Over heated front brakes

[Rassilon]

My rotors pings a lot even after a few autox runs. I think it's normal as the hat expands differently from the ring.

[8500RPM]

Originally Posted by dparm

You can run with MDM on, and the stock brake setup, but you will just need to learn how to manage the brakes for a given track and conditions. That will mean some coasting and driving at 7/10ths versus 9 or 10/10ths.

So the MDM hits the brakes when it starts loosing traction? I thought it pulled throttle input to manage wheel spin. I assume for a newb that's about to start tracking this should be a non-issue just leaving MDM on? Luckily my local track is pretty fast. Long straights and not too many turns.

[roastbeef]

Originally Posted by 8500RPM

So the MDM hits the brakes when it starts loosing traction? I thought it pulled throttle input to manage wheel spin. I assume for a newb that's about to start tracking this should be a non-issue just leaving MDM on? Luckily my local track is pretty fast. Long straights and not too many turns.

it reacts to driver input and wheel spin to figure out what you're trying to do and it can manipulate individual brake presses to influence under/over steer and it cuts power when necessary to keep the car under control.

for example, if you're in a large diameter right turn sweeper and the rear end isn't slipping, the car might pinch the passenger front brake to increase the car's turning if you're starting to scrub and understeer. if you get on the power hard with a high steering angle, the car might limit power where it knows there would be a traction issue to keep the car going the direction you are pointing it. there is nothing it can do with the front brakes in that situation, so it limits power. in a scenario where oversteer is iminent, but the rear hasn't lost traction yet, the car can pinch the front brake opposite of the turn direction to encourage understeer.

dogbone has posted a ton of info and data proving that MDM uses the front brakes most of the time.

[gmx]

What OEM replacement rotors are people using? Are Zimmermans semi floating or full floating?

[8500RPM]

Originally Posted by roastbeef

it reacts to driver input and wheel spin to figure out what you're trying to do and it can manipulate individual brake presses to influence under/over steer and it cuts power when necessary to keep the car under control.

for example, if you're in a large diameter right turn sweeper and the rear end isn't slipping, the car might pinch the passenger front brake to increase the car's turning if you're starting to scrub and understeer. if you get on the power hard with a high steering angle, the car might limit power where it knows there would be a traction issue to keep the car going the direction you are pointing it. there is nothing it can do with the front brakes in that situation, so it limits power. in a scenario where oversteer is iminent, but the rear hasn't lost traction yet, the car can pinch the front brake opposite of the turn direction to encourage understeer.

dogbone has posted a ton of info and data proving that MDM uses the front brakes most of the time.

Wow had no clue it was that in depth. Is the Euro MDM much better? I see a lot of people like the Euro version.

[roastbeef]

Originally Posted by 8500RPM

Wow had no clue it was that in depth. Is the Euro MDM much better? I see a lot of people like the Euro version.

Euro MDM works the same, but allows for a larger slip angle.

[dparm]

Originally Posted by 8500RPM

So the MDM hits the brakes when it starts loosing traction? I thought it pulled throttle input to manage wheel spin. I assume for a newb that's about to start tracking this should be a non-issue just leaving MDM on? Luckily my local track is pretty fast. Long straights and not too many turns.

It can tap an individual brake or pull throttle, yes. Traction control is just one part of it, as roastbeef said. You won't even see any indication that it is helping you until you push really hard, but sometimes you can smell your brakes even though you aren't using the brake pedal.

The "Euro" mode allows for a little bit more slip angle.

[jritt@essex]

To the OP...

It looks like your pads caught fire. What pads were you running?

When you said the brakes went away...did the brake pedal remain firm, or did it go to the floor? If the pedal stayed firm but the car didn't slow, that's pad fade. Based on the looks of the disc face, you were running a pad that exceeded its maximum operating temperature. Once that happened it lost all ability to generate friction. It also started to melt/go to pieces. A good racing pad will avoid that issue.

If the pedal went soft, that means you boiled your fluid. Air bubbles form in the lines, and those bubbles compress, giving you a squishy pedal. You need a good racing fluid that can handle track temps and not boil.

All of the above said, and as noted by others, the disc is the root source of the issue, and caliper retrofits alone will not cure your woes.

A disc absorbs and sheds the heat generated by your brakes. It is a big heat sink. The mass of the pads is tiny in comparison to the discs. A properly designed racing disc in a brake kit is typically larger than stock. That gives it more thermal mass to store heat. Design features such as curved, directional internal vanes, and lots of them, allow the disc to flow more air and shed the heat.

If your discs aren't able to absorb and disperse the heat you're pouring into them, everything else in your brake system isn't going to work properly. Hot discs heat up the pads, which heat up the caliper pistons, which heats up the brake fluid and caliper body. Think of your brakes as one big chain reaction. Hot discs = hot everything else.

