Quote:
Originally Posted by The HACK
(no you do not calculate all 6 piston, the ratio of slave pistons to master cylinder is per CLAMPING SIDE ONLY)
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Why?
I see a statement but no physical/mathematical deduction.
Anyway, tons of people use the 135i calipers on m3's/z4m's on track and have no problem what so ever. It's a really common mod. There are multiple suppliers here (mostly germany) that make brackets or complete kits.
Also if you look at a tried and tested set for the z4/m3: the ap 6 piston bbk, that has 2x 27mm pistons, 2x 31.8mm pistons and 2x 38.1mm pistons. Thats per side a piston area of 2507mm˛
Compared to the OEM one cilinder caliper that 11,1% decrease (1 side) and the 135i caliper has a 13.8% decrease (1 side).
You wont convince me that that 2,7% difference is the border between having a fantastic BBK and having a worthless BBK.
I think there's a reason that the piston area from a AP bbk (designed, tried and tested on the z4m) and the 135i caliper (Brembo designed caliper) are so incredible close. It's only 69mm˛ difference per side.