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A Track Braking Review of 2015

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Old 12-31-2015, 03:09 PM
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Default A Track Braking Review of 2015

After owning a 2006 S2000 since 2010, I sold it off at the end of 2014 to be replaced with a 2008 CR. Through 2015 I autocrossed and tracked the CR from bone stock to fully dialed for SCCA’s STR class.

I drove on three different tracks in 2015: Circuit of the Americas, Texas World Speedway, and Harris Hill Road; in two different cars, the CR and a Boxster Sypder; on five different tires, Hankook RS-3 V2, Bridgestone RE-71R, Michelin Pilot Sport Cup 2, BFGoodrich Rival S, and Nitto NT-01. I have now driven an S2000 on four different tracks: Driveway Austin and H2R, starting in 2013, and adding CotA and TWS for 2015.

I drove on nearly the same brake configuration through the first four years of S2000 ownership. I started with OEM rotors and pads, swapped to Ferodo DS2500s, and later upgraded to Science of Speed’s Speed Engineering rotors. This is where the CR started.

In December 2014 I took the CR out for three twenty minute sessions at H2R. The car was lightly modified, with autocross brakes, anti-roll bars, 255mm Hankook RS-3 V2s on 17x9s, and alignment. H2R reaches speeds just above 100MPH but braking demands are low. Fifteen minutes into each session the brakes began to smell, the pedal softened, stability decreased, and stopping distance increased. I wore away ¼ of the front pads and over ½ of the rear pads that day.



By the end of January I had added power, a differential, coil-overs, bushings, turned the SoS rotors, and upgraded the track pads to Carbotech XP10/XP8. CotA is extremely demanding on brakes, providing four 100+MPH straights ending in 45MPH corners. I ran three thirty minute sessions the first day. The rotors showed signs of pad smearing but braking was consistent and strong. I ran five thirty minute sessions the second day, with a final forty minute session that did the brakes in. Again, the braking was stable, but the distances went deeper and deeper at the end of T12, a 125MPH straight ending in a 45MPH corner, until finally the car nearly went off the back of T12. Wear was monumental! Shortly before the brakes went out, I posted a 2:42.22 on worn Hankook RS-3 V2s.



Since a BBK is legal in STR, but brake ducts are not, I upgraded before my July trip to CotA. I had to adjust the wheel offset from +63 to +55 to fit the StopTech ST-40 but I saved 1.5lbs per wheel over OEM. I ran four twenty minute sessions with StopTechs and Cobalt XR2s up front and SoS and XP8s in back. Braking balance was decent for the first few laps but gradually shifted forward through the session. The balance shift forward, combined with a temporary switch back to the OEM Torsen, produced increased instability on anything but straight-line braking. The front brakes showed little wear while the rear showed some signs of pad smearing. Heat, traffic, the Torsen, and eventually rain prevented me from improving my best.



Around August the URGE Flow rear rotors were shipping. Unfortunately I didn’t get them installed before my September CotA weekend. I had an opportunity to drive a Boxster Spyder instead, so I took it. The extra power and torque over the S2000 was good for 4+ seconds per lap, but the brakes and front tires were only good for about fifteen minutes before braking distances began to increase.



I ordered the URGE Flow rotors, with the modified rear brackets, during the introductory sale. This was my first real interaction with URGE and I found everything about URGE and the Flow kit to be quality. Patrick provided numerous updates leading up to shipment of the rotors. He checked in periodically to see if I had received the rotors, if I had any questions as I installed them, and how they were working once installed. The rotors are 3.5mm wider, vented, and came in at 8.4lbs to my 10lb SoS rotors. The modified brackets are machined, cleaned, and painted. Everything installed with OEM fitment, a rare quality in most aftermarket parts. The only thing missing was fresh lube on the caliper pins. My worn Ferodos were barely worn the 2mm necessary to accommodate the wider rotors.



October was my first track day with the URGE Flow rear rotors. I ran H2R with XR2s up front and XP8s in back, with a passenger for each of the four twenty minute sessions. The brakes were spot on through the entire day despite the extra weight of the passengers. The day left little evidence of the abuse given to the brakes. Passengers usually add .2-.4s on a typical 45s autocross course so I was pleasantly surprised to set my personal best of 1:29.31 that day.

My final track day of the year was this past November at TWS. I swapped in my now trusty XR2s and XP8s and headed to one of the most historic tracks of Texas. TWS is a medium-braking-demand track. Although speeds are higher than CotA, the speed differentials are smaller. I ran five thirty minute sessions the first day and finished with a forty-five minute session. I ran another five sessions with a long sixth the second day. The brakes stayed happy the entire weekend regardless of how long my sessions went. On the final session of the second day I had to pull into hot pits to fix my datalogger- the brakes were hot enough to billow smoke! My pass-check instructor said a fast street tire S2000 should post a 2:02; I posted a 2:00 on NT01s and a 2:01 on Rivals. Minimal wear was present after the weekend.



