argonaut

Is it just me or is NJMP Thunderbolt particularly hard on brakes? I've never tried to take any measurments on brake usage to compare one track to another but two days on Thunderbolt this past weekend sure ate up my pads. This started me thinking and trying to decide which tracks are hard on brakes and which aren't and how do you objectively determine it.

I'd be interested in hearing what you'all think: which tracks are hard on brakes and why?

Thanks, Brad

96CollectorSport

A track can be hard on brakes in two ways, Road America is hard on rotors because you have heavy downhill braking from high speeds followed by long straits so your rotors really get a workout between hot and cool.
Tracks like Blackhawk Farms are hard on pads because there is a lot of repetitive braking without much time to cool. That's where pad selection comes into play.
It's kind of the difference between Pocano and Bristol for NASCAR.

AU N EGL

High speed sections going into hard tight corners, where speeds must be reduced quickly. Many of these on a track make it hard on brakes.

rfn026

The short course at Sebring is the toughest I've driven. Performance Friction used to use the short course to test Indy car brakes. They may still use it.

You never get a chance for the brakes to cool off. The short course is simply a series of short chutes and corners. Actually the short course is like a totally different world from the regular Sebring course - even though they use the same pavement. You just never get a break on the short course.

Richard Newton

68sixspeed

Also I find I use a lot more brake up getting use to a new car or new track, I was surprised to only use 1/16" of pad on a full day, over 100 miles on lime rock this week and that was only running hp+ pads. It's easier on the brakes if you don't slow down for the corner!

argonaut

Interesting information, thanks. I never thought of hard on rotors vs hard on pads but it makes sense.

geerookie

That's why you never have to replace brakes in a Miata

AU N EGL

I had and instructor early on who taught me to go a bit slower, use less brake and more momentum though corners.

My lap times dropped with out trying.

JRitt@essex

1. High speed stops
Remember physics 101...energy isn't created or destroyed, it just changes form. When you stop your car, your tires stop the car through their interface with the ground. Your brakes are just transferring kinetic energy (spinning motion of your discs) into heat (thermal) energy. The amount of energy in a stop being transferred from motion to heat is directly related the speed from which you're stopping (mass x velocity squared). The velocity squared part is what is important. A stop from 100 mph is transferring exponentially more energy than one from 60mph. That means a track with high speed stops put a huge burden on your brakes. Going from 140mph down to 70mph is much harder on your brakes than going from 60 mph down to 5 mph. Think about how many more times a fixed spot on your rotor passes the brake caliper at 115mph vs. 45mph.

2. Distance/time between stops
If your brakes don't have time to cool off between stops, they get heat soaked. Depending on how the turns are laid out, your brakes may not be getting much of a rest between stops.

As collectorsport said, the most stress on discs comes from heating and cooling cycles. They heat up, they expand, they cool, the shrink. That fatigues the iron and causes stress fractures. You also have to factor how much air is getting to your discs. A track with high speed straights is pumping more air through your ducts into your discs. That's why you'll see some race teams with ducts partially blocked, completely blocked, or open. They're typically shooting for a nice sweet spot of something like 1100-1200F disc temperature. They try to keep the disc closer to a certain temp so it doesn't oscillate/swing so much = less stress on the disc.

As others have said, technique plays a big role. I've seen drivers on the same exact car have vastly different wear rates. That's why it's really tough to make a recommendation to someone on pads. There are so many variables. Some guys stand on the brakes hard, some guys trail brake deep into turns, Some guys get on them, off, and back on again, some guys start braking early and stay on the brakes a long time...lots of possibilities. For the average guy, inconsistent technique is probably the most common technique. They do it different on every turn.

There's a lot of bashing that goes on here and elsewhere about NASCAR. The reality is however, that those guys are as hard on brakes as anyone. A good deal of AP Racing's current technology was developed specifically to address the braking needs for Sprint Cup. If you are hard on your brakes every six seconds, braking from 180+mph, down to a slow speed for sharp turn in some cases...that is extremely difficult on brakes.

JRitt@essex

I just bought a miata that I'm going to use as a track toy. I can't wait to drive it back-to-back with my C5Z. They should require some fairly different techniques.