Calling the Specialist: Brake help

[LtMash1A]

I use my 2003 Z06 for track events only. I use Carbotech racing pads, SS brake lines, Motul 600 brake fld. I bleed before each event. At one time I over bled my MC ( to the point that there was still fluid at the bottom, in the neck, but reservoir almost dry). My problem is excessive brake pedal travel. I have been to the dealer twice to resolve the problem. It gets better or at least acceptable for an event or two and I get the problem back. I have a lift in my garage and have inspected everything, no leaks. I got the excessive brake pedal travel code on the EASE diagnostic. The brakes are not spongy, just a pedal travel problem. I have bled the brakes, activated the ABS and bled again several times but it didn't help. I have also asked the dealer to activate the ABS and bleed. This happened to someone else. They fought the problem for a long time and finally ended up replacing the MC to resolve it. Unless you have any other suggestions, I plan on doing that next.
Thanks/David

 

[c4c5specialist]

HI there,
I am surprized that noone has done a pressure test on all the calipers to determine where the problem lies.
This would be the best way to determine if there is a problem with the master or other components.
I have done some masters, so it is a possibility.
Proper diagnosis is critical.
Allthebest, c4c5

 

[LtMash1A]

How much pressure should the front and back calipers hold?

 

[c4c5specialist]

Hm, I dont have my specs in front of me. Aside from that, I use a pressure gauge to load the brake pedal in an accurate fashion, so my leg pressure is NOT the changing factor between cars.
Have your techs check one car, it doesnt have to be Z, and then check yours.
A difference of no less than 50 lbs should be noted
I normally check a car that does not have a concern, and then check the problem car.
Be it c5 or ZO6, they should be very close to the same.
Allthebest, and please keep us posted, c4c5

 

[LtMash1A]

Thanks,I'll let you know what happens.
Dave

 

[LtMash1A]

Well, I have bench bled the MC and rebled the hydrolic system. No change. There are no leaks and no air coming out of the system anywhere. The MC behaved like it should when I bench bled it. I don't know if there could still be a leak between the primary and secondary pistons. I quess the next step is to have the tech put a scanner on the ABS system and open up the secondary system and bleed to hopefully restore pedal height.

 

[MsSchroder]

LTMash1a,

I am curious, what are the symptoms? Do you get more and more travel as the brakes heat up?

(My son is experiencing this on his acura, even after bleeding the brakes. )

 

[Bob Chadwick]

LTMash1a,

I am curious, what are the symptoms? Do you get more and more travel as the brakes heat up?

(My son is experiencing this on his acura, even after bleeding the brakes. )

Tammy,

This is a known problem with the Acuras. My Legend had it and it was corrected by replacing the master cylinder.

Bob