[dradernh]

Originally Posted by smchuck

Hi friends,

I need some thoughts on my brakes. I have M Sport brakes with basic rotors and Hawk HP Plus pads, steel lines and high temp fluid. I’ve run a handful of track days with this setup and the brakes always worked perfectly. Yesterday, I took a step up in my driving speed and braking aggressiveness and after a few laps the brakes started to chatter/pulse/vibrate under hard braking. I took a cool down lap and they returned to normal. A handful of aggressive laps and problem returned. I inspected everything today and don’t see any problems. Rotors look fine and plenty of pad left. I didn’t take the pads out to inspect them. Thoughts?

Thanks,

Chuck

The chart in the upper left-hand corner of this page showing Hawk Motorsports compounds indicates that the HP Plus is very much a street/track pad: https://www.hawkperformance.com/compounds/motorsports. The thing with street/track pads is that they're really street pads and not track pads at all unless you've got a light and lower-powered car like, say, a Miata.

If you've gotten after it on a race track with that pad, you could easily have exceeded its temperature capacity, and as a result you may have pad deposits on your rotors. If you do, they could account for the pulsations you're feeling. I experienced that effect many years ago (i.e., pulsations on the track when everything was heated-up and I had pad deposits on my rotors). I can't recall now if that went away after the rotors and pads had cooled off.

Can you take a close-up photo of one or both front rotors so we can judge whether or not they have pad deposits on them (at this time)?

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Just saw your 2nd post. "Judder" is the word for the phenomenon, all right. The Hawk Motorsport chart tells me that on a race track you want a pad on the order of the DTC 60 or the DTC 50. Note that on that page you can compare compound qualities by clicking on the white, bold-faced names with black backgrounds of multiple compounds. That might be useful, especially if you want to run the same pad on the street and the track and have considerations about noise and dust on the street.

Something to be aware of: if you increase the braking capacity of your pads by running a genuine track pad, and you're running a street tire like a Michelin Pilot Super Sport or Pilot 4S, you need to consider upgrading to a stickier tire. That is, the braking capacity of your pads must be reasonably matched with the tires you're running to get the most out of each.