Differential rebuild

[F34R]

I have my 3.46 LSD out and I am going to replace the gaskets and seals. Should I go ahead and replace the diff and pinion bearings?

I am also not very sure on what my LSD is, the metal tag is gone and the case has seen better days. I marked the pinion output shaft and the drive shaft flange then counted the times it went around with one turn.

It was around 3.5 turns with one wheel spin. So I am guessing from a list of diffs I looked up that is a 3.46 med LSD. But it is smaller then the open diff I removed from the '87 325e sedan.

I just got it dirt cheap and it works very smooth. I just have never heard it going down the road.

So I figured might as well rebuild it while it is out. I
I am just worried about ordering all this stuff and it turns out my diff is not the same as the parts ordered for it. Is there a place inside that might have numbers? I'll snap a few pictures later and post them to help with the IDing of it.

All I know is it is a 3.46 and looks just like my open end diff but the cover is bigger on my open end one. I tried swapping them out because the open end one is nicer.

[F34R]

Looks like no one knows...

Well it is now a rebuild, I tore down both of my LSD rearends. There is an issue, the small case 3.46 has a broken bearing flange. I think it can be welded or replaced with a new one. It is held on with allen head bolts around 10-12ish. The bearing goes over the flange to hold it there when installing the gearing into the case.

Does anyone know where I can buy new gearing parts?

One other question, I thought the 3.46 LSD I have is a med case. Thing is that I have another one, it is larger and it is also an LSD. The covers that the spindles go through for the wheels is held on by 4 bolts(small) and the larger one is held on by 6 bolts. What size cases do I have?

The larger case came from a 1987 325e sedan that FrankM on r3v owned locally. I know it is not stock, not sure if he put it in.

Here is pictures:

First two are of the smaller case
3rd is of the gearing removed, small case and larger one(see on the front of the gearing how there is bolts all around? that is where the flange broke off. It can be removed but I don't know where to get another)
4th is of the broken flange(the broken edges seal TIGHT and cannot be told other wise)
5th is of the larger case

So in the end should I just use the larger case? I would guess that it is stronger, but I will figure out the ratio soon and make up my mind about it. The small case is fine just that broken flange, maybe I can source a new piece for it.

[F34R]

Bump, no one knows? PM me if you know someone on here that does diff work.

[F34R]

After some searching it seems the e30 never came with a small case 3.46 LSD. Does this make mine rare or hard to find?

Med case is a 2.93 (Update after build)

[F34R]

Well after a few hours of breaking down the three LSDs I have laying around. I decided to go with the 3.25 or 3.46 MED case (no clue on what ratio yet). *2.93 ratio*(update since build)

I searched found the right years and part #s. I now have a wonderful box of goodies coming!!! Seals, bearings, gaskets, o-rings and other fun stuff. Detailed pictures and DYI coming, sense there is nothing really around on what to buy and what you need.

[Doughnut]

I had an oddball diff out of an e28 which was an 3:46 LSD.

I was told all I needed to do when swapping an e28 diff into an e30 was to swap your e30 cover and output flanges.

Turns out the e30 cover was alittle too small to fit the diff but the output flanges were the same. I ended up just swapping the LSD centre into my e30 case as my original open diff was already a 3:46 (my favorite for the m30 swap too)

Thought I'd share, sorry I don't have any answers to your questions however I do know that there is a thread floating around on the forums somewhere where someone completely rebuilt their diff and replaced just about everything.

[F34R]

Well the differential is done and refreshed. Replaced everything but the gears. When I started the diff would not turn, it took SO much effort to turn. Now it is smooth and quite!

I bought everything from these guys:

BimmerSpecialist.com It shipped SUPER fast and well packed.

I took a few pictures, but the ones on installing were hard to take with grease cutter and grease all over my hands. I did not want to yuck my MacBook.

[AndrewG]

What ratio did you end up going with? Did your Uncle help you set up the preload, depth, and lash or is it making tons of noise already because he didn't?

I'm going to start rebuilding 1 or 2 of mine in the next few weeks so if you're working on that tutorial, it might come in handy. I think my friend has the proper tools for setting the preload and stuff so I should be fine regardless, but I'm scouting out as much info as I can at the moment so I don't run into any surprises.

[Wanganstyle]

What ratio did you end up going with? Did your Uncle help you set up the preload, depth, and lash or is it making tons of noise already because he didn't?

I'm going to start rebuilding 1 or 2 of mine in the next few weeks so if you're working on that tutorial, it might come in handy. I think my friend has the proper tools for setting the preload and stuff so I should be fine regardless, but I'm scouting out as much info as I can at the moment so I don't run into any surprises.

try to hunt down the online TIS for e30 M3, it has full rebuild spec etc direct from BMW :)

[F34R]

What ratio did you end up going with? Did your Uncle help you set up the preload, depth, and lash or is it making tons of noise already because he didn't?

I'm going to start rebuilding 1 or 2 of mine in the next few weeks so if you're working on that tutorial, it might come in handy. I think my friend has the proper tools for setting the preload and stuff so I should be fine regardless, but I'm scouting out as much info as I can at the moment so I don't run into any surprises.

I did it myself, it is perfect. Very happy with the 2.93, I am now rebuilding a 3.46 for my m50 turbo build.