E30 Zone

Hi,

Does anyone have first hand knowledge of using a medium case diff from an E34 on their E30?

I plan to use the gearbox that came from the donor 328i so obviously that means sourcing a diff with the right ratio.

I've seen a few 3.23 E34 diffs come up but I've read conflicting information regarding fitment to E30. Some say will be fine with my E30 diff backing plate but some say output flanges need swapping over. If that is the case, are any specialist tools required?

Not sure if the main body is the same but if so the back plate just bolts on and the out put flanges can be levered out and pushed back in very easy to do once you get a good leverage point and break the sticktion of 20 years

Cool, I think I'll just take a punt and see how I get on. Is 3.23 ratio going to be ok with E36 gearbox? Driving style will be leaning more toward track action then daily driver if that helps.

looking at doing the same with my e30
and are still haven,t made my mind up using either e30 or e36 box
but from the info i have been looking at all say the only diff thats suitable is the e28 diff not the e34 one
and swap over rear cover and flanges
on the bright side i also read you can use the e34 internals (eg lsd) in the e30 diff but takes a bit of work to set up lash etc,
good if you know what your doing expensive if you have to pay someone to do

dan

The diffs are very different, but the internals are the same so you can fit a CWP (or entire diff unit) into the e30 diff.

I picked up a 3.23 slipper last weekend from an e34 for this purpose. Very good ratio when used with the ZF

Overdrive ratio on an E30 'box is 0.81, so a 3.23 diff. on an E36 box is the equivalent of a 3.23/0.81 = 3.99 diff. on an E30 'box.

CWP is Crown Wheel (big cog) and pinion (small cog) and yes the whole internals can be interchanged.
if you want to change ratio the the pinion and crown wheel from the e34 need to be kept together and will require setting up of the pinnion depth and backlash on the crown wheel a very lenghty process and requires alot of different size shims. so getting a 3.23 slipper aint such a easy swap but changing the standard e30 ratio open diff withwith a lsd unit is fairly straight forward

CWP is Crown Wheel (big cog) and pinion (small cog) and yes the whole internals can be interchanged.
if you want to change ratio the the pinion and crown wheel from the e34 need to be kept together and will require setting up of the pinnion depth and backlash on the crown wheel a very lenghty process and requires alot of different size shims. so getting a 3.23 slipper aint such a easy swap but changing the standard e30 ratio open diff withwith a lsd unit is fairly straight forward