Overheating steel discs
10-23-2004, 07:07 PM
#19
Instructor
Stephen,
Originally Posted by MatroxMGA
braking for longer periods will create more heat........
Why?
Stephen,
Have you ever seen a train axle being friction welded?? The longer two surfaces are in contact, the higher the temps go. As MDS said, it's all down to driver style. Some people hammer into a bend, stand on the brakes and get off them again, some people ride their brakes.I was always guilty of riding the brakes into and through the bend. Not good!!
If you think Mk 2's are bad, try a Mk 1. Porsche totally forgot to allow for brake cooling.
I have fitted the motorsport ducts to my car, and although they need a bit of alteration, work very well.
the next step is to get some fully floating discs. Quaife make a hat for use with the GT3 which they say allows you to use the standard calipers. This and some slotted disc's may just do the trick.
For you lot in the US, Quaife sell over there, so it might be worth checking out.
Regards,
Steve
Originally Posted by MatroxMGA
braking for longer periods will create more heat........
Why?
Stephen,
Have you ever seen a train axle being friction welded?? The longer two surfaces are in contact, the higher the temps go. As MDS said, it's all down to driver style. Some people hammer into a bend, stand on the brakes and get off them again, some people ride their brakes.I was always guilty of riding the brakes into and through the bend. Not good!!
If you think Mk 2's are bad, try a Mk 1. Porsche totally forgot to allow for brake cooling.
I have fitted the motorsport ducts to my car, and although they need a bit of alteration, work very well.
the next step is to get some fully floating discs. Quaife make a hat for use with the GT3 which they say allows you to use the standard calipers. This and some slotted disc's may just do the trick.
For you lot in the US, Quaife sell over there, so it might be worth checking out.
Regards,
Steve
10-23-2004, 09:33 PM
#20
Burning Brakes
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Originally Posted by Bass GT3
Have you ever seen a train axle being friction welded?? The longer two surfaces are in contact, the higher the temps go. As MDS said, it's all down to driver style. Some people hammer into a bend, stand on the brakes and get off them again, some people ride their brakes.I was always guilty of riding the brakes into and through the bend. Not good!!
I grant you that if one slows beyond what they need to (the newbie mistake of braking too much and entering the corner slow and then powering all of the way through the corner) then your brakes will generate more heat because the driver is slowing more than necessary.
But as I said before, if you brake from 150 MPH to 50 MPH then the brakes are going to generate the same amount of heat no matter how you go about it.
By the way, the disk brake pads remain in contact with the rotors the entire period. It is simply a matter of how much pressure is being put on them.
Stephen
10-23-2004, 09:45 PM
#21
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Stephen, I agree with you that a given delta velocity will result is the same total energy transfer no matter your technique.
However, it is clear that technique does have an effect on peak temperature. For example, if you brake very, very lightly for a very, very long time peak temperature will be lower even though total energy is the same.
I speculate that pad wear and disc cracking rate is more related to peak temperature than total energy.
So I feel the trick is to find a good technique that keeps temps lower and does not sacrifice lap times. I think this is what Danny Sullivan must be doing.
However, it is clear that technique does have an effect on peak temperature. For example, if you brake very, very lightly for a very, very long time peak temperature will be lower even though total energy is the same.
I speculate that pad wear and disc cracking rate is more related to peak temperature than total energy.
So I feel the trick is to find a good technique that keeps temps lower and does not sacrifice lap times. I think this is what Danny Sullivan must be doing.
Last edited by mds; 10-23-2004 at 11:18 PM.
10-23-2004, 11:38 PM
#22
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Originally Posted by mds
Stephen, I agree with you that a given delta velocity will result is the same total energy transfer no matter your technique.
However, it is clear that technique does have an effect on peak temperature. For example, if you brake very, very lightly for a very, very long time peak temperature will be lower even though total energy is the same.
I speculate that pad wear and disc cracking rate is more related to peak temperature than total energy.
So I feel the trick is to find a good technique that keeps temps lower and does not sacrifice lap times. I think this is what Danny Sullivan must be doing.
However, it is clear that technique does have an effect on peak temperature. For example, if you brake very, very lightly for a very, very long time peak temperature will be lower even though total energy is the same.
I speculate that pad wear and disc cracking rate is more related to peak temperature than total energy.
So I feel the trick is to find a good technique that keeps temps lower and does not sacrifice lap times. I think this is what Danny Sullivan must be doing.
But note this is the exact opposite of what others have mentioned as optimal (hard braking over a short period of time). And it is hardly practical on a race track either.
I suspect Mr. Sullivan's technique is to brake less and enter corners faster. Less braking means less heat and higher speeds mean shorter lap times. Not a bad combination. Sort of explains why some of the fastest racers are the ones that abuse their brakes the least.
Stephen
10-24-2004, 04:49 AM
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Braking technique is a major part of track driving. The longer the pad is against the rotor more unnecessary heat is produced. If you brake hard and quickly cooling of the brakes will start as soon as you let go=longer cooling periods.
Last edited by MatroxMGA; 10-24-2004 at 02:16 PM.
10-24-2004, 10:09 AM
#24
Instructor
Guy's,
This was taken from the AP Brakes web site. I think they know their stuff.
As the iten says, it's the wide variation of temperature which will cause a brake to crack.
http://www.apracing.com/car/brakedisc/temperature.htm
"Circuits and drivers vary enormously in the amount of work they demand from the brakes and therefore the brake system has to be tuned for each circuit by adjustment of the cooling airflow. The temptation to over cool the disc should be resisted. The aim is to keep the temperature as stable as possible within the working temperature range. High maximum to low minimum temperature cycles are the enemy of disc life."
Regards,
Steve
This was taken from the AP Brakes web site. I think they know their stuff.
As the iten says, it's the wide variation of temperature which will cause a brake to crack.
http://www.apracing.com/car/brakedisc/temperature.htm
"Circuits and drivers vary enormously in the amount of work they demand from the brakes and therefore the brake system has to be tuned for each circuit by adjustment of the cooling airflow. The temptation to over cool the disc should be resisted. The aim is to keep the temperature as stable as possible within the working temperature range. High maximum to low minimum temperature cycles are the enemy of disc life."
Regards,
Steve
10-24-2004, 10:51 AM
#25
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Braking physics
Conversion of energy - motion to heat
The greater the speed the mpre brake pedal pressure can be applied
Threshold Braking
A braking technique used to keep the tire at the "threshold" of lock-up (right to ABS) to minimize stopping distance.
Quickly applying hard braking pressure then ease to compensate for the loss in speed.
Having taken rides with some of the best drivers (H. Haywood, David Murry, Jack Baldwin) and experienced what threshold is all about is a real eye opener....and like they said most people are amazed ar how forcefull the braking application is (-g's).
Conversion of energy - motion to heat
The greater the speed the mpre brake pedal pressure can be applied
Threshold Braking
A braking technique used to keep the tire at the "threshold" of lock-up (right to ABS) to minimize stopping distance.
Quickly applying hard braking pressure then ease to compensate for the loss in speed.
Having taken rides with some of the best drivers (H. Haywood, David Murry, Jack Baldwin) and experienced what threshold is all about is a real eye opener....and like they said most people are amazed ar how forcefull the braking application is (-g's).
