991.2 Carrera - Track Journal!
07-17-2018, 04:14 PM
#32
Rennlist Member
John Mclane: "Fluid fade -
If there is too much energy being transferred to the caliper and fluid, it can boil the fluid. These gas bubbles being compressible, the pedal travel increases and becomes "spongy" with poor modulation. (This is a gradual process with advanced warning). Solutions include: Changing brake fluid to one with a higher boiling point, using a different pad compound with better heat transfer properties, or improving the cooling to prevent the fluid from boiling."
One thing you forgot to mention that is sometimes a factor at track events. The pad is the only thermal insulation between the fluid and the red hot brake rotor. At 50% pad thickness, 50% of thermal insulation is worn away. So, running the pads down thin for economy is a no-no. Our Chicago Region recognizes that, and does not allow a car to run a track event with pads less than 50% of new pad thickness. A wise rule!
If there is too much energy being transferred to the caliper and fluid, it can boil the fluid. These gas bubbles being compressible, the pedal travel increases and becomes "spongy" with poor modulation. (This is a gradual process with advanced warning). Solutions include: Changing brake fluid to one with a higher boiling point, using a different pad compound with better heat transfer properties, or improving the cooling to prevent the fluid from boiling."
One thing you forgot to mention that is sometimes a factor at track events. The pad is the only thermal insulation between the fluid and the red hot brake rotor. At 50% pad thickness, 50% of thermal insulation is worn away. So, running the pads down thin for economy is a no-no. Our Chicago Region recognizes that, and does not allow a car to run a track event with pads less than 50% of new pad thickness. A wise rule!
07-17-2018, 05:09 PM
#33
Rennlist Member
Thread Starter
John Mclane: "Fluid fade -
If there is too much energy being transferred to the caliper and fluid, it can boil the fluid. These gas bubbles being compressible, the pedal travel increases and becomes "spongy" with poor modulation. (This is a gradual process with advanced warning). Solutions include: Changing brake fluid to one with a higher boiling point, using a different pad compound with better heat transfer properties, or improving the cooling to prevent the fluid from boiling."
One thing you forgot to mention that is sometimes a factor at track events. The pad is the only thermal insulation between the fluid and the red hot brake rotor. At 50% pad thickness, 50% of thermal insulation is worn away. So, running the pads down thin for economy is a no-no. Our Chicago Region recognizes that, and does not allow a car to run a track event with pads less than 50% of new pad thickness. A wise rule!
If there is too much energy being transferred to the caliper and fluid, it can boil the fluid. These gas bubbles being compressible, the pedal travel increases and becomes "spongy" with poor modulation. (This is a gradual process with advanced warning). Solutions include: Changing brake fluid to one with a higher boiling point, using a different pad compound with better heat transfer properties, or improving the cooling to prevent the fluid from boiling."
One thing you forgot to mention that is sometimes a factor at track events. The pad is the only thermal insulation between the fluid and the red hot brake rotor. At 50% pad thickness, 50% of thermal insulation is worn away. So, running the pads down thin for economy is a no-no. Our Chicago Region recognizes that, and does not allow a car to run a track event with pads less than 50% of new pad thickness. A wise rule!
07-19-2018, 02:48 PM
#35
Rennlist Member
What are the best DE event tire pressures for a C2S?
07-19-2018, 03:54 PM
#37
Rennlist Member
07-19-2018, 04:33 PM
#38
Rennlist Member
Thanks for your input!!! I have some obligations that will keep me off track for the next month or so, but am planning to be back at Autobahn on 6/18.
I had a similar experience as you with tire pressures...also started out around 30 psi front, 32 rear...had to bleed them 3 times as I drove the car harder and harder and the ambient temp rose.
Castrol SRF is more out of habit than anything else...have used Motul RBF660 in past cars with great success, but have been buying Castrol lately. Will see what the best value is when I swap fluid now, but the easy button is Castrol for me. Thanks for the tips on the rear pads though...will keep an eye on them!!! Will be excited to try new pads after using these for a while.
I had a similar experience as you with tire pressures...also started out around 30 psi front, 32 rear...had to bleed them 3 times as I drove the car harder and harder and the ambient temp rose.
Castrol SRF is more out of habit than anything else...have used Motul RBF660 in past cars with great success, but have been buying Castrol lately. Will see what the best value is when I swap fluid now, but the easy button is Castrol for me. Thanks for the tips on the rear pads though...will keep an eye on them!!! Will be excited to try new pads after using these for a while.
07-19-2018, 09:17 PM
#39
The addiction is real...
I upgraded to Pagid RS29s and Motul 600 last year, and upgraded to SRF this year. SRF is more expensive, but also lasts longer than 600, so the prices are actually closer than just doing an ounce-to-ounce comparison. I have heard good things about Pagid RSL29s, which seem to be the new RS.
I have been starting out at 26 PSI with a hot temp of 34 PSI for PZeroes. I do not think they can handle a full 20-min session on a hot, hilly track. They completely fell off in the last three laps of the last two sessions at my last day at Palmer. They did not feel over inflated, just as though the tires were trying, and failing to grip. I will probably aim for 32 or 33PSI tomorrow, though it is a far less demanding track.
I just replaced my rears this week, and probably jumping to PS4S next year when all four corners are shot. Otherwise, I might just buy a dedicated set of 19"s wheels and track tires.
