aggie_corvette

Wilwood SL6 w/thermlocks.
Pads track:F-XP12, R-XP9, Street:Q (no dust 5k miles old).
Fluid: Ford HD (i bleed often).
DRM ducts, LG spindle holders, NAPA rotors. V700 (315's on all 4)

Before track day brakes were firm ~2in of pedal travel then solid.

i work my brakes hard on the track. During day of 1 track weekend my pedal eventually went to the floor. At the end of the day i bleed the brakes, F/R. Fluid was clean. During day 2, pedal again slowly worked its way to the floor. Bleed brakes again, F/R. Fluid was clean.
Front Pads are slightly tapered, rear pads ok.

Street pads on the road. During normal driving the pad is firm, ~2in travel then solid. BUT when i do a hard stop 70-0 my pedal gets firm but sinks all the way to the floor. (not engaging ABS) Braking force does not get stronger with more pedal.
No pad taper

Any ideas??
Could something have happened to the master cylinder? Is it possible to spread the wilwoods? Did i fry the o-rings in the wilwoods (no fluid is leaking around caliper)?

John Shiels

Considering what I have done to mine I doubt the spread. I would dump the Ford fluid and get some SRF. My seals were not leaking and still in decent shape after 3-4 thousand track miles. They were very sligtly hardened on exterior face of seal.

with this you may have other issues

Cbntmn

I had my brakes bled at the dealer before and HPDE last month. Same type of problem started. I took it back to the dealer and they said "it feels fine to us" BS

I had a mechanic come to my house and we put it on the lift and he used a vacum system to completely empty the brake fluid and then we put "race blue" fluid in. (i may have the name wrong, he is a porsche guy)

Brakes were completly different at Sebring last weekend. They were amazingly strong all weekend. They only got a little soft at the end of the weekend because of pad wear.

XP10s on front, Hawk DT70s rear, stock napa, SS lines, Ducts, SS pistons in stock calipers.

If you want the exact name of the fluid i can let you know.

aggie_corvette

I don't believe the issue is with the fluid, as i bleed the system before, during, after events. John you don't think its the front calipers and that makes sense. although mine are no longer black, more of shade of purple from heat.

when on the street testing i am not pushing hard enough to engange the ABS. I could but the pedal still slowly sinks to the floor. (i also have SS lines)

The sensation is that of the fluid boiling but it happens on the street with thick street pads and fresh fluid.

I have checked that there are no leaks in the system.

What else could cause this effect?

AU N EGL

Still have air in the lines.

Dump the Ford HD brake fluid and use SRF, Motul ore ATE 200.

and when you test Get on that ABS.