diff question

Post Thu Apr 04, 2013 11:17 am

I have a m50 with a 318 box. Currently running a standard 318 diff which is very short. Whats the best ratio to go for?
I was think a 3.25 ratio would be good.

Post Thu Apr 04, 2013 12:33 pm

I would think a 3.64:1 if you want it to be more of a cruiser. A 3.25:1 would be good with an E36 box.
A 3.91:1 would mean less revs than your current diff but still with a bit of get up and go.

I've fitted a 3.91:1 to my 318i and its made it much nicer to drive, I think my M40 would struggle with a 3.64:1 but an M50 should be ok.

Post Thu Apr 04, 2013 6:44 pm

Thanks mate, will keep a look out for either a 3.64 or 3.25

Post Thu Apr 04, 2013 7:20 pm

A 3.25:1 ratio will only be good for motorway cruising with the box you have. It will kill acceleration and the M50 will have to work hard at lower revs/pulling away.

You could try a 3.46:1 diff as I think some guys with M50s run these for a more relaxed car. It depends what you use the car for.

Although the M50 would pull with 3.25:1 diff and an E30 box, personally I wouldn't go that low geared unless the car spends all day every day on the motorway, and even then it would be overkill.