Is COTA hard on brakes? Ayep.
09-06-2016, 08:04 PM
#16
Rennlist Member
I tend to analyze it like this:
Laguna Seca at a moderate pace. lets say T2 SCCA record pace. (3300lb car with about 320rwhp) 1:39 lap time
in the first 1:10 seconds from start finish, you have 3 x 120/130mph to 40mph
(and one 110 to 85 and 80 to 60 braking zones)
for the next 1:30 you have one 110 to 80mph zone and a 110 to 40mph zone
COTA 2:30 lap time for T2 SCCA (stock'sh mustang GT)
0-1:00 you start out 130mph down to 40mph
1:32 150-40mph
1:40 80 to 50mph
so, over the first time period like laguna at 1:40ish total elapsed time, you do a lot less braking KE vs time
then, the next period of time to make your 2:30-2:35 lap time:
1:51 90-40mph
2:10 105 to 65
2:25 100 to 45
that would be a LOT less than the next lap of laguna seca for the next min.
By comparing like for like braking forces and times, you can see what is the most taxing on the brakes is that one 150 to 40mph straight to turn-in, but overall there is plenty of time for cooling and for a given 30min race, there should be little difference in the wear on the brake system or temps.
Dave hit it on the head by saying its one of the most taxing tracks on brakes around. But there are a few that are harder or at least equal.
Here is a video of COTA via a T2 car at 3300lbs +
09-07-2016, 08:36 AM
#17
Burning Brakes
I have an answer for you ... stopping power of the ST-41, that wont kill the rotors. basically as nice to rotors as the Pagid blacks but higher temp rating.
try them... you will not be disappointed.
however, i dont know what rotors the Supra has, but generally, they are very thin on the far-eastern econ-o boxes. sometimes if they are too thin, no matter what you do, a track like daytona can kill them. sounds like you put heat in and out of the rotors and it couldnt take it... the main problem with daytona is that you get things really hot and then relatively cool every lap... that expansion and contraction causes a thinner rotor to crack. Porsches come stock with 32mm thick rotors with great metallurgy qualities. you need to find this to help the rotors survive some uses.
try them... you will not be disappointed.
however, i dont know what rotors the Supra has, but generally, they are very thin on the far-eastern econ-o boxes. sometimes if they are too thin, no matter what you do, a track like daytona can kill them. sounds like you put heat in and out of the rotors and it couldnt take it... the main problem with daytona is that you get things really hot and then relatively cool every lap... that expansion and contraction causes a thinner rotor to crack. Porsches come stock with 32mm thick rotors with great metallurgy qualities. you need to find this to help the rotors survive some uses.
(Supra rotors look a lot like plain 1984 era Carrera rotors. We use Stop-Tech slotted, and have cooling ducts on the front.)
09-07-2016, 10:19 AM
#18
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Mark - this is where data comes in. There is no need to guess or ball park KE or anything else. Even with a simple GPS Long G, we can figure out total distance on the brakes, time on the brakes, total speed loss in G or time (at 1 G). Then if you add some specific sensors like brake temp (IR or rubbing), you can easily determine total brake heat added, total cooling, heat rise time, cool time, etc.
This is why data is important for a full effort and development of a system. Anything else is guessing.
This is why data is important for a full effort and development of a system. Anything else is guessing.
09-07-2016, 10:40 AM
#19
Drifting
Thread Starter
Mark - this is where data comes in. There is no need to guess or ball park KE or anything else. Even with a simple GPS Long G, we can figure out total distance on the brakes, time on the brakes, total speed loss in G or time (at 1 G). Then if you add some specific sensors like brake temp (IR or rubbing), you can easily determine total brake heat added, total cooling, heat rise time, cool time, etc.
This is why data is important for a full effort and development of a system. Anything else is guessing.
This is why data is important for a full effort and development of a system. Anything else is guessing.
My track memory is truly horrible. If not for video and data I wouldn't be able to figure much out.
-Mike
09-07-2016, 10:57 AM
#20
Rennlist Member
Mark - this is where data comes in. There is no need to guess or ball park KE or anything else. Even with a simple GPS Long G, we can figure out total distance on the brakes, time on the brakes, total speed loss in G or time (at 1 G). Then if you add some specific sensors like brake temp (IR or rubbing), you can easily determine total brake heat added, total cooling, heat rise time, cool time, etc. This is why data is important for a full effort and development of a system. Anything else is guessing.
