diff question.

Mon Jan 19, 2015 12:12 pm

Hi all, I'm plotting an M52 conversion for my Touring. Currently it has an M20B25 with gearbox and prop from a 320i. It also has a 3.91 lsd. I've been reading on here that a gearbox/prop from a 328i is a stronger combo. Wondering if it's possible to re-use my 3.91 lsd with the 328i box/prop or will it be too short? Many thanks. Joe.

Mon Jan 19, 2015 12:20 pm

You'll need something like a 3.07:1, 3.15:1 or 3.25:1 with the E36 328i gearbox.

Mon Jan 19, 2015 12:42 pm

Thanks James. Maybe I'll try it on existing running gear while I look out for those other bits.

Mon Jan 19, 2015 2:45 pm

I'm currently in the process of taking the internals out of an e36 open diff 3;25 ratio and fitting them in my 3:91lsd to make an e30 3:25 lsd so I'll keep you posted I've been running the m52 box with the 3:91 diff for about a month and it's crap!! 1st and 2nd are pretty much useless

Mon Jan 19, 2015 3:34 pm

Nice one, that'd be ideal. Do you know if e39 diff bits are swappable in the same way?

Mon Jan 19, 2015 4:02 pm

z3 Torsen Lsd if you can find it, then swap out the output flanges for the e30 medium case ones.

I think mine is a 3.25 or 3.15 and it's perfect with the e36 328i zf box.

Otherwise just keep the m20 box if it's good and use the existing LSD.

Mon Jan 19, 2015 7:18 pm

Unfortunally e39 arnt which is a bigger as there 10 a penny but e34 and e28 ones are though as I'm told all I'm using from a doner diff is the crown wheel and pinion to change the ratio and keep my lsd unit