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Tracking / Autocross / HPDE / Drifting What these cars were built for!


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Old 11-18-2021, 10:21 PM   #57
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Originally Posted by Goingnowherefast View Post
Nope, energy change has nothing to do with this. It's a function of vehicle starting velocity, ending velocity, vehicle mass, and time. The shape of the energy flux into the pad is affected by friction changes (like you're mentioning), but the overall energy absorption for the pad is a function of the vehicle parameters mentioned above. The phenomenon that you're describing with the increased wear rate of your pad in this example is likely due to the pad having very non-linear wear versus temperature characteristics - in which the peaks of energy input at peak deceleration causes accelerated pad wear. Have you guys done a brake dyno test regarding wear at different temperatures like that described in SAE J2707? That will likely confirm that hypothesis.
I'm not an expert, but besides the temperature affecting the wear rate I can imagine that pressure also affects the wear rate.

Imagine the optimal braking is achieved at 1000 psi of brake pressure, and a pad has accelerated wear past 1200 psi or brake pressure.
If you apply 1100 psi of pressure (a bit too much), the ABS might switch between 900 and 1100 psi at high frequency, generating 1000 psi on average.

Now imagine you're pushing 1500 psi instead.
ABS can alternate between 1500 and 500, and each time it goes in the 1200–1500 range the wear will be
much higher than in the previous case, or in case of optimal braking.
Kinda like drilling a hole in concrete with a regular drill vs impact drill.

So even though the amount of energy is the same, and thus temperatures should be (roughly? exactly?) the same,
it's possible that other things can significantly change the wear rate.
Hopefully this mental exercise isn't too far from what's happening.
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Old 11-18-2021, 10:24 PM   #58
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Nope, energy change has nothing to do with this. It's a function of vehicle starting velocity, ending velocity, vehicle mass, and time. The shape of the energy flux into the pad is affected by friction changes (like you're mentioning), but the overall energy absorption for the pad is a function of the vehicle parameters mentioned above. The phenomenon that you're describing with the increased wear rate of your pad in this example is likely due to the pad having very non-linear wear versus temperature characteristics - in which the peaks of energy input at peak deceleration causes accelerated pad wear. Have you guys done a brake dyno test regarding wear at different temperatures like that described in SAE J2707? That will likely confirm that hypothesis.
No, it is not! If it was true, then you would see same temperatures on different rotor/material configurations. If you check the raw data, you can see even in the same material/rotor configuration a variance on the temps. Much more you can see on the different materials.
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Old 11-18-2021, 10:27 PM   #59
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I'm not an expert, but besides the temperature affecting the wear rate I can imagine that pressure also affects the wear rate.

Imagine the optimal braking is achieved at 1000 psi of brake pressure, and a pad has accelerated wear past 1200 psi or brake pressure.
If you apply 1100 psi of pressure (a bit too much), the ABS might switch between 900 and 1100 psi at high frequency, generating 1000 psi on average.

Now imagine you're pushing 1500 psi instead.
ABS can alternate between 1500 and 500, and each time it goes in the 1200–1500 range the wear will be
much higher than in the previous case, or in case of optimal braking.
Kinda like drilling a hole in concrete with a regular drill vs impact drill.

So even though the amount of energy is the same, and thus temperatures should be (roughly? exactly?) the same,
it's possible that other things can significantly change the wear rate.
Hopefully this mental exercise isn't too far from what's happening.

Brake system is sensitive to the apply rate, temperature, pressure and speed (this is covered by AK Master).

One evidence for me of what is going on is to compare the heat checks on the brakes, where in one you can see much more pronunced cracks. Which for me, leads to thinking that may had heat spots, which happens in case of BTV or other issues.
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Old 11-18-2021, 10:29 PM   #60
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The information is available for folks with serious purchasing inquiries via direct contact with CSG. (email them)
That's a strange sale tactic, to be honest.
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Old 11-18-2021, 10:48 PM   #61
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That's a strange sale tactic, to be honest.
You're probably one of those customers who want information for free but won't spend your own money doing your own testing.
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Old 11-18-2021, 10:52 PM   #62
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What makes it even more interesting is one of the days was in the rain with a wet track all day (NASA Fall Finale) and my last track day was wet for the first two sessions.
I dare say wet and trying to be fast with TC nannies on wears brakes. Yes/No
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Old 11-18-2021, 11:05 PM   #63
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That's a strange sale tactic, to be honest.
That's because it's not a sales tactic.
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Old 11-18-2021, 11:13 PM   #64
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Sure, if you ignore all the chemistry involved. If it were as simple as the bolded, then there would be very little variety to brake pads.
Yeah and chemistry is cool, but still not cool enough to break the laws of thermodymanics. No one is belittling your pads - I'm sure they are great, especially considering the mountains of happy C1/C2 users. No pad has it all, and brake manufacturers have an extremely difficult job of navigating a multitude of attributes like noise, fade resistance, wear rate, friction etc. to make a marketable pad for a specific application. It's a hard job, and I'm glad you guys do it. I just want to set the physics straight, especially when claiming that ABS use results in higher pad temperatures. That is simply demonstrably false.
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Old 11-18-2021, 11:17 PM   #65
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You're probably one of those customers who want information for free but won't spend your own money doing your own testing.
I'm not the "want everything without doing anything" kind of guy.
I personally organized and crowdsourced a lot of information on another popular caliper (thread 1, thread 2).
I put a lot of my own time into that, and shared that information with everyone, for free.

