One of my winter mods was to go for a new master cylinder, as I do think mine is going down hill,..........

Current set up is standard ford rear brake drums and on the front are Princess 4 pot calipers, and NO servo, currently the brakes work, but do require a hefty shove on the pedal to stop quickly

So, if my current master cylinder set up is 19.05mm bore, what is the better choice, larger bore or smaller bore ?
also, by changing the bore size, what would I expect to be the difference

regards

steve

One thing I just read about is that drum brakes are supposed to have a residual pressure valve to keep a small amount of pressure in the system, usually around 10%. Might be something to think about.

For more braking force with the same amount of pedal pressure you want to move to a smaller bore, but that will result in a slight increase in pedal travel.

Dave

quote:

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Originally posted by dave_424
One thing I just read about is that drum brakes are supposed to have a residual pressure valve to keep a small amount of pressure in the system, usually around 10%. Might be something to think about.

For more braking force with the same amount of pedal pressure you want to move to a smaller bore, but that will result in a slight increase in pedal travel.

Dave

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By slight increase of brake pedal travel, what type of meauserment are we looking at ?
1"/2.5 cm is fine
2"/5cm, will be reaching the limit of my short little legs !!

if you go to a smaller master cylinder, the pedal travel will be further, but with less effort

you can also do this by moving the 'pick up' point on the pedal itself.

Avoid Wilwood m/cs, they are poo.

From a quick think of things, if you half the bore of the master cylinder, pedal travel would be multiplied by 4. But that doesn't seem right in my head.

From what I can imagine, going for something smaller won't make the pedal travel to the extent that you run out of legs

THIS is what I am using. 17.6mm (11/16" is the smallest commonly available. Changing from 19mm to 17.6mm will decrease pedal effort by 16%

Cheers
Davie

Thanks for the responses,
A smaller bore it will be !
I will probably stay with the mk2 escort cylinder, as everything is already configured for it

steve

I put a mk1 Fiesta non servo one on mine to replace the Sierra one, It made so much difference it was unbelievable!
didn't notice the extra travel, just the fantastic feel I got instead of the solid pedal and pushing so hard it hurt my leg!