09-07-2016, 01:06 PM
#21
Rennlist Member
dont get too excited. you can learn quite a bit of information with video. usually, not always, its enough. in this case we are just looking at what tracks are harder or hard on brakes and why. you just look at the decel occurrences and their spacing and you get a REAL good idea. its not like you are going to make some major changes.. just an understanding of the playing field. that's it.
usually most of ours are the same. the video is a great reminder of what happens. my advice would be more downshifting when decelling for a red flag and less brakes. certainly you want your foot totally off the brakes as much as possible as you slow and as you sit
Yep, no argument there. but, anything else is not "guessing", it's just old school, manual. perfectly acceptatble if you dont have the "data" or equipment to gather it.
I've given you , based on the video the number of slow downs and their spacing. guessing would be the "decl rates" which are important, but not essential for the answer i was looking for. I have time of brake engagement and frequency per period of time. you can see that COTA is no different and probably even a little easier on the brakes based on this "gross" information compared to laguna. Just an interesting comparison, not a guess, a ball park estimation. In science , sport and other disciplines its not uncommon to look at factors this way first and then back it up or contradict it with the actual data afterwards.
If you have actual data of same car at both tracks like what might be found from a SCCA T2 or WCGT/GTS car, that would be very interesting. i would imagine based on the video, that both tracks are near equally hard on brakes over a given time period. However, that one turn approach from 150 is going to be given a LOT of weight factor, right?
NO , not the ST41, they are rotor chewers!!!!! the PFC-11s you should try! you will not be disappointed. if you have stoptech rotors and are having these issues then my recommendation should work well. i use that size and grade rotor as well with a heavier car going a little faster, so you should be in good shape.
One very minor thing I like about having data is afterwards I questioned if I sat there with my foot on the brake the whole time while worrying about the "oil leak". Not a good thing to do with literally smoking hot brakes. Data clearly shows I didn't.
My track memory is truly horrible. If not for video and data I wouldn't be able to figure much out.
-Mike
My track memory is truly horrible. If not for video and data I wouldn't be able to figure much out.
-Mike
Mark - this is where data comes in. There is no need to guess or ball park KE or anything else. Even with a simple GPS Long G, we can figure out total distance on the brakes, time on the brakes, total speed loss in G or time (at 1 G). Then if you add some specific sensors like brake temp (IR or rubbing), you can easily determine total brake heat added, total cooling, heat rise time, cool time, etc.
This is why data is important for a full effort and development of a system. Anything else is guessing.
This is why data is important for a full effort and development of a system. Anything else is guessing.
I've given you , based on the video the number of slow downs and their spacing. guessing would be the "decl rates" which are important, but not essential for the answer i was looking for. I have time of brake engagement and frequency per period of time. you can see that COTA is no different and probably even a little easier on the brakes based on this "gross" information compared to laguna. Just an interesting comparison, not a guess, a ball park estimation. In science , sport and other disciplines its not uncommon to look at factors this way first and then back it up or contradict it with the actual data afterwards.
If you have actual data of same car at both tracks like what might be found from a SCCA T2 or WCGT/GTS car, that would be very interesting. i would imagine based on the video, that both tracks are near equally hard on brakes over a given time period. However, that one turn approach from 150 is going to be given a LOT of weight factor, right?
Thanks for the advice on the ST-41. We'll give them a try in the next race, which will probably be Rd Atlanta in Feb 2017. The 24 hr at VIR pretty much wore out our car completely.
(Supra rotors look a lot like plain 1984 era Carrera rotors. We use Stop-Tech slotted, and have cooling ducts on the front.)
(Supra rotors look a lot like plain 1984 era Carrera rotors. We use Stop-Tech slotted, and have cooling ducts on the front.)
09-07-2016, 01:42 PM
#22
Burning Brakes
NO , not the ST41, they are rotor chewers!!!!! the PFC-11s you should try! you will not be disappointed. if you have stoptech rotors and are having these issues then my recommendation should work well. i use that size and grade rotor as well with a heavier car going a little faster, so you should be in good shape.
The ones we have found that fit are made by EBC, Porterfield, Raybestos, Carbotech, and G-LOC.
