ddd4114
forum member
I've been struggling with a squishy brake pedal for over a year, and I'm just about stumped. Unfortunately, I can't exactly remember when I started noticing the problem. I have a 2011 Mustang GT that almost exclusively is a track car. I have a Stoptech ST40 front brake package (w/ SS lines), and I have the OEM rear brake setup. I use Hawk DTC60 brake pads on all corners, and I use Motul RBF600 fluid.
What's strange about the squishy pedal is that once the brakes are hot, the problem completely goes away, and the pedal feels fantastic. This only takes about 1/2 of the warm-up lap on a road course or after thoroughly bedding in new pads on the street. I've also noticed that while the pedal is squishy when the brakes are cold, stopping power doesn't feel compromised at all. At first, I thought it was a fried master cylinder, but if I stand on the brakes, the pedal doesn't sink at all (while the engine is running).
With a squishy pedal, the culprit is almost always air in the system, but even after bleeding the brakes many times all last year, I couldn't get rid of it. I just replaced/rebuilt all of my calipers, bled the system with new fluid, and it still feels the same. I'm reluctant to have a dealership use their special tool to bleed the ABS module because I'd think air in those lines would still cause the pedal to feel soft when the brakes are hot. I also don't see how the booster could cause this because if anything, it feels like there's too much assist. I still have the OEM rubber lines on the rear brakes, but again, if they were expanding, I don't see how heating them up would make the pedal feel better.
Has anybody else experienced a problem like this before? Fortunately, it doesn't seem to be a safety issue, but it sure feels disconcerting on the street. I'd appreciate any suggestions.
Thanks.
What's strange about the squishy pedal is that once the brakes are hot, the problem completely goes away, and the pedal feels fantastic. This only takes about 1/2 of the warm-up lap on a road course or after thoroughly bedding in new pads on the street. I've also noticed that while the pedal is squishy when the brakes are cold, stopping power doesn't feel compromised at all. At first, I thought it was a fried master cylinder, but if I stand on the brakes, the pedal doesn't sink at all (while the engine is running).
With a squishy pedal, the culprit is almost always air in the system, but even after bleeding the brakes many times all last year, I couldn't get rid of it. I just replaced/rebuilt all of my calipers, bled the system with new fluid, and it still feels the same. I'm reluctant to have a dealership use their special tool to bleed the ABS module because I'd think air in those lines would still cause the pedal to feel soft when the brakes are hot. I also don't see how the booster could cause this because if anything, it feels like there's too much assist. I still have the OEM rubber lines on the rear brakes, but again, if they were expanding, I don't see how heating them up would make the pedal feel better.
Has anybody else experienced a problem like this before? Fortunately, it doesn't seem to be a safety issue, but it sure feels disconcerting on the street. I'd appreciate any suggestions.
Thanks.
