Track day soft brake pedal - what to do?

[gtorpedo]

Stoli
Here is my take on the brake issues you are having.
XP10/8 combo is not sufficient for for either S197 or S550 Mustangs. I have run Carbotechs on my Mustangs for 6 years now and currently run XP24/12 combination, you will not lose pedal to the floor because of these pads and they will be economical in the long run as they will last longer than the 10/8 combo.

Hey Steve, i'm running the GLOC R10/8 combo on my car and after 3 days at Summit Point Main the fronts pads are done and rears are not far behind. This is also with the FTBR brake cooling kit and factory rotors. I'm still running on street tires (275/40/18 RE-11s squared) so I've been hesitant to move to a more aggressive compound. I see you are running on slicks but curious if you have experience running the Carbotech/GLOC pads on street tires?

Sorry if this detracts from the thread, but I think this is useful info for everyone using the Carbotech/GLOC pads.

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[M3Convert]

I think you are too hard core for the carbotechs...

I think the Ferodo race pads are a step up in performance [and price]

 

[M3Convert]

Hey Steve, i'm running the GLOC R10/8 combo on my car and after 3 days at Summit Point Main the fronts pads are done and rears are not far behind. This is also with the FTBR brake cooling kit and factory rotors. I'm still running on street tires (275/40/18 RE-11s squared) so I've been hesitant to move to a more aggressive compound. I see you are running on slicks but curious if you have experience running the Carbotech/GLOC pads on street tires?

Sorry if this detracts from the thread, but I think this is useful info for everyone using the Carbotech/GLOC pads.

I am running Carbotech XP-10s on my Nitto NT555s and the tires give up long before the pads do...but I am happy with that based on my sub-optimal track day count.

 

[pstoppani]

So that last two track days after 5 or 6 hard laps the pedal gets extremely soft. One or two cool down laps and it's right back to normal.

When I was running the oem Brembo pads and Motul 600 I didn't have this issue - it only started after I switched to Carbotech xp10/xp8 and am still on using Motul - it was 'fresh' prior to the last track day. I suspect this is merely coincidence, but figured it worthy of pointing out.

While I didn't bleed the brake before today's session, I did before the last one when I had the same issues.

Bad fluid? Something else? Any suggestions welcome. ;)

Given the behavior of the pedal, I'd say the brake system is simply overheating.

If nothing else has changed other than the pads, then it must be the pads (which I think are a bit whimpy for your cars; I'd go xp12/xp10 at a minimum).

Since you live in a humid area, I'd switch to a brake fluid that has a higher "wet" boiling point. Brembo's fluid, Torque RT700 and Castrol SRF are all great choices. I used to only use SRF until Brembo and Torque came out and now use one of those two since they are just as good IMO and cheaper.

 

[steveespo]

Hey Steve, i'm running the GLOC R10/8 combo on my car and after 3 days at Summit Point Main the fronts pads are done and rears are not far behind. This is also with the FTBR brake cooling kit and factory rotors. I'm still running on street tires (275/40/18 RE-11s squared) so I've been hesitant to move to a more aggressive compound. I see you are running on slicks but curious if you have experience running the Carbotech/GLOC pads on street tires?

Sorry if this detracts from the thread, but I think this is useful info for everyone using the Carbotech/GLOC pads.

Yes I have run my Carbotech combo with Michelin PSSs, Toyo R888s Conti Challenge slicks, Pirelli DH slicks, Pirelli PZero OEM tires and Hoosiers.
The tire choice matters but not as much as the driver's right foot, I brake at between -1.1g (street tires) and -1.45g (Hoosier R7/Pirelli DH) and rarely have the ABS engage in the dry. You should use the best compound you can for the temperature range the brakes will see. Also try other brands, I now run PFC 08 on the back of my S197 Mustang with Carbo XP 24s up front. They give me better wear and feel during long sessions than the XP 12s do on that car. I have also run GLocs on the S550, good pads, have a set arriving today for my trip to Indy next week.

