Braking Systems Design

[Gerard87]

Hey, I'm currently building a single seater racer as a college project. We're using a 600cc motorbike engine and it weighs 300kgs. I am currently designing the Braking System of the car. I am restricted in using a single caliper mounted to the differential at the rear.
I am trying to design a pedal box to house the brake pedal but i'm having trouble figuring out how to determine the distance between the push rods of the Master Cylinders. I am using a balance bar with a spherical bearing. i have no idea were to start with the design. If you have any advice or information that may help it would be greatfully appreciated.

Thanks, Gerard.

g_grindel@hotmail.com

[Belatti]

Hi Gerard, so you have to figure out a pedal ratio (pivot to pushrod distance vs. pivot to foot pressure center distance)a good start would be between 4 to 6.

The driver should make a force of arround 30Kg, translate that to the pushrod, then to the pump piston, then to pressure in the line and then to force in the caliper piston... you know how it goes.

Try to find a balance in your design, its desirable a system with low pressure, big caliper pistons and a small disk.

[Gerard87]

Thanks for the advice.

Most of the components have been purchased from previous years projects. I have no choice on them unless I can make a strong argument against them.

I have worked out the Pedal Ratio is 3.454
The two master cylinders Front + Rear bore diameter 0.442 and 0.75 inches.
Two pot calipers all round 1.6141 inch Piston , Two on the front and one on the back axle. (Calipers tested to 1000 Psi)
The car weighs 300 Kg (120kg front, 180kg rear)
Ive made an excel spreadsheet with some of the major calculations:

I calculated the torque needed ( front 1103 Nm , rear 393 Nm)

With a 50/50 split in the balance bar + 30Kg input, i'm getting a line pressure of
( front: 744.66 Psi , Rear : 258.63 Psi )

I have calculated a braking torque of achievable
( front 1,407 Nm , rear 244 Nm )

What do you think of my figures?
Can / Should the balance bar be used to give greater pressure to the rear?
Are the line Pressures too high?