NYSpeed Track Day #1 - Friday June 15th, 2007

NYSpeed Automotive
481

Me neither. If anything, this is the kind of discussion an automotive forum should have more of.

I know that maxium braking is best for LAP TIMES. Hence the reason I was braking as late as possible and as hard as possible, up until my brakes overheated. It goes back to using 100% of your traction. To be as fast as possible you want to use all your traction all the time. If you’re in a corner, 100% should be turning. If you give 100% traction to turning and you find you’re cutting to the inside, it means you’ve got some traction to spare that you could be using for going faster. etc etc, it gets a little more complicated, but that’s the general idea. Same thing with braking. If you’re going in a straight line and you’re only using 50% of your available traction to stop, you’re wasting 50% of your traction. You should have been using it to accelerate, and then used 100% of your traction to stop later.

But that only works if your “race car” is capable of giving you 100% lap after lap.

Which brings us back to:

Nope, you have it backwards. Think of it in terms of acceleration first. To accelerate my pig of a car to 60 mph in 4.8 seconds, it takes 400 HP. HP is just a measure of force, specifically the ability to lift 33000lbs one foot in one minute (thank you Mr James Watts). 400 HP is the force acting on the car to change it’s state from motionless, to 60 MPH. With 200 HP it would never reach 60 MPH in 4.8 seconds, because you’re only putting 200 HP worth of force into the equation.

So once you’ve put all this HP into the fat pig of a car to get it to reach 60 MPH, it carries a certain amount of kinetic energy. I’m probably going to screw up the math, but you’ll get the idea.

60mph = 26.8 Meters/Second
3800 lbs = 1723 Kilograms
Kinetic energy = 1/2 (M * (V * V)), or 618763.76 Joules.

So the fat pig of a GTO has 618763.76 Joules of energy simply “existing” at 60 MPH. Since energy can be neither created nor destroyed, the brakes have to disapate this energy in order to bring the car back down to zero meters/second.

Kinetic energy is the energy of a moving object, and is dependent on the mass of the object and the velocity at which it is traveling. Heavier objects and faster moving objects have more kinetic energy — that is to say, a semi-truck traveling at highway speeds has more kinetic energy than a baby carriage traveling at walking speed. You could stop a baby carriage with your hand, but a semi-truck would barely slow down at all as it ran you over because it has a lot more energy. Kinetic energy is the energy required to bring an object up to a velocity, or to stop the object which is traveling at that velocity.

So, it will take more kinetic energy to decelerate in less distance than it would to decelerate in more distance. Same as it would take more kinetic energy to accelerate in less distance. More energy being disapated by brakes = more heat, since brakes basically do nothing but convert kinetic energy to heat. It doesn’t matter than you’re on the brakes for less time because you’re forcing them to do much more work.

Remove the brakes from this and think of it another way. You’re running with a wheelbarrow full of rocks that weighs about 150 pounds. You’re running just as fast as you can. Which will require more effort on your part.

  1. Stopping the wheelbarrow in 2 feet.
  2. Stopping the wheelbarrow in 20 feet.

Yep, you’ll need to put much more energy into stopping in 2 feet than you would in stopping in 20 feet. If there was a brake on that wheelbarrow, it would still be following the same physics laws.

Terrible example in this case, because you’re introducing a new force and not accounting for it… GRAVITY.

Instead of riding your brakes all the way down, lets assume you don’t touch the brakes at all, or use engine braking, and you remove the friction from the air that would slow your car down as the speed increased. At the bottom of the hill your car would be going 1000 mph or so, and if you stood on your brakes to the point of ABS engagement they would fail MUCH MUCH MUCH worse than had you simply rode them all the way down.

We really need BikerFry to get back from his damn honeymoon and school us with his engineering skills. My software engineering isn’t helping me here, and it’s been a while since I was in school and worked with these formulas.

482

^^What he said!

483

I wasnt argueing that it took more energy to stop the car.

i was just saying its Less damaging to your brake pads/rotors to apply the most amount of force between the two for the shortest amount of time to scrub off speed.

take something like a bench grinding wheel. and take a plate of steel.

with the wheel spinning at full rpm. switch off the power and press the steel against the wheel at say 10lbs./sq in. untill it stops.

and then take the same wheel and steel plate and press the steel against the wheel at say 5lbs./sq in. untill it stops.

which steel plate will have more damage done to it. and be hotter? it still took the same amount of kinetic energy out of the rotating wheel. but the plate that had more time at less pressure will be significantly hotter. the heat is what warps your rotors & erases brake pads.

theres a reason why street pads arent good on a track situation. the same reason why track pads arent good on the street. ITs how much heat they can handle.

and im all for some more PIX.

isnt there a motorsports FORUM just for pix?

484

I’m making an album slowly but surely. They take forever to upload. Might have them done by next week, or maybe tomorrow if it thunderstorms.

485

dur buy some real brakes and show me the pics

486

You guys can argue physics and theories all day til you’re blue in the face but it’s this simple:

Braking harder and shorter CONSERVES brakes - the less time the pad and rotor touch, the less heat is transfered between the VERY hot rotor and into the brake fluid. The rotor’s job in addition to providing adhesive AND frictive force (if you don’t get the difference / what I mean, stop arguing now and research more) is also as a heat sink.

