Diff?

[weedcookie]

I got a question,

i have a 89 325, and a broken diff. i think its a 2.93...pretty sure...
a friend of mine has a 3.91 from 88-89 325 , what difference will it make if i put the 3.91 in my 89 325?

[gearheadE30]

Look at the tag on the back of it. It is not a 2.93 if it is an '89. If it was an 88 or something, I could see that. 2.93s came on the etas, not the i motor.

Is your car auto or stick? Sticks had a 3.73 and autos a 4.10 with the i motor, which you have if its actually an '89. The 3.91 will be either a tad higher or lower than what you had in there.

[weedcookie]

yeah i think thast the way i bought the car wiht the eta diff. ... 2.9 smthign on the tag and im gona use the 3.9 from ix

my cars manual

[Collin]

yeah i think thast the way i bought the car wiht the eta diff. ... 2.9 smthign on the tag and im gona use the 3.9 from ix

my cars manual

Then you will go from a ratio of 2.93:1 to a ratio of 3.91:1 at the back end. You'll start moving faster, but it will lower your top speed.

I really really want a 4.10.

[SynSyx]

so my '89 325i (auto cabrio) has a 4.10?

also, i too am a member of the 1/2 db 1/2 pb divison of the alpine command haha

[Collin]

also, i too am a member of the 1/2 db 1/2 pb divison of the alpine command haha

For those of us too lazy to finish the job

[nando]

You'll start moving faster, but it will lower your top speed.

not really. Most E30s don't have enough power to be gear-limited at their top speeds, they are simply limited by the brick shape surface & lack of power.

[miles318]

If you switch to the 3.91 you'l probably have to shift a crapload. Also make sure the diff you put in is the same case size(there are large medium and small) i don't know for sure, but the one you have is probably medium

[HiTheNameIsBJ]

Go to bimmerworld.com and click on the tech section, there is a exel file where you can input your gear ratios and it will tell you your speed in 500rpm increments.

[808BMW]

If you switch to the 3.91 you'l probably have to shift a crapload. Also make sure the diff you put in is the same case size(there are large medium and small) i don't know for sure, but the one you have is probably medium

3 sizes? I know 318's came with small case diffs and 325's came with large case, where is the third?

[Holland]

Question! What fluid should I use in a LSD rear end? I'm switching to an LSD so I'm wondering what my options are.

[decay]

changed from a 3.73S to a 3.91V (iX diff) in my first e30. top speed didn't change- as nando said it was drag-limited, so i was just turning more RPM and probably got there slightly quicker. didn't really notice a difference in freeway gas mileage either.

i personally thought it was a great mod, and if i had another m20-powered e30, i'd do it again, only with a markD chip to complement it- that'd put the new redline at about the same speed in each gear (edit: same speed as my old 3.73, not your eta diff).

[willybustaE30]

Question! What fluid should I use in a LSD rear end? I'm switching to an LSD so I'm wondering what my options are.

i use redline heavy shock-proof 75-90 with a friction modifier for the clutches. i went from a 2.73-2.79? (cant remember, it's e-car w/genuine dinan chip)but i went to a 4.10. it will climb a brick wall-lol! i can get 4th gear scratch on a good day. it really woke the car up, but still is slow compared to my volkswagen bus.

[Julien]

i use redline heavy shock-proof 75-90 with a friction modifier for the clutches. i went from a 2.73-2.79? (cant remember, it's e-car w/genuine dinan chip)but i went to a 4.10. it will climb a brick wall-lol! i can get 4th gear scratch on a good day. it really woke the car up, but still is slow compared to my volkswagen bus.

you must have some really shitty tires

[willybustaE30]

you must have some really shitty tires

gee thanks,