Rear brake issue

[bjurasz]

It was suggested I post to this forum this question about my rear brakes. I did a track day at Texas World Speedway. Car is a 2006 model has about 7,000 miles. Stock rotors. Stock tires. Pads were Hawk HP-S and were very new, and I bedded them as best as I knew how. Fluid was fresh Wilwood 570. The symptom was a firm pedal and hard braking in early laps, but a soft and long pedal with not-so-impressive braking as the laps went on. I noticed the rear rotors appeared to be glazing over on me, but they were not grooving. Next session pedal started firm again, etc. I tried to bleed the brakes after the third session but I nearly rounded a Speedbleeder in the process and decided to not risk it further.

At this point I am suspecting the rear brakes over-heated and caused the soft pedal. And I'm wondering if the reason was that I forgot to turn off stability control or not.

Pictures:
http://mercphoto.smugmug.com/gallery/3230756#178517350

[Coop]

I think it could be you VCS (?), but how do you drive? Are you hard on the brakes then off, or do you brake early and long?

[bjurasz]

This was my first track event in a car in almost 10 years. Last time I was driving on a track was road racing an 80cc shifter kart, about 4 years ago (on this track too!). So I'm a bit out of practice.

Coop, I know that on some turns I was on the brakes hard and then off, which is the best way as it allows more time for cooling. But some turns I was on the brakes early and long as I was trying to learn the track and learn my car. Also, probably a hold-over from my karting days, on one turnI had a habbit of trail braking the car to the apex. Was probably not smart of me to do but its the fastest way in a kart and I'm kinda used to doing it.

Think the rotors and pads can be salvaged or are they "street driving only" now?

[gomarlins3]

My guess would be that you cooked the fluid. 570 is a high temp, but it can cook as well. Is your fluid in the reservoir still a nice light color or is it darker now?

[ajay]

That's a reasonable assumption - especially with the long pedal. A flush of the system is probably not a bad thing to do anyway, but I think Bill is trying to determine whether anyone has experience with VSA on track and causing this kind of brake symptom.

Bill - you will need to shake some of those karting habits for the car though. You don't want to be steering with the brakes as much.

Interesting side note, there was a guy in a new Miata this weekend. He was very quick - I spoke to him and he fessed up that he left foot brakes everywhere and accidently gut the clutch rather than the brake. I think he did this several times as he came off quite a bit :rofl:

[bjurasz]

Bill - you will need to shake some of those karting habits for the car though. You don't want to be steering with the brakes as much.
Yup, you're right. And yes, I am trying to figure out if VSA had anything to do with it, especially since it appeared to be a rear-brake-only issue.

Is this you? I think it is. :)
http://mercphoto.smugmug.com/photos/178236022-M.jpg

[Slambo]

See this similar topic,

From my original post in that topic.
The vehicle stability assist (VSA) system helps to stabilize the vehicle during cornering if the vehicle turns more or less than desired. It also assists you in maintaining traction while accelerating on loose or slippery road surfaces. It does this by regulating the engine’s output, and by selectively applying the brakes.


"Honda's VSA system makes the S2000 more stable and forgiving during street driving or in inclement weather conditions. Working in concert with the Drive-by-Wire system, VSA continuously monitors yaw rate, steering input, throttle input, and braking pressure to determine if the car is following the driver's intended path, and can independently coordinate each of the disk brakes through the 4-channel anti-lock brake system, along with the throttle, to enhance vehicle stability. While this serves to effectively enhance driver control during acceleration, braking, and cornering, the system can be disabled with the touch of a button when conditions warrant it. To help provide optimum stopping power, the braking system also features Electronic Brake Distribution (EBD) and Brake Assist."

http://www.rsportscars.com/eng/cars/honda_s2000.asp


http://forums.s2kca.com/showthread.php?t=15534&page=2

[ajay]

Yup, you're right. And yes, I am trying to figure out if VSA had anything to do with it, especially since it appeared to be a rear-brake-only issue.

Is this you? I think it is. :)
http://mercphoto.smugmug.com/photos/178236022-M.jpg


Bill - Based on the info from Slambo, it seems like that may be the source of your problem, coupled with some driving habits that you may need to shake. I think you are going to have to do another track event without VSA to find out for sure. And I can't come up with any negatives for that :)

Nice picture - that is me. You do great work. Can you PM me with pricing for prints.

[desmo4]

Did you bed in the pads? If not glazing might occur.

Jonathan

[bjurasz]

I did bed the pads but who knows if I did it properly. Its kinda hard to drive like that in surbria without attracting the attention of local law enforcement. And my local law enforcement is rather aggressive with enforcing traffic laws around here (which is often a good thing, admittedly).

I'm going to street drive the car with only a brake bleeding but I'm strongly considering a new set of Cobalt pads and new rotors if I track it again.

[desmo4]

I did bed the pads but who knows if I did it properly. Its kinda hard to drive like that in surbria without attracting the attention of local law enforcement. And my local law enforcement is rather aggressive with enforcing traffic laws around here (which is often a good thing, admittedly).

