HP+ rotor wear . . . measurements
10-30-2007, 08:45 AM
#1
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HP+ rotor wear . . . measurements
I recently upgraded to HP+ for track use. I have seen a lot of discussion about excessive rotor wear in addition to the noise and dust issues, so I decided to take some measurements. I use ATE super Blue fluid. My car is an otherwise stock base 2005 6MT with appearance package. I am using stock tires (Dunlop 8090's). The pads were bedded-in following Hawk's procedure which is outlined on the box.
I just did a 3-day HPDE with 2 days of dry weather and 1 rain day. Temps were in the 50's for both dry days and upper 60's during the rain day. The event was held at New Hampshire International Speedway which has a 1.6 mile 12-turn road course. We used the chicane-chicane config for those who are familiar. The braking zones are as follows (braking zone entry speeds I am sure of . . . turn-in speeds are estimated since I am not looking down when turning in.)
Turn 1: 101 - 60
Turn 3: 86 - 35
Turn 6: 90 - 55
Turn 9: 88 - 55
Turn 11: 78 - 40
All rotor measurements are taken with an outside micrometer with a range of 0.3-1.3" and a resolution of 0.001". I confirm accuracy with the 0.3" standard at the beginning and end of each measuring session. I take three readings on each rotor and use the lowest reading since most inaccurate readings will be high (i.e if the micrometer is not perfectly perpendicular to the rotor surface.)
I just did a 3-day HPDE with 2 days of dry weather and 1 rain day. Temps were in the 50's for both dry days and upper 60's during the rain day. The event was held at New Hampshire International Speedway which has a 1.6 mile 12-turn road course. We used the chicane-chicane config for those who are familiar. The braking zones are as follows (braking zone entry speeds I am sure of . . . turn-in speeds are estimated since I am not looking down when turning in.)
Turn 1: 101 - 60
Turn 3: 86 - 35
Turn 6: 90 - 55
Turn 9: 88 - 55
Turn 11: 78 - 40
All rotor measurements are taken with an outside micrometer with a range of 0.3-1.3" and a resolution of 0.001". I confirm accuracy with the 0.3" standard at the beginning and end of each measuring session. I take three readings on each rotor and use the lowest reading since most inaccurate readings will be high (i.e if the micrometer is not perfectly perpendicular to the rotor surface.)
Last edited by RX8Maine; 10-30-2007 at 09:41 AM.
10-30-2007, 08:46 AM
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Front Rotors
Front Rotors: OEM (New Spec = 24mm = 0.945"; Minimum Spec = 22mm = 0.866")
Thickness when HP+ installed
---Right: 0.916"
---Left: 0.914"
Calculated wear from OEM pads (18150 total miles, including approx 250 track miles)
---Right: 0.029"
---Left: 0.031"
Thickness when HP+ removed
---Right: 0.913"
---Left: 0.911"
Calculated wear from HP+ pads (820 total miles, 305 track miles)
---Right: 0.003"
---Left: 0.003"
Thickness when HP+ installed
---Right: 0.916"
---Left: 0.914"
Calculated wear from OEM pads (18150 total miles, including approx 250 track miles)
---Right: 0.029"
---Left: 0.031"
Thickness when HP+ removed
---Right: 0.913"
---Left: 0.911"
Calculated wear from HP+ pads (820 total miles, 305 track miles)
---Right: 0.003"
---Left: 0.003"
Last edited by RX8Maine; 10-30-2007 at 08:56 AM.
10-30-2007, 08:55 AM
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Rear Rotors
Rear Rotors: OEM (New Spec = 18mm = 0.709"; Minimum Spec = 16mm = 0.630"); (I bought a new one and it measured out at 0.712")
Thickness when HP+ installed
---Right: 0.712" (NEW rotor, damaged old one measured at 0.705")
---Left: 0.0.708"
Calculated wear from OEM pads (See mileage above; I am using a new thickness of 0.712", as measured)
---Right: 0.007"
---Left: 0.004"
Thickness when HP+ removed
---Right: 0.708"
---Left: 0.705"
Calculated wear from HP+ pads (820 total miles, 305 track miles)
---Right: 0.004"
---Left: 0.003"
Thickness when HP+ installed
---Right: 0.712" (NEW rotor, damaged old one measured at 0.705")
---Left: 0.0.708"
Calculated wear from OEM pads (See mileage above; I am using a new thickness of 0.712", as measured)
---Right: 0.007"
---Left: 0.004"
Thickness when HP+ removed
---Right: 0.708"
---Left: 0.705"
Calculated wear from HP+ pads (820 total miles, 305 track miles)
---Right: 0.004"
---Left: 0.003"
Last edited by RX8Maine; 10-30-2007 at 08:57 AM.
