Thread: Need some Master Cylinder Edumacation...

Tweet

I have always replaced brakes by application, so it is something I have never tried. What happens if you use a power brake master cylinder ( say off a 76 caprice ) on a manual disc/drum brake setup ?? I have had some say " its hard pedal like when you kill the engine" and someone different say " its the booster without vaccume that makes the pedal hard, not the M/C".... Just curious...

The larger the bore on the MC, the more fluid it will move for a given length of stroke. It will also take more effort to move the piston. A typical power brake MC might be 1 1/8" bore.

On the flip side, a manual brake MC might be 7/8" bore. It will move less fluid for a given length of stroke, but will take less effort to move the piston. So, you have to move the piston farther down in the bore to move the same amount of fluid.

Bottom line:
Big bore, short travel, high leg effort.
Small bore, long travel, lower leg effort.

So, it can be done, it would just take 4 men, a pack mule, and 3 circus midgets to push the pedal. Thanks Tech, that cleared it up alot.