Not sure what could be wrong with my brakes. I have had Hawk HPS and now have Carbotech Bobcats and the problem is the same. After repeated heavy braking and under normal braking from 70 mph +, I get what I think is brake fade. I know that it's not the pads because I've had Hawks on several cars and the hotter they get the better they seem to work. After changing pads recently, there is no difference.

If I press the pedal down say 70% and keep it there, I can definately feel the pedal go soft and I have to push harder and harder to get the car to stop faster. Normal driving there are no problems, it's only stopping from high speeds and repeated heavy braking.

What do you guys think it could be? I am thinking either the fluid that the brake shop put in sucks, because that is when the problem seems to have started. Or maybe my calipers are worn, I do have 104K miles. By the way, stock rotors as well. Any insight to this problem would be appreciated. Thanks!

 

TTT, anyone have any ideas at all???

 

It sounds to me like they didn't do a good job in bleeding the brakes. There may be air or moisture in the system. If you have the means, I would completely flush out the system with new fluid. The only other thing that comes to mind is possibly a bad brake master cylinder?

 

If it after a series of quick, repeated stops from 70+, you very well could be boiling the fluid. The spongy pedal is a good sign of that. Once the brakes cool, the pedal probably feels close to normal again I'm guessing.

I'd probably start by upgrading the fluid and doing a good bleed on the brakes on all corners and see where that gets you.

And, you can overheat Hawk and Bobcat pads pretty easily if you really beat on them.

 

cool, thanks guys. Yes, once they cool, pedal feel goes back to normal. I thought it might be the fluid, I'll start there. What would a good replacement fluid be?

 

I think ATE Super Blue is popular, and since it's blue, it's easy to tell when you have bled out all the original amber colored fluid. ATE has an amber equivalent to this as well (TYP 200?) so you can alternate and be sure you've completely removed the prior fluid... That's mainly useful for racers who bleed frequently.

 

thanks, do you know which sponsors carry it or it I can pick it up locally in Dallas?

 

nevermind, I did some searching and found out that Strano carries Super Blue, so I'll be ordering that soon. Also talked to some more people and everyone seems to agree that it sounds like I have air in the system. Thanks again for the help and I will update the results in a few weeks.

 

Well, I just flushed my brake system and replaced the old fluid with ATE super blue. There was air in the system, but only the rears. After testing the car it stopped great, problem fixed. Shortly after, on my way home, the spongy pedal was back again after so 70mph + stops on the highway.

Also, after doing further research, I did not bleed the ABS module. On my test stops I did get the ABS system to engage. Any hints on how to do this or a write up?

My dad is thinking the master cylinder is bad and letting air in since I have no fluid leaks on my garage at all. If anyone has any tips or a guide to replacing the master cylinder I would appreciate it.