The E36 Diff Thread

[RRSperry]

If you have the 4 bolt. All you need is the diff.

It is a direct swap. Check the new (used diff) for leaks. It's easy to replace the seals on the output shafts, or the rear cover.

If you are getting gears, you really need to know how to set up a differential. You should replace all the bearings and the seals, along with the crush sleve. It also makes sense to add another clutch to the pack, (3 new ones, instead of 2 old ones and 1 new one). That changes the lockup from 25% to 40%. It's likely that a used diff isn't 25% anymore either....)

The BMW TIS (E30 M3 section) has all the rebuild procedures and shows what tools you need. If you've never done it, I highly suggest that you send it out. Dan at Diffs online and a couple of other do great work. (but really any old time chevy mechanic could do it. it's a diff...)

Jon Thayer, (Mcoupemindy) rebuilt mine, and the total cost for everything was $900 on top of the diff.

[BMWe36AS]

I wish OP's pics still worked

I'm in the process of rebuilding a differential after the ring gear and pinion decided to not like each other anymore.

Can anyone tell me the procedure of settting up pinion depth from zero? i have all new shims from bmw i just don't know where to start. The pinion shows a +3 i think thats a starting point for shimming?

If anybody can pass on some guidance that would be awesome, looking to tackle this myself.

[cmoody]

I wish OP's pics still worked

Firefox and Chrome have extensions that fix this.

[RRSperry]

It's also in the BMW TIS (tech info system CD) in the BMW E30 M3 repair section. I keep a old windows Xp computer in the garage that has the EKT (parts) TIS and ETM (electrical manual) The CD's are available on Ebay for about $10.

[mslevin]

Does anyone know of a good source for pressure ramp plates? During my diff teardown last night I found mine are destroyed. Don't really want to deal with getting them machined then trying to figure out the right spacing.

Diffsonline sells good condition used units, but its $225 + $100 core deposit (which I'd forfeit, as mine are unusable).

Pics below. One is left, one is right.

[jakermac]

I've got some in much better condition than those. How fast do you need them?

[Cobra1956]

Dumb question but why couldn't you machine them like you would a head? Top pic looks like it is workable.

[jakermac]

The surface is very hard, so not machining as much as grinding. However that's something an automotive machine shop should be able to do. But then the shimming/stack height would need to be adjusted.

[Cobra1956]

The top pic looks very similar to what I had and I was able to get most of the deposits off with a razor blade. Since there is some play in the ramps if you slightly machined the bottom it should/might be better than what he currently has. Just throwing ideas out there

[TehE39]

You can get those brand new from Johnathan Thayer from Thayermotorsports, I purchased all my bearings and etc. from him for my diff rebuild and he was kind enough to answer the noob questions that mattered.

[st4t1c]

So I just bought a 3.38 locally to install in my 95 M3 (Currently has 3.15). I'm going to take it to a shop to have them swap the input flange (4 to 6 bolt) as well as inspect gears, bearings, before filling it up with some redline and installing (I will be doing the heavy lifting).

I found one website that shows the RPM/Speed calculations but I wanted to get someones opinion on how much faster I can expect the car to be? What kind of performance gains can I see under 100mph? I almost never go about 120mph as the car starts to really show its signs of age (Coming up on 25 years), so gas milleage is not a concern.

[Cobra1956]

Simple answer is you wont be going any faster but you will get there quicker. I currently run a 3.46 in my track car and am switching to a 3.64. What is it you are trying to accomplish?

[aeronaut]

It'll feel a little spunkier. Then you'll get used to it, and ask yourself...what next?

[NeilM]

Simple answer is you wont be going any faster but you will get there quicker. I currently run a 3.46 in my track car and am switching to a 3.64. What is it you are trying to accomplish?

I've been running a 3.73 for several years and have just switched to a 3.46. Much better in an E36 M3! ;-)

Neil
96 M3

[Cobra1956]

I have an S54 so the switch will be just fine as this is track only car working north of 7500 rpms....but your point is correct that you need to find the combo that works for what you are doing.

[RRSperry]

An extra 1000 rpm from the S54 does sure help with gearing choices...

[Ceekers]

hey folks I went through the build thread and it's great! But I can't seem to find anywhere indicating specifically how to remove the ring gear from a open diff/ lsd diff.
Could anyone elaborate on how to remove it?

Do I need to remove a bearing to take it off?

[justinco]

hey folks I went through the build thread and it's great! But I can't seem to find anywhere indicating specifically how to remove the ring gear from a open diff/ lsd diff.
Could anyone elaborate on how to remove it?

Do I need to remove a bearing to take it off?

You shouldn't need to remove a bearing, the ring gear should be larger than it. You just need to remove the ring gear retainers/bolts and then pry it off.

My videos below should be able to help:

Ring gear removal (different diff same concept):
https://youtu.be/YQbHA6zT59Y

e36 diff rebuild:

[Cobra1956]

I removed the ring gear by backing off the bolts and tapping them with a dead blow hammer. After a bit of time I had a gap between the gear and the flange on the housing. Make sense?

[mikyyy]

guys, I have a disassembled lsd coming from a 3.07 case, can I install it safely in an open case always 3.07? the bearings are the same between lsd and open case? thank you

[Cobra1956]

The internals are what make it different, so yes. An area of concern might/should be the tolerances between cases, shims and what not. From what I have seen and read you might have a bit of work. On my own project I purchased a bunch of parts that "should" have all worked but in the end needed some TLC and expertise that I was not comfortable doing myself. I decided to send it cross country to Wanganstyle and had it done right. Very happy I did!

[babciadementor]

Hey I have E36 M52B28 for track days use with small type lsd(168). Its old and it doesnt work as it should so im doing rebuild. As its written on first page this diff can hold between 200-300 ft/lb of torque. Would it be necessary to change this diff for medium type diff (188)?

[Cobra1956]

If it were me I would focus on what the ratio is. I think you are okay on the torque spec but I like quicker versus faster asa one is achievable and the other is only theory in stock form.

[Keda]

Great thread.

Can anyone describe how various ramp angles affect driving? I’m looking at a 3 clutch 3.46 with either 35/60 or 30/90. I’ve read that the lower loaded angle will increase understeer. But how much?

It seems like 35/60 might be a good mix, but it’s hard to know having never been in a car with this setup.

[babciadementor]

Diff ratio will be 3.91 or 4.44. The problem is if this small type diff will last long especially with slighty moded M52B28 in track day use? Some says that they drive 5+ years with small type diff & 2.5/2.8 and diff still works excellent and some say that it will last one training/trackday. So I'm little bit confused and dunno what to do.