rear diff swap

[sl600sl560]

Gurus:

Is it feasible to replace a 2001 325ic rear diff----3.46 ratio with a 2000 328i-----a 2.93 ratio????? Is this a somewhat simple direct fit???

Thank you in advance
Mike

[dhurley34]

Simple direct fit. You may have to change output flanges but that takes about 3 minutes per side but chances are you wont have to.

[TonyAngel]

Why are you doing this? I'm just curious because I have a 2001 325i. I mean, my E46 is slow out of the hole, but it isn't super quick either. Wouldn't this decrease acceleration? Unless you are doing this to complement a mod, in which case, I'm still interested.

[EWCMR2]

Yep, easy swap.
Swap makes first gear useful and lowers highway cruising rpm.

[sl600sl560]

Thank you for your replies.......the reason is to lower highway cruising RPM, quieter and probably slightly better hwy MPG. This engine/gearing combo was never "fast"......this is a gentle cruising car. I've always been puzzled by this BMW engineering decision

I appreciate the depth of this forum's knowledge

[EWCMR2]

After diff swap my M56 325i gets 30-34mpg on long highway trips. Around town didn't change, 23-25mpg.