LSD FOR MY 325I e30, advice on ratio

[anton]

hi all
so im going to fit an lsd to my e30.
a friend advised to use the diff from e30 323i which is 3.46:1
he reckons this is the best.
3.91 being better but scarce...

any opinions?

I can get the 4.46:1 for R1200 which is equiv to 80gbp.

cheers
Anton

[anton]

sorry i meant 3.46:1

[anton]

the thing is, my current standard diff on the 325i has a leaking left output shaft seal. to replace the seal all the EXPENSIVE best money can buy diff oil needs to be replaced.... so i thought i might as well gofor a lsdiff.

3.46:1 should i do it?? or should i look for something else?

[Speedtouch]

3.46:1 will give you a nice high ratio for decent mpg and motorway cruising, at the expense of acceleration. The later Tech 2 325i Sport had 3.91:1 as standard, while most 6-cyl 320i/325i models here had 3.64:1.

[jack148]

how can you tell what kind of diff you've got??

[Speedtouch]

Jack up the back end of the car, place on axle stands, then spin a wheel: if it's an LSD, the other wheel will rotate the SAME direction, if it's the normal open type diff, the other wheel spins in the OPPOSITE direction.

Ratio is usually indicated by a tag on the diff, eg S3,91 = LSD (S) 3.91:1, while 3,64 = Open type 3.64:1

[DHFiS]

I have tried to show the tag in this picture. This one is maked S 410 so its a LSD with a 4.10 ratio

[jack148]

Cheers guys!

I have just aquired a spare rear axle, which included a diff. I have just had a look at it and have found that the tag as mentioned is rusted and shows no numbers. I also tried the drive shart method, these turned in the same direction. So I think I might have a LSD. There is a number on the casing(1210 421)dont know if that is relevant??

[anton]

mines says 40:11S0684 what would this mean, its on the tag?

[e30bmlover]

mine says S3.64.... yer boi!!

[fannyj]

Hi Anton, 40.11 is a normal 3.64diff. I've recently acquired a 3.91 and it says 43.11 on the tag (43/11=3.91) or thereabouts..40/11=3.64 Hope that helps

[fannyj]

Another thing, i fitted the diff 3.91 diff lastweek. Definitely better in my opinion than the 3.64.When on the highway in 5th i am now lying at 3300rpm as opposed to 2950rpm with the 3.64,so it isn't too ridiculous.My motor is stock as well

[Rav335uk]

Fannyj you PM

[Aiello]

you can find out your ratio by marking where the axle turns with some white out or something and count how many times it turns around for you. so turn the shaft where the tailshaft attaches around 3.6 or 3.9 and 4.1 etc and the axle shaft should have turned once by then and lined up with the mark again, its a little un accurate but atleast you will ruffly know, besides if you really want rip the back cover off the diff since you should really clean it out first and attach a new cover gasket and see iff its a big open lump or you have some sexy clutch packs for a lsd in there. let me know how you went

[anton]

can anyone give me the part # of a diff gasket ?