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    Rain + PCCB = Trouble + TC = Big Trouble

    I was driving in the rain yesterday and when I approached a red light I touched the brakes which did not respond (!) so I stood on the brake pedal. The car eventually stopped but the feeling was very unsettling. If this happened in bumper-to-bumper I surely would have rear-ended the car in front of me. This has been reported previously by other PCCB owners. So I thought I'd borrow a old racing trick, namely, ride the brake pedal while driving to heat up the rotors and get back that immediate braking response we all love about the PCCBs. No go! However lightly I ride the brake pedal or however heavily I ride the accelerator pedal, the car will shut power after a few seconds. This happens with sport on or off and with PSM on or off. I tried all four combinations of sport and PSM and none turned this very annoying TC feature off.

    Does any one know how to turn TC off completely and stop this from happening? Or even better, a good safe way to heat up the rotors very quickly in normal street driving?

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    It's not heat - it water in the brakes!

    If you have been driving through some big puddles or a very wet highway, just squeeze out your brakes every so-often when there is not someone behind you. That way when you really need them they will be ok.

    Same for steel brakes.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Actually, this has been a known problem with Audis, equipped with ceramic brakes (A8, S8). They just won't initially respond in the rain, or will do so with unequal distribution.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Well I had it recently when it was chucking-it-down on the M4 here. I went to use my brakes and nothing happened. I then squeezed the PCCB brakes out 3 or 4 times and then they were fine.

    This has happened to me before on various other cars through the years and they have all been steel brakes (incl. my old 997 Carrera).

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    It is a matter of drying the rotors in intervals so that the accumulation of water doesn't render them ineffective. Mercedes electronic braking system (now abandoned) had a feature that automatically applied the brakes slightly every so often in the wet in order to avoid these incidents. Perhaps ceramics are more sensitive to this than steel brakes. But normal brakes are not altogether immune.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    SOB! _THAT_ must have been a literal terror. You hit the brakes and you expect results: period. Sorry to hear it. You (we all) just have to think ahead a bit when it's raining.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Quote:
    hatchback said:However lightly I ride the brake pedal or however heavily I ride the accelerator pedal, the car will shut power after a few seconds. This happens with sport on or off and with PSM on or off. I tried all four combinations of sport and PSM and none turned this very annoying TC feature off.



    In order to be able to activate throttle and brake simultaneously you will have to do it in reverse order.

    I.e. if you are on the throttle and you then hit the brake, the car will interpret that you want to suddently stop and will kill the throttle for safety reasons.

    However, if you are on the brakes and you then apply the throttle, the car will interpret you are just matching revs with heel-toe and will NOT kill the throttle, otherwise you would not be able to heel-toe at all in the 996/997.

    So you will have to pay attention to the order by with each pedal is activated, you have to press the brake and then afterwards apply the throttle.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Quote:
    Carlos from Spain said:
    Quote:
    hatchback said:However lightly I ride the brake pedal or however heavily I ride the accelerator pedal, the car will shut power after a few seconds. This happens with sport on or off and with PSM on or off. I tried all four combinations of sport and PSM and none turned this very annoying TC feature off.



    In order to be able to activate throttle and brake simultaneously you will have to do it in reverse order.

    I.e. if you are on the throttle and you then hit the brake, the car will interpret that you want to suddently stop and will kill the throttle for safety reasons.

    However, if you are on the brakes and you then apply the throttle, the car will interpret you are just matching revs with heel-toe and will NOT kill the throttle, otherwise you would not be able to heel-toe at all in the 996/997.

    So you will have to pay attention to the order by with each pedal is activated, you have to press the brake and then afterwards apply the throttle.



    Thats a great tip Carlos - thanks

    I've often tried to quickly dry the brakes this way after washing the car...but get the cut-off. Now I know what to do..

    Great help - thanks again..

