Over heated front brakes

[coneill]

Had my car at the track today and was pushing pretty hard when I got no pedal feel going into a turn. Got off the track and the front passenger rotor just had pad material smeared all over it and I think maybe a small fire. bubbled off the paint on the caliper and melted my caliper pin covers and the piston boot. all other rotors/pads looked fine for track use, no broken brake lines or fluid drop on the master. Any ideas what might have happened here and what I should be taking a look at?

Running PFC 08 pads all around, Stock rotors, Motul 600 fluid. https://photos.app.goo.gl/yCyvVsCiALGL2paHA
https://photos.app.goo.gl/UW9Ce24fYpzHPBDL7
https://drive.google.com/file/d/1-1S...ew?usp=sharing[

[roastbeef]

They got too hot. Fluid is shot and start thinking about a bbk if you're going to keep doing this. Once the boots go, crap gets in there and accelerates wear on the caliper.

Problem is the oem rotors can't get rid of heat, so even if you have great pads, the rotors don't do their job well.

[coneill]

yea I figured the fluid needs to be completely replaced after that. Any suggestions on BBK's?

[roastbeef]

Originally Posted by coneill

yea I figured the fluid needs to be completely replaced after that. Any suggestions on BBK's?

Ap racing or pfc.

[Richbot]

MDM on?

[coneill]

@richbot yes mdm. I've usually only had an issue with that punishing the rears though

[roastbeef]

Originally Posted by coneill

@richbot yes mdm. I've usually only had an issue with that punishing the rears though

Mdm uses the front brakes most of the time. It's a big contributing factor.

[coneill]

Originally Posted by roastbeef

Mdm uses the front brakes most of the time. It's a big contributing factor.

Is there anyway to adjust this or is the only option to run with the the aids completely off.

[roastbeef]

Originally Posted by coneill

Is there anyway to adjust this or is the only option to run with the the aids completely off.

No adjustment. Mdm off is the only way. I still track with mdm on, by the way. My ap racing kit can take it, but I have excessive pad consumption.

[jballer123]

I track my m3 alot and purchashed the gt3 lower control arm brake ducts for less than $15 , they helped me out , saving the front brakes, search google, its easy to install also

[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.

[Bimmer Barney]

Originally Posted by roastbeef

They got too hot. Fluid is shot and start thinking about a bbk if you're going to keep doing this. Once the boots go, crap gets in there and accelerates wear on the caliper.

Problem is the oem rotors can't get rid of heat, so even if you have great pads, the rotors don't do their job well.

You mean calipers? I thought oem rotors were fine with heat?

[Ximian]

Originally Posted by Bimmer Barney

You mean calipers? I thought oem rotors were fine with heat?

Both, if anything. I went with Zimmermann branded version of the rotors and they're holding up a lot better than the GenuineBMW version, even though they should be "exactly the same." You can tell you've overheated your rotors when you start hearing a pinging or ticking noise from them. When that happens, pad deposits are likely.

[Ximian]

Originally Posted by coneill

Any ideas what might have happened here and what I should be taking a look at?

Running PFC 08 pads all around, Stock rotors, Motul 600 fluid. https://photos.app.goo.gl/yCyvVsCiALGL2paHA
https://photos.app.goo.gl/UW9Ce24fYpzHPBDL7
https://drive.google.com/file/d/1-1S...ew?usp=sharing[

It takes a lot of heat to get the pad to start transferring that much material to the rotor. Could the pads or piston be sticking? That's what I would check first since the problem is only on one corner.

[roastbeef]

Originally Posted by Bimmer Barney

You mean calipers? I thought oem rotors were fine with heat?

Nope. It's the rotors. That's why I've always said the caliper retrofits are garbage.
Caliper's job is to hold the pads and be rigid. Rotor's sole job is to convert energy via heat exchange.

