Okay. I've got a real mystery for all mechanically inclined.
I was running in a PCA DE at Watkins Glen in my '72 RS replica. I'm lapping comfortably, building my tempo. I'm approaching the Bus Stop. Everything is good. I'm going around the long right hand sweeper, the Carrousel. Everything is still good. I'm diving down the Chute into turn 6 (down hill banked left hander) and the brake pedal goes to the floor. But just once. On the next pump the pedal is back. At first I thought I'd missed the pedal all together. I kept going without issue. Next time around in exactly the same spot it happens again. The pedal goes to the floor again and is back on the second pump.
What da fu...? Has anyone ever had the same experience?
I bled the brakes at the end of the day but it did it again the next day. I continued on, making sure I gave the brake pedal a little stab with my left foot before fully commitiing to all the more serious braking zones. Most of the way around I was fine. But everytime into 6 if I didn't do a full left foot pump it would go to the floor again.
I asked a few guys at the track and all suggested a brake bleed and then suspected the master cylinder. I bled the brakes thoroughly. If it had been air in the lines I'd have had the problem all the way around. No?
The only other suggestion was that I may have a bad or loose front wheel bearing allowing the rotor to push back the brake pads and caliper pistons, displacing enough brake fluid from the caliper to require two pumps to move the pistons and pads all the way to the rotor again. It sounded like a stretch to me but when I got home my mechanic suggested the same thing. Then we checked the front wheel bearings and hubs. Everything was fine.
I'm using Brembo calipers all around with Brembo floating rotors on the front and 930 rotors in the back. The master cylinder is the only thing we haven't looked at yet.
I sure would love to hear some thoughts on this from anyone who has some.
Thanks guys.
A.T.
P.S. Is there ever a time when everything is working on these cars, some kind of mechanical plateau free of overlapping issues? Jeez!!!