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Welcome back to Summit Racing Quick flicks, today we are going to address some frequently
asked questions about master cylinder bore sizing so prepare to be bored.
In our previous videos about braking system components as far as master cylinders and
disc brake versus drum brakes go we addressed some generalities as far as what master cylinders
are right for an application. The thing about it is that is one of those things where you
really have to do your research to determine which one is going to be correct if you are
building a custom system because there is a lot of different ranges of master cylinders
out there that are available. The main factor that is going to come into play is the bore
sizing of the master cylinder which I think most people have a little bit of confusion
about as far as what is right for what type of system. In reality you’re going to come
to find that bore size is critical to how that brake system is going to function and
it has a lot to do with pressure as well as capacity. Logic would tell you that a larger
bore size in a master cylinder should produce more pressure but that is actually not true.
Because of fluid velocity and fluid movement in most cases the smaller the bore of the
master cylinder means the more pressure you are going to have at the caliper assembly
or the wheel cylinder assembly. Whereas if you have a larger bore master cylinder it
is actually going to produce less pressure its actually going to give you a harder pedal
feel as an end result. Having a general understanding of bore size is critical to selecting the
proper master cylinder for your application. Getting the right master cylinder is all about
proper pressure whether it be at the caliper or at the wheel cylinder. Generally speaking
we want the pressure at the caliper to be somewhere between nine hundred and twelve
hundred PSI, question is how do you know if that master cylinder is going to make that
pressure at that caliper assembly. The thing about it is, you won’t know it is kind of
one of those things that become a guessing game in the end to determine which one is
going to be right. With the right amount of pedal pressure you will almost always be able
to get there the thing about it is what kind of pedal fill do you really want from that
vehicle and how do you really want the brakes to respond. Some prime examples of figuring
out which way you need to go with the master cylinder is let’s say you put a master cylinder
on and the pedal pressure seems pretty extreme it’s got a hard pedal that usually is an
indication that bore cylinder or the piston size of that master cylinder is too large
meaning that it’s not creating enough pressure at the caliper assembly to go ahead and give
you that loose pedal fill that you want but good braking the opposite can kind of be true
where you have an extremely soft pedal where the brakes are real grabby well that can actually
mean that the bore size is too small and you are building too much pressure too quickly
therefore you have to go up in size as far as the bore size of the master cylinder. Supplying
information on which master cylinder is exactly right for your application is really not possible
for us to do via a video. Every application is completely different from the next and
will have specific needs. So if you need more information or more help on selecting which
master cylinder is right for your application please contact our tech department at 330-360-0240.