How far do your caliper pistons travel?

[razzendahcuben]

Hi, I am curious as to what distances your caliper pistons are traveling. At present I have designed the brakes around a piston travel of 0.03", but this requires very true rotors and it seems that this would be difficult to set up. Yet if I increase this distance at all, the pedal travel increases proportionally, creating an absurd pedal travel (especially with a pedal ratio of 5:1, which seems reasonable).

So how many pistons are you running per caliper? What is your piston travel distance? What's your resulting pedal travel? Pedal ratio?

Any insight would be greatly appreciated. Thanks.

[CU - Andrew]

You'll have to talk to our brake guy...

[PaulR]

As long as your running floating rotors I dont think you will have any dramas.

[rjwoods77]

Razz,

I assume you mean .03 for each piston to travel to contact the rotor. That is on the high side for well designed caliper for piston retraction. Really good calipers will have about 1/64" and less. So you are roughly on the ball with that one. It all has to do with the design of the seal geometry on the calipers. Most people dont know but this is the actual crucial part about caliper design. Another reason why Wilwood makes junkhttp://fsae.com/groupee_common/emoticons/icon_smile.gif You are correct on needing rotors with very little runout. This is easy to achieve if the rotors are blanchard ground. Most people just laser cut a piece of metal and call it even then wonder why they have so much piston kickback. Call mcp brakes. They offer custon laser cut and blanchard ground rotors for a really good price. If a shop cant grind a rotor plus/minus 0.001" over less than a foot length then they shouldnt be in buisness. There is also somewhat of a falicy about floating rotors that Paul made a comment about. In a perfect world a fixed caliper will push the pistons on each side out even. Problem is that they dont always do that. The hydraulic chambers rely on a axial resistive force of the rotor to distribute fluid pressure even on both sides. Same concept as the old in floor hydraulic car lifts. If there is some stiction in the caliper then what it will do is push the one side pistons out more than the other side. This will push the floating rotor to one side. You MUST make sure that there is enough throat width in the caliper vs your rotor width vs your floating buttons/mechanism to ensure you dont start grinding the brake rotor on the caliper.