Brakes locking on - 986 Forum - The Community for Porsche Boxster & Cayman Owners

DFW02S · 01-13-2011, 08:05 PM

Your garage guy makes no sense to me.
Topless does, check the brake booster ... I wouldn't wait long.
My brake booster failed at 110 (another car) and blew a line off a caliper. You can imagine how well the brakes worked then.

As Topless said, "Brakes are sorta important." LOL

jcb986 · 01-14-2011, 04:09 AM

Like the other guys, I also say checkout the master cylinder. Spongy brakes usually indicate a failing master cylinder. Also, if the caliper piston boot is broken causing dirt and moisture to get to the piston, this will cause sticking pads to the rotors.

Dale_K · 01-14-2011, 05:02 AM

I've had some Brembo equipped cars that would also get sticky brakes if the car sat for a few days in wet conditions. They would actually make a popping noise at each wheel when the car first moved. Surface rust is normal for all cast iron brake discs if they get wet. Mine rust in the few seconds after I wash the wheels. The first time you use the brakes there is a little grinding sound as the rust is scraped away.

The sponginess I can't explain. The brakes on my 2000 S lack feel and bite and I suspected a failed booster but I can hear it "breath" when I press the brake with the motor off. If I press the pedal about 6 times (motor off) and then start the car with my foot on the pedal I can feel it react to the fresh vacuum and sink under the weight of my foot. On my car pressing the pedal hard enough will activate the ABS so I need to do a little more investigation. I know the discs are worn but I think that should only come into play from multiple brake applications (fade) and my car's brakes act funny all the time. I wish I had a chance to feel the brakes on a new Boxster. My 2010 GMC pickup actually feels like it has better brakes.

jmatta · 01-14-2011, 06:09 AM

Back to the original post, you don't state how old your car is, when or if the brakes have ever been serviced, etc. Brake fluid should be flushed every two years, since it has a great tendency to absorb moisture (can make the pedal soft)...when was the last time yours was done? It is difficult to "guess" at the problem, when the simple facts haven't even been disclosed.