[seanm]

Khiem from MotoIQ posted an article detailing some modeling he did of hard braking for a shorter amount of time vs lighter braking for a long time.

Check out the article.

http://www.motoiq.co...brake-fade.aspx

The lesson here is that harder braking is better. Either you end up going faster and have basically the same rotor temps, or you go the same speed with lower rotor temps as compared to being too light on the brakes. Lower rotor temps should translate into less brake fade and also lower pad and rotor wear. Harder braking means less time on the brakes too, so that may also translate into less pad and rotor wear. So don't be afraid of the brake pedal and stomp on it!

One of the charts.

http://www.motoiq.co...brake-fade.aspx

 

[DocNrock]

Cool stuff, Sean. Thanks for posting it.

 

[nlpamg]

Interesting, thanks for posting! Makes me rethink things.

I was trained to do the late brake, hit harder camp. But recently, at some tracks, the instructors have advised me to brake earlier and lighter to reduce my fade and brake temps (and it worked at those tracks, specifically Buttonwillow where my pedal went to the floor, not in the GT-R).

For late/harder braking, higher temp fluid is also a must.

 

[descartesfool]

Brake as late and as hard as possible, that's my moto. And then release smoothly so as to not upset the car's balance.

Keep your throttle pedal all the way down for as long as you dare too!

And a data logger is your friend if you want to really improve your driving technique. I had some friends who thought they drove fast on track and when I lent them my logger, some of them found they were braking well below 1g on most corners, not wanting to really get on the brake pedal hard. With a little coaching and coaxing, they are now braking later and harder, and going faster.

 

[prov1]

Sean, this is great thanks,
I am at Roebling Road, GA this weekend and this info helps a lot.

"quote name='descartesfool' timestamp='1320360893' post='789000"
Brake as late and as hard as possible, that's my moto. And then release smoothly so as to not upset the car's balance.

I will try des

 

[thistle]

Thanks!

 

[NJNYCGTR]

very useful information, thank you for the post.
Now I have to try and remember that next time I'm out at the track.

 

[NNL21]

Just gained some good knowledge. Thanks.

 

[[email protected]]

Sean,
Thanks for sharing. This is exactly what the instructors informed me of as well at the Jim Russell race school I attended last year.

On a side note (minor thread jack) another interesting bit of info I learned was how to handle understeer. The instructor riding with me and I were discussing what I do in understeer situtations. I said I typically go to neutral throttle or lift slightly. And to be honest occassionaly will put additional steering angle into the car even though I know that's not the correct thing to do

He said the next time we go out to intentionally put the car into a bit of an understeer and instead of my usual inputs to simply maintain throttle position and "unwind" the wheel a bit. It was a very hard thing for me to do, but he was right. By changing the tire angle slightly with steering input I was able to maintain or increase corner speed by not overworking the tire with too much angle. Makes perfect sense in discussion but is still hard for my brain to put into practice. In moderate/extreme understeer circumstances this is not applicable. But if encountering mild understeer and your still more or less on line it should correct the situation and be the quicker way through the corner. Another one of those techniques that makes perfect sense in conversation but is much more difficult to implement in real time.

 

[Yellokilo]

Sean,
Thanks for sharing. This is exactly what the instructors informed me of as well at the Jim Russell race school I attended last year.

On a side note (minor thread jack) another interesting bit of info I learned was how to handle understeer. The instructor riding with me and I were discussing what I do in understeer situtations. I said I typically go to neutral throttle or lift slightly. And to be honest occassionaly will put additional steering angle into the car even though I know that's not the correct thing to do

He said the next time we go out to intentionally put the car into a bit of an understeer and instead of my usual inputs to simply maintain throttle position and "unwind" the wheel a bit. It was a very hard thing for me to do, but he was right. By changing the tire angle slightly with steering input I was able to maintain or increase corner speed by not overworking the tire with too much angle. Makes perfect sense in discussion but is still hard for my brain to put into practice. In moderate/extreme understeer circumstances this is not applicable. But if encountering mild understeer and your still more or less on line it should correct the situation and be the quicker way through the corner. Another one of those techniques that makes perfect sense in conversation but is much more difficult to implement in real time.