Edit to add: I am in a .1 C2S
I upgraded to Pagid RS29s and Motul 600 last year, and upgraded to SRF this year. SRF is more expensive, but also lasts longer than 600, so the prices are actually closer than just doing an ounce-to-ounce comparison. I have heard good things about Pagid RSL29s, which seem to be the new RS.
I have been starting out at 26 PSI with a hot temp of 34 PSI for PZeroes. I do not think they can handle a full 20-min session on a hot, hilly track. They completely fell off in the last three laps of the last two sessions at my last day at Palmer. They did not feel over inflated, just as though the tires were trying, and failing to grip. I will probably aim for 32 or 33PSI tomorrow, though it is a far less demanding track.
I just replaced my rears this week, and probably jumping to PS4S next year when all four corners are shot. Otherwise, I might just buy a dedicated set of 19"s wheels and track tires.
Edit to add: I am in a .1 C2S
07-20-2018, 04:43 PM
#40
Rennlist Member
The addiction is real...
I upgraded to Pagid RS29s and Motul 600 last year, and upgraded to SRF this year. SRF is more expensive, but also lasts longer than 600, so the prices are actually closer than just doing an ounce-to-ounce comparison. I have heard good things about Pagid RSL29s, which seem to be the new RS.
I have been starting out at 26 PSI with a hot temp of 34 PSI for PZeroes. I do not think they can handle a full 20-min session on a hot, hilly track. They completely fell off in the last three laps of the last two sessions at my last day at Palmer. They did not feel over inflated, just as though the tires were trying, and failing to grip. I will probably aim for 32 or 33PSI tomorrow, though it is a far less demanding track.
I just replaced my rears this week, and probably jumping to PS4S next year when all four corners are shot. Otherwise, I might just buy a dedicated set of 19"s wheels and track tires.
Edit to add: I am in a .1 C2S
I upgraded to Pagid RS29s and Motul 600 last year, and upgraded to SRF this year. SRF is more expensive, but also lasts longer than 600, so the prices are actually closer than just doing an ounce-to-ounce comparison. I have heard good things about Pagid RSL29s, which seem to be the new RS.
I have been starting out at 26 PSI with a hot temp of 34 PSI for PZeroes. I do not think they can handle a full 20-min session on a hot, hilly track. They completely fell off in the last three laps of the last two sessions at my last day at Palmer. They did not feel over inflated, just as though the tires were trying, and failing to grip. I will probably aim for 32 or 33PSI tomorrow, though it is a far less demanding track.
I just replaced my rears this week, and probably jumping to PS4S next year when all four corners are shot. Otherwise, I might just buy a dedicated set of 19"s wheels and track tires.
Edit to add: I am in a .1 C2S
07-20-2018, 11:52 PM
#41
Rennlist Member
07-21-2018, 09:34 AM
#42
I agree with 19" wheels and Cup2s, or other track tires.
I started at 25PSI cold and ran 32/33 hot yesterday and they felt pretty good, but Thompson is far less demanding than Palmer. They still fell off a bit toward the end of the third and fourth sessions, so they would have probably gotten killed at Palmer.
They are going to feel way too soft if you are used to running higher temps
07-21-2018, 10:20 AM
#43
Rennlist Member
John Mclane: "Fluid fade -
If there is too much energy being transferred to the caliper and fluid, it can boil the fluid. These gas bubbles being compressible, the pedal travel increases and becomes "spongy" with poor modulation. (This is a gradual process with advanced warning). Solutions include: Changing brake fluid to one with a higher boiling point, using a different pad compound with better heat transfer properties, or improving the cooling to prevent the fluid from boiling."
One thing you forgot to mention that is sometimes a factor at track events. The pad is the only thermal insulation between the fluid and the red hot brake rotor. At 50% pad thickness, 50% of thermal insulation is worn away. So, running the pads down thin for economy is a no-no. Our Chicago Region recognizes that, and does not allow a car to run a track event with pads less than 50% of new pad thickness. A wise rule!
If there is too much energy being transferred to the caliper and fluid, it can boil the fluid. These gas bubbles being compressible, the pedal travel increases and becomes "spongy" with poor modulation. (This is a gradual process with advanced warning). Solutions include: Changing brake fluid to one with a higher boiling point, using a different pad compound with better heat transfer properties, or improving the cooling to prevent the fluid from boiling."
One thing you forgot to mention that is sometimes a factor at track events. The pad is the only thermal insulation between the fluid and the red hot brake rotor. At 50% pad thickness, 50% of thermal insulation is worn away. So, running the pads down thin for economy is a no-no. Our Chicago Region recognizes that, and does not allow a car to run a track event with pads less than 50% of new pad thickness. A wise rule!
07-21-2018, 12:17 PM
#44
Rennlist Member
38 hot? Were the center treads wearing out prematurely? That is way too hot for tracks I have run in summer temps; my center treads were wearing a bit faster than the rest of the tire running 37 - 34 hot at the track, and 38 PSI on the street.
I agree with 19" wheels and Cup2s, or other track tires.
I started at 25PSI cold and ran 32/33 hot yesterday and they felt pretty good, but Thompson is far less demanding than Palmer. They still fell off a bit toward the end of the third and fourth sessions, so they would have probably gotten killed at Palmer.
They are going to feel way too soft if you are used to running higher temps
07-21-2018, 12:38 PM
#45
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I'm also impressed with my Porsche C2S showroom stock on track. The suspension is surprisingly buttoned down and very predictable with the stock Pirelli's. Not sure how it will fare with stickies though.