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brake master cylinder sizing question
will121 - 13/5/12 at 12:20 PM

im looking at changing the current single master cylinder/servo on my track day fiesta for a twin master cylinder bias bar arrangement.
is there a caculation for sizing the master cylinders? i no basics of smaller front for more force but i currently have a bit of a miss-match arrangement with larger escort cosworth calipers upfront with standard rear drums on rear so also need to consider master cylinder to piston ratio

johnH20 - 19/5/12 at 08:01 PM

I think you will find this has been covered before if you do a search. To go back to basics try and get hold of a copy of Fred Puhn's book ' Brake handbook' by HPbooks ( ISBN 0-89586-232-8). Its all about hydraulic ratios and weight distribution, no difficult maths involved. Good Luck!

britishtrident - 26/5/12 at 06:29 AM

quote:
Originally posted by will121
im looking at changing the current single master cylinder/servo on my track day fiesta for a twin master cylinder bias bar arrangement.
is there a caculation for sizing the master cylinders? i no basics of smaller front for more force but i currently have a bit of a miss-match arrangement with larger escort cosworth calipers upfront with standard rear drums on rear so also need to consider master cylinder to piston ratio


Stop !

You need to to stop and think before doing anything as with the standard Fiesta master cylinder Escort Cosworth callipers on the front you should be able to lock the fronts with no problem. The rear brakes on small short wheel base FWD hatches do sweet FA under heavy braking.

If you find you need excessive pedal pressure to lock the fronts I would suggest that perhaps you have the brake pad friction a material that is much too hard.

You haven't told us what model of Fiesta you have but many Fiesta models have hydraulic pressure regulator valves screwed into the outlets from the mastercylinder which limits the pressure going to the rear brakes.

[Edited on 26/5/12 by britishtrident]