Same thing as doing a "sawing motion" with the steering.
F1 drivers do that all the time.

 

[[email protected]]

Same thing as doing a "sawing motion" with the steering.
F1 drivers do that all the time.

Similar. Most of the time I am "sawing" it is to counter oversteer as opposed to countering understeer.

 

[David_Yu]

Yeah it's very counter-instinctive to leave braking late and hard and the opposite to good road driving, but I believe the data and it's what I do when racing (as opposed to track days).
I just don't like upsetting the balance of the car and of course you are eating into your safety margins, e.g. if you do suffer fade or the fluid boils!

 

[roketman]

Brake as late and as hard as possible, that's my moto. And then release smoothly so as to not upset the car's balance.

Keep your throttle pedal all the way down for as long as you dare too!

And a data logger is your friend if you want to really improve your driving technique. I had some friends who thought they drove fast on track and when I lent them my logger, some of them found they were braking well below 1g on most corners, not wanting to really get on the brake pedal hard. With a little coaching and coaxing, they are now braking later and harder, and going faster.

Bingo! You got it! Squeeze and ease is the technique .Balancing the car is everything .You need to do all your inputs smoothly.I find breaking is the one skill no one thinks to perfect and practice.
Data logging and video is the best learning tool out there.Data logging makes you humble! I think its to bad we can't some how down load the data info off our cars.All the info is there ,we just need to save and store it.

 

[DocNrock]

Bingo! You got it! Squeeze and ease is the technique .Balancing the car is everything .You need to do all your inputs smoothly.I find breaking is the one skill no one thinks to perfect and practice.
Data logging and video is the best learning tool out there.Data logging makes you humble! I think its to bad we can't some how down load the data info off our cars.All the info is there ,we just need to save and store it.

That's what I love about the Traqmate. I can watch my videos with superimposed data and easily see where I can pick up at least a second if not more. Data logging makes one very humble.

 

[roketman]

That's what I love about the Traqmate. I can watch my videos with superimposed data and easily see where I can pick up at least a second if not more. Data logging makes one very humble.

Doc,
Your my kinda guy! A track junkie! If you ever head out to Watkins Glen or Limerock make sure you let me know!

 

[zebekias]

They pull their conclusion out of their ass, it's not supported by their own data.

Case 2 pumps a higher amount of thermal energy into the rotor (car is going faster) and has higher peak temp than case 1. Better lap time (car is going faster) but someone please tell me how that is any good for brake fade.

As for Case 3, I am utterly perplexed what the two rotor temp charts are showing. When the car decelerates from the same speed A to the same speed B at different rates of deceleration, it pumps the exact same amount of thermal energy into the rotor. Someone please explain the vast temperature differences between case 1 and case 3.

 

[descartesfool]

The mathematical model is not representative of reality. Brake rotor temps do not drop as shown on those charts. The shape is wrong. If you look at data logger traces from IR brake temperature sensors, peak temp is obtained quickly and drops much faster toward the low temperature, with a much more exponential drop. Case 3 in the example is pointless. Case 2 is faster around the track, but has higher peak temps as shown on the temp vs time chart, whcih is what you would expect. Not sure what the charts are trying to compare. A slow lap has cooler brakes is all it says really. Peak temps are important, but so are the average temps.

 

[Santorican]

Still a nice write up

 

[tyndago]

Better late than never. Kheim just emailed me on this with a little more explanation.

Case 1 and Case 2 have the same peak velocity and the same minimum velocity. The change in kinetic energy is the same due to the same high and low speeds and therefore the same energy into the brakes. If he looked at the velocity vs distance chart, he'd understand why Case 3 has a much lower temp.

The real world traces certainly have a different velocity profile which has the car accelerating and increasing velocity (and therefore increasing the rate of heat rejection due to the increased air velocity) probably almost the whole time until it hits the next brake zone. In my hypothetical, it sits at a constant velocity most of the time.