S2000 owners quintuples pad life at track via our Competition BBK!10.09.2015
One of our S2000 customers recently posted some feedback on S2ki about our Essex Designed Competition Big Brake Kit and Ferodo DS1.11 pads. After switching to our BBK, he got five times the life out of his pads vs. the same compound used in his OEM calipers! His thoughts below:
"I purchased the AP Racing BBK from
Urge Designs over a year ago. Since then, I have participated in 22
HPDE days at CMP, VIR, RdAtl, BMP, and AMP. I have only used one pad in
that time, and it is the same pad I used on my OEM brakes, Ferodo
DS1.11, therefore, I can eliminate the variable of different pads from
contaminating my results. My driving skills have gone from novice to
advanced in that same time, so there is something to consider with this.
My ability to truly understand the difference between OEM and BBK was
based on novice skills at the time I made the change (and now that I am
an advanced driver, I’m not going to put the OEM kit back on to compare
them again). Therefore, this review is perhaps better suited for novice
drivers looking to improve their braking system and stopping ability.
The AP Racing BBK differs from the OEM in two major ways, consistency and durability.
My first point is a fact you can find in any high school physics book. Though it is difficult to believe, the size of the brake pad has nothing to do with stopping force. Stopping force = coefficient of friction (Mu) x applied force. Surface area is not in this equation. Therefore, if you want to increase your stopping power, you should ultimately change your pads. But don’t run off to read the pad reviews just yet. Novice track drivers need to be more concerned with consistency than stopping power – consistency throughout each stop and consistency from lap to lap. Here, calipers, rotors, and pad size make a huge difference because the coefficient of friction of the pad material changes drastically depending on its temperature. Small calipers have small thermal mass and hold tiny pads with tiny thermal mass, and the small OEM rotors with small thermal mass and small vents that dissipate less heat. While braking, momentum is converted to heat energy, and less thermal mass means small brake pads get much hotter per unit of mass and their coefficient of friction (Mu) changes dramatically as does stopping force. So your high school physics book was technically right; surface area is not directly related to stopping power, but in real applications, it is indirectly related as heat impacts Mu. The other variable is the applied force (in this case pedal pressure transferred hydraulically) and excessive heat can boil the brake fluid causing the applied force to drop (this is an ugly can of worms I don’t want to open, but suffice it to say, better heat management = more consistent stopping all around.)
Sorry for the physics lesson, but this is extremely important. The fact is, my OEM system stopped just as hard as my BBK …on the first stop of my session. As I added laps, heat built up, and I started experiencing brake fade, so I had to increase my brake zone throughout the session. This is exactly the opposite of what a novice driver should be doing. As a novice driver, I needed to focus on my threshold braking skills and shortening my braking zones. I needed to gradually shorten the brake zone with each lap based on the previous lap’s stopping distance. For this exercise, I clearly needed to have consistent braking. (Only change one variable at a time, in this case, driver skill – not Mu.) All too often, I read about people trying to solve brake fade by changing the pad material, but changing pad material changes every variable except heat management (the one that matters the most). Mu, heat generation, and consistency all change when you change pad material causing a setback in the learning process. Now I have much shorter stopping distances than most other cars I encounter on track. Physically, this is a function of the pad material - and that has not changed since I had OEM brakes. Mentally, this comes from confidence, and confidence comes from knowing my car will stop precisely as hard this lap as it did the last. Now that I am a fairly consistent driver and have consistent heat management, I can change a new variable – different pad material. Actually, I reached this level long ago thanks to the consistency of the AP Racing BBK, but I’m just now using up my first set of pads ...which brings us to durability.
Durability is directly related to heat management too. In general, pads wear out faster when they are overheated. Small OEM pads overheat more quickly and thus wear out faster (decreasing their thermal mass) therefore getting even hotter faster ...see where this is leading? Obviously, BBK pads are much larger to begin with, so there is more material to wear; less obvious is that the BBK system keeps the heat down, so the pads literally wear slower. (Note, this is why even BBK race pads start to wear quickly as they get thin – under 3/16” check them after every session)
For comparison, I went through a set of OEM-size Ferodo 2500 in two days at CMP, and Ferodo DS1.11 only lasted 2 days at CMP plus 2 days at VIR (~1/8” remaining when I changed to BBK). After changing to the BBK, I did 20 days on the Ferodo DS1.11 (one pad was down to the backing plate and the others were close). The rotor is starting to show wear toward the center but the full J-hook is still fully visible – no cracks. I have not done the math, but I expect am close to paying for the kit in wear-part savings.
Other points: The kit is designed extremely well, but you can read all the technical details on other reviews. Several highly advanced drivers have written very detailed reviews of the technical aspects, and I encourage you to read them even if they are too technical at this point. One member did a detailed cost analysis, with projected ROI. The Urge and AP Racing webpages also have a lot of good information. In particular, watch the AP Racing video on bedding brake pads - http://www.essexpart...ads/post/Bed-in (you’ll never run track pads on the street after learning the difference between abrasive and adherent properties.)
Drawbacks: A minor drawback is that the pistons are harder to compress when you need to change pads. There is no fancy tool to push them in like with the OEM, but this is probably the case with any opposing-piston system. Wheel fitment can also be a disadvantage depending on your objective. The ever-popular Enkie PF01 8” fits with ~2.5mm to spare (I ran this setup for 20 track days). However, when I started looking for wide square wheels and keep the wheels inside the OEM fenders (to meet Honda Challenge HC1 guidelines,) my options got very limited. I ended up getting the CWW wheels from Urge, and I am very happy with them too.
In summary, I have consistent braking after 40 minutes on track, it helped me to make huge improvements as a student, and the quality is top-notch. AP Racing BBK increased my pad life by ~5x. If you are just starting to track your car, I highly recommend this setup. It will help you improve your skills, and over time it pays for itself. I recommend them to every S2000 owner I meet at the track, and now that I am allowed to carry passengers they are welcome to experience them from the right seat (brown pants recommended). Discuss your skill level and tracks with Patrick - he can help you select a good pad material."
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