09-07-2016, 01:46 PM
#23
Rennlist Member
Try Carbotech
09-07-2016, 01:49 PM
#24
Rennlist Member
Matt and Dave,.... just did a quick review of the numbers based on the video of the same class car running the same comparative lap times
Here is some interesting information. (using the old familiar "VR"s instead of Joules) ( * a VR is speed^2 in MPH x 1/2 weight in lbs)
Total energy decelerating for both tracks for a 3000lb car running near record T2 SCCA lap times. 1:39 Laguna and 2:31 for COTA
COTA 87.87M VR's over 2:31 time period
Laguna SECA 84.3M VR's over a 1:39 time period
IN 40% less time, Laguna burns up near the same total energy braking
LAGUNA SECA over the first 1:10 , is 60.1M VR's
COTA over the first 1:10 is 20.95 VR's
in the first 1:40 seconds of a lap of COTA, equal to a lap of Laguna,
laguna seca 84.3M VRs
COTA 55.95M VRs
Laguna burns up 50% more energy slowing than COTA in the first 1:40.
in the last min of COTA , you only burn up 31.92M VRs
vs what would be the next lap of Laguna seca to turn 6, or 49.9M VRs. or 30% more energy for the last part of COTA
summary:
in the first 1:40 seconds of both tracks , braking at laguna is 50% harder
in the next 1min or so at COTA, Laguna is 30% harder. over all, its 40% harder on brakes for the same time period of a 2:31 lap at COTA
so you can see, laguna is FAR harder on brakes. not even close
you can grab all the data you want and it wont be much different than the numbers i provided above.
if someone has information or ideas that might be to the contrary, i would love to hear it, but i thought this was an interesting exercise on comparing braking energy over the same period of time to see which track might be harder.
i left out a few of the brake taps (braking for less than .5 seconds) for both track as i didn't see them altering the numbers significantly.
Here is some interesting information. (using the old familiar "VR"s instead of Joules) ( * a VR is speed^2 in MPH x 1/2 weight in lbs)
Total energy decelerating for both tracks for a 3000lb car running near record T2 SCCA lap times. 1:39 Laguna and 2:31 for COTA
COTA 87.87M VR's over 2:31 time period
Laguna SECA 84.3M VR's over a 1:39 time period
IN 40% less time, Laguna burns up near the same total energy braking
LAGUNA SECA over the first 1:10 , is 60.1M VR's
COTA over the first 1:10 is 20.95 VR's
in the first 1:40 seconds of a lap of COTA, equal to a lap of Laguna,
laguna seca 84.3M VRs
COTA 55.95M VRs
Laguna burns up 50% more energy slowing than COTA in the first 1:40.
in the last min of COTA , you only burn up 31.92M VRs
vs what would be the next lap of Laguna seca to turn 6, or 49.9M VRs. or 30% more energy for the last part of COTA
summary:
in the first 1:40 seconds of both tracks , braking at laguna is 50% harder
in the next 1min or so at COTA, Laguna is 30% harder. over all, its 40% harder on brakes for the same time period of a 2:31 lap at COTA
so you can see, laguna is FAR harder on brakes. not even close
you can grab all the data you want and it wont be much different than the numbers i provided above.
if someone has information or ideas that might be to the contrary, i would love to hear it, but i thought this was an interesting exercise on comparing braking energy over the same period of time to see which track might be harder.
i left out a few of the brake taps (braking for less than .5 seconds) for both track as i didn't see them altering the numbers significantly.
Mark - this is where data comes in. There is no need to guess or ball park KE or anything else. Even with a simple GPS Long G, we can figure out total distance on the brakes, time on the brakes, total speed loss in G or time (at 1 G). Then if you add some specific sensors like brake temp (IR or rubbing), you can easily determine total brake heat added, total cooling, heat rise time, cool time, etc.
This is why data is important for a full effort and development of a system. Anything else is guessing.
This is why data is important for a full effort and development of a system. Anything else is guessing.
Last edited by mark kibort; 09-07-2016 at 01:58 PM. Reason: spelling
09-07-2016, 02:00 PM
#25
Burning Brakes
We tried the Carbotech RP2 in the fronts and XP10 in the rear and liked them. The fronts lasted through a 14 hour at Rd Atlanta and looked like they had maybe 1-2 more hours in them. The rears were good enough to use for another 2 races.
Maybe I'm looking for a unicorn, hoping for a relatively small pad that will fit a stock caliper in a heavy car, and still last 24 hours. Having to change pads in the middle of the night cost us about 25 minutes, but most people had to change, I think.
No big deal, appreciate the info.