I started my tracking at the end of 2014 by melting away half a set of DS2500s at H2R. I then melted a set of XP10s and half a set of XP8s at CotA. Balance was off when I added the StopTechs but braking wear slowed dramatically. With the URGE rotors, balance came back and wear has come to a screeching halt.

Images courtesy of myself, Sideline Sports Photography, William Fehr, and Cafe Photo

[EDIT 1/2016]
Another track day, another solid brake performance. I went back to TWS this past weekend for a private coaching event. With only six of us, and a come-and-go format, we got all the laps we wanted. The car went out for six total sessions, totaling around three hours; approximately forty five minutes of that time had an extra 200+lb passenger. The same XR2s and XP8s were used again. No issues; not even appreciable wear! My personal best is now a 1:58.500, a time I set before the coaches started helping.
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Old 12-31-2015, 07:22 PM
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Nice write-up. That rear bbk looks pretty sweet, should help prevent destroying the rear wheel bearings. I have to replace both of mine this winter.
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Old 12-31-2015, 08:50 PM
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Nice write up on your brake development! Good to know about the rear rotors! Thank you for sharing
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Old 01-01-2016, 02:20 AM
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Nice write up. Urge looks to have some pretty awesome brake options available!
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Old 01-01-2016, 09:09 AM
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So with the Urge rear rotors, you've noticed a marked decrease in pad wear? Seriously considering getting a set.
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Old 01-02-2016, 05:44 AM
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Originally Posted by Ricky_Flowers_ View Post
So with the Urge rear rotors, you've noticed a marked decrease in pad wear? Seriously considering getting a set.
My pad wear has decreased significantly. I attribute it to improving both the front and rear.

Square tires and a relatively stock braking system could push either end beyond thermal capacity. By upgrading the front stopping power and thermal capacity, it became evident that the rears were fading and requiring more and more work from the fronts. This is likely the cause of the accelerated wear on the fronts, with stock brakes, as well as the increasing instability with big front brakes. Adding the vented rear rotors improved the thermal capacity, keeping the brake pads in their thermal range, in turn decreasing wear.

I'll get some photos of my rotors and pads in the next day or two. The front XR2s have four track days (three weekends) and the rear XP8s have six track days (four weekends). The front rotors have around seventy-five autocross runs and four track days while the rears have around thirty runs and three track days. No StopTech or URGE rotor has been resurfaced. Any OEM-like rotor I had prior (OEM or SoS) had to be resurfaced after a track weekend.
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Old 01-02-2016, 06:49 AM
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in what order would you put the tires for fastest lap? longevity?
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Old 01-02-2016, 07:13 AM
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Thanks for the detailed writeup.

Originally Posted by imstimpy View Post
Braking balance was decent for the first few laps but gradually shifted forward through the session. The balance shift forward, combined with a temporary switch back to the OEM Torsen, produced increased instability on anything but straight-line braking.
This is surprising. As you said, the balance shifts fwd as rear brakes overheat but I would expect braking distances to increase and stability to remain good since the rear of the is not as likely to enter ABS.
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Old 01-03-2016, 09:18 PM
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Yes, thank you for the write-up.

Why did you go with the cobalts in front and carbotechs in back once you got your BBK? When I get back on the track with my stoptech BBK, I was thinking about using XP10's in the front and back compared to when I used XP10/XP8 on OEM rotors.
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Old 01-04-2016, 04:40 AM
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Originally Posted by chuhsi View Post
Yes, thank you for the write-up.

Why did you go with the cobalts in front and carbotechs in back once you got your BBK? When I get back on the track with my stoptech BBK, I was thinking about using XP10's in the front and back compared to when I used XP10/XP8 on OEM rotors.
I switched to Cobalt XR2s in the front for the following reasons:
* The OEM-style XP10 backing plates bent and Cobalt has stronger backing plates. With an increased thermal capacity and a better force distribution, you may not bend the backing plates with the ST-40.
* It took FOREVER to get the Carbotechs to stop howling, regardless of how many times I tried to bed them.
* I needed a new pad for the front and wanted to try Cobalt; the XP8s stayed in the rear because they still had life left.

The downside to Cobalt pads is corrosive brake dust; Andie says they are a no-compromise racing compound. Cost for ST-40 pads is $349 (Cobalt) vs $205 (Carbotech).

I am switching to Cobalt XR3s in the rear because they will make pads in any thickness. For OEM rotors that isn't a big deal but the Flow rotors require -2mm per pad from the OEM 15mm thickness. Cost is $179 (Cobalt) vs $162 (Carbotech). The alternative to custom thickness pads is to replace only one pad at a time; Cobalt discouraged sanding the material or the backing plate.

Other than synergies between track and street/autocross pads, I see no reason to keep front and rear pads the same manufacturer. Since my street/autocross pads have no synergy, I just re-bed each time I swap pads. This way I can keep trying compounds until I find a brand or coumpound I really like.
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