Braking Distance CCB vs Stock

[FTS]

Certainly, but I think part of the view is also that M4 had the worst braking performance of all those cars in that test

[consolidated]

Originally Posted by BhamDavid

The point is that stopping distances are a very small part of evaluating braking systems. I'm not saying CCB's are better than the steel discs, although at least one reviewer stated that the CCB's were the best part of the car, but rather than don't get so hung up on braking distance as a measure of the quality of the system.

Agree, good braking is about consistency, repeatability, reliable pedal feel with feedback.

[BhamDavid]

Originally Posted by FTS

Certainly, but I think part of the view is also that M4 had the worst braking performance of all those cars in that test

I believe their braking test procedure is to engage the anti-lock system. Again, this says nothing about the ability to control the car under braking. What it says is how fast you can stop under emergency conditions.

[CanAutM3]

Originally Posted by BhamDavid

A story: A year or so ago I did a major overhaul of my braking system: new high quality disks, Akabono pads, SS lines, meticulously bled the lines with new fluid.

I can't say my stopping distances improved, but now I can feel what's going on at the tires under braking like I never could before. I think I just hit a great combo of components. In fact, I now enjoying braking as much as accelerating.

The point is that stopping distances are a very small part of evaluating braking systems. I'm not saying CCB's are better than the steel discs, although at least one reviewer stated that the CCB's were the best part of the car, but rather than don't get so hung up on braking distance as a measure of the quality of the system.

Agreed. But this thread is specifically about braking distances.

There many other threads that discuss the other aspects of the CCB vs irons.

[Mandi90TT]

Originally Posted by BhamDavid

The point is that stopping distances are a very small part of evaluating braking systems. I'm not saying CCB's are better than the steel discs, although at least one reviewer stated that the CCB's were the best part of the car, but rather than don't get so hung up on braking distance as a measure of the quality of the system.

Actuaally (single test) stopping distances have almost nothing to do with the brakes themselves, and have everything to do with the cars weight, and the size and compostion of the contact patch (the tires, in other words).

Every modern (and by modern, I really mean from 80s on, if not earlier) car can lock up the brakes from any speed. The brakes have more than enough stopping power, for single stops, to do this. When the strength of a braking system comes into play is its heat capacity, its ability to stand up to repeated stops.

This has likely been said over and over in this thread, but I wanted to repeat it in response to your comment.

[FTS]

Originally Posted by Dave 90TT

Actuaally (single test) stopping distances have almost nothing to do with the brakes themselves, and have everything to do with the cars weight, and the size and compostion of the contact patch (the tires, in other words).

I certainly agree, however how would we to speculate then about the differences between M235i and M4 in this test?

[BhamDavid]

Originally Posted by CanAutM3

Agreed. But this thread is specifically about braking distances.

There many other threads that discuss the other aspects of the CCB vs irons.

Agreed also, but this forum seems to be infested with people that continually take things out of context and I felt that a polite nudge to their thought patterns might be in order so as to not use this tread, particularly the stopping distance data table, as a basis for screaming to the world that the M4 has crappy brakes.

[FTS]

I feel so ashamed that I hurt your delicate feelings

[BhamDavid]

Originally Posted by FTS

I feel so ashamed that I hurt your delicate feelings

You certainly didn't hurt my feelings but I'm sure your comment got some folks thinking. Maybe I underestimate the average automotive intelligence on this board... Naaaa!

[swamp2]

Originally Posted by CanAutM3

Again, as was discussed more than once, stock for stock, the CCB will likely have better fade resitance at the track, I am not disputing this.

Originally Posted by CanAutM3

The CCB setup is a higher performing option than the iron setup. I am not debating this.

Thanks for the good data, I never say that original article. However...

You are being far too generous to the pro CCB folks in this discussion.

There has been ZERO empirical evidence that the CCB system has ANY benefits whatsoever over the standard cast iron system, except weight. BMW makes plenty of claims about lifetime but again there is NO empirical evidence. And again, unless BMW has done something pretty novel, the pedal feel (consistency, technically) and stopping distance evidence from the Porsche data does not bode well for the BMW system.

