Anybody have these pads?
02-25-10, 03:36 PM
#16
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Everything else in the braking system does something. It just doesn't impact stopping distance because the rest of it is not the limiting factor. Traction is always the limiting factor if the braking system is fully capable of stopping the vehicle.
About the author (since you seem to indicate maybe he's not addressed the details)
He's also been a lecturer for SAE Symposiums on brake systems and stability control systems. I doubt his arithmetic is wrong.
About the author (since you seem to indicate maybe he's not addressed the details)
James Walker, Jr.
StopTech Consultant
James Walker, Jr. is currently the supervisor of vehicle performance development for brake control systems at Delphi Energy & Chassis. His prior professional experience includes brake control system development, design, release, and application engineering at Kelsey-Hayes, Saturn Corporation, General Motors, Bosch, and the Ford Motor Company. Mr. Walker created scR motorsports consulting in 1997, and subsequently competed in seven years of SCCA Club Racing in the Showroom Stock and Improved Touring categories.
Through scR motorsports, he has served actively as an industry advisor to Kettering University in the fields of brake system design and brake control systems. In addition, Mr. Walker contributes regularly to several automotive publications focusing on brake system analysis, design, and modification for racing and other high-performance applications. He is a recipient of the SAE Forest R. McFarland Award for distinction in professional development/education. Mr. Walker has a B.S. in mechanical engineering from GMI Engineering & Management Institute.
To find out more about Mr. Walker and scR Motorsports, visit their website at www.teamscR.com.
StopTech Consultant
James Walker, Jr. is currently the supervisor of vehicle performance development for brake control systems at Delphi Energy & Chassis. His prior professional experience includes brake control system development, design, release, and application engineering at Kelsey-Hayes, Saturn Corporation, General Motors, Bosch, and the Ford Motor Company. Mr. Walker created scR motorsports consulting in 1997, and subsequently competed in seven years of SCCA Club Racing in the Showroom Stock and Improved Touring categories.
Through scR motorsports, he has served actively as an industry advisor to Kettering University in the fields of brake system design and brake control systems. In addition, Mr. Walker contributes regularly to several automotive publications focusing on brake system analysis, design, and modification for racing and other high-performance applications. He is a recipient of the SAE Forest R. McFarland Award for distinction in professional development/education. Mr. Walker has a B.S. in mechanical engineering from GMI Engineering & Management Institute.
To find out more about Mr. Walker and scR Motorsports, visit their website at www.teamscR.com.
02-25-10, 03:44 PM
#17
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I'm not trying to discredit him, I'm just saying 80/20 to me implies a 4:1 ratio with him having the value of 80. Ultimately, I doubt it changes anything.
I guess what I'd really like to see is:
For a given set of tires, how do you calculate the maximum force that it can apply to the ground. If that force is less than what stock brakes apply, then I would easily conclude that brakes do not affect stopping distance. But if that force is greater than the amount of force the stock brakes can generate to the wheels, then I would presume changing brakes does have an impact. How much different it makes would be more calculations I guess, but I like concrete numbers like that.
I guess what I'd really like to see is:
For a given set of tires, how do you calculate the maximum force that it can apply to the ground. If that force is less than what stock brakes apply, then I would easily conclude that brakes do not affect stopping distance. But if that force is greater than the amount of force the stock brakes can generate to the wheels, then I would presume changing brakes does have an impact. How much different it makes would be more calculations I guess, but I like concrete numbers like that.
02-25-10, 05:03 PM
#18
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Register for this course. You'll be able to calculate to your heart's content.
But you're still missing the math problem. 4:1 is the same as 80/20, so his arithmetic is correct.
But you're still missing the math problem. 4:1 is the same as 80/20, so his arithmetic is correct.
02-25-10, 05:45 PM
#19
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ok all this math is great all i want to know is should the dealer cover my rotors since they have alot of rust build up on them. especially for a car thats only 3 yrs old. Second thing is there anything i can do to get the dealer to cover them.
PS i called corp and the lady said she was going to call the dealer and get back to me in a couple of days to see what they come up with.
PS i called corp and the lady said she was going to call the dealer and get back to me in a couple of days to see what they come up with.
02-25-10, 05:46 PM
#20
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Register for this course. You'll be able to calculate to your heart's content.
But you're still missing the math problem. 4:1 is the same as 80/20, so his arithmetic is correct.
But you're still missing the math problem. 4:1 is the same as 80/20, so his arithmetic is correct.
He has a value of 942 which represents the 80. To get the value of 20, he takes 20% and gets 188.4. Unless I'm misunderstanding 80/20, he should be taking 25% and getting 245.5.
942:245.5 is 4:1.