One thing I didn't mention in my reply to Stoli is the need for cooling ducts on the front, again really heavy street car that goes real fast needs to dissipate all that heat, pstoppani is right overheating is the most likely cause.
Steve

 

[Brent Dalton]

Lots of good information in here... and some misinformation as well. Here is an article that explains/defines the difference between brake pad fade and fluid boiling.

http://www.amsperformance.com/resources/technical-articles/55-ams-explains-brake-fade

What is Brake Fade?
Brake fade is the term used when there is a reduction in braking power due to excessive heat between your rotor and pad.

Why Does Brake Fade Happen?
Brake fade most commonly happens during high performance driving. During repeated high speed braking events or panic stops, heat builds up in the rotor and pad causing the pad materials to overheat and lose its friction properties. During this type of fade, the brake pedal is firm, but stopping power is reduced. Brake pad fade can be overcome in a variety of ways.

Another Type of Brake Fade
Overheating brake fluid is another common occurrence during track days. Like pad fade, boiling your brake fluid occurs during repeated high speed braking events. During braking, your calipers could reach temperatures in excess of 650 degrees. Brake fluid travels in and out of your calipers to compress and retract the pistons which clasp your brake pads against the rotor. During this process the fluid will boil and expel gas which collects in your brake lines. This in turn creates a spongy/soft pedal. The most effective way to combat this is to regularly bleed or flush your brake fluid with high quality high temp fluid. This is also the only way to remedy overheated brake fluid. The most commonly used fluid is Motul RBF 600.

Brake Pad Break Down
Brake pads are made up of different compounds which result in different characteristics. Standard OEM brake pads are designed to grip at a low operating temperature during daily commutes, while high performance “Track Pads” are designed to accommodate repeated extreme heat braking. Though track pads are great for the road course, they are a nuisance on the street and two separate sets of pads are recommended for avid track day enthusiasts. Track pads have a very high operating temperature which in turn serves no purpose during daily driving. Friction levels (Bite) at low operating temperature is almost non-existent and constant squealing is straining to ears. For people who only attend a few track days a year or drive very spiritedly on the street, a multi-purpose compound may be suitable. Performance Friction has introduced the Metallic Z line of pads. These pads work great for both the street and the occasional track day/AutoX.

Controlling Fade Through Driving Technique
Brake fade can be dramatically reduced through your driving style. Instead of lightly applying the brakes for long intervals, Use short bursts of braking to allow your rotors and pads to avoid extreme temperatures. Engine braking when combined with standard braking is another method that greatly reduces fade however this method comes with experience, we do not recommend this method for novice drivers.

Again, a soft pedal in an OEM system is almost always fluid boiling. If you've done an HPDE, you've probably sat in a class that the instructor has told you, "If you go to brake and the pedal goes to the floor, try to pump the pedal to get pressure back in the system." That's so you can attempt to "pump" the air bubbles away from the caliper and move more fluid in that isn't boiling. That's important for anyone to know so I'll throw it out there. Line compliance could also cause the feel, but with a new car with a OEM system, this would be extremely rare.

Like Steve said, brakes are what make our track world go round. Without the confidence in our brakes, we aren't really going to push the car or ourselves. I fabricated a full manual setup on my actual race car in 2009 and learned alot in the process. Triple master cylinder(front brakes, rear brakes, and clutch) to include sizing master cylinders and setting the bias bar, fabricating all of the hard lines, blah, blah, blah. I'm sure there are several on here that have done the same. IMO, there is no benefit to doing this over the OEM system for most people. It requires constant adjustment for any number of variables. What brake pad combo works on Saturday, might not work on Sunday, even with a bias adjustment. I had to go this due to my roll cage protruding through the front firewall and connecting to the front frame rail(I had to give up my brake booster and abs locations). I've wanted to pull my hair out(when I still had hair) several times during the process over the years, but I wouldn't trade the experience for anything. It is truly nothing short of amazing how much OEM systems compensate for conditions.

One of the versions of the brake set up:

If nothing else, the external resevoirs make cool g meters in videos and if you can't be fast... you might as well look cool
[ame]


I run 295/40/18 Hoosier R7's with Carbotech XP12 front and XP10 Rear with Castrol SRF. Below was from the last session at Road Atlanta in June when outside temps were around 95 degrees after 3 days of driving. I've had ZERO fluid boil and ZERO pad fade with everything else being stock minus the pads and fluid.


Video of that session for reference:
[ame]

I also run the same pads at the AutoX with 275/35/18 RE71R's without issue. Video from Saturday:
[ame]

So what is the "so what" for all of this?

