it back on), you'll screw that bearing up. Also, there are other orings inside the diff nut that would need to be replaced, there is a chance the threads will start leaking, etc.

If you remove the diff nut and don't set it properly, you need to remove the entire transmission from the car to properly set the preload with a scale (its described in detail int he workshop manual).

[Emit]

ead it back on)Also, there are other orings inside the diff nut that would need to be replaced, there is a chance the threads will start leaking, etc.

If you remove the diff nut and don't set it properly, you need to remove the entire transmission from the car to properly set the preload with a scale (its described in detail int he workshop manual).

Thanks for the reply, I'm glad to say that I have the transmission on the bench, so I don't mind getting into it and changing all the o rings and seals there (I have the kit), having a look at the workshop manual it looks like I don't even need to use the scale:

8. Tighten differential nut until the proper reading is obtained.
New Bearings: 10-30 NM ( 3 - 7 ft. lb.)
Used Bearings: Differential should turn free without any play in the bearings.

So the sticking point seems to be how/if I can remove and tighten up the big nut without the special tool J28866

[82DMC12]

Thanks for the reply, I'm glad to say that I have the transmission on the bench, so I don't mind getting into it and changing all the o rings and seals there (I have the kit), having a look at the workshop manual it looks like I don't even need to use the scale:

8. Tighten differential nut until the proper reading is obtained.
New Bearings: 10-30 NM ( 3 - 7 ft. lb.)
Used Bearings: Differential should turn free without any play in the bearings.

So the sticking point seems to be how/if I can remove and tighten up the big nut without the special tool J28866

If you do this, you should be able to achieve the needed tension using a brass drift and a mallet to tighten the adjusting nut. It's not pretty but it will work. I have the special tool as well which just makes it easier.

Note that it's common for the diff adjusting nut to start leaking through the threads if you mess with it and it wasn't leaking before. If you do this, make sure to replace the o-ring (oiled first), clean the threads with solvent before installation, dry the threads, and lay a bead of hylomar on the threads before you do the final install. Also much easier to tap in the output shaft seal with the diff nut on the bench while you're at it.

Yes it is important that you follow the shop manual instructions exactly, which is to assemble the case halves without shafts or sealant, but all case hardware installed and torqued in the correct order. Then you use the spring scale to set the pre-tension, then you disassemble the case halves and put it back together again, finally, with anaerobic sealant and re-torqueing according the required sequence.

70870 70871

[Emit]

If you do this, you should be able to achieve the needed tension using a brass drift and a mallet to tighten the adjusting nut. It's not pretty but it will work. I have the special tool as well which just makes it easier.

Note that it's common for the diff adjusting nut to start leaking through the threads if you mess with it and it wasn't leaking before. If you do this, make sure to replace the o-ring (oiled first), clean the threads with solvent before installation, dry the threads, and lay a bead of hylomar on the threads before you do the final install. Also much easier to tap in the output shaft seal with the diff nut on the bench while you're at it.

Yes it is important that you follow the shop manual instructions exactly, which is to assemble the case halves without shafts or sealant, but all case hardware installed and torqued in the correct order. Then you use the spring scale to set the pre-tension, then you disassemble the case halves and put it back together again, finally, with anaerobic sealant and re-torqueing according the required sequence.


Thanks very much :)

I'm now very committed to this!

The drivers side seal seems to have been gone a long time as there is a quite a lot of grit on the bearing

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