Diff rebuild, well sortof.. :D

[Mux213]

Hey Guys,

Okay sorry this is not going to be a complete writeup... yet...

This weekend me and Ivan head out to my DeLorean buddy Ed from DMC Service so we could use his workshop to rebuild and adjust a couple of stock differentials. Last time I visited Ed he had plenty of space and nice workbenches and all the tools we needed but when we came in however we were greeted by 5! DeLoreans spread around the work floor in various states of restauration, including one that was being completely rebuild no expenses spared.

Luckely however some room was quickly created for us to work on one of the work benches and having a rich environment of tools and more important, the handy expertise of Ed around, we went to work...

Well almost, we still had to buy some GL5 LS oil, very easily obtainable here in Hoofddorp (but I had forgotten to buy it), but seemingly nobody around Grootebroek has ever heard of the stuff

The purpose of the day was to learn since neither me nor Ivan had ever done this before. We had hoped to build 2 units and install at least one. One unit would be build using a new RNP combined with an already rebuild diff, and another with a used RNP and a diff we would rebuild ourselves. Eventually we only ended up building the second setup but ran out of time to actually test it out so we still have no idea if we screwed it up or not

Ivan had brought a whopping 4 LSDs in various states of deterioration and 3 diff housings one of which was ruined so we desided to do some testing on it. We had assumed we need a press to get the pinion out but the thing had alot of play, needless to say the minuted we unscrewed the top nut, the whole thing came flying out.

I think the attached picture says enough..

[Mux213]

Next we decided to try and rebuild one of the diffs that was in better condition. I won't go through the whole process but it was pretty easy really, if you pay good attention when you take the diff appart, it really is easy as can be to put it back together again with new parts. The only trick is to unscrew and later fasten the bolts on the top of the diff in a cross pattern. Also use some locktite when fastening them again.

We had two major issues. First, when rebuilding you replace the clutch plates and stuff that are on the side gears, no problem there, and the two little plates that sit against center piece. Now we lost those two little plates so we ended up using the old ones. Not good Irritating was that we found the replacement plates when cleaning up at the end of the day but it was to late then

The other issue was with the side bearings on the diff that we also wanted to replace. They were impossible to free up. Luckely Ed put some of his welding skills to good use to get them off. This is a problem with not having the right tools because it requires a good puller that has small enough hooks to fit underneath the lower rim of the bearings. Also heating the bearings would have helped a lot but that was the only piece of equipment in the shop that had broken down a day or two ago.

[Mux213]

The real challenge was putting the diff back into the housing.

I'm not going to talk much about that now. First of all, we don't know yet if we did this correctly, second of all, this story wouldn't be complete without the information about pinion installation but we decided to reuse an already installed pinion that looked like it was in very good shape.

Installing the LSD means putting it into place, putting the end caps on, then bolting the brackets on that keep it in place (this really is alot of fiddling to get right) and then adjusting the end caps until the LSD sits in the right position.

If we've done it correctly adjusting means clamping the flange to which the driveshaft would be fitted so the pinion can't rotate, then measuring the play on the ring gear as the diff moves. If the ring gear sits further away from the pinion this play will increase, if it comes closer it decreases. You need to get this play to about 0.2mm.

After this you need to tighten the LSD in place but only so tight as to get it to clamp. Hard to explain right now, I'm not 100% sure we got this bit right yet. Its only now after a day of thinking about what we've done I'm starting to understand what we should have done here but I think the end result will be correct, I'm only afraid we might have made it to tight which would create stress on the bearings, but I have no idea how bad.

Anyways, once the LSD is installed we'll find out if it runs correctly or not, if not we'll remove it and adjust it again until we get a hang of it

We're going to build one more diff from scratch at least and we'll document that one from the start hopefully write a how to about it...

[Ivan141]

ahh finally some pictures of that busy day..
Rebuilding diffs is a hell of a job to undertake. Probably made a couple of mistakes on this one, but that's what secondhand crap is for...learning!
I'm not even sure this ringgear and the pinion we used are a matching set.. since 2 diffs got a bit mixed up in my basement. Time will tell, we'll check the contact pattern before installing it, if it's wrong, we'll just throw the LSD into the correct 3rd member and readjust.

I'm postponing the install of my brandnew 4.5 gears until we get the hang of it though, and untill I get a solid pinion spacer for it.

I also brought along the open diff that went with that chewed up pinion.. it was still in good nick, so we had Ed have a go at it with some MIG&TIG action..
So I now have a spare CO2-LSD too.