First, I'd get the fluid boiling under control. Fluid upgrade is great place to start. From there, figure out what temperature your brakes are getting by using something like this:
https://www.amazon.com/ALC-THS0080X285-Alcon-Caliper-Indicator-Strip/dp/B005GWRVN6

Or this:
https://www.amazon.com/dp/B000UZEI6..._m=ATVPDKIKX0DER&pf_rd_r=B7GH32ZCXQ0347FZNJCT

Once you know your temperature range, you can go to your respective brake pad site, such as carbotech or hawk, and find a pad that fits into your heat range:
http://www.ctbrakes.com/brake-compounds.asp

 

[stoli]

Thanks for all the great info.

I'm going to start with switching the fluid from the Motul to Torque RT700 that I already have on hand and then taking [MENTION=14263]Brent Dalton[/MENTION]'s suggestion of monitoring the temps and take it from there.

 

[OppositeLock]

Not sure if Hawk makes them for the s550(never bothered to look since ive been using this car for daily/autox only), but i always had great results on my Evo 8 with their DTC-60/70 pads and Srf fluid. Put almost 5k track miles on that car over the years, full weight, running ra1's or r888's. Tried the various carbotech/ferodo/st-43 pads and while they all stood up reasonably well, the hawk pads lasted long and resisted fade better. Maybe doesn't apply...just thought id give my two cents

 

[Brent Dalton]

Hawk DTC 70F/60R is my favorite combo(PFC 01 front with HT10 rear is a close 2nd)! I don't believe they have been released yet :(. I checked with Jay Andrew of Andrew Racing(located right next to the Hawk factory in Ohio) back in Jan/Feb. He said to check back in June(I haven't checked back yet) so they might be available now. It's kind of odd that it is taking this long. Normally you can send in a backing plate and they will cut it that week and be done with it. I'm sure there is something holding it up, but I have no idea what.

 

[dbasql]

How many bottles is required Castrol SRF?

 

[stoli]

First, I'd get the fluid boiling under control. Fluid upgrade is great place to start. From there, figure out what temperature your brakes are getting by using something like this:
https://www.amazon.com/ALC-THS0080X285-Alcon-Caliper-Indicator-Strip/dp/B005GWRVN6

Or this:
https://www.amazon.com/dp/B000UZEI6..._m=ATVPDKIKX0DER&pf_rd_r=B7GH32ZCXQ0347FZNJCT

That's some expensive paint and stickers. .

 

[Brent Dalton]

Yep, there are probably cheaper ones out there. I just posted those as they were the first ones that popped up.

 

[JeremyGSU]

Stoli
Here is my take on the brake issues you are having.
XP10/8 combo is not sufficient for for either S197 or S550 Mustangs. I have run Carbotechs on my Mustangs for 6 years now and currently run XP24/12 combination, you will not lose pedal to the floor because of these pads and they will be economical in the long run as they will last longer than the 10/8 combo.

Second invest in the Castrol SRF, it lasts longer than the Motul fluids which deteriorate when over heated and lose performance. This could be the problem you experienced in conjunction with the next item.

When bleeding the brakes you should engage the ABS before, then bleed the 4 wheels, then test drive and engage the ABS and then rebleed to check for trapped air. Ford procedure uses their computer system to activate the ABS solenoids in the shop, activating it on the street sort of simulates this. I have personally had good results from this. The extra bleed is a little over the top but I have gotten a bubble or two occasionally.

If you experience this problem after doing the above I would check that left rear brake hose connection that you say was factory stripped, under high temp/high load conditions it could be leaking enough to give you soft pedal then feel normal under daily driving conditions.

Good luck and be careful with the brakes, most important part of a road racing car.
Steve

I concur on this.

 

[M3Convert]

Are there Performance Friction pads out for S550 PP? These were my favorites for my M3. Hawks caused the most scoring on the rotor face, and Carbotechs seemed to have the lowest wear. Never tried the Pagid yellows, but they were regarded as the best, with a price tag to match.

I defaulted to C-techs as I am running 300 tires so the compound is less critical and these were the most available. It looks like a tuned S550 on slicks needs a lot of pad!

 

[MaverickGT]

Good info here.

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