I told my “student” in the Z06 this: Don’t “street” brake - despite what you think, it’s harder on the brakes, even if you’re trying to be “gentle” to them.

As far as braking “too early” I was def. braking a bit earlier than I could have / should have but was ALSO off them earlier and then back on the gas into the first turn - the “wrong” thing to do IMO was to brake, stay on the brakes, coast, brake more, then turn at 2 (the sharper / 2nd right hander).

But I won’t profess to be an expert or by any means the fastest out there - just offering my $.02 - JayS, RedrRocket is right about less time / more force (short of locking things up completely).

487

It doesn’t matter if you brake hard or soft, if you slow from one speed to another hard then soft, you are still converting the same amount of energy into heat, you can’t “conserve” the brakes by braking later, you will of course be going faster if you brake later, which means scrubbing more speed, which means using up more brakes, and if you brake later, you will have to brake harder. The only thing that matters is how long you are on the brakes, because the longer you are on the brakes, the less time you are on the gas, and the point is to be on the gas as long as possible, witch means braking as late and hard as possible.

488

No, this is a terrible example because you are assuming too much. Assuming there is no friction also assumes you cannot stop. But let’s go with it anyways. If you are going 1000 mph and still have brakes, the car will slow X amount. If you are going 50 mph and you have over heated your brakes to the point that they loose their chemical adhesion and they have started to get “greasy”, no mechanical friction (or very little) will occur and the car will not slow as well as you’d like. This is just going off of what I learned it engineering school, motorsports seminars, racing schools, 30 track days, and working in the automotive industry for over 5 years. I’m no expert, but I have been around them long enough to learn a thing or two. I also know that I am generalizing quite a bit, there are always exceptions for certain scenarios.

489

that is correct.

490

Interesting.

491

I think y’all should get better brakes and quit yer bitchin’.

X…

492

Yeah, god forbid we actually have a decent automotive discussion on this automotive board, and allow the “why is my ass bleeding” thread to fall off page 1. :bloated:

493

Great advice from someone with experience. After watching my videos I can’t believe how much I was letting off the gas before going into the corners… I was taking it real easy on my brakes & car. I think it all has to do with when I was at Watkins Glen and lost my brakes. This happened to me twice - one time was because my fluid boiled and I didn’t do enough prep on the brakes. The 2nd time I was at the Glen, I had brand new Hawk pads, brand new motul 5.1 fluid, and bled all brakes right before going on the track. I also broke the pads in on the street. After the first hard lap at the Glen coming into turn 1 my brake pads felt all mushy and the pedal went to the floor and the car didn’t stop too well. If I would have went into the turn full force, it would have been over. After that the pads must have heated up and felt fine but it’s always scary losing your brakes. I’m sure Dave can tell you this from last week’s track day.

494

:lol:

X…

495

Correct me if I’m wrong, but the HPS’ are made for high performance street driving…so no matter if you are braking early or late, they just aren’t made for track day applications like this.

I ran HP+'s this time around and was very pleased by how they stood up. At one point I thought they were fading a little, but then I realized I was just retarded and wasn’t on the brake as much as I thought I was.

496

Yeah. I ran HPS’s all around and those at TMP saw how well those worked :bloated:. I think most people should start with good fluid and lines. I am currently running an aggressive track pad up front (DTC-60) and HP+ in the rear and I am much happier with this setup. Others may want to look at something similar for track days because losing your brakes is about as dangerous as it can get on track. I have gotten some really good advice about brake setup recently and it has really enhanced my safety and the performance of my car, especially after the 15 minute mark when others seem to consistently experience substantial brake fade.

497

ferodo pads for me, No problem with brake fading and still tons of life left on them. Also agree with Sam on the lines and fluids

498

i just swapped out ferodos in the front and have my axxis ultimates in the rear.

I havent changed the fluid or lines since ive owned the car. 4 years this august?

i have probably 5-600 track miles on the car. with over 100 of them from last friday.

driving home on the ferodos was interesting. I had a Pin sticking in my right front caliper. which i fixed last nite.

I now understand why i had so much OPEN track time. Guys running street pad material or autoX pad material on this short of a track. they get scary really quick.

i did a couple of “pace laps” at the glen with 4 peeps in the car last summer and the axis ultimates i had in got greasy by the 3 rd lap.

499

JayS, next time you go to a track day, try Porterfield R4-E Carbon/Kevlar pads. They will be up to the task and they work well with heavy cars like yours for track day applications. That and some Motul 600 would do the trick for your fat pig.

500

I found out that the 9x to 03 C5 Vette pads fit perfectly in my calipers, so that opens up a whole new world of options when it comes to pads.

PS… at no point was I trying to say any driving style was going to work well with my stock pads. And I realize the HPS’s aren’t real track pads either, but I needed some kind of pad so I could drive to work on Monday, and the HPS’s seemed like a much better idea than the shitty Autozone duralasts.

I’m still having trouble believing braking harder for a shorter period of time is easier on brakes, based both on my understanding of physics and my experience at TMP in the Fiero and Dunnville in the GTO. When braking harder later I was losing my brakes. When braking lighter but earlier, I was having no issue with 20 minute sessions. :shrug: Maybe I was trading off less heat for more wear, which I could understand.

Regardless, before I hit another track day there will be at minimum some real track pads, and better fluid.