bmwe21.net forums

Hi,
I´m working on a brake system swap (from 318i original) and I´ve read that the E12 master cylinder is the way to go. I´ve seen on RealOEM that there are two types, one that is 22,20 mm diameter (part no 34311122145) and one that is 23,81 mm (part no 34311120832). The latter is for 525i and up. Is it sufficient with the 22,20 mm or would you recommend going for the big one? Anyone with experience of this? The original master cylinder is 20,64 mm.

And a following question: does the E12 mastercylinder fit right on to the E21 brake booster?

Thanks!

Believe stock E21 is 20.64mm for all models? What plans do you have for your brakes? If you're going to move substantially more fluid than you may want the bigger one. On my 323i I upgraded the front to 4 pot Wilwood and the rear to E30 and that works just great with the stock master.

Jeroen wrote:Believe stock E21 is 20.64mm for all models? What plans do you have for your brakes? If you're going to move substantially more fluid than you may want the bigger one. On my 323i I upgraded the front to 4 pot Wilwood and the rear to E30 and that works just great with the stock master.

Ok thanks for your info! Did you notice any differece in brake feel/pedal travel when changing the brakes? As I understand thats the main reason to change the master cyl..?

Nope, nothing at all I believe. Travel is pretty much the same and the pedal is as firm as can be.