geek49203 wrote:
hfmaxi wrote:
Most master cylinders I've run need to be extended all the way so the reservoir hole will feed the cylinder. On the other side, are you using MC's that will tolerate going all the way to the internal stop? Many will damage the valve. Also you don't want to hit the stop cause once you are there pushing harder won't give you any more brake.
Kinda figured that going to the all-in stop on either direction isn't good for all sorts of reasons. Any ideas on how must travel will normally be needed?
Thanks!
Tim
The master must be allowed to extend completely. So when you are off the brake pedal the pushrod is not applying any pressure to the master cylinder but not loose either. It's not really the travel that you need it's the force that you can apply with your leg and then what the math works out to for the calipers and pedal ratio you are using.
From Wilwood:(#2 is the reason for the extension)
Brake pedals should be free to return when no pressure is being applied, allowing the master cylinder pushrod to return
to its undepressed position. In some cases, the master cylinder spring (internal) may not be strong enough to fully return
the pushrod; in this case an additional pedal return spring can be used. There are two important items for consideration:
1. The brake pedal should have an adjustable return stop on it when a strong pedal return spring is used. This
prevents the master cylinder from excessively banging the snap ring stop inside the master cylinder bore (visible
under the rubber boot). Adjust the stop so the pedal stops returning at the point when the master cylinder piston
retracts against the snap ring, Figure 1.
2. The master cylinder piston must fully retract. If the master cylinder piston is not allowed to fully retract when the brake
pedal is not applied, the primary inside seal will not return past the small pressure relief hole (visible within the master
cylinder reservoir on some master cylinders). This can cause excessive residual line pressure and contribute to brake
drag and an overheating condition, see Figure 1, Detail “A”.