Brake Master Cylinder - Is it bad?
05-21-2009, 02:08 PM
#1
Terminal Vette Addict
Thread Starter
Brake Master Cylinder - Is it bad?
Ok.
I'm on good rotors, plenty of meat. Hawks, plenty fine. 1 year old OEM C5Z Calipers, no leaks. motul RBF600 fresh full system and bled well. SS lines.
I have 3/4" of pedal travel before I feel good pedal. its been like this for a bit now. I have been in my buddies car, and his pedal is hard with Viagra! And he is not as well set up! All OE, old fuild even.
If I pump the pedal 4 times fast, I get a stiff pedal like I would expect for one good solid brake use. RIGHT there and solid, like his. Then with a few secs... the pedal travel fades again. Cold/hot run no difference.
I'm thinking Master has to be replaced... thoughts?
I'm on good rotors, plenty of meat. Hawks, plenty fine. 1 year old OEM C5Z Calipers, no leaks. motul RBF600 fresh full system and bled well. SS lines.
I have 3/4" of pedal travel before I feel good pedal. its been like this for a bit now. I have been in my buddies car, and his pedal is hard with Viagra! And he is not as well set up! All OE, old fuild even.
If I pump the pedal 4 times fast, I get a stiff pedal like I would expect for one good solid brake use. RIGHT there and solid, like his. Then with a few secs... the pedal travel fades again. Cold/hot run no difference.
I'm thinking Master has to be replaced... thoughts?
05-21-2009, 02:17 PM
#2
Le Mans Master
You say 3/4" pedal travel. Did you mean 3/4 travel? 3/4" is way too close to the top of the travel for my comfort, I like it about 1/3-1/2 travel.
If it's 3/4 travel, then did this start happening right after your recent track day? If so, and you're running the pads you had on the track, then you're probably experiencing pad taper. Various factors play into it, but mainly the leading edge of the pad (the first part of the pad swept by the rotor) wears down slightly more than the trailing edge. After a few days of normal day to day driving the pads square up again and the pedal returns to its normal position.
HTH, and have a good one,
Mike
If it's 3/4 travel, then did this start happening right after your recent track day? If so, and you're running the pads you had on the track, then you're probably experiencing pad taper. Various factors play into it, but mainly the leading edge of the pad (the first part of the pad swept by the rotor) wears down slightly more than the trailing edge. After a few days of normal day to day driving the pads square up again and the pedal returns to its normal position.
HTH, and have a good one,
Mike
05-22-2009, 08:52 AM
#4
If you decide it is the Master Cylinder, I have one (C5 Z06) with about 10K miles on it. I will make it very cost effective as I have no use for it anymore. PM if interested. Good luck.
05-22-2009, 11:27 AM
#5
Melting Slicks
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Do a Tech 2 bleed before you change out the master. The pedal will feel soft if there is air in the ABS, only way to get it out is with a Tech 2 bleed.
05-22-2009, 02:01 PM
#6
Terminal Vette Addict
Thread Starter
05-22-2009, 02:03 PM
#7
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yup 3/4" before i get good feel... my buddies car is about 1/4" to feel, then after 1/2" you get good feel! I agree its too much, which is why i ask.