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    My pleasure, I don't know if there is a 2nd mechanism that will "eventually" cut throttle off this way (though it would have to take into account if you are trying to do a launch, since you have to raise the revs before you let go of the clutch and if it cuts off the throttle it would not make for a good launch ), but it works, you can match-rev, you can raise the revs while standing still, you can access the throttle before fully letting go of the braks comming out of a corner, etc. But not the other way arounf, you cannot left-foot brake for example like on front wheel cars, etc.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Another reason I passed on pccbs'.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Quote:
    TT Surgeon said:
    Another reason I passed on pccbs'.



    Your loss mate - I LOVE mine; one of THE best things about the car.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Quote:
    Carlos from Spain said:However, if you are on the brakes and you then apply the throttle, the car will interpret you are just matching revs with heel-toe and will NOT kill the throttle, otherwise you would not be able to heel-toe at all in the 996/997.



    Normally heel-toe is accomplished with the clutch pedal depressed. With the clutch not engaged, you don't have to be concerned about applying "throttle first" or "brake first".

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Same problem happened to me, at least once. I reported it on Rennteam. Very unsettling when you step on the brakes and the car doesn't respond like you expect it to. Haven't had this problem for a long time now.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Quote:
    Alex_ said:
    Quote:
    TT Surgeon said:
    Another reason I passed on pccbs'.



    Your loss mate - I LOVE mine; one of THE best things about the car.



    +1 These brakes are one of the BEST features about the car.

    I admit that when it first happened to me, I was a bit unsettled too but since then I've gotten used to it. It's become second nature for me to remember to press the pedal harder after driving in the wet for some time. Also, according to the manual the system actually "primes" the brakes for you I presume by lightly touching the rotors when and if you release the gas pedal suddenly. I'm not sure if that actually happens.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    This only happened to me once, but it was almost fatal. It came after six hours of 80mph driving in heavy rain. A car suddenly pulled into my lane from the right, I hit the brakes hard and very little happened-- I managed to swerve into the shoulder, but for a moment I was sure I was dead. I pulled off on the next exit, adrenaline pumping, and hit the brakes repeatedly... they quickly returned to normal.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Quote:
    TT Surgeon said:
    Another reason I passed on pccbs'.



    Same thing happens on steel brakes...

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Never had that happen on steels. Had my brake fluid boiling one time at limerock, that was about it. But I got 7,999 other reasons for not getting them....

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    I'm with Chris on this one. My ex-997S had PCCB and I had a few scary moment in rains and after car washes. It didn't happen often, but it gave me an insecure feeling when driving in the wet.

    My club coupe now has steel brakes. It doesn't have the initial strong bite of PCCB, but its brake power is still better than most cars out there. Only at the end of a track day it fades a little. The only advantage I see with PCCB is the reduced unsprung weights at track use.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    After washing my wheels with a hose on my old 997C2S (steel brakes) I had to squeeze out the water about 10 times driving round the block at speed. They were scary how little they worked after a quick wash.

    With my Turbo (PCCB) I only have to squeeze them out once or twice, nowhere near as forcefully and only go about 20 yards in the process.

    Perhaps this is a PCCB generation thing?!

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Quote:
    Targa Tim said:
    I'm with Chris on this one. My ex-997S had PCCB and I had a few scary moment in rains and after car washes. It didn't happen often, but it gave me an insecure feeling when driving in the wet.




    Yes. The one or two times it's happened to me were probably after having my car washed.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Quote:
    TT Surgeon said:
    Another reason I passed on pccbs'.



    This is unrelated to PCCBs. Either his car has a problem or the brakes were wet.

    Some manufacturers are now automatically lightly pressing brake pads against disk brakes when the wipers are turned on, to dry the disk surfaces. Short of that, it is a good idea to gently apply brakes when it starts raining to dry the disks.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Quote:
    TT Surgeon said:
    Never had that happen on steels. Had my brake fluid boiling one time at limerock, that was about it. But I got 7,999 other reasons for not getting them....



    don't you mean 8,840 reasons LOL!!

