Hello everyone.

I am new to this site but need your help. Have just purchased a BMW 320i, 2 series (for diffing purposes only!) Welded the diff in and it held out well but now want to take it a step further and get a limited slip diff for it. Only problem is, i can't get one. Does anyone know of anyone selling one or where i could get one? Any information on this topic would be really helpful.

Thankyou.

Try FAB on 01594 860325 or http://www.fabdirect.com - www.fabdirect.com

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

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!!!!

got my info about the 320is diff from a letter posted in either bmw car or total bmw about 6 months ago. guy wrote in wanting to know the best diff for the e30 they said the 320is cause it was different to the 325is.

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

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 http://www.bmwmregistry.com - www.bmwmregistry.com  - FAQ's

http://www.europeancarweb.com - 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.