Sorry if this has been discussed before, I couldn't use "M3" for keyword search (3 letter min.), so I couldn't find anything via the search feature.

I'm considering buying an E36 325is to both autocross in STX class and also for time trials/track days and wondered what's involved with upgrading to E36 M3 brakes, front and rear. Of course, the calipers, caliper mounting brackets, rotors, and pads are different (but allowed in STX class), but would I also have to do anything that would be illegal in STX class, like swap hubs and/or rear trailing arms and/or rear axles, etc.? I really don't want to invest in an aftermarket big brake kit, M3 parts would really be my only (affordable) option, since used calipers can be found pretty easily.

According to TMS, you need new spindles and hubs for the front.

You might also need to go to the M3 master cylinder (not 100% sure about that.)

http://www.turnermotorsport.com/html/detail.asp?PRODUCT_ID=325toM3brakes

For the front, you need to replace the spindles, and in the rear, you pretty much have to replace everything (entire subframe).

For the rear, the best "bolt on" brake upgrade would probably be the E46 328 rear brakes. The calipers and rotors bolt right on, and the 328 rotors are a little bigger, and are vented. Do a search in the E36 forum for E46 brakes, etc..

I would say it's well worth it to also install the master cylinder because of pedal feel. With the M3 brakes, you need a bigger volume of fluid to work the brakes, so with the 325 cylinder, you have to push the pedal nearly to the floor (I was doing that last Friday night, Saturday we put the M3 cylinder in). Now, something interesting my mech and I learned (from looking at the parts CD) was that any car with traction control has the same size master cylinder as the M3. So you don't need to find one out of an M car, just any car with traction control.

Enjoy...

-Saint