Manual brake master size and problem? - Lateral-g Forums

usa-69z · #1 08-11-2013, 12:21 AM

Guys , i curious on your thoughts about this,, my new brake set up in non assisted (pedal ratio changed), wilwood dynalite 4 spots ,11inch rotors, rears are right stuff 11inch single piston calipers,, wilwood 7/8 master and summit proportioning valve..when i jump in for a drive the pedal is soft and goes to the floor.. so i drive it and within half a mile or less the pedal is like a rock and the brakes are locking on.. there pumping up somehow??? any thoughts on this?

Gav

65_LS1_T56 · #2 08-11-2013, 06:06 AM

I would suspect air in the system still, or possibly a small leak. The size of the master should not effect the pedal being soft then hard after use, only effort in combination with pedal ratio.
If you have air in it, it could be working it's way back to the master while sitting then when you pump the pedal the air is replaced with fluid.

**GregWeld** · #3 08-11-2013, 09:32 AM

Did you BENCH BLEED the master before installation? This is a must do step!

When the car is "cold" -- have you looked (removing the wheels - getting it up on stands or a lift - maybe the night before so you don't have to touch the brakes) at the spacing of the pads? Pad knock-back can act like this -- where the pads retract or get pushed back - and the first pedal action is just moving the pads back near the rotor.... This is usually something that happens when on a track due to deflection of the rotor pushing the pads back too far... but since we're just guessing here -- I'm tossing this out there.

Have you bled the brakes using the gravity method? Or?

Have you put a bunch of pressure on the pedal and just held there for a minute or so to see if there is a change or drop in the pedal?

usa-69z · #4 08-11-2013, 05:27 PM

Greg , to answer those questions,, i have vacuum bled , reverse bled and old school 2 man bleed these brakes to get 'pedal'. As far as a bench bleed , i did do this 'on car' by levelling the master out and bleeding as on a bench but while attached.. all seemed air free and got me half a pedal of pressure..I made adjustments and i can only get an inch from the floor before some sort of braking happens , but not at all safe. The only thing i have failed to do is wind up the rear calipers from new for the emergency brake. Obviously that will play a big part ive now come to realize.
within half a mile the pedal is like a rock and trying to stop the car and all four discs are almost on fire..Its been a fun exercise so far.