And again, as I've noted prior, fade resistance is much more about pad compound than rotor material. Also, from much prior debate and analysis with actual numbers from similar brake systems it isn't even 100% clear that CSiC rotors even have more thermal capacity. Yes they can operate at higher temperatures but equivalent brake power probably produces higher temperatures due to the rotors lower mass. Again on this particular detail it is really about mass x specific heat of iron vs. the same product for the CSiC. Temperature rise is inversely proportional this product (assuming equal brake power and cooling of course). We know the mass is less and in older systems I calculated that mass x specific heat was very likely LESS in one particular CSiC system...

[swamp2]

Originally Posted by TrakBch

If you consider Brakes to be rotating heatsinks you'll get a better picture of CCB's vs std. brakes. CCB has a higher heat threshold, but it also means since they are absorbing more friction they are absorbing and radiating more heat.

The right idea but not quite correct.

They are ultimately a power sink, converted to heat.

They also don't absorb more friction. They convert friction to heat. For a given braking power they will have a different temperature rise due to their different mass and specific heat, specifically that product.

Originally Posted by TrakBch

I've tracked a F10 M5 with CCB's while instructing a DE. The pedal travel was 70 percent gone after three corners. Should have known since stock fluid is rated to 475F. Switched to RBF 600 in the paddock and lost a session. It still wasn't perfect as there was increasing fade on the 10th plus laps. This was likely the Fluid heating up from the radiant heat. The pad life indicators on the idrive started @ 70,000 miles and by the time I was done for the day it was already alerting for service with pads 3,000 miles remaining. This was after 6, 20 minute sessions on a brake abusive track. This as I mentioned before is very different from how most pressers will ever experience the vehicles so anything they say should be taken with a grain of salt.

Excellent first hand evidence that BMWs claims about their CSiC system are not at all 100% factual.

Originally Posted by TrakBch

CCB's for the ///M division is as much a marketing decision as it is a performance and engineering decision.

Bingo, we have a winner!

[M4TW]

Originally Posted by swamp2

There has been ZERO empirical evidence that the CCB system has ANY benefits whatsoever over the standard cast iron system, except weight. BMW makes plenty of claims about lifetime but again there is NO empirical evidence. And again, unless BMW has done something pretty novel, the pedal feel (consistency, technically) and stopping distance evidence from the Porsche data does not bode well for the BMW system.

There is equally ZERO empirical evidence proving the CCB's aren't superior. Therefore we can conclude that the CCB system is vastly superior to the iron one, since there is zero empirical evidence to dispute it.

[FTS]

Originally Posted by BhamDavid

You certainly didn't hurt my feelings but I'm sure your comment got some folks thinking. Maybe I underestimate the average automotive intelligence on this board... Naaaa!

Aaah yes! The all-time deadly, superiority-proving, discussion ending attack to intelligence; it had to come at some point, well done

Originally Posted by swamp2

There has been ZERO empirical evidence that the CCB system has ANY benefits whatsoever over the standard cast iron system, except weight.

And again, as I've noted prior, fade resistance is much more about pad compound than rotor material. Also, from much prior debate and analysis with actual numbers from similar brake systems it isn't even 100% clear that CSiC rotors even have more thermal capacity. Yes they can operate at higher temperatures but equivalent brake power probably produces higher temperatures due to the rotors lower mass.

It is not just about mass, it is primarily about the chemical composition and manufacturing process of the discs. Although the following is not the exclamation point in this discussion, I am only linking it as additional info:

[BhamDavid]

Originally Posted by FTS

Aaah yes! The all-time deadly, superiority-proving, discussion ending attack to intelligence; it had to come at some point, well done

NOW, you've hurt my feelings...

[swamp2]

Originally Posted by M4TW

There is equally ZERO empirical evidence proving the CCB's aren't superior. Therefore we can conclude that the CCB system is vastly superior to the iron one, since there is zero empirical evidence to dispute it.

WTF, honestly, WTF. Talk about an enormous logical fallacy...

