Engine and trans swap

[V8touring]

I have a 92 e34 touring 525 with a great body and poor engine , I also have a 95 540 6spd with a poor body. Does anybody know if the engine and transmission from the 540 will fit in the 525 without too many problems. I have been told the transmission may not fit. Is this the case??

[John in CT]

Well, they must physically fit because BMW did it, right? I'm sure others with more experience will chime in but having both cars on hand will certainly make the job easier. I see wiring the engine managment systems as one potential pitfall. Would you be doing the work or a shop?

Conceptually a very nice project too,

John

[shogun]

compare the parts of both cars on RealOEM.com Online BMW Parts Catalog

Maybe the final drive of the 525 is smaller and also the connections, but as you have it all there in the other car, just transfer what is required.
Besides engine, drive etc you probably also have to change engine wire looms, control modules, radiator etc.

[632 Regal]

You will have an issue with the brake booster setup, you can probably swap it over to the 525. Take a look at that. The transmission will fit no issue however the drive shaft will not bolt up. You can use the 540 drive shaft but you will need to swap the rear end over. The 540 and M series have the larger differential carrier and for a swap to happen painlessly you want to bring that into the 525.

Do not remove the 525 badge.

[genphreak]

I would plan to swap the entire contents of the engine bay and the driveline & brakes. It's a big job but rewarding. Beware all the wear items that will cost you in the process.

In terms of electronics, the '95 will need the DWA, EWS, steering column, instrument cluster have other body electronics (RM/GM) to bring- in fact you'll need to bring the body loom and modify the 540 one with a small amount of rear loom wiring the touring has. You might find the GM is different, and 540 touring GMs and RMs will be hard to find if they are unique to 540 Tourings (check). Some of the rear body touring loom will plug in to the sedan central loom (under the rear seat), some will need thought & joining.

Look under the back seats of each car and compare the make up of the connectors under the rear Rear Power Distribution box where the GM and RM are (need to remove, pull up and inspect the underside for different loom colours/wires) Note the DWA hidden between the RPD box and the seat base, when doing this.

***It is hard not to get it mixed up with parts/placement/fitment when moving in between the 2 cars***, so be scientific and take notes+pics before moving things over.

Also, given that they are a couple of years apart, you may be doing all the wiring in the dash as well (different blower and some controls for sure). Perhaps plan to do that, and thus be pleasantly surprised if you don't. Sounds hard, but also a very good result- the best BMW ever made (?)