? about diffs

[e30sam]

What is the number that comes after the ratio? Its a 3.73 S, Did it likely come off a 325is(big diff)? What is the difference in putting the smaller diff on the 325i?

[e304eva]

s signifys limited slip and its a big case diff. you cant interchange big and small case diffs. if i understand your question

[AdamF 88iS]

Actually you can interchange the diffs, but the 6cyl would pop the small case diff in no time.

A S3,73 diff would be a large case though.

[oskard]

i've run a small diff in my 325i with no problems :)

i will be running a small diff with my m50 engine also...

[MR 325]

You will break that diff in no time with a m50 engine, it should have broken already with the m20 engine.

[e30sam]

Would an e28 535 diff fit in a '90 325i? I'm thinking not. Can I at least take the insides?

[decay]

Would an e28 535 diff fit in a '90 325i? I'm thinking not. Can I at least take the insides?

the diff in my car is from an e28 m5, so yes, they should use the same medium case (meaning the whole thing will fit).

[X2theZ3]

You will break that diff in no time with a m50 engine, it should have broken already with the m20 engine.

You know what? I've heard a lot of people say that, but I think it's more myth than fact. I've talked to several people that have run the small diff in the 325i's and the m20 hasn't broken it.

[Rob]

it all depends on how you drive. Hell people have broken small diffs with small motors, shit happens, I'd plan on upgrading though

[nando]

heh, yeah I had a 318 in my old dart botled up to the stock 2.72 7-1/4" slant-6 rear diff. everyone told me it would break.. but it never did (that car was no slouch either!). :)

although there's no way and hell I'd try it on an E30, although the small case diff is a lot lighter. you'd want a lower gear ratio with an M50 anyway, correct?

[X2theZ3]

heh, yeah I had a 318 in my old dart botled up to the stock 2.72 7-1/4" slant-6 rear diff. everyone told me it would break.. but it never did (that car was no slouch either!). :)

although there's no way and hell I'd try it on an E30, although the small case diff is a lot lighter. you'd want a lower gear ratio with an M50 anyway, correct?

Yes, because the tranny ratios. 5th gear is 1:1.

[Stu]

An experienced, smooth, consistent driver will have no problems running the small-flange rear end behind a 6. An on/off, drop the clutch and jump on the throttle driver, will blow up a small-case. I blew mine up with a stock motor, with plenty of youthful, spirited, heavy-throttle driving. My dad ran a small-case 3.45 behind a supercharged 24v pushing 300 at the wheels, with no trouble after a few years. It's not always about the machinery itself.

[oskard]

You will break that diff in no time with a m50 engine, it should have broken already with the m20 engine.

naaw my buddy has a 325i cabrio with a small diff and the diff handels
doughnuts and drifts easy.

I say this is just a myth, if the diff brakes there was something wrong with
it, it did now give in because of power.

But my car will be ready on monday, ill do some spirited driving and see
if i can brake the diff :)

[Stu]

You will break that diff in no time with a m50 engine, it should have broken already with the m20 engine.

naaw my buddy has a 325i cabrio with a small diff and the diff handels
doughnuts and drifts easy.

I say this is just a myth, if the diff brakes there was something wrong with
it, it did now give in because of power.

But my car will be ready on monday, ill do some spirited driving and see
if i can brake the diff :)

See if it brakes. Check to see if your E30 break booster brakes as well.

[E30godz]

so witty