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Hey, I'm currently building a single seater racer as a college project, Formula Student.
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, to achieve correct set up. I'm not sure where to start.
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 leg input,
i'm getting a line pressure of
( front: 744.66 Psi , Rear : 258.63 Psi )
I have calculated a disk torque 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?
Any advice information or criticism is welcomed and would be greatfully appreciated.
Just a couple of things:
What is the initial lever arm length of the pedal?
Try to work in either metric OR imperial
What size brake hose are you using -3 or -4 thus what are the burst and working pressures?
What size are the brake discs and what co-efficent of friction are you using to calculate the required force,are you assuming the brake force at the disc is distributed evenly through the pad (then what size pad are you using?)
Are you assuming the braking force of 300N (ish) is distributed evenly between the master cylinders? I ask that as if you (as suggested in the OP) the smaller diameter M/C on the front you will end up with a longer travel as you have to fill more cylinders on the front thus either additional bending will be applied to the distrubution bar or more pressure will be applied to the rear mastercylinder?
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, to achieve correct set up. I'm not sure where to start.
missed this bit, if you have a pedal ratio of say 1:2 and a pedal length of 300mm (centre of pivot to centre of the foot plate) then the master cylinder should connect to the pedal 150mm from the piviot.
If the ratio is increased to 1:3 then the M/C should be connected 100mm from the piviot
It's a simple moment calculation, take moments about the foot pedal (force applied x distance to piviot) then taking that calculated moment, divide by the distance to the M/C connection will give you the force applied to the master cylinder.
Because of this direct relationship you can take the force applied (30xG) and multiply by the pedal ratio so 30*9.81*3.454=1016.5N total applied force to the balance bar.
