Miata Club w/ 12.88" GWR rotors pulsating on track
Posted: Fri Jun 25, 2021 4:19 pm
I have a 2021 Miata Club with Brembo front brakes equipped with 12.88" GWR rotors and Hawk HP+ pads.
Rear brakes are OEM with Hawk HP+ pads.
The last two track days I have experienced pretty significant pulsations from the brakes ONLY after they have been used 4-6 times during a 20 minute session.
I purchased the GWR rotors about 5 months ago. They have about 2500 miles on them including a total of 4 track days.
The first time I noticed the pulsations was at Daytona Speedway. This was before I changed the rear pads from OEM to Hawk HP+.
The second time was recently at Thunderhill on a 5 mile course. This most recent time, the pulsations became so pronounced that I was braking easier than I would have liked to coming into sharp turns after straightaways.
After each track session was completed and the brakes had been cooled down (with e-brake off), the brakes started the next session fine, but the pulsations came back after the brakes heated up every session.
Other than the above two most recent track days and a slight amount of squealing at the end of slow speed road stops (attributed to the Hawk pads), the brakes have performed as expected.
When I mentioned the brake pulsations to others at the recent track day, the response I received was maybe your rotors are warped. I don't see how that can be the cause as the pulsations go away every time after the brakes have cooled - only to return after they have heated up on the track.
I see no visual evidence of cracking or warping of any of the for rotors.
I will also note that the brakes never seemed to be fading (fresh DOT 4 fluid being used), but that the pulsations were so noticeable under hard braking when hot that the car was vibrating, not just the brake pedal.
I'm looking for some guidance (especially from Brian G) related to my problem. I'd also like to know what if any warranty applies to the GWR 12.88" rotors.
Rear brakes are OEM with Hawk HP+ pads.
The last two track days I have experienced pretty significant pulsations from the brakes ONLY after they have been used 4-6 times during a 20 minute session.
I purchased the GWR rotors about 5 months ago. They have about 2500 miles on them including a total of 4 track days.
The first time I noticed the pulsations was at Daytona Speedway. This was before I changed the rear pads from OEM to Hawk HP+.
The second time was recently at Thunderhill on a 5 mile course. This most recent time, the pulsations became so pronounced that I was braking easier than I would have liked to coming into sharp turns after straightaways.
After each track session was completed and the brakes had been cooled down (with e-brake off), the brakes started the next session fine, but the pulsations came back after the brakes heated up every session.
Other than the above two most recent track days and a slight amount of squealing at the end of slow speed road stops (attributed to the Hawk pads), the brakes have performed as expected.
When I mentioned the brake pulsations to others at the recent track day, the response I received was maybe your rotors are warped. I don't see how that can be the cause as the pulsations go away every time after the brakes have cooled - only to return after they have heated up on the track.
I see no visual evidence of cracking or warping of any of the for rotors.
I will also note that the brakes never seemed to be fading (fresh DOT 4 fluid being used), but that the pulsations were so noticeable under hard braking when hot that the car was vibrating, not just the brake pedal.
I'm looking for some guidance (especially from Brian G) related to my problem. I'd also like to know what if any warranty applies to the GWR 12.88" rotors.