I've been noticing a mildly disturbing behavior in the brakes no my '08 C2S (20K miles). When I've been driving for any significant distance, the first pedal press goes a fairly long way down, then the second press has the brakes back up at the top of travel (where they should be).

I've seen this before in race cars under heavy cornering, where the pads push back into the calipers and need an initial half-pedal push to re-set them close to the rotor. This is happening even on straight roads, though, where I wouldn't expect to see enough flex to cause knock-back.

Is this normal for these brakes, or should I have them checked for warped rotor or some other problem? I wouldn't have thought I needed to drive this car like an enduro racer for the daily commute.....?

 

When was your last brake fluid flush?

 

Beats the heck out of me. I bought the car in November from the local dealership - CPO, so I assumed (perhaps incorrectly) that any of that sort of maintenance had been done.

 

Good place to start. Service interval is every 2 years.

 

This happens to a small extent in all cars. As you pump the brake pedal, it starts resisting earlier..

Sounds like you need new brake fluid to me.

 

Sure, that's normal pad knock-back from the rotors. What I'm experiencing is way beyond normal, though - enough to have me a bit concerned.

OK, that's two votes for checking/replacing the brake fluid, but why? Not disagreeing, just curious as to how old fluid would cause this behavior. I would expect a soft pedal from stale fluid; not sure how it can cause this problem......?

 

I would suspect moisture or air in your hydraulic system. I would start there. Do a complete flush and I bet your problems go away.

 

Time for a brake flush, chances are the previous owner overlooked that 2 year service requirement.

 

I hope it is just brake fluid, that would be the easiest fix. I have never had brake fluid failure, so I do not know the symptoms. I do change mine as directed in my 997. But other cars I have driven 150000- 200000 miles without changing with out incident (none of which had PCCB or high end breaks, however). Good luck.

 

Well, the service mgr at the local dealership thinks it's a bad brake booster. We'll see..... Frankly, that would be better for me than the fluid changeout, since it would be covered (CPO).

 

What was the actual issue? Ever found it?

 

Holy thread resurrection!

Believe the owner of this yellow car just sold it