M30 + small case diff?

Post Wed Feb 26, 2014 12:56 pm

Am working through an M30 swap at the moment and have a diff question.

The diff on my car is a small case LSD, think the ratio is 3.25 or so. I'd be happy enough with the ratio - just wondering has anyone run a small cased one on their swapped E30 and had it last more than a week?!?

Currently looking to swap it out for a medium cased one but just curious as to whether or not I actually need to.

Cheers

Post Wed Feb 26, 2014 6:37 pm

Yes, i ran a small case 4.1 initially, it was fine. If it's for normal sprirted driving i'm sure it will be fine, track use would be a different matter though.

Small case 3.25 LSD must be a rare diff though, not heard of those before

Post Wed Feb 26, 2014 7:45 pm

Ratio is good, keep it or swap with me I have a med 3:46 lad.

Post Wed Feb 26, 2014 8:15 pm

Not 100% certain on the ratio to be honest - anywhere I read says an 83 323i auto had a 3.25 diff, but that's an open diff. Just checked spec sheet and it didn't help either.

Post Wed Feb 26, 2014 8:23 pm

This is Gareth running a small case diff at pod..

IIRC

Post Wed Feb 26, 2014 8:24 pm

maxfield wrote:

This is Gareth running a small case diff at pod..

IIRC

Brilliant - a picture tells a thousand words!

Post Wed Feb 26, 2014 9:09 pm

Build sheet says

S209A SPERRDIFFERENTIAL 25% Differential lock 25%

Think I'll be selling it on and going for the medium case anyway.

Post Wed Feb 26, 2014 9:16 pm

I have a 3.46 in my M30 and i think it's just pefect but most of my driving is motorway. If you are a country lane demon you might want a 3.64 or 3.7x

Post Wed Feb 26, 2014 9:18 pm

3.46 would definitely suit me perfectly - just keeping an eye out for one now.

Post Wed Feb 26, 2014 9:21 pm

cool, iirc with the 3.64 on 15"BBS and the e34 manual box then 70mph is just 2550rpm so nice and wafty.

Post Thu Feb 27, 2014 12:08 am

kdevitt wrote:
maxfield wrote:

This is Gareth running a small case diff at pod..

IIRC
Brilliant - a picture tells a thousand words!

Haha, that was 6.5 years ago!

Good memory!

Here's the link to the gruesome damage.
http://www.e30zone.net/modules.php?name ... postmortem
So in short, NO! Don't use a medium case diff with M30 torquesss!

Post Thu Feb 27, 2014 8:40 pm

Gareth - I can remember it like it was yesterday. Didn't realise it was that long ago tho

Post Thu Feb 27, 2014 8:50 pm

No... Scary or what! I had a look at my logbook the other day, i've owned my E30 for 9.5 years! WTF?!

Post Tue Apr 15, 2014 12:42 pm

So out of interest - where are people sourcing their medium 3.46 diffs from? Seems that the prices have gone nuts in the past year.

Post Tue Apr 22, 2014 7:22 pm

I recently picked up a e28 3.46 diff and swapped the output shafts and back plate. Works perfectly and find a good ratio for the m30

Post Sun Jan 04, 2015 8:59 pm

I currently have a small case on my m30b35 turbo...

Post Tue Jan 06, 2015 8:41 pm

I predict bad things!

Post Tue Jan 06, 2015 8:47 pm

See above

Post Wed Jan 07, 2015 2:47 pm

I'm currently running (drifting) a small case with my E28 M535i Motronic 1.3. All good so far, though I will be going medium case and when I can be assed!

Post Wed Jan 07, 2015 6:10 pm

When you say small case on the E28, do you mean 188mm? AFAIK the small (168mm) case wasn't used on the E28, just 188mm and 210mm. The E30 got 168mm and 188mm.

So 'small' on a E28 is 'large' on a E30. Or more broadly speaking, both are 'medium' case!

Post Thu Jan 08, 2015 8:56 am

I put it very confusingly! I meant E28 M535i engine running motronic 1.3 inside my E30 (extra bhpz)! Which is running a random E30 small case.

Post Thu Jan 08, 2015 11:55 pm

Ahaa, makes sense. In which case I refer to my previous comment!