You think the problem is that they spent their money and time on doing the research on B-M4 wheel fitment?
If so, that sounds like an ineffective business model.
Nothing prevents me (or someone else) from crowdsourcing that.
Surely that shouldn't be an existential threat to them?
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Old 11-18-2021, 11:42 PM   #66
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Yeah and chemistry is cool, but still not cool enough to break the laws of thermodymanics. No one is belittling your pads - I'm sure they are great, especially considering the mountains of happy C1/C2 users. No pad has it all, and brake manufacturers have an extremely difficult job of navigating a multitude of attributes like noise, fade resistance, wear rate, friction etc. to make a marketable pad for a specific application. It's a hard job, and I'm glad you guys do it. I just want to set the physics straight, especially when claiming that ABS use results in higher pad temperatures. That is simply demonstrably false.
You know how ideal gas law should theoretically apply to everything, but doesn't?

Your application of thermodynamics is also ideal, but doesn't actually apply.

Pressure = heat; ice melts faster if you're pressing down on it.

Imagine overactive use of ABS, from way, way too much pressure. What happens now?

This is very, VERY basic example.
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Old 11-19-2021, 07:19 AM   #67
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Also set up some data logging where you can see the brake pressure data.
RaceChrono + OBDLink MX+ is the cheapest way.
Garmin Catalyst can't log brake pressure data.



Sanity checking: do you know if your wheels will fit over B-M4?

@CSG Mike is there a list of wheels that fit over B-M4, similar to the one for PP Brembos?
Yep I’m working with CSG and they told me it fits over my 57CR, my other set of Enkei TSV’s have even more spacing so that shouldn’t be an issue.
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Old 11-19-2021, 08:25 AM   #68
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I'm not an expert, but besides the temperature affecting the wear rate I can imagine that pressure also affects the wear rate.
Wasn't going to get into the "physics of braking" argument because I kinda think it misses the point, but...
Yeah, makes some sense that wear rate with ABS cycling right around lockup pressure could be significantly higher than maintaining pressure just below lockup.

Any case, if you're *hard* on the brakes *deep* into every corner, ABS or not, it makes sense that's gonna wear pads out more quickly, and it's not the fastest way around either... I can see how ABS could make the wear rate worse. Also, with some nannies still on, more excessive brake consumption...

With or without ABS, driving style will play a major role in heat into the brakes and wear rate. This is obviously the case at all HPDE driver levels but it's also true at the highest levels of motorsport. Different drivers, even turning the same lap times in the same car, have different brake usage and needs.

@CSG Mike helped me out with my brake pad selection. I resisted C2s because of $$$ but ultimately that's where I've wound up and they work great *for me*. But it's not "one size fits all. Mike has a lot of practical knowledge of what works best with different kinds of usage and driver demands, so @Jstyle I think yer in good hands...

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Old 11-19-2021, 01:32 PM   #69
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Man, this derailed quickly. But lets keep going to see where it gets us. In my own personnal experience, with excesive use of ABS the brakes were hotter for me than without ABS use (minimal) or completely removing ABS (module was taken out, prop valve installed instead). There is another driver with the same car, same brake kit, same disc and same pad in the events I go to, he relies on ABS a bit too much and I can tell, just by looking at his rotors (his fronts are about done in 1 year of use, mine have done 2 seasons and are still rocking, his car is an NA frs without aero running 200TW tires, mine is an LS swapped, heavy aero car running stickier tires).

So, @Goingnowherefast, I would like to know why is there more heat on his car, or why was there more heat in mine before I got better (and ultimately went much faster) at managing ABS. Im always up for learning something.
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Old 11-19-2021, 01:43 PM   #70
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just by looking at his rotors [...] I would like to know why is there more heat on his car, or why was there more heat in mine before I got better (and ultimately went much faster) at managing ABS.
Is my understanding correct that you've never directly measured heat/temperature of the brakes,
but only visually estimated the heat based on wear patterns and overall wear over time?
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