Brake Fade -- looking for budget solution to track problem
So I'm having some problems with brake fade at the track, and am looking for a way to stave off the fade for just a little bit longer, or possibly diagnose something I'm doing wrong.
Here's the story:
Track Day #1: I go out on street tires with (almost) stock brakes. I flushed ATE Super through the system the week before, when I replaced the rubber hoses with braided metal ones. Brakes faded part way through the third session; not horrible, just mushy enough to concern me. They hadn't cooled enough by the 4th session to go back out, so I aborted the last session. Brakes were responding normally half an hour after I left the track.
Track Day #2: Installed slotted rotors and Mintex Extreme pads, bled with Amsoil's brake fluid. I go out on street tires and fade isn't evident until halfway through the last session. Not too bad.
Track Day #3: Bled with Amsoil again, shifted over to slicks (tired of chewing up my street tires). Added ghetto-style brake ducts (2" silicon tubing from front bumper to the inside of the rotor). Fade started early in the 3rd session. There was a long break between sessions 3 and 4, so they weren't terrible in the 4th session, but ... the pedal was a lot softer than I like. Drove home, then drove back out to the track the next morning -- pedal STILL mushy. I ran the first session (wet track) on street tires, slowly, and the brake fade wasn't really an issue because we were all moving so slowly. Second session was dry track, and the pedal was nearly to the floor. Bad. So I pitted in an aborted the rest of the day.
Glazed pads? Inadequate pads? Bad master cylinder? Overheated the fluid and destroyed it, and just need to flush better fluid through it? Just too much extra force from running on slicks, and the brakes can't hack it? 2" brake ducts not quite enough?
Open to ideas here. It's not urgent -- I'm not going back to the track until the spring. But I'd like to start working towards a solution to this thing. Losing track time (that I've paid for!) because my brakes can't hack it is painful.