brake questions

man2007 · 10-28-2009, 10:23 PM

took my 2007 mustang to the track to run a road course this week. i notice that as the day went on that the brake pedal would get softer. my question is why you get a softer pedal after a few laps? is it the temp of the brake fluid, brake pads. is this normal?

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antonio1988 · 10-28-2009, 10:32 PM

the answer is volumetric expansion of the factory brake lines as they are composed of inferior materials. If you want to lose the mushy feel, replace the lines with stainless steel brake lines and that mushy feel will never come back, I think steeda sells some on their site

charliebrown266 · 10-28-2009, 10:40 PM

+ 1 and some good brake fluid!

Argonaut · 10-29-2009, 09:03 AM

What track were you on, Lime Rock?
What pads did you have in?

Gassed up and ready to roll this car is roughly 3600lbs and capable of hitting 120-130 or more on a typical straight. Stopping from 120 down to ~40-50 and doing it lap after lap is brutal on the brakes. The stock brake pads and fuild are not up to the task. The fluid can boil, resulting in air in the lines and a mushy pedal. Street pads can be completely evaporated in just a few hard sessions or can turn to stone and give no stopping power. The basic brake upgrades for any Mustang that sees more than just a day or two of track time are:
- Dot 4 fluid - ATE Super Blue, Motul, etc
- Good quality track pads: Carbotech XP series, Hawk DTC series or HTs, etc
- SS lines
- Brake ducts on the front: Agent 47, Quantum, etc.

Welcome to the forum. I for one love to hear from folks who track their Stang. It's such a capable car, I only wish that more guys would take advantage of its capabilities, hit the track and truly learn where the limits are.

Brad

Sam Strano · 10-29-2009, 02:48 PM

What happened to you was more the pads and fluid fading than the lines expanding. Even stock lines are braided--they aren't rubber. They are braided fiberglass and covered in rubber. Vs. Braided stainless steel. Yes, there is some expansion, and yes stainless lines can give better pedal feel. But lines don't fade. However, fluid and pad compounds can and do. And if you are going to swap fluid and want the best pedal you can have, it sort of makes sense to do lines at the same time.....

I have Goodridge lines and ATE Super Blue in stock. I also sell most major brands of pads, Hawk more than anything.

Philostang · 10-29-2009, 04:12 PM

Sam's observation (unsurprisingly) is especially apt. If the lines were the real cause of what you experienced, you would have most likely felt it the first time you hit the brakes hard. The lines are not going to "soften up" substantially over the course of a day, which is what you experienced.

What you experienced is exactly what happens with brake fade and fluid boiling. Heat builds up into them and they can't dissipate it quick enough before it exceeds their ratings. Lots of folks complain about their brakes, but they never take time to analyze what they are complaining about. "It won't stop well" isn't enough.

As a general rule of thumb, if "it won't stop well" because the pedal is progressively going further and further to the floor, then you're boiling your fluid, until it'll just go to the floor (ouch, NOT a good feeling...ask me how I know). The fluid is becoming gaseous and therefore compressible, whereas under cooler conditions it was an incompressible fluid. If "it won't stop well" because your pedal is fairly high (or wherever it has been all day) and the car isn't responding to more pedal pressure, then you're cooking your pads. The compound is being taxed beyond its ability to absorb heat, it may be gassing out or glazing or whatever it is that compounds do these days when they're just done.

Knowing what you're experiencing when the "brakes won't stop well" helps you pinpoint the area of the system that needs attention. At the end of the day, as Sam points out, most of us just do up the pads, fluid, and lines all at once since you're in there anyway and the extra cost (all things told) isn't that much.

Oh, and another hearty WELCOME! Good to hear one more Mustang will be out at the tracks.

Best,
-j

nemosgt · 10-29-2009, 07:30 PM

[quote=man2007;6600936]took my 2007 mustang to the track to run a road course this week. i notice that as the day went on that the brake pedal would get softer. my question is why you get a softer pedal after a few laps? is it the temp of the brake fluid, brake pads. is this normal?[/QUOTE

Good info and advice from all the posters.

Remember also that the Mustang is a heavy car with just enough stock brake to give you one or two panic stops from speed on the street. When doing track days, you will have to take care of them unless you upgrade. If you are just starting out, work on technique and not absolute speed. Avoid "hail Mary" late braking. Slow in, fast out is your mantra. There are usually one or two important max braking areas. The rest of the time,try earlier lighter braking to give them some recovery time. Keep your sessions down to 15 or 20 minutes. And remember not to set your park brake between session.

Track days are fun aren't they?

Cheers.

man2007 · 10-29-2009, 08:48 PM

thanks for all your input. i mainly run at new hampshire motor speedway road course. i have run there about ten time in the past with my mazda rx8. i have only had the mustang out two times. i upgraded the brake pads to Hawk performance ceramic pads and change the brake fluid to dot 4. i am not yet running the car to its max performance at the track being my second time at the track with the mustang. i am still learning the feel and the limits of the car at this point. i noticed that the brakes did seem to get softer as the day went on. the instrustor that was with me said i could drive the course a little faster than i was. but feeliing i was getting from the brakes was telling me not to. that is why i am looking for advice from some experienced mustang trackers.

thank for all your help

Red06 · 10-29-2009, 09:12 PM

Most first timers drag their brakes way too much (begin to brake way too early and hold the brakes, even if they realized they're braking too early). This causes heat to build up in the brake pads and calipers eventually boiling the fluid. The idea is to get on the brakes and then get off of them again, as soon as safely possible, to keep heat from building up in the system.

I have a friend at work with a G8 who has gone to the track with my group a couple times this year. The policy of our group is that the newbies ride with experienced drivers (group 1) during their session. I would then ride with him during his first session to reinforce what we talked about. The two thing he has problems with are treating the throttle like a switch (flooring it at the apex, Oy!) and braking waaaaay too early. Even after explaining how to use the cones in the brake zones, showing him he could safely make the turns beginning to brake between the second and third cones (out from the corner) and explaining that riding the brakes would boil his fluid... He eventually boiled his fluid after lunch continuing to brake too early. I'm hoping the experience will keep him off the brakes and finally upgrade to a good dot 4 brake fluid.

Sam Strano · 10-30-2009, 12:26 PM

Quote:

Originally Posted by man2007

thanks for all your input. i mainly run at new hampshire motor speedway road course. i have run there about ten time in the past with my mazda rx8. i have only had the mustang out two times. i upgraded the brake pads to Hawk performance ceramic pads and change the brake fluid to dot 4. i am not yet running the car to its max performance at the track being my second time at the track with the mustang. i am still learning the feel and the limits of the car at this point. i noticed that the brakes did seem to get softer as the day went on. the instrustor that was with me said i could drive the course a little faster than i was. but feeliing i was getting from the brakes was telling me not to. that is why i am looking for advice from some experienced mustang trackers.

thank for all your help

A few points:

1. Hawk Ceramics aren't up for that use. And in fact I hate them (currently on my Mustang) IMO HPS's are way better. None the less those are track worthy pads, and you most assuredly smoked them.

2. The RX8 is much lighther, and not as fast, and better balanced. All 3 make it much easier on brakes than the Mustang.

3. The more you go to the track, the faster you will get--and that will mean you will need/use more and more brake.

Don't kill yourself, put some time and money into the brakes with appropriate parts because there isn't much worse than not being able to stop.