Hot Rods early ford brake cylinder bore size

I am building a 1923 T touring with a stock model T frame, 21 stud flatmotor and 1956 F 100 front brakes and 1940 rear brakes. I need to buy master cylinders for each of those but can't figure out what master cylinder bore size to use. I have asked everyone I can think of what the bore size of original master cylinder would have been, but can't get a definitive answer.
This car is going to be a tribute to my buddy Norm Grabowski and his 1923 red T touring which appeared in the movie "High school hell cats" as well as a number of magazines. The car will not be a clone but instead my concept of what the car would look like today after having a hard hot rod life....a beater with that Grabowski charm.
Please help a poor hot rod boy out if you know what size bore master cylinders I should use.

 

theres only one master cylinder per car....... are you talking about WHEEL cylinders? the 40 ford brakes use a 2 diff size setup, the 56 ford willl be one size. any napa will be able to look up what size you need just ask for a wheel cylinder rebuild kit.

if youre asking what size master cylinder to buy, get over 7/8ths for drum drum. i find 1 or 1 1/16. but not to big you will lose pedal leverage.

 

Agree with johnny bondo on master cyl size but as he said,it looks like you're looking for wheel cylinder sizes.I'm using '56 F100 brakes on the front of my 'A'.The wheel cyl diameter is 1 1/16th inch.
Regarding the rear brakes,if you have the old cylinders,take them apart.The size will be moulded into the rubber seal.That will tell you what you have.

 

For the master cylinder, the 1953-56 F-100 master cylinder has the same bore size as the 1939-48, which is 1-1/16".

For your 40 Ford rear wheel cylinders, the size for all rears for 1939-48 is 1x1-1/8". I would just use the normal sized 1939-48 rears, and the normal F-100 fronts.

 

Not wheel cylinder, master cylinder. I am using stock 56 F 100 wheel cylinders in front and stock 40 ford wheel cylinders in the rear. I am using firewall mounted swinging petals which will have one master cylinder operating front brakes and another which operates rear brakes. It is those 2 master cylinders I need to determine what bore size to order.

 

As said 1&1/16 for both !!!!!!!!!!!!!!!

 

Thank you for your help.
Danny

 

two master cylinders??? what the hell....... just run a T fitting off the one master. or get a dual one.

 

Given that a single 1 1/16" dia master cylinder is designed to be used to operate the brakes at all four wheels, by running two of them (if I read you correctly), one for the front and one for the rear means that you effectively will suffer a loss of leverage by half .

This setup will produce a very short pedal travel but heavy at the same time.

The increase in leverage from the action of the foot at the pedal to the pressure applied at the wheel cylinder is the ratio of the area of the master cylinder over the combined areas of all the wheel cylinders.

That ratio will be reduce by one half because of the addition of the second master cylinder.

In order to restore the correct ratio of area of m/c versus wheel cylinders then the combined area of both m/c will need to be reduced by half.

If you do the maths then that translates to a diameter of 3/4" for each cylinder. Otherwise to restore the same pedal effort you will need to double the length of the pedal and that would probably put the pedal pad through the floor.