Toasted Brakes at a Lapping Event - Need Advice

[martin_nj]

starting to go faster and brake harder.

for a street tire, not an r comp tire this seems hard to believe

 

[SoundGuyDave]

Oh, not really... Driver experience can easily overwhelm the stock brake packages ability to dissipate heat. Yes, R-comps will exacerbate the problem, but it still boils down to heat dissipation (pun intended). Very few manufacturers design a base, stock brake package to withstand the rigors involved in running a road course. The basic minimum necessity is to be able to haul the car down from 80MPH to a dead stop without fade. Once. The first things we do are pads and good fluids to be able to withstand the heat generated. Once the "sump is full," i.e. the rotor temps exceed the ability of the pad to act as an insulator, and heat transfers into the caliper and fluid, we add brake ducts to push fresh air to the rotor, effectively enlarging that heat sump. Once we max that, it's time for the next step, which is larger rotors; more mass, larger sump. We've all seen pics of cars under braking with the rotors glowing cherry red, and all that heat needs to go somewhere...

 

[ddd4114]

Also, rotor cracking usually takes place during cool down. It's good practice to to touch the brakes several time on final lap and even drive the paddock for a few minutes gently applying brakes which will holds temps in a little longer.

Brake ducts can sometime shock a rotor on a long straight following hard braking.

Yeah, I've heard this before, but of course, I always seem to forget about it until after I shut my engine off in the paddock. Maybe I should write a note on my steering wheel or something...

Just thought of another thing... What wheels do you have? Gotta make sure they clear the Brembos.

This was actually going to be my next question...

My track wheels are the 2010 GT500 SVT wheels, which I've read are compatible with the GT500 Brembo calipers. However, my street wheels are the factory non-Brembo 18" wheels, which I doubt are compatible. Can I get away without replacing the wheels if I add spacers? If so, what is the smallest spacer needed for adequate clearance? I've read everything from 0.5" to 1", and I'd rather keep it as small as possible to keep the scrub radius down.

Thanks everyone for the feedback so far.

 

[DRock]

I did the same thing to my brakes a few months ago......went to Brembos and never looked back

 

[JAJ]

...what the hell am I doing wrong?...

You have exactly two issues:

1. You're braking too late on corner entry - you should be hard on the brakes and taper back smoothly as you get to the turn-in point. It'll keep the car balanced better and the brakes won't get nearly as hot. You'll also carry more speed through the corner and lower your lap times.

2. You have to toss the pads at 1/2 worn out. The pad material is an insulator and if you run them down to the metal they'll boil the fluid and melt the caliper. Run them half way and they'll be fine.

From looking at the damage on the stock brakes, your Brembo's won't really solve the problem - you'll just cook them too. Change your technique and you can go fast in just about anything.

 

[Sky Render]

2. You have to toss the pads at 1/2 worn out. The pad material is an insulator and if you run them down to the metal they'll boil the fluid and melt the caliper. Run them half way and they'll be fine.

I've never heard this before. Good advice!

 

[908ssp]

Get rid of that screen in your brake ducts on the track. You're loosing half if not more of your air with that setup of yours. You can't have too much air blowing on the rotors as long as your brakes are working. On some pads and carbon rotors they need to maintain a minimum temperature but I don't see that as your problem. The Australian Super Cars spray water on the rotors from the inside we used to do it racing BMWs that can remove a lot of heat and won't crack rotors.

Also make sure you check your wheel bearings. You can boil away the grease with the temperatures you were seeing.

 

[2008 V6]

Get rid of that screen in your brake ducts on the track. You're loosing half if not more of your air with that setup of yours. You can't have too much air blowing on the rotors as long as your brakes are working. On some pads and carbon rotors they need to maintain a minimum temperature but I don't see that as your problem. The Australian Super Cars spray water on the rotors from the inside we used to do it racing BMWs that can remove a lot of heat and won't crack rotors.

Also make sure you check your wheel bearings. You can boil away the grease with the temperatures you were seeing.