10-30-2007, 09:19 AM
#4
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Calculated wear rates
The OEM pads used the front rotors at a rate of 0.3"/18150 miles = 1.65x10(-6) inches per mile and used the rear rotors at a pretty negligible rate with mostly street driving and 250 miles of track use. Unfortunately, I have no measurements to help determine how much of the wear was caused on the track versus the street.
The Hawk HP+ pads used the front and rear rotors roughly equally at a rate of 3.70x10(-6) per mile, with a slightly higher rate on the right rear that may not be real (the difference is within the resolution of the micrometer).
Given that there were only 505 street miles (75% highway) on the HP+, and that we can assume a much higher wear rate at the track, I am going to assume that all of that wear is attributable to the track. That means that the track wear rate for the HP+ is 0.003"/305 miles = 9.84x10(-6) inches per mile for the front and rear rotors.
The Hawk HP+ pads used the front and rear rotors roughly equally at a rate of 3.70x10(-6) per mile, with a slightly higher rate on the right rear that may not be real (the difference is within the resolution of the micrometer).
Given that there were only 505 street miles (75% highway) on the HP+, and that we can assume a much higher wear rate at the track, I am going to assume that all of that wear is attributable to the track. That means that the track wear rate for the HP+ is 0.003"/305 miles = 9.84x10(-6) inches per mile for the front and rear rotors.
10-30-2007, 09:30 AM
#5
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Objective results
The Hawk HP+ pads used on the track probably cause a higher rate of wear on the rear rotors than OEM, but I do not have enough data to determine whether this is true on the front.
The difference between new spec and minimum spec for both front and rear is 2mm or 0.079". At the calculated rate of 9.84x10(-6) inches per mile for the Hawk HP+ pads, I would expect to get 8000 miles of track use from the rotors, assuming the car is not driven for anything else.
To be conservative, I actually am going to assume that there was negligible rotor wear during my rain day (80 miles) when I was unable to use the brakes as hard. That would give me a new rate of 1.33x10(-5) inches per mile in good weather. I would also never start a track day with less than 22.4/16.4mm or 0.882"/0.646" (F/R). That means I can more conservatively get about 4700 track miles from the rotors. That translates into about 40 days at NHIS, probably fewer elsewhere since higher speeds would mean more miles (and may mean higher wear rates as well.)
The difference between new spec and minimum spec for both front and rear is 2mm or 0.079". At the calculated rate of 9.84x10(-6) inches per mile for the Hawk HP+ pads, I would expect to get 8000 miles of track use from the rotors, assuming the car is not driven for anything else.
To be conservative, I actually am going to assume that there was negligible rotor wear during my rain day (80 miles) when I was unable to use the brakes as hard. That would give me a new rate of 1.33x10(-5) inches per mile in good weather. I would also never start a track day with less than 22.4/16.4mm or 0.882"/0.646" (F/R). That means I can more conservatively get about 4700 track miles from the rotors. That translates into about 40 days at NHIS, probably fewer elsewhere since higher speeds would mean more miles (and may mean higher wear rates as well.)
Last edited by RX8Maine; 10-30-2007 at 09:34 AM.
10-30-2007, 09:53 AM
#6
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Objective conclusion
So, up above I have posted some objective information regarding rotor wear. It is not possible to draw real comparisons to OEM pads given the vast difference in the amount of street use and no way to know how much wear is attributable to it. Despite that, I think that the amount of wear that I saw on the track with the HP+ pads was acceptable even with a conservative estimate of how long I could expect the rotors to last.
