Quote:
Originally Posted by PeanuKeeyes
One track day with these PFC 11 pads. They were ok, but for a pad advertised as having good initial bite, I was a little disappointed. Could they be glazed?
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It doesn't look to me like they're glazed. I'm assuming their bright areas are due to the lighting in the room or a flash. Glazed pads are generally very shiny across most or all of a pad's surface.
Quote:
Originally Posted by msendit
Doubt this is glazing. No direct experience with the PFC11, but they look like they like their heat [1], just look at that friction coefficient climbing all the way ... (Pics look fine too, just regular pads)
I'd guess the opposite actually -- not enough heat in them. The giveaway is the noise -- race pads squeal their worst when cold -- they get abrasive cold and scrub the transfer layer on the rotor (which is what gives them their braking torque). So... press the brake pedal harder? 
I'm not joking actually -- it's pretty typical to not use all your available braking, even for drivers with much more experience. A simple exercise with modern cars is to just pick a session and a big braking zone and stomp on the pedal until you get deep into the ABS zone. Next lap, stomp a little less. Lather and repeat until you get just under the ABS engagement point. If you're recording data, you can look for micro-lockups of the front inner wheel [2].
Much much less likely, but you could have a setup issue -- too aggressive pads for the tires you're running, so the brakes never get up to working temp. I only mention this because I've noticed the Hankook RS4s have a lot less braking grip than their lateral grip would suggest. But if that was the case -- you would've been locking up all over the place, with lots of smoke. And ABS. Much more likely, simply not braking hard enough to get up to temp. |
I haven't run PFC 11s, but I suspect they're a lot of pad for RS-4s. Braking normally, OP could easily have been well into the ABS in most of the braking zones.
Although a ~2:30 lap isn't fast at the Glen, a car with power will still be going pretty fast into the braking zones. The Glen is rightly known as a high-speed, heavy-braking track. It's hard to imagine not getting enough heat into pads on that track. Too little tire won't let you really use the brakes, though.
Below are some data I collected from a much faster lap in a much different car at Watkins Glen. They show that a capable driver spends ~1/8 of a lap on the brakes, with most of that distance devoted to brake-steering the car down to the apexes.
The graphic following shows an example of the brake-steering profile for T1. A few of the other turns are quite similar; a driver skilled at trail-braking is greatly rewarded at that track. It helps having tires with not too many heat cycles on them. I learned early to change tires out when they were slowing me down or preventing me from advancing my skills.
I was taught a different routine for determining a car's maximum braking capability:
1) Find a place where the car can be safely run up to 70 MPH in 3rd gear. Preferably, this is on smooth pavement.
2) Put a cone out and use it as the point at which to begin braking
3) Run the car up to 70 MPH and upon reaching the start cone press the brake pedal as hard as possible; i.e., max ABS
4) Mark the car's stopping point with another cone
5) Run the car again up to 70 MPH and brake at the starting cone using what you estimate is "3/4 ABS" (e.g., go up to max ABS and immediately release the appropriate amount of pedal pressure); then, mark that stopping point
6) Do it again at 1/2 ABS, then again at 1/4 ABS, then again at just before ABS; mark the stopping points as you find necessary
7) When done you'll know how use of the brake pedal in your car, with your braking components and your fresh tires, creates maximum stopping power.
In the car I put through this exercise, it was 3/4 ABS that stopped the car in the shortest distance (IIRC, it was ~5' shorter than max ABS). I never bothered with my M240i. At Mid-Ohio with 255 R888Rs and Hawk DTC-70s and with the track's single heavy-braking zone, I made it a point to stay out of the ABS. As hot as the brakes were already getting, I didn't want to work them any harder.
