Wanted: Limited Slip Diff

try bavarian autoparts.co.uk they have just broken a 750 with a limited slip diff

Try FAB on 01594 860325 or www.fabdirect.com

try to get hold of an lsd from a 320is they are much better for acceleration.

What does the 320is have fitted then?  4.10? Hope you like noisey motorway driving.

i think most early 325i sports use the diff from a 316 or 318, slightly modified, to give better acceleration, the lsd was only an option.

the e30 16v 320is made mainly for the italian market had a different lsd to the 325i sport. it gave much better acceleration, not sure of the ratio. hence they are really rare but you can get them if you look hard enough!!!!

I've just looked on the ETK thingy,

and for the 320is it has lasted a Differential drive housing (complete) as a 25% diff of 3.46 ratio.
(BMW# 33.10.1.211.072)

This diff is also fitted to the follwing cars (as indicated on the ETK)

E30 320is, 323i, 325e, 325i

But if you look up just the internalls ie diff unit without external case (BMW # 33.14.1.209.653), this is fitted to the following:-

E30 320is, 323i, 324td, 325e, 325i & M3
E28 518/i, 520i, 524d/td, 525e, 525i, 528i, 535i, M535i
E34 518g, 518iM40/M43, 520iM20/M50, 524td, 525i, 530i/M30/60, 535i
E36 323i, 325i, 325td, 328i

So if that means you can take the guts out of one of the above and refit it in your existing diff housing I do not know. Hope this helps rather than confusing the matter.

Someone correct me if I'm wrong, but isn't the 320is fitted with a close ratio 'box with 5th being 1:1 (same as 4th on the 325i and 325is. It's not a dogleg like the M box though. Pretty sure the diff ratio is the same as the 325, a 3.46 as Mark R suggests. Anyone out there with a 320is who could confirm?

e30-325isp wrote: i think most early 325i sports use the diff from a 316 or 318, slightly modified, to give better acceleration, the lsd was only an option. the e30 16v 320is made mainly for the italian market had a different lsd to the 325i sport. it gave much better acceleration, not sure of the ratio. hence they are really rare but you can get them if you look hard enough!!!!

Yes, the car didn't have a LSD to begin with, we welded the diff in it and now that we are happy with the car, we want a LSD for it. Don't know what the ratio is, will find out. Also don't really have a clue what you guys are on about. Please sympathise with my limited knowledge on car mechanics and explain yourselves! lol

 

Edited by c9thg

diff. ratios.

316(i),318i,320- 3.64

320i- 3.45 (with optional 3.64 LSD)

323i- 3.45 (with sport gearbox 3.25)

m3- North American- 4.10 LSD, Euro- 3.25 LSD

320is- 3.46 LSD

325is- 3.73 LSD or 3.91 LSD (ZF Unit)  -  (non LSD-3.64)

325e- 2.93

the 325is and 320is DID have DIFFERENT LSD's, the 320is also had the dogleg box from the Euro m3

making the car quicker or more drivable is more about finding a diff. and gearbox that work well together. The e30 m3 LSD will fit most other e30's(6Cyl.) but without the m3's gearbox your more lightly to get a car thats not perfotming at its best. Your better staying with the diff. BMW gave it(320i-3.45), unless you want to change the gearbox as well!!if you want a similar spec LSD you are better getting a 320is LSD cause the ratio is closer to the standard diff and will allow the car to perform at its best. If you cant find a 320is LSD(they are rare) then try to get a Hartge or Alpina diff from an e30 with a similar ratio as the slip was unrated in most cases to to 30%(from 25%).

Info available from www.bmwmregistry.com - FAQ's

www.europeancarweb.com - Tech letters

Haynes manual No. 0815 - section 8

Total BMW august 2003(pg83-83), january 2001(pg77-80), april2001(pg 83), march 2001(pg83-84)

its the 316i/318i 1983-1986 that have a diff ratio of 3.64

if you want to know the gain by changing diff. do the math's!!

current ratio : 3.15

new ratio      : 3.46

3.46 - 3.15 = .31

.31/3.15     =0.098 (x100=9.8%)

so changing from a 3.15 diff to 3.46 diff means that, if you take your current rpm at any given speed and add 9.8% then this is your new rpm. e.g. if your currently doing 70mph at 3000rpm with a 3.15 diff then changing to a 3.46 diff means 70mph arrives at 3294rpm.

this also means your getting the engine into its peak power band at a 10% lower road speed, which translates into faster acceleration.

changing the diff on a e30 wont really hurt top speed as most had an overdrive fifth and they never had the high end torque to attain max. rpm.