odb812

During my fourth session in my first of 3 track days this weekend I boiled my brake fluid. While I was on the track, I noticed something weird with the brakes, but it was distinctly different from brake fade. Instead of a feeling like a firm pedal is pushing on marshmallows that you get with brake fade, it felt like the pedal was weaker. I slowed it down and came in at my next opportunity and did a couple laps around the paddock without touching the brakes to cool down. When I came to my parking spot, I pressed the brake pedal and it went straight to the floor and the car didn't slow one bit. I hit my tool box and started pushing it, so I put it in 4th, side stepped the clutch, and stalled it out.

After everything cooled down, I flushed the fluid for fresh Motul RBF600. I popped the front pads out to check them out and ended up replacing them as well at the recommendation of my neighbor in the paddock. He was saying you should have at least as much thickness in pad material as pad backing to help absorb heat. Does anyone else subscribe to this?

After the pad and fluid swap, I missed my last session, so I went on the skidpad and tested everything was working properly. I didn't have any problems the rest of the weekend. We were practicing passing under braking and being in one of the lowest hp cars out there, I had to stay on the gas longer than everyone else and really stand on the brakes to pass after the longer straights and the brake performance was solid and confidence-inspiring.

My car is a stock CR with Hawk HP+ pads and 225/255 RS3s. I have a receipt that the fluid was completely flushed at a dealership using OEM fluid a month before I bought the car(this past April). I had done 5 track days on that fluid before this past Friday when I boiled it. My weekend could have gone horribly if some little angel or Shigeru Uehara didn't pop up on my shoulder and say "Why don't you bring it in and check it out." So if you have done a couple events on OEM fluid, you may want to consider flushing it for something with a higher boiling point or some fresh OEM fluid if you're not planning on hitting the track that much. And yes, I realize I am a lucky bastard.

Squirtle

Both the OEM fluid and your brake pads are probably not going to be sufficient for your needs after 6 track days. Something to consider. You're probably going a lot faster now too, and the problem is becoming more apparent.

anorexicpoodle

This isn't terribly uncommon, especially when using a less track oriented pad like the HP+ since as that pad (or other street / autoX pads) heats up their bite begins to fall off resulting in you having to stay on the brakes longer and longer, putting more and more heat into the system.

I experienced this at auto club back in February when I went on Porterfield R4S pads and was totally unprepared for the amount of brake abuse that track would dish out. I quickly discovered that switching to a more race friendly compound (I'm now using the Porterfield R4) resulted in shortened intervals on the brake due to higher bite, so less time generating heat, and more time shedding it, and as a result, no more boiled fluid.

adrs2k

I had the same problems in my last s2000 with Hp+ pads. I hated those things, but i got them for $100 new front and rear so I gave them a shot.

OEM brake fluid is also not up to the task of track duty.

2000ths

yup, dot 4 makes a big difference.

odb812

To be clear, I'm using HP+, not HPS. HP+ are the equivalent of the R4 and the HPS are the equivalent of the R4S. The pads themselves are not the problem, I had changed the pads after my first two events with the car, so I only had 3 events on the pads. I had ordered the Motul fluid to change out when I changed the pads, but it didn't arrive in time. I'm not sure if keeping at least the pad backing thickness in pad material is necessary, but that's only a contributor. The main cause of the problem is that I didn't flush the fluid as soon as the new stuff came in.

I'm also not going that much faster. I had only done 5 track days on my s2000 before the 3 this weekend, but I have tracked other cars plenty of times in the past.

BTW, Ryan, I'm going to get you a paypal for those links later today. Sorry, I got hung up trying to get out of town last week.

takchi

Pretty sure HP+ is not equivalent to R4...

HP+ = up to 1000ºF
R4 = up to 1400ºF (operating 450-1200ºF)

odb812

I'm not saying they're the same or anything, but simply they are in the same class of pad. HPS and R4S are both performance oriented street pads. HP+ and R4 are street friendly(rotor friendly) track/autocross pads. These two pairings are the closest for comparison. You wouldn't compare the Hankook v12 to the z1 star spec because they're not in the same class, but the RS3 and Z1 are.

takchi

I do recommend the Hawk DTC-70 or DTC-60 if you want to stick to Hawk. I also recommend RBF660 over RBF600. For some reason, the S2k likes the RBF660 better. Psychoazn and some of the other S2k Challenge guys might want to chime in on that topic.

anorexicpoodle

I made the comment I did because of the temp ranges and uses that Hawk advertises for the HP+. I would say the DTC-60 or HT-10 would be closer to the R4 in temp and performance. All of those are full race pads. The HP+ is a light track / autocross pad. There is a world of difference in there. The HP+ is actually very similar to the R4S in performance, all marketing fluff aside, which makes my and your experience fairly parallel.

Long story short, step up in pad compound, and of course stick with good brake fluid, and the problem should go away (though you may end up with a rotor eating habit like some of us)