Jumping The Clutch
02-26-2008, 10:38 PM
#1
Jumping The Clutch Can someone please explain to me how jumping the clutch works? I understand it's used in drag racing, where you begin the connection of engine RPM to the transmission quickly to get a jump start. But how is this different from having the engine stall out when you let off the clutch too fast?
Also, is there less wear on the clutch disk when you have it in 1st gear and accidently let off the clutch fast than if the parking brake is up when this happens? In other words, is there a difference in wear on the disk when the engine stalls freely and when it stalls with the parking brake on?
Also, is there less wear on the clutch disk when you have it in 1st gear and accidently let off the clutch fast than if the parking brake is up when this happens? In other words, is there a difference in wear on the disk when the engine stalls freely and when it stalls with the parking brake on?
02-26-2008, 10:44 PM
#2
I think leaving the parking brake on will cause more wear and stress to the drivetrain in general.
Think about it, if the parking brake is on, then the drivetrain doesn't move. That means the whole shock of the stall is put into each part with the clutch taking the brunt of it because it has springs and friction material designed to give a little.
A low rpm stall has the energy transferred into some movement of the car, each bit of the drivetrain moves to absorb the energy, just that the engine couldn't sustain itself once slowed down a certain amount causing a stall.
Still can't be as bad as a 4k rpm clutch dump at the track... now that's being abusive to the whole car.
Think about it, if the parking brake is on, then the drivetrain doesn't move. That means the whole shock of the stall is put into each part with the clutch taking the brunt of it because it has springs and friction material designed to give a little.
A low rpm stall has the energy transferred into some movement of the car, each bit of the drivetrain moves to absorb the energy, just that the engine couldn't sustain itself once slowed down a certain amount causing a stall.
Still can't be as bad as a 4k rpm clutch dump at the track... now that's being abusive to the whole car.
02-26-2008, 10:49 PM
#3
Yes. That make sense.
What does the parking brake grab onto, the wheels or something else?
Wow! People jump off at 4k RPM at drags? Damn. Well, I guess this is where an A4 is at a disadvantage because you have to start at the bottom RPM...
What does the parking brake grab onto, the wheels or something else?
Wow! People jump off at 4k RPM at drags? Damn. Well, I guess this is where an A4 is at a disadvantage because you have to start at the bottom RPM...
02-27-2008, 01:55 AM
#4
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Not really, thats why they make stall converters. Plus I guarantee you I will never miss a shift with my A4. Can't say the same for you.
The parking brake hooks into the rear brakes via cable
The parking brake hooks into the rear brakes via cable
02-27-2008, 08:21 AM
#5
An A4 with a stall should have a pretty damn good advantage over a stick car at launch. Even with my old 88 camaro, I was taking LS1 stick cars off the line 90% of the time. All i had to do was when the lights changed was to stab the gas and the converter would flash to the torque band for me and keep an amazing amount of traction compared to my current car.
The rear brakes on LS1 f-body cars are actually "drums" in the rotor. I was really surprised to see the design when I worked on my brakes the first time. I think that's a good thing for the brakes though, especially after a autocross event or some heavy braking then you need to park, the hot brake pads for the rotor aren't stuck to the rotor and are allowed to cool.
The rear brakes on LS1 f-body cars are actually "drums" in the rotor. I was really surprised to see the design when I worked on my brakes the first time. I think that's a good thing for the brakes though, especially after a autocross event or some heavy braking then you need to park, the hot brake pads for the rotor aren't stuck to the rotor and are allowed to cool.
02-27-2008, 01:49 PM
#6
An A4 with a stall should have a pretty damn good advantage over a stick car at launch. Even with my old 88 camaro, I was taking LS1 stick cars off the line 90% of the time. All i had to do was when the lights changed was to stab the gas and the converter would flash to the torque band for me and keep an amazing amount of traction compared to my current car.
The rear brakes on LS1 f-body cars are actually "drums" in the rotor. I was really surprised to see the design when I worked on my brakes the first time. I think that's a good thing for the brakes though, especially after a autocross event or some heavy braking then you need to park, the hot brake pads for the rotor aren't stuck to the rotor and are allowed to cool.
The rear brakes on LS1 f-body cars are actually "drums" in the rotor. I was really surprised to see the design when I worked on my brakes the first time. I think that's a good thing for the brakes though, especially after a autocross event or some heavy braking then you need to park, the hot brake pads for the rotor aren't stuck to the rotor and are allowed to cool.
