Jeff Curtis

Lately I've noticed that I can stand on my brake pedal, car at rest, running or not, and it sloooOOoOOowly goes down, not all the way to the floor, but quite a bit. It seems a bit worse when at the track and the brakes are hot.

My brakes seem to work very well, but it seems something is amiss, is this a sign of a failing master cylinder or another part?

I have changed out a master cylinder on an SC but not a 964, has anybody out there tackled this issue, if so, how difficult was it? I haven't even visually investigated as of yet.

Also, where is the "good deal" on master cylinders?? A quick look through the Performance Products catalogue yielded quite the gasp! Look yourself, you'll see what I mean.

Adrian

Dear Jeff,
You should do a pressure test on the system to determine if your vacuum boost is working and or leaking.
I cannot remember off the top of my head but I am sure there is a procedure in the Carrera 2 supplement for this.
I would tend to suspect a booster leak. Bad seal or something,
Ciao,
Adrian
911C4

Randall G.

Hi Jeff,

I've never had a problem with the master cylinder in my car, so can't help you there.

As for where to buy a master cylinder, I can say that Sunset Imports is selling parts for cost + 15% + shipping, so you can't do too bad:

Sunset Imports

Happen to have an old Automotion catalog handy, and took a quick glance at the price for a master cylinder. Holy sh**! I see what you mean--$599.98. Considering that the catalog I have here at work is a few years old, one can only hope that the price has dropped.

Bill Gregory

Jeff,

Yup, that's the symptom of a bad master cylinder. If you do need one, call Hendrick Porsche in Charlotte, NC at 800-315-8193. They discount 20%-30%. No affiliation, just satisfied customer. Part number for C2/RSA brake master cylinder is 964.355.015.03.

Bill Wagner

I doubt the booster is causing that. More than likely, the seals/boot of the master cylinder piston are leaking slightly. When you push the pedal down, brake fluid may be seeping past that seal, thus allowing the pedal to SLOOOOOOWLY move further down. If thats the case the problem will get worse.

Just a theory...hope it helps,

Bill Wagner