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PostPosted: Thu Jan 07, 2010 12:06 pm 
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Make sure you have done your homework before deciding on a dedicated race pad. Hawk HT-10's are a very good pad, but they are designed to be used with race tires, not street tires. If you plan to run Hawks with street tires I'd recommend their HP Plus compound.

If you decide to run any Hawk pads there is also another thing to consider, the pad deposits left behind. With any Hawks I'd recommend using dedicated rotors to those pads. If you swap your street pads back onto the rotors afterwards you will likely get a bad shudder. Ask me how I know.

It's a shame BHP went bust because I had EXCELLENT results with their race pads. They could also be swapped in and out with my street pads with no ill affects.

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PostPosted: Thu Jan 07, 2010 12:10 pm 
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Vincent Keene wrote:
Make sure you have done your homework before deciding on a dedicated race pad. Hawk HT-10's are a very good pad, but they are designed to be used with race tires, not street tires. If you plan to run Hawks with street tires I'd recommend their HP Plus compound.

If you decide to run any Hawk pads there is also another thing to consider, the pad deposits left behind. With any Hawks I'd recommend using dedicated rotors to those pads. If you swap your street pads back onto the rotors afterwards you will likely get a bad shudder. Ask me how I know.

It's a shame BHP went bust because I had EXCELLENT results with their race pads. They could also be swapped in and out with my street pads with no ill affects.
Any track pad (for use with street tires) that is ok to put street pads back onto the same rotors after an event?

Do most of you HPDE-ing an otherwise street car just swap the front pads (rotors)?

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PostPosted: Thu Jan 07, 2010 12:21 pm 
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JamesShort wrote:
Any track pad (for use with street tires) that is ok to put street pads back onto the same rotors after an event?


I can only speak about Hawks, but for example if you run their HP+ compound (good with street tires) you would want to swap them out (or at least I would) because they dust really bad on your street wheels. Therefore I would have dedicated rotors because swapping regular street pads back onto the same rotors will likely cause a shudder. On my car this shudder was pretty bad.

JamesShort wrote:
Do most of you HPDE-ing an otherwise street car just swap the front pads (rotors)?


This is what I do, but party because my rears are much more difficult to change.

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PostPosted: Thu Jan 07, 2010 12:51 pm 
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How frequently do you HPDE/TT folks change your brake fluid? If I want to do my first HPDE in the next few months, should I change out the original stuff (car mfg date is 02/09 and it has 5k miles on it)? My intention was probably a flush with super ate in the summer, but maybe I should do it earlier.

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PostPosted: Thu Jan 07, 2010 1:01 pm 
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JamesShort wrote:
How frequently do you HPDE/TT folks change your brake fluid? If I want to do my first HPDE in the next few months, should I change out the original stuff (car mfg date is 02/09 and it has 5k miles on it)? My intention was probably a flush with super ate in the summer, but maybe I should do it earlier.


most organizations require the fluid to be no older than 90 days IIRC

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PostPosted: Thu Jan 07, 2010 1:08 pm 
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clinehall wrote:
JamesShort wrote:
How frequently do you HPDE/TT folks change your brake fluid? If I want to do my first HPDE in the next few months, should I change out the original stuff (car mfg date is 02/09 and it has 5k miles on it)? My intention was probably a flush with super ate in the summer, but maybe I should do it earlier.


most organizations require the fluid to be no older than 90 days IIRC
Good to know, more reason to get the motive 107 bleeder now rather than later :).

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PostPosted: Thu Jan 07, 2010 3:23 pm 
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clinehall wrote:
most organizations require the fluid to be no older than 90 days IIRC


I have never heard or read that. It is up to the discretion of driver. Plus there is not way to check it.

I change mine twice a year in the Camaro...beginning of the race season and the towards the middle of the season. Just because. Since I have switched to Castrol SRF, it will probably be less.

I need to post the photo of my front brakes glowing red braking into turn 1 at Summit :-) and that is with ducting.

