E30 Zone

Hi everyone,

Just looking for some advise really on how to go about getting my engine swap done the best way possible.

As the title suggests, I am looking to go from the 318i engine to the M52B28, I have the gearbox and prop that came with the engine and ecu etc but I wanted to know the following.

If I went for a Getrag 240/260 gearbox, will my Auto prop shaft work still? Are they the same as the manual M40 engines?

I think I will most likely go for the 240 gearbox if it works with my prop shaft. that being the case will I need a new gearbox mount?

Lastly... the kind of driving I will be doing is mostly going to car meets etc. But I plan to also do a euro trip in the car, drive to the south of France and constantly do long drives on the motorway. What would the best ratio for the diff be for me to not be going insane with the RPM and the fuel killing me off.

Thanks in advance everyone

Auto props are too short to use with any manual box.
Best box to use is the one that came with the engine, but this will require a change of diff. to compensate for that box having a direct top gear instead of the overdrive top gear of any E30 box. The overdrive ratio is 0.81, so, comparing with an E30 3.9 diff. you would need 3.9 x 0.81 = 3.16 to achieve the same gearing.
The 240 gearbox can be used, but bare in mind that this was considered by BMW to be too weak for use with a M20B25, although in practice they seem to last. An M40 auto uses a small case (=weak) diff. with a ratio of 4.1 (or possibly even higher). For use with an E30 manual box, you'd need something like a 3.73 medium case diff. from an E30 325i saloon.
You will need to do simple mods to an E30 gearbox crossmember, and to the gear linkage, to accommodate a M40 box attached to a M52.

I did this exact swap with rolling shell 318i.
I have went with getrag box (e36 325i) and 3.73 diff, I drove it with the 4.27 small case and was ridiculous. It's on the wiki pages everything you need and would recommend Magpie (Mick) for any parts you might need.