10-30-2007, 10:39 AM
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Subjective Review
Installation:
Easy, no issues.
Bed-in:
I have done several bed-in procedures in the past with good results. These pads had a pretty significant rear bias prior to bed-in that made it a little tricky to do the procedure. I had to avoid maximal stopping power because the ABS would kick in on the rears. I did a good long highway cruise for cool-down and there was a noticeable vibration when I started using the brakes again, something that had never happened with the OEM pads, and was not evident in 2 days of around town driving before the bed-in. After bed-in, the rear bias was gone, pedal feel was much better, initial bite was awesome, but that vibration under braking continued. I am not sure where I went wrong, but the ABS did kick on in the rears during 2 of my 3 hard stops.
Drivability around town:
Great initial bite with solid pedal feel and great response. The stopping power seemed to increase dramatically below about 15mph requiring me to decrease pressure on the pedal as I slowed or I would end up stopping short in an violent fashion. That took some getting used to. They had noticeably less stopping power when cold compared to warm, but were always better than OEM, even when cold. (Lowest temp was about 31 degrees F)
Noise:
There was a very narrow window of pedal pressure that would result in a quiet stop. Anything more and anything less made noise. Since I wanted to avoid the head whipping sudden stop below 15mph described above, I always reduced pedal input as I approached my stop, loudly announcing my presence. After 2-3 days I determined exactly how to approach my house so that I could be in the garage before making any noise. I am very happy that these pads or off my car until the next track season!
Dust:
Holy crap, I have never seen so much dust. Not just the wheels, but the side skirts and the entire rear bumper. The wheels didn't look that bad at first, but that was only because the coating on the paint was offsetting it. I am very happy that these pads or off my car until the next track season!
Track:
Wow, what a difference. I will start by saying that I still think anyone wanting to try a track day in the RX8 could go with OEM pads and have a good time. They never faded on me, but I used them up in only 3 days, and I now know that they were simply not capable of generating maximum levels of stopping power at high speed. Anyone beyond the novice stage really needs to upgrade the pads. My braking zones were shorter everywhere, but there are 2 corner sequences at NHIS where that allowed me to gain considerable improvements in my line as a result.
Corners 8-9: [sweeping right hander (8) over the crest of a hill into a downhill braking zone for an off-camber left turn(9)]
OEM Pads: Because of the hillcrest before the braking zone, the car gets unsettled. I used to alter my line through 8 to get straightened out before the hillcrest so that my braking zone would be long enough. It felt safer and did not change my speed through that corner (not cornering at limit due to a preceeding slow turn), but I was traveling a longer distance. I would then brake early for the left turn. Despite this, the brake zone would still extent past the optimal turn-in point requiring me to turn-in late, use a tigher radius, losing momentum. I was actually forced to brake MORE as a result, but this was the best it got.
HP+: Dramatically shorter braking zone! I was able to hug the right side of the track all the way through turn 8, with a slight drift out over the hillcrest. Same speed through that corner, but shorter distance and on the throttle longer. The brake zone was shorter at both ends. I would brake later and start my turn-in earlier with a trail-brake into turn 9 carrying much more speed.
Corners 10-11: [downhill right turn (10) into short straight which sets up braking zone into a slow left turn (11) leading onto the main straight
OEM pads: I had optimized my approach into turn 11 so that I could carry as much speed onto the main straight as possible. To have a long enough braking zone, I needed to pinch the track-out from turn 10 and cross to the right side of the straight and turn left into the braking zone. I was making an pronounced s-turn on the straight!
HP+: Again, dramatically shorter braking zone. I could carry all the speed I wanted out of turn 10 (which was benefitting from the turn 8-9 improvements described above), track all the way out to the left, and then make a very subtle left sweep into the braking zone. It felt like it took no more than a tap of the foot to scrub off 40mph of speed and trail-brake into the corner. My exit from turn 11 didn't change, but I was no longer cheating the previous straight in order to set up the longer straight. I was able to maximize them both.
Overall:
Great track pads for OEM suspension and street tires. Terrible daily driver pads.
