View Full Version : gearset for E30 318i

03-12-2005, 08:51 AM
Are there any gearsets for the l/s diff that are interchangeable from another car that will work w/ an 85 318I? I would like to change the diff to a lower ratio w/o spending $1000.


03-12-2005, 11:51 AM
You are better off just getting the entire diff, get a 4.10 LSD off of an 89-91 325is automatic. look on www.car-part.com (http://www.car-part.com) they are always there for about $150-$300.

chuck baader
03-12-2005, 12:16 PM
A quick note. The flanges on the 318 diff are different from the 6 cylinder cars. However, they interchange. i.e., remove the flanges from your diff and install in any e30 diff. You might, also, look for a 4.27 diff for that car.

Chuck Baader
#36 ITA E30 BMW
Alabama Region Divisional Registrar

03-12-2005, 01:41 PM
If I'm not mistaken, the 318 has the "small" diff. the 325 diff is the "large" diff. I think you would have to change axles as well. Also the "large" diff didn't come in the 318 so it would be illegal. Which is too bad because that would be a great place if you had to add weight. You might check with the E30 318is some of those came with a "small" 4.10 also there is great interchangability between all the "small" BMW diffs. You can swap gear sets between them. Check with RiDS 1-818-361-1937.
Good luck.
John Norris

03-12-2005, 07:02 PM
I always thought the diff housings were exactly the same for all e30's and were completely interchangeable. I have just started building my car. I'll have to look into ot further I guess.

03-14-2005, 12:17 AM
The ring and pinions on all of the the E21's (320i) and the early 318i's (with the M10) motor are exactly the same and interchangable, only the pumpkins are different.

You'll find the 320i 5speed has the 3.9 (I think the auto has a 3.6 - not positive). The '84-'85 318i auto trans has the 4:10 gear set.

Good Luck
Dave Austin
'82 320i ITB#1

03-14-2005, 09:40 AM
I have a 3-Series Bentley service manual for my 318i, but it doesn't cover anything about opening the diff. Are there any instructions online or any real shop manuals that I can get that will give me the information I need to do the job? I called a BMW dealership to inquire about a book and they said the only book they have is the one that I currently own.

03-15-2005, 09:48 PM
Call Bob Smart at Smarty's Auto.
518-622-0329 ext 11

He and I both race 320's. He can walk you through it because I watched him do a swap in under 15 minutes!!

Good luck.

Dave Austin
ITB #1

04-20-2005, 11:03 PM
if anyone with a 318 is still looking for a diff i have a 4.44 lsd with new lsd discs.i also have many other custom parts such as a header(designed for the e30 with a burns collector)and solid rear subframe.if interested please contact me by email.
[email protected]