New dif going in (3.91 LSD), did I F myself...

[Cha Ching]

Hi guys, I'm a newb to the E30 scene, my ride of choice being a '88 325i vert w/5spd & 200K on the clock (& the rest of the car, for that matter).

Anyhow, I had a local BMW specialty shop (Accent BMW in Lawndale, CA) look the car over & they say that besides new wheel bearings, it sounds like the dif output needs to be addressed (the car makes a humming" noise under throttle & while driving which sounds like it's coming from the rear dif).

I just picked up a 3.91 (or 3.93, gotta clean the tag) LSD dif to swap in, but I'm not sure if it will fit. Somewhere I read that this gear ratio is supposed to be for 4 cyls. only, can someone here confirm?

Thanks for helping the new guy...

[Van Westervelt]

What car did it come out of?

[Cha Ching]

Not sure, the seller thought it came out of a '87 or '88 325.

[Mossman]

uh oh, probably a 2.93 which will be a dog, get that tag clean or count the input shaft spins to output shaft spin ratio before you take the trouble of swapping it in

[Cha Ching]

uh oh, probably a 2.93 which will be a dog, get that tag clean or count the input shaft spins to output shaft spin ratio before you take the trouble of swapping it in

The tag definitely says 3.91 (or .93, I have to go check).

[SpecM]

US market 325iX's came with a 3.91 LSD (different LSD unit than a 3.73/4.10, tho)

or maybe it is a 2.93 out of a 86-88 325/e/es

[Cha Ching]

SpecM is spot on...The tag says 3.91 which means it probably came out of a iX. Overall the condition is pretty darn good. Doesn't look like it's been taken apart or damaged in any way. The guy I bought it from left it dirty so I could see that it's not leaking, that the bearings aren't going bad, etc.

I'll try to get pics up just for giggles...

[kronus]

list of diffs: (stolen from da 'tech)


318i/is

1984-1985 - 3.64 (84 open for Auto)
1991 - 4.10 (Manual)



318ic

1991-1992 - 4.27 (Manual w/ LSD option)


325

1988 - 2.93


325e/es

1984 - 1985 - 2.79 w/ LSD option
1986 - 1987 - 2.93 (es = LSD)


325i/is/ic

1987 - 1988 - 3.73 (is = LSD)
1988 - 3.73 (Automatic; iS = LSD)
1989 - 1993 - 3.73 (Manual; is = LSD)
1989 - 1992 - 4.10 (Automatic; is = LSD)


325iX

1988 - 3.91
1989 - 1991 - 3.91 (Manual)
1989 - 1991 - 4.10 (Automatic)



M3

1988 - 1991 - 4.10
1988 - 1991 - 4.45 (rare)


325i Touring

3.91 (LSD = option)

[alpinweib30]

dude if you are replacing the whole diff its easy.4hours of work. i just did it to my car twice in one week AND took apart the lsd for my first time. 2.93 open to 2.93 lsd. im a noob as well but these things are easy to work on

[wagonizzle]

I believe this diff is viscous instead of clutch packs, if you didn't already know.

[e30polak]

list of diffs: (stolen from da 'tech)


318i/is

1984-1985 - 3.64 (84 open for Auto)

That ratio with a 6 speed would be soooooooooooo much fun!