I am running a Stoptech 13" kit with Pagid black pads in the front of my Z and have logged 6 track events and never experienced brake fade or had it boiled my brake fluid. However, this weekend I had my brake fluid boil and I experienced alot of brake fade. The funny thing is this is the same course I have run the last 4 events without problems and some of the events were in extreme heat. I also just flushed my brake fluid about three weeks ago and I bled the brakes the day before the event and had no air in the system. Has anyone experienced anything similair with a brake kit?

 

STX,
I've only had my 332mm kit fade once as well. You have to wail the Z pretty hard to make that happen. Were you out on the track for a longer session? Were your speeds significantly higher (did you get faster, add power, or drop weight from your car)? Also, have you done anything to alter the airflow to the brakes (new front bumper, underspoiler, etc.)?

I'd recommed 2 potential courses of action.
1. We offer titanium backing plates for the back of your pads. These will keep some of the heat out of the caliper and out of your fluid (we've seen as much as a 150+ degree difference). The part # is 68-080-0372, and they cost $79 for the set of 4. I'd try this as your first step.

2. Ducting. If the backing plates don't do the trick, you're going to have to do some form of ducting. I know Nick at N-Tech Engineering was working on a revision of his duct kit, but I'm not sure what else is out there for our cars right now.

Those are your options if you're already using a good fluid (I'm assuming you're using Motul RBF600).

After that, your next option would be to go up to a 355mm kit and some 18 inch wheels and tires.

 

J Ritt, the only thing different is that I took 100 lbs out of the car. It did make a significant improvement in lap times but I thought I was actually using the brakes less because I was carrying alot more speed entering and exiting the corners.

I will try the titanium backing plates and see if that helps.

Thanks for the help!

 

stx,
The reason I ask about the car's weight is sort of counter-intuitive. Many people think that mass is the most important determinant for brake requirements. In reality, the vehicle's velocity is more important to some extent. Here's the equation to determine how much kinetic energy is generated when you are braking:

Kinetic Energy=1/2 MVsquared. To spell it out...Kinetic Energy equals 0.5 times mass times velocity squared.

I don't have time to run through all of the math...but the bottom line is that velocity is squared in the equation. Even though you take mass out of the car (which decreases the amount of energy produced, and decreases the amount of brake thermal capacity), the decrease is linear. However, when you are increasing velocity into each corner (and then squaring it), you are increasing the amount of energy generated, and increasing the amount of heat capacity you need to handle the braking event.

To give you a gross idea of the impact, if you increase your velocity from 60-80mph, you are roughly doubling the amount of kinetic energy that is generated.

In other words, if you drop 100lbs, add 15hp, improve your driving, and carry 10mph more than you used to into a heavy brake zone at the end of a long straight, you are substantially increasing the thermal capacity needed by the system...which in your case, may just put you over the edge in terms of heat capacity requirements.

Here's a more formal definition if you want to walk through it...
kinetic energy is defined as 1/2 m v2 (said "one half m v squared", or "one half times mass times velocity squared"). Now as for units, 1/2 doesn't use units (of course), mass has units of kilograms, and velocity/speed has units of meters per second (m·s-1).
So kinetic energy has units of
kg·(m·s-1)2.
Which, rearranging, is
kg·(m2·s-2)
or just our old/new friend
m2·kg·s-2
Energy.

This all might look less unfamiliar as
1/2 m v2
kg × (m / s)2
kg × (m / s) × (m / s)
kg × m / s × m / s
kg × m × m / s / s
m × m × kg / s / s

 

That is great info. I never thought about it like that. I thought less weight was better on the brakes never thinking about actual speed. Now it makes complete sense looking at the math and it proves what happens on the track.

 

the fact that i completely understood that and actually know what you are talking about astonishes me hehe, guess those physics classes did pay off!

 

Very informative thread. The great thing about this board is that we have some very competent people here.

 

Good problem solving.