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Speed3 pancaked at 125 mph - dude survives


BOXRPWR

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This is a case where "brakes like a sonnovabitch" for one stop due to electronic brake assistance or greater vaccum brake boost does not equal heat capacity or even a track capable system...

 

Only rotor mass, pad compound and caliper heat dissapation characteristics can compensate for track driving.

 

Looking at the MS3 brakes and the physycal heat capacity although large for a street car, it was pretty silly tracking the car with OEM brake parts.

 

The pads would have exceeded the optimal heat range VERY early and the pad compound would have started breaking down.

 

Electronic brake assist in new modern cars is a double edged sword. In one hand you get quicker reaction as the car pre-brakes as it detects rapid lifts in the accelerator pedal. The system draws the pads close to the rotor and enhances the hydraulic force and reaction time.

 

On the flip side it can overcompensate and create excessive heat in the braking system. If one wheel is not braking as fast as the other wheel the ABS sensors pick this up. The brake assist routes more brake force to the wheel. If that wheel has a glazed pad the increased force will produce more heat and the pad will disinergrate. Its a self feeding loop, the computer will continue to detect a lack of brake torque in the problem wheel and try to compnsate by redistributing more hydrualic force. The end result is brake failure. This is done without driver knowlege.

 

This I beleive is exactly what happened. The inside pad got glazed. Computer tried to compensate until total brake failure. This was no malfunction it did exactly what it was programmed to do.

 

It also increases drag and heats up the system in the pre braking process. The sytem tries to predict when the driver is trying to brake. So a rapid lift in the accelerator pedal will cause the system to pre-brake causing excess and unneeded drag.

 

As far as running bobcats for a track event... don't do it... kinetic energy in= energy out in heat. The manufacturer already warns not to do it. It will exceed 950F in very short order and the pads will glaze and if pushed or if the Electronic brake assist compensates by adding more brake force they will start disinergrating.

 

No amount of electronic assistance is gonna compensate for the physycal energy exchange. Nowadays we gotta be careful fancy electronics and software wizardry can inspire confidence and hide real hardware deficencies. Sometimes we don't notice till its too late.

 

I wouldn't take my legacy with 4 vented discs and more brake system mass beefier calipers and heat capacity to a track event and drive it hard without track pads.

 

Why would I take a ms3 with 2 vented discs and 2 solid discs with less mass and heat capacity and drive it hard and not expect disaster. Albeit with electronic brake assist...

 

Refrences: http://www.aa1car.com/library/2004/bf110412.htm

 

http://www.audiusa.com/audi/us/en2/tools/glossary/safety/brake_assistant.html

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A simple way of thinking about braking power is to compare it to acceleration. It takes good power to accelerate a car to 60mph in 5 seconds but it can the brakes can slow a car from 60 to 0 in a fraction of that time. That means the braking power could be equivalent to 1000hp. All that energy is turned into heat and will easily overpower a stock brake system in a few stops.
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This is a case where "brakes like a sonnovabitch" for one stop due to electronic brake assistance or greater vaccum brake boost does not equal heat capacity or even a track capable system...

 

Only rotor mass, pad compound and caliper heat dissapation characteristics can compensate for track driving.

 

Looking at the MS3 brakes and the physycal heat capacity although large for a street car, it was pretty silly tracking the car with OEM brake parts.

 

The pads would have exceeded the optimal heat range VERY early and the pad compound would have started breaking down.

 

Electronic brake assist in new modern cars is a double edged sword. In one hand you get quicker reaction as the car pre-brakes as it detects rapid lifts in the accelerator pedal. The system draws the pads close to the rotor and enhances the hydraulic force and reaction time.

 

On the flip side it can overcompensate and create excessive heat in the braking system. If one wheel is not braking as fast as the other wheel the ABS sensors pick this up. The brake assist routes more brake force to the wheel. If that wheel has a glazed pad the increased force will produce more heat and the pad will disinergrate. Its a self feeding loop, the computer will continue to detect a lack of brake torque in the problem wheel and try to compnsate by redistributing more hydrualic force. The end result is brake failure. This is done without driver knowlege.

 

This I beleive is exactly what happened. The inside pad got glazed. Computer tried to compensate until total brake failure. This was no malfunction it did exactly what it was programmed to do.

 

It also increases drag and heats up the system in the pre braking process. The sytem tries to predict when the driver is trying to brake. So a rapid lift in the accelerator pedal will cause the system to pre-brake causing excess and unneeded drag.

 

As far as running bobcats for a track event... don't do it... kinetic energy in= energy out in heat. The manufacturer already warns not to do it. It will exceed 950F in very short order and the pads will glaze and if pushed or if the Electronic brake assist compensates by adding more brake force they will start disinergrating.

 

No amount of electronic assistance is gonna compensate for the physycal energy exchange. Nowadays we gotta be careful fancy electronics and software wizardry can inspire confidence and hide real hardware deficencies. Sometimes we don't notice till its too late.

 

I wouldn't take my legacy with 4 vented discs and more brake system mass beefier calipers and heat capacity to a track event and drive it hard without track pads.

 

Why would I take a ms3 with 2 vented discs and 2 solid discs with less mass and heat capacity and drive it hard and not expect disaster. Albeit with electronic brake assist...

 

Refrences: http://www.aa1car.com/library/2004/bf110412.htm

 

http://www.audiusa.com/audi/us/en2/tools/glossary/safety/brake_assistant.html

Awesome post, and I truly agree...

 

Great street brakes are a VERY different animal vs. great track brakes. Actually, the really good track pads will be piss poor street brakes :lol:

:spin:
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