20 replies to this topic

[ditonics]

I'm going to be doing this in sections as I go so I don't forget bits.

I'm assuming you have the gearbox out of the car already.

This is just a guide to help and I take no responsibility for any mistakes or inaccuracies.

And lastly I'm not going to list every single took you will need but you will need a decent quality 8mm allen key that you can use with a break bar and a torque wrench that is capable of 90nm.

 

The first thing you need to do is remove the plug covering the end of the intermediate shaft. GM recommend removing this with a slide hammer and a self tapping screw attachment. This didn't work for me and I drove a screw driver through the middle of the plug and carefully levered it out. Remember there is a large sealed bearing behind the plug held in with a big 'c' clip so don't go mad and damage it.

 

This picture clearly shows the plug in the bell housing that needs to be removed.

 

 

And this is the mess you are left with once it is removed.

Disguard the plug and the plastic cap behind it. I will add the part numbers once I have them confirmed tomorrow with AutoVaux.

 

 

And this is what you are after, the 8mm allen bolt.

 

[ditonics]

To undo the 8mm allen bolt you are going to need a strong allen key, I broke my 3/8 socket one and had to pop out and get a 1/2 Halford pro one. If that breaks they will replace it for life in theory.....happy days. I used a 24" break bar and didn't need to get the scaffold pole out  The next thing is to stop the intermediate shaft from rotating while undoing the 8mm allen bolt. GM have a special tool for this but I'm a back yard mechanic so I used a round jaw set of mole grips and put one of the bell house bolts back as seen here:

 

 

Make sure the box has 1st engaged.

Be a little bit sensible how you lock off the input shaft, it is hardened and I found the mole grip method didn't mark it at all for me but if you have an old clutch use the spindle off this to make up a better solution. 

 

Once you have that bolt out its time to undo the bolts that hold the two halves of the gearbox together, from memory there are 7 inside the bell housing and 

19 in total. They are all the same size so if you remove any that are different put them back. Once you are happy all the bolts are removed its time to split the gearbox case into its two halves.....exciting.

 

Unfortunately it isn't a simple case of parting them, you have to drift the intermediate shaft out of its bearing while you split the case. I used a 1/2 15mm impact socket and an extension in conjunction with a copper/brass faced hammer. Avoid a steel hammer if possible. Make sure you are drifting the shaft and not the bearing.

 

 

And if all is well this is what you should end up with:

 

 

Note the diff is not held in so split the case the way round shown in the picture or the diff will fall out and hit the floor.

Now the gearbox is apart I would advise you to be mindful to keep any form of junk out of it, Eg cover it if you are not actually working on it.

[ditonics]

My simple cheap way to keep things covered

 

 

While the box is split check the magnet built into the case, a light covering of filings is fine and normal, if you have any actual swarf then something is wrong and will need further investigation.

 

 

lifted out to clean it

 

[ditonics]

Lift the diff out as you are going to need the crown ring for your new diff.

I put the old diff in a large vice and used a break bar to undo the 10 bolts. I would recommend undoing them in a similar fashion to a cylinder head Eg in stages and in a star pattern.

 

 

Once you have the 10 bolts out the crown ring will come off the old diff with a little persuasion from a wooden or leather faced mallet.

The bolts are going to look a little grubby like these

 

 

And I would clean and degrease them well ready to go back. Personally I used a brass brush followed by degreaser and a fun way to get rid of the residue

 

[ditonics]

Hopefully you now have a pile of bits like this ready to go

 

 

Use half the bolts to line up the crown ring onto the new diff, first apply a firm grade of thread lock. you really don't want these coming undone.

 

 

Do the crown ring bolts up with a wrench to about 50nm (medium firm with a standard ratchet set).

Then I would recommend doing them all to 60nm, then 75nm and finally 90nm with a torque wrench. 

 

And this is what you should have, the original crown ring on the new diff.

 

[Chris P Duck]

Brilliant guide. I'd consider making it a PDF now if you can for when all the pics inevitably disappear. Particularly like

about 50nm (medium firm with a standard ratchet set).  

