Author Topic: 325 lsd into 318is (Read 7855 times)

gtatbrissy · « **on:** June 22, 2010, 02:36:10 AM »

Hi all
just wanted to know if a e30 325 lsd center fits into the case of a 318is with an open center...
thanks

BMWGM42 · « **Reply #1 on:** June 22, 2010, 09:56:36 AM »

no, youre going from a smaller case to a bigger case. why not just swap the diffs?

1991 E30 M42 · « **Reply #2 on:** June 22, 2010, 07:13:28 PM »

Quote from: BMWGM42;93815

no, youre going from a smaller case to a bigger case. why not just swap the diffs?

Yes it fits with no modifications, I am running a 3.73 from a 325, they hold more power and you can actually get parts for them. I think a Z3 diff will fit as well.

jscribble · « **Reply #3 on:** June 22, 2010, 07:27:59 PM »

Good to know. 325 lsd common? I remember reading something about a z3 diff with a different (better?) kind of locker too...

Wizard · « **Reply #4 on:** June 22, 2010, 07:39:51 PM »

You can install the entire differential into the 318is but you can not swap internals...The 318is came with a SMALL CASE diff...The 325 uses a MEDIUM CASE diff...

deekay · « **Reply #5 on:** June 23, 2010, 01:05:46 AM »

Quote from: 1991 E30 M42;93828

Yes it fits with no modifications, I am running a 3.73 from a 325, they hold more power and you can actually get parts for them. I think a Z3 diff will fit as well.

confirmed, i'm running a z3 torsen diff in my car. had to swap the cover over but it's a bolt-on deal.

BMWGM42 · « **Reply #6 on:** June 23, 2010, 02:12:55 AM »

Quote from: Wizard;93831

You can install the entire differential into the 318is but you can not swap internals...The 318is came with a SMALL CASE diff...The 325 uses a MEDIUM CASE diff...

thanks, i knew i wasn't wrong...

jscribble · « **Reply #7 on:** June 23, 2010, 09:21:34 AM »

Quote from: deekay;93838

confirmed, i'm running a z3 torsen diff in my car. had to swap the cover over but it's a bolt-on deal.

Awesome. Thank you.

EN318isPDX · « **Reply #8 on:** June 23, 2010, 01:12:55 PM »

I have a medium case LSD that i put in to replace my blown small case (harder to find) 4.10

DesktopDave · « **Reply #9 on:** June 23, 2010, 11:03:56 PM »

I replaced my small case open 4.10 too when it started the coffee grinder routine. Bolt-in swap was pretty easy, just clumsy to lift that heavy medium diff while under the car. I like the 3.73 I put in, makes the car slower but more driveable in suburban stop-sign hell. LSD is overrated, but I might go for a Torsen if one comes up.

jscribble · « **Reply #10 on:** June 23, 2010, 11:59:24 PM »

Are all the z3 diffs torsen?

deekay · « **Reply #11 on:** June 24, 2010, 01:31:15 AM »

no, you're gonna be looking for a specific 6cyl based on what ratio you want. the info is out there, but i don't have a link handy. i got mine from Jordan S. @ Lone Star in TX, and he got the ratio i asked for and beat every FS price i've seen on bfc by about $100.

you can either find him on e30tech (username "St�ck"), or shoot me a PM and i'll pass along his email addy.

harvey2 · « **Reply #12 on:** June 24, 2010, 11:59:10 PM »

The most complete info I have found on quick search is this from E30tech:

Good diff. info. in this thread, thanks to the OP for posting his experience. I'll just add that a good source for Torsen diffs. is the non-M Z3s (MZ3s only had clutch packs). Here are the ratios:

Clutch Packs:
Z3 M52 2.8 Manual 3.15
Z3 M52 2.8 Auto 4.10

Torsen units:
Z3 M52tu 2.5 Manual 3.15
Z3 M52tu 2.5 Auto 4.27
Z3 M52tu 2.8 Manual 3.15
Z3 M52tu 2.8 Auto 4.10
Z3 M54 2.5 Manual 3.46
Z3 M54 2.5 Auto 3.64
Z3 M54 3.0 Manual 3.07
Z3 M54 3.0 Auto 3.46

Clutch Packs
Z3 S52 3.2 Manual 3.23
Z3 S54 3.2 Manual 3.15

Info. on the Z3 Torsen on this site: http://www.zvolution.com/documents/0...troduction.pdf

full thread here:http://www.e30tech.com/forum/showthread.php?t=83982

I've got the 4.27 ratio torsen in my 318. It is truly great in autocross competition. You need to force the rear end to stay on the ground by stiffening up the front sway bar as much as you can, that's what works for me.

jscribble · « **Reply #13 on:** June 25, 2010, 08:01:03 AM »

Awesome info, thank you!

no1_jazz · « **Reply #14 on:** June 25, 2010, 03:19:06 PM »

hi there mate i have a 325i motorsport 3.91 LSD in my 31.8is and i can say that it is quicker of the line than the standard 4.10 open diff that i had on there before also top end is reduced using the 3.91LSD you will get more top end out of a 4.10diff to a 3.91.