942:188.4 is 5:1.
Anyways, I don't care enough to take a course on it (especially one that's not free). It'd just be nice for anyone who states that tires are the only upgrade that would make a difference in stopping distance to be able to substantiate the claim with their own understanding. I just keep thinking that if you can put more force on the rotors, then that would in turn cause more force to be applied to the wheels (and tires), causing more resistance to the ground. I can understand better tires being able to provide a higher percentage of that resistance to the ground, but I can't quite figure out how more force wouldn't make any difference. Anyways, too OT now.
02-26-10, 05:12 AM
#22
I just keep thinking that if you can put more force on the rotors, then that would in turn cause more force to be applied to the wheels (and tires), causing more resistance to the ground. I can understand better tires being able to provide a higher percentage of that resistance to the ground, but I can't quite figure out how more force wouldn't make any difference. Anyways, too OT now.
Because you're already beyond the limits of the tires with the stock amount of braking force.
Additional force is completely wasted force.
Hence the only way to reduce stopping distance is better tires that can handle more braking force.
And with street-legal tires you will never get tires whose "limit" is beyond the force even the OEM brakes can produce. Hence "better" brakes will do absolutely nothing to stop you any shorter.
If amount of force X will lock the wheels (or engage ABS for ABS cars) then X+Y force won't do you the slightest bit of good.
02-26-10, 11:23 AM
#23
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Because you're already beyond the limits of the tires with the stock amount of braking force.
Additional force is completely wasted force.
Hence the only way to reduce stopping distance is better tires that can handle more braking force.
And with street-legal tires you will never get tires whose "limit" is beyond the force even the OEM brakes can produce. Hence "better" brakes will do absolutely nothing to stop you any shorter.
If amount of force X will lock the wheels (or engage ABS for ABS cars) then X+Y force won't do you the slightest bit of good.
Additional force is completely wasted force.
Hence the only way to reduce stopping distance is better tires that can handle more braking force.
And with street-legal tires you will never get tires whose "limit" is beyond the force even the OEM brakes can produce. Hence "better" brakes will do absolutely nothing to stop you any shorter.
If amount of force X will lock the wheels (or engage ABS for ABS cars) then X+Y force won't do you the slightest bit of good.
As far as force X locking the wheels, I would think X+Y would lock the wheels marginally faster (because you can cause more friction) for a negligible effect.
Am I still off?
02-26-10, 11:53 AM
#24
That's what I figure is true, although I like numbers. Then again, I think of Fred Flintstone trying to slow down by putting both feet down. Since he can't push down on the ground any harder than his own weight (+ the weight of the Flintstone car), it is what it is and he can't stop any faster.
As far as force X locking the wheels, I would think X+Y would lock the wheels marginally faster (because you can cause more friction) for a negligible effect.
Am I still off?
As far as force X locking the wheels, I would think X+Y would lock the wheels marginally faster (because you can cause more friction) for a negligible effect.
Am I still off?
Yeah, because more force doesn't mean "faster" force.
The only thing more friction in the braking system does for you here is reduce how hard you need to press the brake pedal.
Or as the brake engineer puts it:
By increasing the coefficient of friction of the brake pads, the results are the same as increasing the caliper piston diameter--higher forces will be generated for the same input.
....
As the brake force is gradually increased, the deceleration rate will also increase until the point at which the tires lock. Beyond this point, additional force applied to the brake pedal does nothing more than make the driver's leg sore. The vehicle will continue to decelerate at the rate governed by the coefficient of friction between the tires and the road.
....
As the brake force is gradually increased, the deceleration rate will also increase until the point at which the tires lock. Beyond this point, additional force applied to the brake pedal does nothing more than make the driver's leg sore. The vehicle will continue to decelerate at the rate governed by the coefficient of friction between the tires and the road.
02-28-10, 02:02 AM
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I need rear rotors any suggestions don't want to pay the dealer $150 per rotor. Contacted ray@autotech he quoted me $85 (pair) for stoptech oem replacements but i think he made a typo so i am waiting on his reply with a corrected price. Any other good brands you may suggest im looking into centric premieum rotors 34.50 each. Im not sure about the quality please let me know.
03-01-10, 06:59 AM
#26
I need rear rotors any suggestions don't want to pay the dealer $150 per rotor. Contacted ray@autotech he quoted me $85 (pair) for stoptech oem replacements but i think he made a typo so i am waiting on his reply with a corrected price. Any other good brands you may suggest im looking into centric premieum rotors 34.50 each. Im not sure about the quality please let me know.
anyway, where did you get that price for the centrics?
Last edited by carlos; 03-01-10 at 07:03 AM.
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