The components of a proper track brake system all work together to combat heat. Discs with a lot of vanes (the ones in our AP Racing kits have 84 vanes) flow a lot of air and provide a very stable disc face. The J Hook slot pattern distributes the heat more evenly, spreading the pad material on the disc face more evenly. The discs are larger than stock, and have more mass to absorb and store heat. The calipers have stainless steel pistons, which transfer heat to the fluid much more slowly than the aluminum OEM ones. They're also ventilated, so cooling air flows behind them. Our CP9668 front six piston uses a 25mm thick pad, so it is a thicker barrier through which heat has to travel to get to the pistons and the fluid. All of the air gaps around the AP Racing Radi-CAL caliper also allow cooling air to touch more surface area on the caliper, further cooling the brake fluid.

As you can see, it all works together in harmony...it's not just about the individual component. Therein lies the power of a properly designed track brake kit.


Check out our Essex Designed AP Racing Radi-CAL front and rear systems

Our systems weigh very close to the what carbon ceramic setups weigh, without all the associated pitfalls and expense, so you also get massive unsprung weight savings vs. stock brakes.

You can see lots of customer feedback on our blog, including lots of feedback from M3 owners.

Videos that detail the entire system, design concept, Radi-CAL technology, etc. can be found here.

Feel free to PM, email, or call for more details. Thanks for your consideration!

[coneill]

Originally Posted by jritt@essex

To the OP...

It looks like your pads caught fire. What pads were you running?

When you said the brakes went away...did the brake pedal remain firm, or did it go to the floor? If the pedal stayed firm but the car didn't slow, that's pad fade. Based on the looks of the disc face, you were running a pad that exceeded its maximum operating temperature. Once that happened it lost all ability to generate friction. It also started to melt/go to pieces. A good racing pad will avoid that issue.

If the pedal went soft, that means you boiled your fluid. Air bubbles form in the lines, and those bubbles compress, giving you a squishy pedal. You need a good racing fluid that can handle track temps and not boil.

All of the above said, and as noted by others, the disc is the root source of the issue, and caliper retrofits alone will not cure your woes.

A disc absorbs and sheds the heat generated by your brakes. It is a big heat sink. The mass of the pads is tiny in comparison to the discs. A properly designed racing disc in a brake kit is typically larger than stock. That gives it more thermal mass to store heat. Design features such as curved, directional internal vanes, and lots of them, allow the disc to flow more air and shed the heat.

If your discs aren't able to absorb and disperse the heat you're pouring into them, everything else in your brake system isn't going to work properly. Hot discs heat up the pads, which heat up the caliper pistons, which heats up the brake fluid and caliper body. Think of your brakes as one big chain reaction. Hot discs = hot everything else.

The components of a proper track brake system all work together to combat heat. Discs with a lot of vanes (the ones in our AP Racing kits have 84 vanes) flow a lot of air and provide a very stable disc face. The J Hook slot pattern distributes the heat more evenly, spreading the pad material on the disc face more evenly. The discs are larger than stock, and have more mass to absorb and store heat. The calipers have stainless steel pistons, which transfer heat to the fluid much more slowly than the aluminum OEM ones. They're also ventilated, so cooling air flows behind them. Our CP9668 front six piston uses a 25mm thick pad, so it is a thicker barrier through which heat has to travel to get to the pistons and the fluid. All of the air gaps around the AP Racing Radi-CAL caliper also allow cooling air to touch more surface area on the caliper, further cooling the brake fluid.

As you can see, it all works together in harmony...it's not just about the individual component. Therein lies the power of a properly designed track brake kit.


Check out our Essex Designed AP Racing Radi-CAL front and rear systems

Our systems weigh very close to the what carbon ceramic setups weigh, without all the associated pitfalls and expense, so you also get massive unsprung weight savings vs. stock brakes.

You can see lots of customer feedback on our blog, including lots of feedback from M3 owners.

Videos that detail the entire system, design concept, Radi-CAL technology, etc. can be found here.

Feel free to PM, email, or call for more details. Thanks for your consideration!

Hey thanks for the info. I've definitely looked at AP Racing setups from some of the recommendations here and they look like great setups but I think right now I may be looking for a more dedicated HPDE only car.

I was running PFC 08 compounds all around with fresh Motul 600 and OEM Rotors. This HPDE I was definitely pushing a bit harder than I usually do and I think my chain of events up to my off went something like this.

Turn 7 NJMP Lightning is a sharp left with a heavy braking zone. I really got into the brakes here where towards the end of the braking zone they started to not feel 'right' like the pedal was starting to not be firm anymore almost like I could feel it slowly going further into the floor. As you said this is where my rotors have probably overheated and are now start overheating the pads and fluid. There's really not a lot of braking all the way from turn 7 down to turn 1 and now starting to brake for I have very little stopping power, the pedal is spongy and definitely goes to the floor. Didn't get any pedal feel back for the rest of the lap trying to get back to the pits at around 30-35 mph. Came off and the pics are what you see as the aftermath

So long story short I'm sure you're right on that I got the rotors overheated and then it was just a cascade after that.

[Bartledoo]

[dogbone]

Originally Posted by roastbeef

dogbone has posted a ton of info and data proving that MDM uses the front brakes most of the time.

Here's the post where I show data from an AIM Solo DL that illustrates MDM's braking behaviors a number of different tracks: https://www.m3post.com/forums/showpo...&postcount=747