M3 diff

[tomk]

Now starting to seriously consider the M3 conversion, The engine l have been offered has the gearbox but was wondering what do most people do about diffs?

[fuzzy]

a custom made prop can be made for about £100 allowing you to use an e30 lsd with your ratio of choice is one option.

[dannyboy759]

Hi,
I take it your on about an e30 m3! and dogleg box,
As long as you use a diff from a 6 pot car its up to you how you play it.
Lsd or not up to you and the ratio is up to you too, obviously the standard diff is 3.25 but you could go 3.64 or 3.73 which is what i have in my car at the mo but you could go 3.91 but it depends how much motorway millage you do, but a 3.73 is ideal.

Dan

[fuzzy]

i was assuming he meant an e36 m3.

[jmc330i]

Looking at his other post about the ECU, Im fairly sure he does mean the E36 M3.

In which case, the E36 diff will be no good. If youve got the E36 M3 5spd box, an E30 M3 diff and prop are the way forward - they fit straight into the car and bolt up to the gearbox with no messing. You can also use the medium case diffs from the E28 by changing the rear cover and output flanges for the E30 items - these have longer ratios again (better for motorway munching) and can still be used with the E30 M3 prop.

If the E30 M3 prop is hard to find, you can get a custom one made as Fuzzy said. If you have the E36 M3 6spd box, then you will need a custom prop and gearbox mount (the diff is still E30).

[curryp]

an E30 M3 diff and prop are the way forward

could a M coupe 315 ratio diff be used if you change backing plates?

[oze30]

No need to change the diff back. It's the same. I fitted one and it was a bolt off bolt on job. No need to change anything over.

[Kos]

an E30 M3 diff and prop are the way forward

could a M coupe 315 ratio diff be used if you change backing plates?

back plate wont need changing but oput put shafts will

[oze30]

mine didnt. ;)

[Kos]

2.8 Z yours was , ZM is different i belive so there

[oze30]

oh.. didn't know that! I stand corrected!!

[curryp]

back plate wont need changing but oput put shafts will

why flanges? are they bigger or too many holes?

what flanges would you use?