well, ABS Ice Mode finally got me...
04-03-2011, 03:03 PM
#61
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I've just gone through this thread to figure out what the hell you guys are talking about. The notion of the "ice mode" concept had me thinking in another direction initially.
I think it's purely a mechanical issue and one that most production-based cars have. I've experienced this thousands of times and it's never been an issue.
On my race team, we call it "knock back" and that refers to the brake pads getting "knocked back" towards the outside of caliper, away from the rotor. On track, each wheel is subjected to extreme forces, from cornering loads to bumps, beyond any OE specification and the rotor will actually deflect, moving the pad and forcing the fluid back into the system. With all the lines, tubing, valves and the booster, pressure in the system can build up anywhere and can result in a hard pedal.
To remedy this, I often tap the brake pedal with my left foot to help the system equalize the pressure. Simple as that!
(Yes, I also do this to build pressure in the system when my pedal starts to go soft, but that's the subject of another thread.)
I think it's purely a mechanical issue and one that most production-based cars have. I've experienced this thousands of times and it's never been an issue.
On my race team, we call it "knock back" and that refers to the brake pads getting "knocked back" towards the outside of caliper, away from the rotor. On track, each wheel is subjected to extreme forces, from cornering loads to bumps, beyond any OE specification and the rotor will actually deflect, moving the pad and forcing the fluid back into the system. With all the lines, tubing, valves and the booster, pressure in the system can build up anywhere and can result in a hard pedal.
To remedy this, I often tap the brake pedal with my left foot to help the system equalize the pressure. Simple as that!
(Yes, I also do this to build pressure in the system when my pedal starts to go soft, but that's the subject of another thread.)
04-03-2011, 03:21 PM
#62
I've just gone through this thread to figure out what the hell you guys are talking about. The notion of the "ice mode" concept had me thinking in another direction initially.
I think it's purely a mechanical issue and one that most production-based cars have. I've experienced this thousands of times and it's never been an issue.
On my race team, we call it "knock back" and that refers to the brake pads getting "knocked back" towards the outside of caliper, away from the rotor. On track, each wheel is subjected to extreme forces, from cornering loads to bumps, beyond any OE specification and the rotor will actually deflect, moving the pad and forcing the fluid back into the system. With all the lines, tubing, valves and the booster, pressure in the system can build up anywhere and can result in a hard pedal.
To remedy this, I often tap the brake pedal with my left foot to help the system equalize the pressure. Simple as that!
(Yes, I also do this to build pressure in the system when my pedal starts to go soft, but that's the subject of another thread.)
I think it's purely a mechanical issue and one that most production-based cars have. I've experienced this thousands of times and it's never been an issue.
On my race team, we call it "knock back" and that refers to the brake pads getting "knocked back" towards the outside of caliper, away from the rotor. On track, each wheel is subjected to extreme forces, from cornering loads to bumps, beyond any OE specification and the rotor will actually deflect, moving the pad and forcing the fluid back into the system. With all the lines, tubing, valves and the booster, pressure in the system can build up anywhere and can result in a hard pedal.
To remedy this, I often tap the brake pedal with my left foot to help the system equalize the pressure. Simple as that!
(Yes, I also do this to build pressure in the system when my pedal starts to go soft, but that's the subject of another thread.)
Knock back is usually caused by a thin pad knocking the piston all the way in followed by a very low pedal because of the fluid that's required to now push the knocked in pad back out. When you tap up the pedal you're creating a firm pedal if it was already firm you wouldn't bother.
The ICE thing going on has nothing to do with knock back.
I always tap up a bit for both a high pedal to assist in heel toe and also for a quicker brake pedal etc......
See vid: http://www.youtube.com/my_videos?feature=mhum
04-03-2011, 03:46 PM
#63
I've just gone through this thread to figure out what the hell you guys are talking about. The notion of the "ice mode" concept had me thinking in another direction initially.
I think it's purely a mechanical issue and one that most production-based cars have. I've experienced this thousands of times and it's never been an issue.
On my race team, we call it "knock back" and that refers to the brake pads getting "knocked back" towards the outside of caliper, away from the rotor. On track, each wheel is subjected to extreme forces, from cornering loads to bumps, beyond any OE specification and the rotor will actually deflect, moving the pad and forcing the fluid back into the system. With all the lines, tubing, valves and the booster, pressure in the system can build up anywhere and can result in a hard pedal.