Maybe I'm looking for a unicorn, hoping for a relatively small pad that will fit a stock caliper in a heavy car, and still last 24 hours. Having to change pads in the middle of the night cost us about 25 minutes, but most people had to change, I think.
No big deal, appreciate the info.
09-07-2016, 02:09 PM
#26
Rennlist Member
what calipers do you have? im using a VERY small pad (stoptech ST40 size) and have had great luck with PFC-01 or 11s. However, see if pagid makes a pad for you in a RS14.. again, same type of performance, that wont chew rotors.
We tried the Carbotech RP2 in the fronts and XP10 in the rear and liked them. The fronts lasted through a 14 hour at Rd Atlanta and looked like they had maybe 1-2 more hours in them. The rears were good enough to use for another 2 races.
Maybe I'm looking for a unicorn, hoping for a relatively small pad that will fit a stock caliper in a heavy car, and still last 24 hours. Having to change pads in the middle of the night cost us about 25 minutes, but most people had to change, I think.
No big deal, appreciate the info.
Maybe I'm looking for a unicorn, hoping for a relatively small pad that will fit a stock caliper in a heavy car, and still last 24 hours. Having to change pads in the middle of the night cost us about 25 minutes, but most people had to change, I think.
No big deal, appreciate the info.
09-07-2016, 03:38 PM
#27
Rennlist Member
Looks like Road America is on par with Laguna Seca for hardest on brakes.
in the first 1:40 of RA (equal to one lap at laguna seca), Road america at a 2:25 pace is 86.5M VR's slightly higher than laguna seca
(using jason Hart's newest video from RA )
but over all. both tracks AVERAGE decelleration power required for an entire lap is about the same (about 50M/min VR's )
overall Road america requires near 120.7M VR's which is 43% more energy to decel than COTA with closer full lap times 2:31 vs 2:25
Here is my data from the video:
7 major decels over a lap
145-80MPH turn 1 21.9M VR's
118-70 turn 2 13.6M VRs
147-50 turn 3 28.7M VRs
90-65 turn 4 5.9M VRs
120-60 turn 6 16.2M VRs
___________1:40 86.5M (SUBTOTAL) VR's to this point
145-65 into canada corner region
105-70 final turn and to finish line after this turn
_____________
120.7M VR's for an entire lap
in the first 1:40 of RA (equal to one lap at laguna seca), Road america at a 2:25 pace is 86.5M VR's slightly higher than laguna seca
(using jason Hart's newest video from RA )
but over all. both tracks AVERAGE decelleration power required for an entire lap is about the same (about 50M/min VR's )
overall Road america requires near 120.7M VR's which is 43% more energy to decel than COTA with closer full lap times 2:31 vs 2:25
Here is my data from the video:
7 major decels over a lap
145-80MPH turn 1 21.9M VR's
118-70 turn 2 13.6M VRs
147-50 turn 3 28.7M VRs
90-65 turn 4 5.9M VRs
120-60 turn 6 16.2M VRs
___________1:40 86.5M (SUBTOTAL) VR's to this point
145-65 into canada corner region
105-70 final turn and to finish line after this turn
_____________
120.7M VR's for an entire lap
Matt and Dave,.... just did a quick review of the numbers based on the video of the same class car running the same comparative lap times
Here is some interesting information. (using the old familiar "VR"s instead of Joules) ( * a VR is speed^2 in MPH x 1/2 weight in lbs)
Total energy decelerating for both tracks for a 3000lb car running near record T2 SCCA lap times. 1:39 Laguna and 2:31 for COTA
COTA 87.87M VR's over 2:31 time period
Laguna SECA 84.3M VR's over a 1:39 time period
IN 40% less time, Laguna burns up near the same total energy braking
LAGUNA SECA over the first 1:10 , is 60.1M VR's
COTA over the first 1:10 is 20.95 VR's
in the first 1:40 seconds of a lap of COTA, equal to a lap of Laguna,
laguna seca 84.3M VRs
COTA 55.95M VRs
Laguna burns up 50% more energy slowing than COTA in the first 1:40.
in the last min of COTA , you only burn up 31.92M VRs
vs what would be the next lap of Laguna seca to turn 6, or 49.9M VRs. or 30% more energy for the last part of COTA
summary:
in the first 1:40 seconds of both tracks , braking at laguna is 50% harder
in the next 1min or so at COTA, Laguna is 30% harder. over all, its 40% harder on brakes for the same time period of a 2:31 lap at COTA
so you can see, laguna is FAR harder on brakes. not even close
you can grab all the data you want and it wont be much different than the numbers i provided above.
if someone has information or ideas that might be to the contrary, i would love to hear it, but i thought this was an interesting exercise on comparing braking energy over the same period of time to see which track might be harder.
i left out a few of the brake taps (braking for less than .5 seconds) for both track as i didn't see them altering the numbers significantly.