[Richbot]

The OEM rotors suck out loud compared to aftermarket rotors as air pumps - partially obstructed air path, not enough vanes, oddly shaped inlet, semi-floating rather than full floating

That said, I've seen people make them work, ducting the everloving crap out of them with good pads and fluid, on racecars like SCCA Touring that require a weight penalty for brake upgrades or whatnot. Glowing discs lap after lap at full tilt for 40 minutes at road america is about as good a torture test as you'll get and I talked to them afterward and they seemed like they got it to work ok

[Bimmer Barney]

Originally Posted by roastbeef

Nope. It's the rotors. That's why I've always said the caliper retrofits are garbage.
Caliper's job is to hold the pads and be rigid. Rotor's sole job is to convert energy via heat exchange.

Ok this is interesting. I thought it was the oem calipers that couldn't handle the heat. I was thinking the best budget upgrade was to run a retrofit caliper on oem rotors to deal with the heat. Agreed full BBK with rotors is best but had always thought the heat was ok as long as the caliper can handle it.

[roastbeef]

Originally Posted by Bimmer Barney

Ok this is interesting. I thought it was the oem calipers that couldn't handle the heat. I was thinking the best budget upgrade was to run a retrofit caliper on oem rotors to deal with the heat. Agreed full BBK with rotors is best but had always thought the heat was ok as long as the caliper can handle it.

Well, think about each component and what it's job is. Calipers aren't designed to get rid of heat. Some good calipers are equipped with ventilated pistons to keep heat out of the calipers and brake fluid, and some pistons are machined to be minimal and have good head dissipation properties, but they aren't supposed to be heat sinks.

The rotor surface is designed to exchange friction into heat and dissipate it into the cooling vanes between the rotor faces where it is cooled by air. This also keeps heat out of the hats (because less heat soaks in to the hats) and helps with keeping some other components exposed to less heat.

Retrofitting a larger caliper/pad on to an oem rotor simply gives the oem rotor more heat, which it's already not very efficient in dissipating.

[dparm]

Originally Posted by Ximian

Both, if anything. I went with Zimmermann branded version of the rotors and they're holding up a lot better than the GenuineBMW version, even though they should be "exactly the same." You can tell you've overheated your rotors when you start hearing a pinging or ticking noise from them. When that happens, pad deposits are likely.

The pinging/ticking noise is just the sound of them expanding and contracting, as they are supposed to. Any car with a two-piece design will do this when pushed hard. I always heard it on my M3 when pulling off track and nothing bad ever came of it.

[coneill]

Originally Posted by Ximian

It takes a lot of heat to get the pad to start transferring that much material to the rotor. Could the pads or piston be sticking? That's what I would check first since the problem is only on one corner.

I took apart the caliper when I got home completey and it seemed to be in good shape. was able to push it back easily Wasn't hung or sticking. The bore was fine and even the piston had only some minimal wear on it. Cleaned it up and put everything back together. There is a decent amount of pad transfer on the other side as well. I think I might've just finally hit the limits of what the stock brake setup can take.

[Ximian]

Originally Posted by dparm

The pinging/ticking noise is just the sound of them expanding and contracting, as they are supposed to. Any car with a two-piece design will do this when pushed hard. I always heard it on my M3 when pulling off track and nothing bad ever came of it.

As with anything, it's normal up to a certain point. For these specific rotors, I haven't heard the noise even after really heavy braking sessions with the same PFC 08 pads because I've gotten better at managing my laps throughout a session to avoid overheating any one part. The rotor thickness may have quite a bit to do with it as well with running brand new rotors this year.

But I think the noise is an indicator you're starting to overheat the rotors. Perhaps there's some function that will give us the "too hot" temperature based on number of pings and ticks like there is for cricket chirps, but unfortunately rhyary has a different brake setup so there isn't an abundance of accurate data collected on the matter.

[dparm]

Originally Posted by Ximian

As with anything, it's normal up to a certain point. For these specific rotors, I haven't heard the noise even after really heavy braking sessions with the same PFC 08 pads because I've gotten better at managing my laps throughout a session to avoid overheating any one part. The rotor thickness may have quite a bit to do with it as well with running brand new rotors this year.

But I think the noise is an indicator you're starting to overheat the rotors. Perhaps there's some function that will give us the "too hot" temperature based on number of pings and ticks like there is for cricket chirps, but unfortunately rhyary has a different brake setup so there isn't an abundance of accurate data collected on the matter.

Buy thermographic paint and put it on the vanes.