Rob996

Hi everyone,

I would appreciate your advice with a brake problem I am experiencing on my 2010 GT3. My brake pedal has gotten softer and deeper.. when I pump the pedal, it's gets hard again and less deep before the brakes engage.. I have bled the brakes, flushed them twice, vacuumed and flushed the ABS twice and the problem still persists.

I've just ordered a new master cylinder, however before installing it, I was wondering if any of you have experienced any similar issues in the past and what was the remedy?

Thanks in advance for your advice.

CosmosMpower

Not on a 911 but my friend's E92 M3 had the exact same symptoms and it was the MC that was the culprit.

mm450exc

Has to be the master cylinder.

I had a long pedal on track. Turned out to be the pads - RS29! PFC08 solid all day long.

Rob996

Thanks for your much appreciated feedback..

Having a new master cylinder installed tomorrow, hoping that will remedy the long spongy brake pedal.. BTW. Running PFC 08 pads for years.. they eat rotors with tremendous appetite..

Will report back shortly.

Thanks gentleman

zweebach

I'll be interested to hear your results. My symptoms don't seem as bad, but I feel like the brake pedal firmness used to be better.

grrrmonster

I had similar issues. Seemed to be pad knock back. One pump of brake and pedal came back up. Rebuilt the calipers, installed new MC, then stainless steel brake lines. Read in other threads about how pad knock back can be leading indicator of hub failure. Since rear hubs were replaced a year ago due to different issue- I am installing new front hubs and bearings right now. Hope it solves my symptoms- shall find out in another week

Rob996

Here the update..

After careful inspection, the master cylinder demostrated some leaking in the plunger type rubber seals in the internals of the part.. a brand new master cylinder was installed which completely resolved the spongy soft brake pedal.. there was also some adjustments made to the rear brake pads that were rubbing on the retaining plate.

I hope this information will help others who have suffered from the same problem.

Thanks again to my fellow rennlisters.

zweebach

Thanks for the report. That's great news!