Here is some interesting information. (using the old familiar "VR"s instead of Joules) ( * a VR is speed^2 in MPH x 1/2 weight in lbs)
Total energy decelerating for both tracks for a 3000lb car running near record T2 SCCA lap times. 1:39 Laguna and 2:31 for COTA
COTA 87.87M VR's over 2:31 time period
Laguna SECA 84.3M VR's over a 1:39 time period
IN 40% less time, Laguna burns up near the same total energy braking
LAGUNA SECA over the first 1:10 , is 60.1M VR's
COTA over the first 1:10 is 20.95 VR's
in the first 1:40 seconds of a lap of COTA, equal to a lap of Laguna,
laguna seca 84.3M VRs
COTA 55.95M VRs
Laguna burns up 50% more energy slowing than COTA in the first 1:40.
in the last min of COTA , you only burn up 31.92M VRs
vs what would be the next lap of Laguna seca to turn 6, or 49.9M VRs. or 30% more energy for the last part of COTA
summary:
in the first 1:40 seconds of both tracks , braking at laguna is 50% harder
in the next 1min or so at COTA, Laguna is 30% harder. over all, its 40% harder on brakes for the same time period of a 2:31 lap at COTA
so you can see, laguna is FAR harder on brakes. not even close
you can grab all the data you want and it wont be much different than the numbers i provided above.
if someone has information or ideas that might be to the contrary, i would love to hear it, but i thought this was an interesting exercise on comparing braking energy over the same period of time to see which track might be harder.
i left out a few of the brake taps (braking for less than .5 seconds) for both track as i didn't see them altering the numbers significantly.
Last edited by mark kibort; 09-07-2016 at 03:52 PM. Reason: show work for total energy used for decel over a lap
09-10-2016, 06:27 PM
#28
Drifting
Thread Starter
Brand new canopy weights
Passenger side rotor cracked in 5 places. Driver side rotor cracked in 3-4 places. Fortunately disassembly was without drama. If it wasn't for UPS, I'd be able to reassemble new friction rings this weekend.
Interestingly, neither backside was cracked, only the outside surfaces. I also believe the cracked after the last session as I didn't feel or hear anything in the brakes to suspect they were cracked earlier. I also changed the LF tire just before the session and surely would have noticed a cracked rotor at the time. Brake pads are fine.
-Mike
Interestingly, neither backside was cracked, only the outside surfaces. I also believe the cracked after the last session as I didn't feel or hear anything in the brakes to suspect they were cracked earlier. I also changed the LF tire just before the session and surely would have noticed a cracked rotor at the time. Brake pads are fine.
-Mike
09-10-2016, 08:43 PM
#29
Rennlist Member
After our experience this weekend with a completely cracked through rotor at Hallett, I am certain it was caused by insufficient cool down. I never realized how important that ONE lap was to the integrity of your rotors.
Passenger side rotor cracked in 5 places. Driver side rotor cracked in 3-4 places. Fortunately disassembly was without drama. If it wasn't for UPS, I'd be able to reassemble new friction rings this weekend.
Interestingly, neither backside was cracked, only the outside surfaces. I also believe the cracked after the last session as I didn't feel or hear anything in the brakes to suspect they were cracked earlier. I also changed the LF tire just before the session and surely would have noticed a cracked rotor at the time. Brake pads are fine.
-Mike
Interestingly, neither backside was cracked, only the outside surfaces. I also believe the cracked after the last session as I didn't feel or hear anything in the brakes to suspect they were cracked earlier. I also changed the LF tire just before the session and surely would have noticed a cracked rotor at the time. Brake pads are fine.
-Mike
09-10-2016, 08:54 PM
#30
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www.peterkrause.net
www.gofasternow.com
"Combining the Art and Science of Driving Fast!"
Specializing in Professional, Private Driver Performance Evaluation and Optimization
Consultation Available Remotely and at VIRginia International Raceway