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PostPosted: Thu Jan 07, 2010 3:26 pm 
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jimpastorius wrote:
I change mine twice a year in the Camaro...beginning of the race season and the towards the middle of the season. Just because. Since I have switched to Castrol SRF, it will probably be less.


Interesting. I change mine before every HPDE event. It's cheap enough and easy as pie for me with the Motive power bleeder.

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'06 Ford Mustang GT (track rat)
'15 Dodge Charger R/T (yeah, it's got a HEMI!)
'07 Ford Fusion SE (205,000 miles and counting)
'98 Chevy Z-24 (retired)
'93 Acura Integra (Team SWB 24HOL Car)


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 Post subject: Pads and Fluids
PostPosted: Thu Jan 07, 2010 5:55 pm 
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I hate working the course at autox and I must tell you about it, often.

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Vincent,

With Hawk DTC70/60 for track I ran Hawk Ceramics for street. Their new so-called performance pad in ceramic. Their fine for street use. Super low dust and no mess. Easy to clean off wheels. I put them on right behind the DTC pads with no problems. No shudder, no bedding. Just swap and drive to work on Monday.

Jim is running Castrol SRF. That is the super brake fluid. Somewhere around $90/pint. It lasts a very long time and constant bleeding is not required. The cheaper race fluid most of us use, Motul RBF, Super ATE (yellow or blue), and similar $15-$20/pint stuff doesn't come close. I'm tempted to convert over to the Castrol just to end that constant bleeding.

Graham

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PostPosted: Fri Jan 08, 2010 12:17 pm 
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jimpastorius wrote:
clinehall wrote:
most organizations require the fluid to be no older than 90 days IIRC


I have never heard or read that. It is up to the discretion of driver. Plus there is not way to check it.

I change mine twice a year in the Camaro...beginning of the race season and the towards the middle of the season. Just because. Since I have switched to Castrol SRF, it will probably be less.

I need to post the photo of my front brakes glowing red braking into turn 1 at Summit :-) and that is with ducting.


The tech sheets usually have a check box asking if it has been flushed in 90 days.

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PostPosted: Fri Jan 08, 2010 12:20 pm 
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The brake fluid change recommendation is a STRONG recommendation, for obvious reasons. But basically when the vehicle is teched, the color of the fluid is looked at... if it's a nice light, mostly clear color, we'll pass it.

But I think the tech guide and maybe the tech form say something to the effect that it should have been done within 3 months for TZC/THSCC

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PostPosted: Fri Jan 08, 2010 12:41 pm 
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I'd also add that brake fluid performance is VERY closely related to velocities and weights.

A car that weighs less than 3000 lbs, and never sees the other side of 120 mph might get away with a brake bleed once a year, even if doing 4-6 events per year and being a daily driver, and that sits outside... I'm jus' sayin' :wink:

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PostPosted: Fri Jan 08, 2010 1:47 pm 
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Stacy King wrote:
I'd also add that brake fluid performance is VERY closely related to velocities and weights.

A car that weighs less than 3000 lbs, and never sees the other side of 120 mph might get away with a brake bleed once a year, even if doing 4-6 events per year and being a daily driver, and that sits outside... I'm jus' sayin' :wink:


just because i feel like stirring up trouble today...the amount of work a brake system does (ie, how much heat it has to dissipate) has FAR more to do with the power of the car, not the weight. a 2500lb 350hp car will need bigger/better brakes than a 3500lb 250hp car. power (more accurately energy) in = power out. that's why when >1 engine choices are offered the more powerful model often gets bigger brakes even though the weight increase is relatively small (think 328i vs. m3, or wrx vs. sti, or civic si vs. lx).

bottom line: brake fluid change interval has little to do with vehicle weight alone, it has to do with how hot the fluid gets which is a function of power, aerodynamics, rotor size, ventilation, front to rear bias, pad material, caliper design, vehicle weight, etc.