All of this is very GOOD advise - But you can & will crack Rotors - Especially if they are as hot as his are getting - Depends on how much you spray & mostly the quality of Rotor
- Water is an excellent heat soaking source. I used water sprayers also & it works well if you are restricted as to modifications But PIA to turn on & off when stressed - one more thing to have to think about & deal with.
Current project - I went with 14" / 6 piston Wilwood combo, stock rear with power slots rotors - Only one test session, Willow Springs short course - No ducting for this setup yet - BP20 Wilwood / Carbotec AX6 rear. Fast break in easy on rotors but higher temp rating definitely needed.
The Wilwood Super light 6 piston does not have as large a surface area as other calipers but worked much better than anticipated. I went with this because the piston ratio calculated close & adaptor brackets are off the shelf. My project - DD & weekend training tool for wife. I don’t think a proportioning valve will be necessary but need more testing. I don’t know how large the pad surface area is on the Brembo package.

 

[NEMustang]

I didn't see anywhere that you were running with traction control off...TC will cook the brakes pretty quickly...I do not have a 'sport' mode on my 2007...Just a TC on/off switch.

It seems strange that you should cook DTC-60s that quickly with your setup.

please try to run everything with the stability and traction control systems fully off before you spend any big money.

i will be running dtc70 and motul600 fluid on stock 2013 rotors/calipers in sept

i think i'll be using ducting not 100% sure

 

[knownukes]

I run DTC-70/60-f/r. I have the BAER 6 piston big brake kit that comes with the Super Snake. My car eats the BAER calipers. It is my biggest track expense by far. I get 6-8 track days out of a set of front rotors and another 4 out of the rears. My car weighs in at 3900 lbs and makes 700rwhp. At VIR I am over 160mph at the end of both the front and back straights. So my system is working pretty hard. I use the Brembo 600 brake fluid and don't have any pedal problems.

I very much agree and want to emphasize a few things said here.
1st, you have to change the pads at about half thickness. Not only does their ability to be a heat sink diminish, but the rate of wear goes up as they get hotter and it becomes self sustaining. With as heavy as our cars are, once you start running with the faster run groups, pads are only going to last 1-2 events on the faster tracks.

2. You need to run full 4 inch brake ducts. Not the 3 inch opening that you have. That area where your opening is can be cut out and screened in and still look very nice. I had a similar setup with my car, as it came back from Shelby that way. It had a 3 inch hose that had an expanding piece that went to 4 inches. I cut bigger holes and ran 4 inch holes the full length. It made a difference in my pedal. It is rock solid for 30 minutes now, where before it never went away, just started to get a little squishy.

3. Again with the weight and speed potential of our cars, for tracking purposes, you need a bigger heat sink. 14" rotors minimum. Any 14" kit you purchase will be an upgrade and will fit in the 18" GT500 wheels. My 14 inches with huge 6 piston calipers fit mine until I got something else. It was tight, but they fit and didn't rub. I had one problem where a balancing weight rubbed a caliper. I had the weight move inside a little and it was fine. So be sure to check that every time you get tires and a new balance job. I tell the tire mounter if he is putting weight on the outer edge, he has to move it in to clear my calipers.

Lastly, don't skimp in this area. The biggest HPDE crashes I have seen over the years have been brake failure related. As you get faster, the time in between braking goes down, so the brakes have less time to cool. You are using them harder because you terminal velocity is higher and as your skill level & confidence get better, you brake later and harder. All of this and your car didn't get any lighter and you may have added R compound tires to make matters even worse.

So of course the brakes are going to give up and they are going to talk to you, you are going to say "I only have 10 minutes left in the session....I can make it", and at the end of the back straight the pedal goes to the floor and although you are a better driver now, your not ready for this situation. Hopefully no one is in front of you and you just tear your car up and don't get hurt. Or better yet, there is a large run off area and you don't hurt anything.

Invest in the best braking equipment you can afford. Do it over motor, suspension and tires 1st

Bill

 

[ddd4114]

Sport mode will disable traction control, but it will only tone down the ESC intervention. Yawing the car too much will make ESC straighten the car out. I talked to a friend who works at Ford, and the consensus over there is that ESC was a big part of the overheating. However, since Gingerman is (from what I've heard) notoriously tough on brakes, I probably would have seen a lot of heat/wear either way.

