Question about diffs

[E30drifto]

Ok I have a 318 is which im doing a 3.5 conversion on to be used as a drift car.
Ive heard that the standard diff cannot cope,

My mate has a 325 se, we were thinking of swaping diffs so I'd get a diff that wont explode and he'd get a lower ratio, Is this correct?

How do you tell the difference between a small and a medium cased diff?

What ratio is a 325 se diff and whats a is diffs ratio?

Thanks in advance

[Templ8e30]

A small case diff has 6 bolts on the rear plate, medium case diffs have 8.

A 325i will either be 3.64, 3.73 or 3.91, a 318is should be 4.1.

The only problem with your plan is that your mate will get a small case diff, not a good idea on a 325i. My old 320i shat its standard small case diff, the extra torque from a 2.5 won't help it.

Cheers,

Iain T

[Dave_M3]

Your putting an M30 into an iS

Wait till I tell the the rest of the M42 brigade

[JohnnyBlazE]

It's okay Dave, we accept his modifications.

[v_nitro]

I have a noob question, whats the lsd's ratio? I understand that the number 1.11 or whatever is the ratio of teeth on the shaft from the engine and the axle with the wheels, but what is the ratio of torque that the the lsd applies to the wheel when the other one is spinning?

[dannyboy759]

Standard BMW diffs are 25% and the ratio, say 3.25 means that if you put a drive in to the diff and turn that once the two drive flanges will turn 3.25 times.
Bit simple but thats the jist

[Turbo-Brown]

Standard BMW diffs are 25% and the ratio, say 3.25 means that if you put a drive in to the diff and turn that once the two drive flanges will turn 3.25 times.
Bit simple but thats the jist

Almost, but the other way around so you have to turn the input 3.25 times to get 1 turn of the output flanges.

[v_nitro]

Sweet, cheers guys