Easy, no issues.
Bed-in:
I have done several bed-in procedures in the past with good results. These pads had a pretty significant rear bias prior to bed-in that made it a little tricky to do the procedure. I had to avoid maximal stopping power because the ABS would kick in on the rears. I did a good long highway cruise for cool-down and there was a noticeable vibration when I started using the brakes again, something that had never happened with the OEM pads, and was not evident in 2 days of around town driving before the bed-in. After bed-in, the rear bias was gone, pedal feel was much better, initial bite was awesome, but that vibration under braking continued. I am not sure where I went wrong, but the ABS did kick on in the rears during 2 of my 3 hard stops.
Drivability around town:
Great initial bite with solid pedal feel and great response. The stopping power seemed to increase dramatically below about 15mph requiring me to decrease pressure on the pedal as I slowed or I would end up stopping short in an violent fashion. That took some getting used to. They had noticeably less stopping power when cold compared to warm, but were always better than OEM, even when cold. (Lowest temp was about 31 degrees F)
Noise:
There was a very narrow window of pedal pressure that would result in a quiet stop. Anything more and anything less made noise. Since I wanted to avoid the head whipping sudden stop below 15mph described above, I always reduced pedal input as I approached my stop, loudly announcing my presence. After 2-3 days I determined exactly how to approach my house so that I could be in the garage before making any noise. I am very happy that these pads or off my car until the next track season!
Dust:
Holy crap, I have never seen so much dust. Not just the wheels, but the side skirts and the entire rear bumper. The wheels didn't look that bad at first, but that was only because the coating on the paint was offsetting it. I am very happy that these pads or off my car until the next track season!
Track:
Wow, what a difference. I will start by saying that I still think anyone wanting to try a track day in the RX8 could go with OEM pads and have a good time. They never faded on me, but I used them up in only 3 days, and I now know that they were simply not capable of generating maximum levels of stopping power at high speed. Anyone beyond the novice stage really needs to upgrade the pads. My braking zones were shorter everywhere, but there are 2 corner sequences at NHIS where that allowed me to gain considerable improvements in my line as a result.
Corners 8-9: [sweeping right hander (8) over the crest of a hill into a downhill braking zone for an off-camber left turn(9)]
OEM Pads: Because of the hillcrest before the braking zone, the car gets unsettled. I used to alter my line through 8 to get straightened out before the hillcrest so that my braking zone would be long enough. It felt safer and did not change my speed through that corner (not cornering at limit due to a preceeding slow turn), but I was traveling a longer distance. I would then brake early for the left turn. Despite this, the brake zone would still extent past the optimal turn-in point requiring me to turn-in late, use a tigher radius, losing momentum. I was actually forced to brake MORE as a result, but this was the best it got.
HP+: Dramatically shorter braking zone! I was able to hug the right side of the track all the way through turn 8, with a slight drift out over the hillcrest. Same speed through that corner, but shorter distance and on the throttle longer. The brake zone was shorter at both ends. I would brake later and start my turn-in earlier with a trail-brake into turn 9 carrying much more speed.
Corners 10-11: [downhill right turn (10) into short straight which sets up braking zone into a slow left turn (11) leading onto the main straight
OEM pads: I had optimized my approach into turn 11 so that I could carry as much speed onto the main straight as possible. To have a long enough braking zone, I needed to pinch the track-out from turn 10 and cross to the right side of the straight and turn left into the braking zone. I was making an pronounced s-turn on the straight!
HP+: Again, dramatically shorter braking zone. I could carry all the speed I wanted out of turn 10 (which was benefitting from the turn 8-9 improvements described above), track all the way out to the left, and then make a very subtle left sweep into the braking zone. It felt like it took no more than a tap of the foot to scrub off 40mph of speed and trail-brake into the corner. My exit from turn 11 didn't change, but I was no longer cheating the previous straight in order to set up the longer straight. I was able to maximize them both.
Overall:
Great track pads for OEM suspension and street tires. Terrible daily driver pads.