I'm reluctant to get rid of the screens because I'm afraid of getting something caught in the duct and possibly damaging the rotor. There isn't a whole lot of clearance between the dust shield and the rotor. I do agree that they reduce flow though. I know it sounds kind of silly, but it just makes me nervous.

Since my street wheels will not clear Brembo calipers and I don't really want to mess with spacers, I'm most likely going to replace all of the toasted paperweights with OEM parts. I'll start manning up and disabling the ESC to see how the pad wear changes. I might also stake a thermocouple in each front caliper to see how hot they actually get on track. If I can find a good deal on street wheels/tires and GT500 calipers, I'll probably scoop them up anyway. However, I'm not prepared to dump a ton of money into this right now.

Thanks again for the feedback.

 

[Sky Render]

On 2011+ cars, Sport mode does not disable traction control; it raises the threshold before electronic intervention for both traction and stability control. It does not turn either of them off.

Tapping the AdvanceTrac button once will disable only traction control while keeping stability control set to full on.

Pushing and holding the AdvanceTrac button for 8 seconds while keeping your foot on the brake will completely disable traction and stability controls.

 

[ddd4114]

You're right. I must have misread the owner's guide at first. That means when I'm spinning the rear tires trying to accelerate in the rain, it's putting the rear brakes on...

 

[VTXFrank]

On 2011+ cars, Sport mode does not disable traction control; it raises the threshold before electronic intervention for both traction and stability control. It does not turn either of them off.

Tapping the AdvanceTrac button once will disable only traction control while keeping stability control set to full on.

Pushing and holding the AdvanceTrac button for 8 seconds while keeping your foot on the brake will completely disable traction and stability controls.

On my 2011 Mustang GT, Turning off traction control DOES NOT turn off ESC. I cannot do a donut with just traction control turned off because ESC starts trying to keep the car straight. My buddies 2013 is different. He can just turn off traction control and do donuts without ESC getting in on the action.

 

[Sky Render]

On my 2011 Mustang GT, Turning off traction control DOES NOT turn off ESC. I cannot do a donut with just traction control turned off because ESC starts trying to keep the car straight. My buddies 2013 is different. He can just turn off traction control and do donuts without ESC getting in on the action.

You can do the same thing by turning AdvanceTrac off completely.

 

[2008 V6]

I'm reluctant to get rid of the screens because I'm afraid of getting something caught in the duct and possibly damaging the rotor. There isn't a whole lot of clearance between the dust shield and the rotor. I do agree that they reduce flow though. I know it sounds kind of silly, but it just makes me nervous.

You only need to keep out the big chunks & even then I wouldn't worry about it. Most of the debri will be rubber or small rocks form others of road excursions.

Using temperature sensitive paints will tell you how hot the rotors / caliper / hubs are getting. Put a stripe on the hat, rotor edge & surface where pad does not contact gives you a very good picture of what is needed & heat dissipation. Paints are availible from many souces & temperature ranges.

 

[Sky Render]

Get a different type of screen that has less surface area.

 

[Philostang]

Maybe I'm missing something here, but it looks like a wire screen (not the injection-molded plastic kind found on many trim items). Or is the concern the plastic ring around the opening that is reducing the diameter of the actual opening covered by the screen?

I'm just not seeing that screen (in itself) as limiting much of any airflow.

If it's just that trim ring, then sure, shouldn't be much trouble to remove it and use a larger piece of wire mesh to cover the area. You'll get your large-debris protection and plenty of airflow.

Best,
-j

 

[908ssp]

The trim ring is the bigger problem but he doesn't need the screen either unless he is driving through the pea gravel.

 

[kon5t]

You have exactly two issues:

1. You're braking too late on corner entry - you should be hard on the brakes and taper back smoothly as you get to the turn-in point. It'll keep the car balanced better and the brakes won't get nearly as hot. You'll also carry more speed through the corner and lower your lap times.

that is one technique, braking late and deep into the corner, past the turning pint can be used if to gain traction when your brakes are up to it. This will get you a faster entry speed and more cornering grip.