|
Hi
This part of an email that I got from Gropher, a poster on STF, I havn't heard from him for a while but he said some interesting things in relation to M/C sizing
Steve C
====================================
I've misplaced my cheat sheet on which I had evey Porsche caliper's and rotor's specs: piston sizes, caliper dimensions and mounting style, pad area, rotor dimensions & hat/hub offset,
swept area, etc... And of course part numbers and new prices. If I find it, I'll email it to you. I remember most of it off the top of my head, as brakes were a speciality of mine for a number of years.
I wouldn't fret too much about the master cylinder size. I've driven in more cars with poor brake feel because people alculated the exact M/C size by following their original car's ratio of M/C to piston. Very scientific, yes, but that level of accuracy can be overkill. Sizing the M/C can be as much to your driving style -- some people like more pedal travel so that the brake pedal ends up lower when they start to bite, leaving the pedal
about level with the accelerator for easier heel-and-toe operation.
I would say from my experience that you shouldn't go larger than a 19mm M/C. When I've installed 4-piston Turbo or monobloc kits on the front of 914s but retained the dual piston calipers in the rear (after much bias valve adjustment), the 19mm M/C gave a high, firm pedal with adequate range to control modulation. The same is true even when 4-piston rear Turbo calipers are installed. The 914's stock 17mm M/C will even work with the 4-piston calipers up front, but you have almost as much pedal travel as stock. The advantage is little pedal effort is required. A 23mm Mercedes M/C unit is terrible -- little travel, very hard (lots of pedal effort required) and no possibility of modulation
-CC
|