    Seriously, I had this happen once and now that I know what to expect it is no problem. Would order the PCCB's again in a second. Ceramics are now std. on the F430 BTW, so that's where the future is headed I think.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Quote:
    Dock (Atlanta) said:
    Quote:
    Carlos from Spain said:However, if you are on the brakes and you then apply the throttle, the car will interpret you are just matching revs with heel-toe and will NOT kill the throttle, otherwise you would not be able to heel-toe at all in the 996/997.



    Normally heel-toe is accomplished with the clutch pedal depressed. With the clutch not engaged, you don't have to be concerned about applying "throttle first" or "brake first".



    FWIW, unlike the brake and throttle systems there is no switch or sensor on the clutch or clutch hydraulics to "tell" the ECU whether the clutch is depressed or not.
    In other words, clutch actuation has no influence on the "control strategy" which Carlos was describing.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Quote:
    Carlos from Spain said:
    Quote:
    hatchback said:However lightly I ride the brake pedal or however heavily I ride the accelerator pedal, the car will shut power after a few seconds. This happens with sport on or off and with PSM on or off. I tried all four combinations of sport and PSM and none turned this very annoying TC feature off.



    In order to be able to activate throttle and brake simultaneously you will have to do it in reverse order.

    I.e. if you are on the throttle and you then hit the brake, the car will interpret that you want to suddently stop and will kill the throttle for safety reasons.

    However, if you are on the brakes and you then apply the throttle, the car will interpret you are just matching revs with heel-toe and will NOT kill the throttle, otherwise you would not be able to heel-toe at all in the 996/997.

    So you will have to pay attention to the order by with each pedal is activated, you have to press the brake and then afterwards apply the throttle.



    It works!! Thank you, Carlos.

    P.S. How did you figure that out?

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Quote:
    fritz said:
    Quote:
    Dock (Atlanta) said:
    Quote:
    Carlos from Spain said:However, if you are on the brakes and you then apply the throttle, the car will interpret you are just matching revs with heel-toe and will NOT kill the throttle, otherwise you would not be able to heel-toe at all in the 996/997.



    Normally heel-toe is accomplished with the clutch pedal depressed. With the clutch not engaged, you don't have to be concerned about applying "throttle first" or "brake first".



    FWIW, unlike the brake and throttle systems there is no switch or sensor on the clutch or clutch hydraulics to "tell" the ECU whether the clutch is depressed or not.
    In other words, clutch actuation has no influence on the "control strategy" which Carlos was describing.



    Then it must be looking at something in the transmission, because when rolling along in neutral it doesn't matter which control you actuate first (at least on my 996 Turbo). The car has to be looking at something in addition to which control (brake or throttle) is actuated first.

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    You can also use Carlos' technique to get great a rolling start... Ride the brakes and apply the accelerator together in balance, the accelerator to build boost and the brakes to maintain constant speed. When you want to go, release the brakes and stomp down on what's left of the accelerator and wooooshh away you go at full boost. The turbo is the new king of rolling starts!

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Quote:
    fritz said:
    FWIW, unlike the brake and throttle systems there is no switch or sensor on the clutch or clutch hydraulics to "tell" the ECU whether the clutch is depressed or not.



    On the 987/997 I hear a clicking noise at the end of the clutch pedal's travel. What's the reason for that?

    Re: Rain + PCCB = Trouble + TC = Big Trouble

    Quote:
    Ferdie said:
    Quote:
    fritz said:
    FWIW, unlike the brake and throttle systems there is no switch or sensor on the clutch or clutch hydraulics to "tell" the ECU whether the clutch is depressed or not.



    On the 987/997 I hear a clicking noise at the end of the clutch pedal's travel. What's the reason for that?


    There is a switch at the end of the pedal travel. Its function is for starting the car with the clutch pedal depressed (in some markets I think) and disabling the cruise control before you change gear.

     
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