10-30-2007, 11:58 AM
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I love the pads as they allow me to simply bleed brakes for track day prep, saving the swap time. Given that I track about once a month, that means I'm only replacing pads about every 4th or 5th track event. Great flexibility and they can take a beating on the track- much more so on our cars than on other cars which I've tried using them on.
So, yes, not a good choice for daily driving (noise and dust), yet if your daily driving is simply a means to pass the time between track days, then yes, it's a great pad. If my car were not a daily driver, I'd be using a dedicated track compound.
As for the rotor wear comments, I've read them on several boards but have not experienced excessive rotor wear myself via the use of the pads (no cracked rotors, no excessive outer lip)- at least not excessive for what the pads do for you- brake at the track in the brake zone and brake at the stoplight on the way home.
So, yes, not a good choice for daily driving (noise and dust), yet if your daily driving is simply a means to pass the time between track days, then yes, it's a great pad. If my car were not a daily driver, I'd be using a dedicated track compound.
As for the rotor wear comments, I've read them on several boards but have not experienced excessive rotor wear myself via the use of the pads (no cracked rotors, no excessive outer lip)- at least not excessive for what the pads do for you- brake at the track in the brake zone and brake at the stoplight on the way home.
Last edited by SouthFL; 10-30-2007 at 12:03 PM.
10-30-2007, 02:19 PM
#10
Momentum Keeps Me Going
You've been having a good time analyzing how best to negotiate NHIS I see 
RX8Maine. Careful planning how the car behaves and where and when to do what is essential. Things happen fast on that small track and good reliable braking allows focus on line & handling while braking is kind of automatic.
Good to see the HP+ are working good for you. Nice research & write up. It's interesting walking around the pits and hearing how peoples brakes are giving problems. NHIS is so tough on many brakes, just not ours fortunately.
RX8Maine. Careful planning how the car behaves and where and when to do what is essential. Things happen fast on that small track and good reliable braking allows focus on line & handling while braking is kind of automatic. Good to see the HP+ are working good for you. Nice research & write up. It's interesting walking around the pits and hearing how peoples brakes are giving problems. NHIS is so tough on many brakes, just not ours fortunately.
10-30-2007, 02:48 PM
#12
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I never really gave the ceramics a thought until after I had purchased, but I may go with them next. Have you tried them both? Do the ceramics really work as well on the track? It would be nice to avoid swapping, even though its quick.
10-30-2007, 03:05 PM
#13
The current story is that the Hawk ceramics provide the same performance as the HP+ but without all the squeaking and dusting.
I'm not sure yet as I have yet to get them in, but as soon as I get a chance to take em out to the track I'll definitely write up a review...
I'm not sure yet as I have yet to get them in, but as soon as I get a chance to take em out to the track I'll definitely write up a review...
10-30-2007, 03:23 PM
#14
The hawk performance ceramic pads provide the same stopping power has the hawk hps not the hawk hp + pads. The hp + pads are meant to be track day pads aren't are not with noise or dust in mind. The hawk hps is a performance street pad. The hawk ceramic is a performance street pad with less noise and dust.
This is after reading about these 3 pads on hawks website and checking out user ratings on tirerack.com
This is after reading about these 3 pads on hawks website and checking out user ratings on tirerack.com
10-30-2007, 03:36 PM
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The hawk performance ceramic pads provide the same stopping power has the hawk hps not the hawk hp + pads. The hp + pads are meant to be track day pads aren't are not with noise or dust in mind. The hawk hps is a performance street pad. The hawk ceramic is a performance street pad with less noise and dust.
This is after reading about these 3 pads on hawks website and checking out user ratings on tirerack.com
This is after reading about these 3 pads on hawks website and checking out user ratings on tirerack.com
10-30-2007, 03:39 PM
#16
The hawk performance ceramic pads provide the same stopping power has the hawk hps not the hawk hp + pads. The hp + pads are meant to be track day pads aren't are not with noise or dust in mind. The hawk hps is a performance street pad. The hawk ceramic is a performance street pad with less noise and dust.
This is after reading about these 3 pads on hawks website and checking out user ratings on tirerack.com
This is after reading about these 3 pads on hawks website and checking out user ratings on tirerack.com
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