There is prior data indicating a very similar prior (Porsche system) is overall quite similar in many metrics less the weight advantage. What evidence (for road going cars) is there that the CSiC rotor based system are superior in ANYTHING. Last but not least, I nor anyone else here concluded that the cast iron based system are superior. They are however, radically superior in initial cost, long term maintenance costs and performance per dollar.

[swamp2]

Originally Posted by FTS

It is not just about mass, it is primarily about the chemical composition and manufacturing process of the discs. Although the following is not the exclamation point in this discussion, I am only linking it as additional info:

I don't care of the brake rotor is made of some exotic diamond based $4000/gram unobtanium, the physics is exactly the same. Now not to degrade the cool factor, labor or high tech nature of the process but as I stated rotor thermal performance (with respect to peak temperatures and fade) in road going cars is largely about their thermal mass which is mass x specific heat. That is the same for CSiC or cast iron or whatever. Amazing that physics actually works, is correct and described the real world.

[M4TW]

Originally Posted by swamp2

WTF, honestly, WTF. Talk about an enormous logical fallacy...

There is prior data indicating a very similar prior (Porsche system) is overall quite similar in many metrics less the weight advantage. What evidence (for road going cars) is there that the CSiC rotor based system are superior in ANYTHING. Last but not least, I nor anyone else here concluded that the cast iron based system are superior. They are however, radically superior in initial cost, long term maintenance costs and performance per dollar.

I was merely trying to nudge you into realizing the fallacy of your own reasoning. If there is zero empirical evidence, then we are left with unproven hypotheses. Yet you circularly argue that the same lack of data proves your point. Nothing has been proven yet. FTS above was able to cast serious doubt that the Porsche data can be applied apples to apples to BMW's systems.

You haven't earned your beer yet.

[M5Rlz]

I cracked my steel ones on my m5 after about 17,000 miles of at least daily braking from 100+.

They said I had blue spots on all four rotors from them overheating.


Far from what most people will do

http://f10.m5post.com/forums/showthread.php?t=994215

BMW did a puma case and gave me free rotors, disks, pads all around... They said my brakes looked like someone who tracked the car I just said the highway is my track

[CanAutM3]

Originally Posted by swamp2

You are being far too generous to the pro CCB folks in this discussion.

Am I?

I still think that, on the F8X, a stock CCB setup will have better fade resistance than a stock iron setup. My understanding is that CCB rotors are better to dissipate heat, hence their better fade resistance. I agree that the main benefit of CCB is the weight reduction (which is minimal in the case of the F8X IMO).

Nonetheless, I am still confident that the irons with good track pads will be plenty sufficient for most track use and that the CCB will be cost prohibitive when use extensively at the track. That is why my car has iron rotors at all 4 corners

[M5Rlz]

^ you'd also likely be able to convince BMW to goodwill one set of free ones even if you tracked it... I've never been to a track, but I'm guessing you could go through 2 sets before you had to go into your own pocket and it would probably take a few before you reached 8k where if you burn through the ccb... BMW explicitly says it's on you to replace them under any circumstance other than defect.

[M4TW]

Originally Posted by CanAutM3

Am I?

I still think that, on the F8X, a stock CCB setup will have better fade resistance than a stock iron setup. My understanding is that CCB rotors are better to dissipate heat, hence their better fade resistance. I agree that the main benefit of CCB is the weight reduction (which is minimal in the case of the F8X IMO).

Nonetheless, I am still confident that the irons with good track pads will be plenty sufficient for most track use and that the CCB will be cost prohibitive when use extensively at the track. That is why my car has iron rotors at all 4 corners

When are you taking your car to the track to test them out? What are your impressions of the car so far, brakes and all?

[FTS]

From the review of the RC-F:

"In terms of braking, the RC F stops from 60 mph in 108 feet. The M4 with optional $8000 carbon-ceramic brakes needs 98 feet, the Audi RS 5 requires 104 feet, and the old AMG 507 needed just 103 feet."

Read more: http://www.motortrend.com/roadtests/...#ixzz3ChEl2bmL