Diff ratio question

Post Thu Aug 18, 2005 11:56 pm

Hi,

I have a e36 325i diff ('92) and i was wondering how to work out the ratio?

Thanks,
Stuart

Post Fri Aug 19, 2005 12:41 am

Think you'll find it's a 3.15:1

Post Fri Aug 19, 2005 12:44 am

I've taken the insides of the e36 diff and put it into a e30 casing. I'm going to be running a 2.5 M50...

Do you recon thats worth keeping or should i try and get something with a higher ratio?

Post Fri Aug 19, 2005 8:33 am

stulane wrote:I've taken the insides of the e36 diff and put it into a e30 casing. I'm going to be running a 2.5 M50...

Do you recon thats worth keeping or should i try and get something with a higher ratio?

If you've stripped it and it's a 3.15, it should have 13 teeth on the pinion and 41 on the crownwheel.

Post Fri Aug 19, 2005 9:36 am

Do you recon thats worth keeping or should i try and get something with a higher ratio?

Depends whether you want to sacrifice relaxed motorway cruising for acceleration or vice versa!!!!!

Post Fri Aug 19, 2005 10:15 am

Id rather have good acceleration and lower top end. most of my driving is town driving atm.

Post Fri Aug 19, 2005 4:25 pm

In that case you'll be better off with a 3.9:1 or as a compromise a 3.73:1, both standard E30 fare.

Post Fri Aug 19, 2005 4:30 pm

are you using the m50 engine and gearbox??

if so, iirc the final drive in 5th is 1:1 in the e36 box as opposed to the 1:1 ratio being 4th in an e30 box

ergo you need a much lower final drive ratio to give you comfortable cruising

Post Fri Aug 19, 2005 4:31 pm

Cheers, I'll give this a try and see how i get on.

I guess i'd like better fuel economy anyway.

Post Fri Aug 19, 2005 4:33 pm

are you using the m50 engine and gearbox??

if so, iirc the final drive in 5th is 1:1 in the e36 box as opposed to the 1:1 ratio being 4th in an e30 box

ergo you need a much lower final drive ratio to give you comfortable cruising

I'm using 325 M50 engine with its gearbox with a e36 325 diff.

Post Fri Aug 19, 2005 4:35 pm

stulane wrote:
are you using the m50 engine and gearbox??

if so, iirc the final drive in 5th is 1:1 in the e36 box as opposed to the 1:1 ratio being 4th in an e30 box

ergo you need a much lower final drive ratio to give you comfortable cruising
I'm using 325 M50 engine with its gearbox with a e36 325 diff.

well they should be matched ok -3.15 :1 will be fine