Bigger brake master cylinder options

[Koen Bongers]

So, my car has a lot of travel in the brake pedal. Probably due to the brake master cylinder being too small for the calipers. I want to get an upgrade.

Lots of options are available abroad which look like they used some kind of master cylinder off another vehicle. But of course they don't share part numbers...I don't want to pay a lot of shipping for something that is probably also in stock at the local parts store. The forums mention many versions from cars that are not really common in Europe.

Some data;


My current brake master cylinder. This is a 3/4" (19mm) , even smaller than original (13/16" or 20,63mm)

My front calipers are AP Monte Carlo with a piston surface of 46,6cm2 (original is 40,8cm2) so 12% bigger than stock. Rears are original.

My logic is that I need a 15/16" (23.8mm, 15% bigger than stock) or 7/8" (22.23mm, 8% bigger than stock) to get a pedal travel that suits the car.

Any advice? Preferably with partnumbers to get a new one of a decent brand I don't mind redoing the brake lines, but it should fit the current brakebooster (2-hole, horizontal)

Thanks!

[Dave W]

you should look for M/C that gets you in the [[[bore area]]]] range 7 thru 10 to 1 ratio when comparing front or rear caliper diameters to the M/C bore area. Note a smaller diameter master cylinder applies more pressure on the brake pads. Another option is to change the lever ratio, which give you more stroke at the M/C per pedal travel by moving the push rod location. You do not want the angle of the push rod to be more then 7 degrees.