Which LSD ratio for a 320 cabrio?

[Laith]

Going to fit an LSD before winter and am wondering if anyone can help with which ratio I need for my engine?

[Grrrmachine]

The same ratio as the open diff you already have, I'd expect:

http://www.e30zone.net/e30zonewiki/inde ... tial#Ratio

Although why you'd want an LSD on a 320i cab is beyond me.

[Laith]

I'm thinking it'll give me better traction in the snow coupled with winter tyres.

Plus it'll be there ready for a m20b25 swap in the summer. Would 3.91 be ok?

[Grrrmachine]

There isn't a diff that's good for both a 320i and 325i, so you need to make up your mind what you want.

For a 320i cab (which is slow and heavy) you need something around 4.27. Anything lower than that will blunt the acceleration so severely that it'll feel like driving a glacier.

In contrast, a 3.91 in a 325i is the revvy end of the diff scale - good for quick starts but can get tiring on motorway cruises. I've got a 3.64 in my Touring (same weight as a cab), but I've kept the 320i gearbox so that I have a good mix of around-town gears and long-distance economy.

However, a decent set of winter tyres will give infinitely better results than a 25-year-old unserviced LSD in terms of traction.

[Laith]

Brilliant advice, thank you very much!

So your 3.64 diff ratio + 320 gearbox + 325 engine is a good all-rounder combination sounds like the one to have.

Will get the winter tyres regardless.

[Grrrmachine]

Yep. You can pep up the acceleration a little by fitting a 3.73 diff, but they're not easy to find.