Last edited by Jason Tower on Fri Jan 08, 2010 2:42 pm, edited 1 time in total.

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PostPosted: Fri Jan 08, 2010 2:21 pm 
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If we idealize things a good bit and use the simplest of physics, if you have a 2000lb 250hp car and a 3500 lb 250hp car and they both are going 90 mph at braking application point, simple physics says the brakes on the 3500 car has to dissipate more thermal energy to decrease it's kinetic energy (slow the thing down) to a given level (same for both cars...ie attaining the proper corner exit speed). For mass it is a linear relationship to go from KE pre braking to KE at exit speed. (this also is assuming equal RATE of heat dissipation from the brakes so the heavier one is going to take a longer distance to brake from V1 -> V2)

However, a point to bring up is that let's change the 2 vehicles to a 2000lb/1000hp car and a 2000lb/250hp car. The former is going to be going a lot faster (more kinetic energy) for a given stretch of straight than the 250hp car at the point of brake application and assuming equal lateral grip (ie both cars must slow to the same speed to negotiate the turn properly...same exit speed), then yes the higher hp car needs to dissipate more heat to decrement it's kinetic energy for this given turn. In this case it would be a V^2 relation ship so a little more speed at brake entry equates to a lot more energy to dissipate.

So I think a better way of addressing what 'kind' of car is harder on brakes/fluid is the kind of car that averages higher corner entry speeds for a given weight. So it's not as cut and dry but if 'more hp' means higher turn entry speeds, then sure the amount of hp will have more influence on braking due to the V^2 relationship, but high hp doesn't always mean higher speed :).

But then there is the question of "There is a finite amount of thermal energy to be dissipated to brake to the proper speed". This is going to enter the braking power realm of rotor mass, caliper mass, fluid weight transfer, tires....all that good stuff that takes a ton of analysis to make conjectures about.

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2013/2014.5 President
2013 Top Gun

2015 Fit

22R-EC => 4G63 => D16Y7 + D16Y8 => EJ255 + K24Z2 => K20Z3 + K24Z2 => K24Z2 + M54 => L15B


Last edited by JamesShort on Fri Jan 08, 2010 2:39 pm, edited 1 time in total.

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PostPosted: Fri Jan 08, 2010 2:38 pm 
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JamesShort wrote:
If we idealize things a good bit and use the simplest of physics, if you have a 2000lb 1000hp car and a 3500 lb 250hp car and they both are going 90 mph at braking application point, simple physics says the brakes on the 3500 car has to dissipate more thermal energy to decrease it's kinetic energy (slow the thing down). For mass it is a linear relationship to go from KE pre braking to KE at exit speed.

However, a point to bring up is that let's change the 2 vehicles to a 2000lb/1000hp car and a 2000lb/250hp car. The former is going to be going a lot faster (more kinetic energy) for a given stretch of straight than the 250hp car at the point of brake application and assuming equal lateral grip (ie both cars must slow to the same speed to negotiate the turn properly...same exit speed), then yes the higher hp car needs to dissipate more heat to decrement it's kinetic energy for this given turn. In this case it would be a V^2 relation ship so a little more speed at brake entry equates to a lot more energy to dissipate.

So I think a better way of addressing what 'kind' of car is harder on brakes/fluid is the kind of car that averages higher corner entry speeds for a given weight. So it's not as cut and dry but if 'more hp' means higher turn entry speeds, then sure the amount of hp will have more influence on braking due to the V^2 relationship, but high hp doesn't always mean higher speed :).

But then there is the question of "There is a finite amount of thermal energy to be dissipated to brake to the proper speed". This is going to enter the brake realm of rotor mass, calp mss, fluid weight transfer, tires....all that good stuff that takes a ton of analysis to make conjectures about.


absolutely, there are many factors involved. i'd just hate to have someone read this and think "well my car is pretty light so i don't need to flush my brake fluid very often", then go off in turn 1 when the pedal goes to the floor.


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