View Poll Results: Engine vs Rotor Braking
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Engine vs Rotor Braking
09-20-2002, 05:49 PM
#73
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[QUOTE]Originally posted by S2K2GO!!!
[B]
OK, that's a very typical scenario that would require a single downshift(I don't generally bother to downshift into first). At 45mph in 3rd(4500 RPM), I'd immediately shift into 2nd(6500 rpm +/-) using the technique described a couple of posts ago. I'd generally try to do this with room for the car to slow to about half that speed before bringing in the brakes. Energy varies with the square of velocity, so in this scenario 3/4 of the energy will have been absorbed by the engine and 1/4 by the brakes. From 70 mph in fourth, I'd shift directly into 3rd(7000RPM), then to second at about 48-53 mph(6800-7500RPM), depending on how urgently I was trying to slow down, and so on. This requires active driving, looking ahead and anticipating the need to decellerate, as opposed to re-active driving; stomping on the brakes. If I really need the brakes, I'll use them anytime, anywhere, as hard as necessary, but typically it's just little taps here and there until the final stop. Note that
[B]
OK, that's a very typical scenario that would require a single downshift(I don't generally bother to downshift into first). At 45mph in 3rd(4500 RPM), I'd immediately shift into 2nd(6500 rpm +/-) using the technique described a couple of posts ago. I'd generally try to do this with room for the car to slow to about half that speed before bringing in the brakes. Energy varies with the square of velocity, so in this scenario 3/4 of the energy will have been absorbed by the engine and 1/4 by the brakes. From 70 mph in fourth, I'd shift directly into 3rd(7000RPM), then to second at about 48-53 mph(6800-7500RPM), depending on how urgently I was trying to slow down, and so on. This requires active driving, looking ahead and anticipating the need to decellerate, as opposed to re-active driving; stomping on the brakes. If I really need the brakes, I'll use them anytime, anywhere, as hard as necessary, but typically it's just little taps here and there until the final stop. Note that
09-20-2002, 08:05 PM
#74
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Originally posted by Bieg
So drive anyway you want but downshifting as a means to slow the car down is poor technique for those who are concerned with the "art of driving".
So drive anyway you want but downshifting as a means to slow the car down is poor technique for those who are concerned with the "art of driving".
So if you're rolling down a hill you should not downshift and just keep your foot on the brake?
09-21-2002, 06:17 AM
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Originally posted by Bieg
You guys can drive anyway you want but don't delude yourself ................ but downshifting as a means to slow the car down is poor technique for those who are concerned with the "art of driving".
You guys can drive anyway you want but don't delude yourself ................ but downshifting as a means to slow the car down is poor technique for those who are concerned with the "art of driving".
09-21-2002, 06:57 AM
#78
[QUOTE]Originally posted by Bieg
[B]
I really think many of you have a problem reading.
[B]
I really think many of you have a problem reading.
09-21-2002, 03:21 PM
#79
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[QUOTE]Originally posted by Bieg
[B]
.....Engine braking ONLY brakes the rear wheels. As the car brakes weight shifts to the front and unloads the rear wheels making them less and less effective for braking. This is not a problem when using BRAKES as the car is designed with this weight shift in mind. That is why the front brakes are much bigger. So what you say? It is harmless,....except in a low traction situation where you take too much of downshift and break traction. If you do this in a turn you will get what is called "Trailing Clutch Oversteer". It is similar to going into a wet turn and pulling up the hand brake. Have fun with that when it happens.......
Bieg-
It should be pointed out that virtually all of the weight-shift you are referring to is actually caused by the engagement of the front brakes as the weight of the car, acting as though it were all concentrated at the CG, attempts to rotate over the top of the front wheel's contact patch. This is inherently destabilizing regardless of whether it is done in a turn or on the straight and makes the car want to swap ends. While compression braking in turns also destabilizes the turn by trying to straighten out the car, it actually has a stabilizing efffect when going straight, much like the rudder on a boat. The best strategy, of course, is to enter turns at a speed that permits you to remain under some positive power through the turn.
[B]
.....Engine braking ONLY brakes the rear wheels. As the car brakes weight shifts to the front and unloads the rear wheels making them less and less effective for braking. This is not a problem when using BRAKES as the car is designed with this weight shift in mind. That is why the front brakes are much bigger. So what you say? It is harmless,....except in a low traction situation where you take too much of downshift and break traction. If you do this in a turn you will get what is called "Trailing Clutch Oversteer". It is similar to going into a wet turn and pulling up the hand brake. Have fun with that when it happens.......
Bieg-
It should be pointed out that virtually all of the weight-shift you are referring to is actually caused by the engagement of the front brakes as the weight of the car, acting as though it were all concentrated at the CG, attempts to rotate over the top of the front wheel's contact patch. This is inherently destabilizing regardless of whether it is done in a turn or on the straight and makes the car want to swap ends. While compression braking in turns also destabilizes the turn by trying to straighten out the car, it actually has a stabilizing efffect when going straight, much like the rudder on a boat. The best strategy, of course, is to enter turns at a speed that permits you to remain under some positive power through the turn.
09-21-2002, 07:13 PM
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top formula cars with big wings can decelerate at 1G by simply lifting off completely....which is equal to full braking in an S2K!!!!
Of course its due to up to 4G of downforce and drag at highspeed,
which translates into 4G of negative longitudinal acceleration when stomping on the binders.
engine drag can't stop the car like the brakes, but it can be used to balance the brake bias in certain condition, preserve the function of the brakes in heavy use and make cool deceleration noise when pulling up next to cute babes in their lowrider S-10
Of course its due to up to 4G of downforce and drag at highspeed,
which translates into 4G of negative longitudinal acceleration when stomping on the binders.
engine drag can't stop the car like the brakes, but it can be used to balance the brake bias in certain condition, preserve the function of the brakes in heavy use and make cool deceleration noise when pulling up next to cute babes in their lowrider S-10