Relationship between booster and brake master

[g22]

I'm doing an M50 swap with my 325 but I have e30m3 brakes. There are several different combinations of boosters and masters that will fit.

What I would like to understand is if I go through with my current swap plan and use an e32 booster and master and don't like the feel of the brakes, how do I adjust it? So if the pedal is too soft do I use a larger or smaller master to change it? How does this relationship between the different size masters and boosters work in general?

[jlevie]

Your options for an M50 swap w/respect to brake boosters are somewhat limited by what you can fit in. If what you use results in too much movement of the brake pedal and a soft feel, you can stiffen up the brakes and reduce throw via a larger master cylinder.

[Massive Lee]

The booster options are indeed somewhat limited to a 2002 or e21 unit. They offer limited assistance compared to the bigger e30 unit. Therefore, the pedal will require a bit more effort than you may be used too. The e30 M3 calipers use a stock 23.8mm MC with equal size pistons. Stick to it. If you feel the pedal has too much travel, most likely you need to bleed again. Or you can use a bigger e32 750i MC (25.4mm). Using a torquier pad will also lower the amount of pressure required to stop the car.

[g22]

Thanks Jim and Lee. I actually just ran into a guy that has a Porsche 944 booster that I'm getting for free. The swap section of RV3 seems to think this will work too. My options now are the e32/e30ix booster or the 944 one. Thoughts on which booster and master combo

[Jean]

I've read that you can also use e34 540i boosters, look into that too.