I'm going to street drive the car with only a brake bleeding but I'm strongly considering a new set of Cobalt pads and new rotors if I track it again.

Yes that is quite understandable. But Hawk HPS are not too bad wrto speeding. Hawk blue on the other hand requires 3-4 100 mph stops, which could be cause for a serious legal problems.

Jonathan

[bjurasz]

I had bought my Hawk HP-S from the Tire Rack and their wonderful tech support gave me some good info I wanted to share: "The pads he was using were not appropriate for track use. The rotors MAY be salvageable if they are not scored to deep. The pads are probably cooked. He should get into some better pads to use for track use. Hawk HP would be a much better choice."

The bad thing is the HP-S is the best pad Hawk makes for a 2006 model year. Therefore I'm switching to Cobalt. And their tech support recommended the XR-3 compound in front and XR-5 in back. (The XR-3 rear is a special-order only pad and you have to order at least ten sets!). They also recommended the Stoptech slotted rotors, which, surprisingly, are not much more expensive than factory rotors.

[bjurasz]

A quick test with medium grit sandpaper this morning and I think my rotors are perfectly salvagable with some elbow grease. There is no gouging whatsoever, just a glaze. Saves some $$$. Cobalt pads ordered and hopefully arrive in two weeks!

[alvanderp]

Bill - the 06 uses the exact same front and rear pads as every other S2000, you dont need 06-specific pads.

FYI the XR's are probably a bit aggressive for Daily Driving, so I would be careful using them except to get to and from the event. I run XR2 fronts and GTS rears on my car and I just swap them when I get to the track myself. As to driving with the VSA on, I usually shut it off quickly if I realize mid session that I left it on, I can usually tell on the out lap when it cuts in. I did see a similar issue to yours on some Carbotech Panther + rear pads I was running, I just think the pads werent up to snuff, because the Cobalt's look fine.

[bjurasz]

FYI the XR's are probably a bit aggressive for Daily Driving,
Thanks for the heads-up. I chose the XR3/XR5 combination soley because that was the recommendation from Cobalt tech support. This is how I phrased my car's use to them:

"Car is my second car but I still street drive it, aiming for once or twice to work, plus some on weekends. Pads must be street friendly, even if weather is in the 40s and 50s or raining. I don't drive if it hits the 30s or lower. Car gets three to four autocrosses per year and I hope for three to four HPDE's a year. On the track I do tend to brake hard."

[CoralDoc]

I have observed the same excessive usage of rear pads on newer S2000s with the VSA system. In one case, the rear pads worn worn to the backing plates after about 2 hours on the track. The owner was using OEM pads, so it's likely that your uprated CF pads saved you from a worse outcome.

[bjurasz]

Thanks for the direct confirmation of what I was thinking the issue was. New Cobalt's arrive by UPS Friday!!! Hopefully they go on Saturday morning. In hindsight I probably should have just bought new Hawk rears but oh well. I will sand down all four rotors before installing, especially those rears. But seems like a good idea to do the fronts too. The crowd at S2KCA also talked me out of slotted rotors, which will be a nice expense to not incur. :)

[ajay]

The crowd at S2KCA also talked me out of slotted rotors, which will be a nice expense to not incur. :)

Bill can you elaborate please?

[bjurasz]

Andy, I've had a few PM's with people who run aggressive pads on stock rotors on the track. The consensus has been the slotted or drilled rotors just crack sooner and don't seem to have any real benefit. If people running R-tires on even more aggressive pads are fine with stock rotors I see little reason to buy the others.

[alvanderp]

To elaborate further - slotted/drilled rotors were originally invented to give a place for the gases created by the pad/rotor friction a place to go so the pad would seat against the surface properly. Modern brake pads do not release these gases, so really the only benefit from the slots is scraping dust/water away, which really isnt that big of a deal, and likely not something you would notice on track. And like Bill noted, many track guys have cracked these drilled/slotted rotors, making them even more of a liability than blanks.

The datalogger says I was clearing 1g of braking force last time out at TWS, and I never noticed any kind of performance issue on regular old OE blanks.

[hecash]

The consensus has been the slotted or drilled rotors just crack sooner and don't seem to have any real benefit.

I fully agree with the opinion about drilled rotors but not about slotted rotors. I've never cracked a good slotted rotor and specifically use them on especially high speed tracks like Road America.

Having said that, I have two 18 gallon plastic tubs full of OEM rotors that I've purchased from other S2000 owners over the years for general track use with Hawk Blue pads.

[hecash]

I forgot about the real issue here, VSA. I am 95% sure that this was your rear pad issue and that other cars like the Z06 Corvette have exactly the same issues. The rear pads get a lot more use than necessary on the track due to early engagement by the VSA.

A very good friend of mine nearly welded his rear backers to the rotors on his Z06 because he forgot to turn of the ESC (same as VSA) on the North track at the Autobahn Club.