To remedy this, I often tap the brake pedal with my left foot to help the system equalize the pressure. Simple as that!
(Yes, I also do this to build pressure in the system when my pedal starts to go soft, but that's the subject of another thread.)
I think it's purely a mechanical issue and one that most production-based cars have. I've experienced this thousands of times and it's never been an issue.
On my race team, we call it "knock back" and that refers to the brake pads getting "knocked back" towards the outside of caliper, away from the rotor. On track, each wheel is subjected to extreme forces, from cornering loads to bumps, beyond any OE specification and the rotor will actually deflect, moving the pad and forcing the fluid back into the system. With all the lines, tubing, valves and the booster, pressure in the system can build up anywhere and can result in a hard pedal.
To remedy this, I often tap the brake pedal with my left foot to help the system equalize the pressure. Simple as that!
(Yes, I also do this to build pressure in the system when my pedal starts to go soft, but that's the subject of another thread.)
I can "induce" ice pedal at a point on the track immediately after a high speed downhill, hard braking sequence, so it's not knock-back.
As you say, it's a complex mechanical system and now a much more complex electronic system. Whatever the root cause, the brakes don't work. I find that ... disappointing.
04-03-2011, 09:49 PM
#64
I have to say as a new 997.1 GT3 owner, all these stories about the "ice mode" has me spooked. I've run drivers ed events for the last 12 years in my Carrera, 930 turbo and now my SC track prepared cars. I just bought my new to me GT3, looking forward to my first event in the new car. One of your worst fears is coming to the end of a high speed straight and thinking your brakes might not work. The last thing I want is an off, or worse yet, an off and a smack, in my new car just because of no brakes. It certainly has me concerned after following others experiences and concerns. It sounds like there are things that can be done to possibly reduce the situation, but something I don't look forward to.
04-03-2011, 11:24 PM
#68
I have to say as a new 997.1 GT3 owner, all these stories about the "ice mode" has me spooked. I've run drivers ed events for the last 12 years in my Carrera, 930 turbo and now my SC track prepared cars. I just bought my new to me GT3, looking forward to my first event in the new car. One of your worst fears is coming to the end of a high speed straight and thinking your brakes might not work. The last thing I want is an off, or worse yet, an off and a smack, in my new car just because of no brakes. It certainly has me concerned after following others experiences and concerns. It sounds like there are things that can be done to possibly reduce the situation, but something I don't look forward to.
04-04-2011, 09:31 AM
#69
I have to say as a new 997.1 GT3 owner, all these stories about the "ice mode" has me spooked. I've run drivers ed events for the last 12 years in my Carrera, 930 turbo and now my SC track prepared cars. I just bought my new to me GT3, looking forward to my first event in the new car. One of your worst fears is coming to the end of a high speed straight and thinking your brakes might not work. The last thing I want is an off, or worse yet, an off and a smack, in my new car just because of no brakes. It certainly has me concerned after following others experiences and concerns. It sounds like there are things that can be done to possibly reduce the situation, but something I don't look forward to.
04-04-2011, 10:25 PM
#70
Rennlist Member
I agree. This is not something one should be the least bit concerned about in a 100k plus car built for track use. Once again just like the coolant lines the folks at Porsche may have some explaining to do if something bad happens to someone on the street and I'll repeat hopefully those that have experienced these problems are complaining to Porsche or some other authority that may have the power to force Porsche to put out a TSB to fix this stuff because from what I can tell these are serious issues that should not be remedied by putting water wetter in your car and training yourself to calmly re brake when entering a corner at 150 plus mph. Neither of those solutions are solutions or fixes they are just prayers in the dark.
Just because these cars can offer this kind of performance hardly means the drivers have the skill to handle it. Food for thought.
04-04-2011, 10:41 PM
#71
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yeah, but luck plays a role as well.
depends where it happens.
t17 at sebring at 140mph with walls straight ahead in the run-off are unforgiving.
even to pro drivers as proven recently.
depends where it happens.
t17 at sebring at 140mph with walls straight ahead in the run-off are unforgiving.
even to pro drivers as proven recently.
04-04-2011, 10:43 PM
#72
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No question. Best drivers in the world ball them up all the time...that's driving at the limit.
04-04-2011, 10:58 PM
#74
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