[CocoPops]

Great thread.

[SteveA]

Another alternative to the mole grips is to remove the cover plate from the back of the box and you will see another 8mm hex hole. This will rotate in the opposite direction when you apply force to the front hex. I put a breaker on this and stopped it rotating which will allow it to undo.

[ditonics]

Another alternative to the mole grips is to remove the cover plate from the back of the box and you will see another 8mm hex hole. This will rotate in the opposite direction when you apply force to the front hex. I put a breaker on this and stopped it rotating which will allow it to undo.

I considered this but then you have 50/50 as to which end undoes i believe. And it really does need to be the bell house end. If my thinking is incorrect please tell more. GMs published method is to lock the input shaft. I will continue the guide when i have the parts to continue. I would be grateful if a mod could move this to the guide section. I couldn't start the thread there myself.

Edited by ditonics, 20 March 2017 - 09:42 AM.

[CocoPops]

I would be grateful if a mod could move this to the guide section.

Done

[Exmantaa]

Great guide.

 

Would be good to have some more info how you measured/shimmed the conical diff bearings to the correct heights? If needed at all. (Back in my RWD days, the diff bearing alligment was pretty crucial with the bevel gears...)

Edited by Exmantaa, 20 March 2017 - 09:51 AM.

[SteveA]

 

I considered this but then you have 50/50 as to which end undoes i believe. And it really does need to be the bell house end. If my thinking is incorrect please tell more. GMs published method is to lock the input shaft.

 

I don't think so, I think its just the back part of the half shaft. It's been 5 years + since I did it though so am not sure.

 

I also snapped a hex key undoing it so it deffo needs good quality tools  

Edited by SteveA, 20 March 2017 - 09:56 AM.

[ditonics]

Great guide.   Would be good to have some more info how you measured/shimmed the conical diff bearings to the correct heights? If needed at all. (Back in my RWD days, the diff bearing alligment was pretty crucial with the bevel gears...)

It's inline so the shims are to get the fit of the diff in the housing correct rather than to get the teeth to mesh correctly. Yeah lining pinions up is a whole different ball game and more technical. I'll be calling quaife n autovaux later to confirm a few things before i continue.

[ditonics]

Guide to shim measurement:

 

https://www.speedste...al, Replace.pdf

 

I'm going to get a head ache later doing this one 

[techieboy]

http://www.vx220.org...p-differential/

[ditonics]

Part numbers:

 

Plastic thing under cap 9120609 you need 1 if you broke the original (min order is 5 so I have 4 spare at £2.50 each)

plastic coated metal cap 9120610 you need 1

differential conical bearings 93334162 you will need 2 

The shims are listed on HERE and you will need whatever you measure.

If you skip the shimming process the gearbox will work but you run a good risk of the diff being loose and wearing out the bearings from movement or if you use too larger shims them the load on the bearing will be increased and you will wear it out quicker. 

 

NOTE:

The bearings and the cover come to about £60. If your gearbox needs other things doing you can get full rebuild kits for about £180 that include these bearings and cover.

[Nev]

Super guide, thanks.

[ditonics]

http://www.vx220.org...p-differential/

I hadn't seen that guide, thanks for the link. I was basing my build on prior knowledge, the TIS and there is an official GM video floating round the net too. David always strikes me as a very thorough engineer and has access to more equipment than most. I'll see what i can come up with with more accessible tools etc.

Edited by ditonics, 20 March 2017 - 12:53 PM.

[Raptor]

There's this guide also: http://www.migweb.co...fe-atb-f23.html

 

 

[ditonics]

Try as i might i couldn't get both bearings off without destroying one. Pity as the original ones were in great condition. One side pulls off easy with a puller, the other side i ended up destroying the cage, removing the rollers and heating of the bit of race left. Total bitch.
I had reason to talk to David earlier today and he informed me it took him a long time machining up a custom tool to get his off in one piece with the user of a large hydraulic press. So i had no chance.