MCCB or Steel brakes?

[nicknaz]

I would love a set on a street car to let people know I had the $$$ to spend the equivalent of a used car on brakes

For a car I plan to track.. steel rotors all the way

[swamp2]

Originally Posted by Judah

Well, you can look at it this way, eventually BMW will have the least expensive CC brake option due to their partnership with SGL which I believe supplies the entire VW group.

SGL provides carbon fiber. Carbon ceramic (Carbon-Silicon Carbide, CSiC) is an entirely different sort of material.

[swamp2]

Originally Posted by karussell

The M5's carbon ceramic brakes are made with a thin layer of friction material and it will wear out over time. "service life of the vehicle" you mention is very vague. certainly they will last longer than steel rotors but the difference narrows significantly with heavier use.

The M5's front rotors are 38mm thick. the friction material is a tiny fraction of that. according to that vehicles documenation the minimum servicable thickness is 37.85mm. there is also a minimum weight and visable wear indicators.

the properties of carbon ceramic brakes that make them cool is they are about half the weight of iron disks. In the M5's case they are 13 lbs lighter per corner.

Well they certainly can't be CSiC layered on cast iron or the weight savings would not be present. Are you saying that there is only a thin (wear) layer that is a suitable material for frictional pad contact?

On a side note: I estimate the weight savings of the M4 CSiC brake system to be about 40 lb (saving is over 50 lb on the M5). This is equivalent to losing twice as much non-rotating weight or ~80 lb. That in turn is probably equivalent to about 10 hp. Probably not quite enough to be felt but definitely a significant weight savings.

[gee-m-w]

We're making a lot of assumptions about the price without looking at the scale. This is the first mass market application in an affordable car lots of people buy. The supplier could easily see an order for 100,000+ rotors over 5 years (6-8 per car inclusive of new cars and replacement disks). The economics could change a lot.

[CanAutM3]

Originally Posted by gee-m-w

We're making a lot of assumptions about the price without looking at the scale. This is the first mass market application in an affordable car lots of people buy. The supplier could easily see an order for 100,000+ rotors over 5 years (6-8 per car inclusive of new cars and replacement disks). The economics could change a lot.

Good point about the price. If the volume came make the price come down enough, it could make the otion worthwhile .

[F82_SID]

In case you wondered how CCBs are made:

[CanAutM3]

Originally Posted by swamp2

On a side note: I estimate the weight savings of the M4 CSiC brake system to be about 40 lb (saving is over 50 lb on the M5). This is equivalent to losing twice as much non-rotating weight or ~80 lb. That in turn is probably equivalent to about 10 hp. Probably not quite enough to be felt but definitely a significant weight savings.

Why twice as much? I figure the equivalent mass factor for brake discs on the M4 would be in the 115-120% range. Am I missing something?

[gee-m-w]

Originally Posted by E92_SID

In case you wondered how CCBs are made:

Awesome video. I hope they automate more of that or it is going to cost $9000.

[gee-m-w]

The alternative here is something like the StopTech Trophy kit for $4400 plus pads. You'd only need to do the fronts. Pads for about $360.



http://www.turnermotorsport.com/p-16...FcQ9QgodLwsAcQ

[CanAutM3]

Originally Posted by gee-m-w

The alternative here is something like the StopTech Trophy kit for $4400 plus pads. You'd only need to do the fronts. Pads for about $360.



http://www.turnermotorsport.com/p-16...FcQ9QgodLwsAcQ

Is it really?

Why wouldn't the stock iron discs with better pads do the job?

[gee-m-w]

Originally Posted by CanAutM3

Is it really?

Why wouldn't the stock steel discs with better pads do the job?

Lots of reasons. The pads are smaller. The disc is smaller in both diameter and thickness. The OEM disk is drilled so when the pad is touching it's not grabbing as much.

[CanAutM3]

Originally Posted by gee-m-w

Lots of reasons. The pads are smaller. The disc is smaller in both diameter and thickness. The OEM disk is drilled so when the pad is touching it's not grabbing as much.

All this does not tell me that the stock irons will not do the job...

[gee-m-w]

Originally Posted by CanAutM3

All this does not tell me that the stock steels will not do the job...

The two OEM and the third aftermarket option I mention will do all do the job. The service life is what varies. You'd warp the smallest rotors first and overheat them the soonest.

[CanAutM3]

Originally Posted by gee-m-w

The two OEM and the third aftermarket option I mention will do all do the job. The service life is what varies. You'd warp the smallest rotors first and overheat them the soonest.

Warping rotors is a myth, rotors of that size and robustness don't warp...

IMO, the pads are the weakest link in the braking system, not the rotors. With the proper pads, the stock rotors should be sufficient for most tracks. For me, the biggest benefit of the CCBs is the weight reduction, not gains in braking performance.

Another variable is if better callipers and/or bigger brakes are part of the CCB package.

While it is true we don't yet know the cost (cost of option as new + cost of replacement parts) of the CCB on the F8X, the cost per mile will most likely be greater on the CCB. We still need to figure out by how much.

(PS: I edited my previous posts. I mentioned steel rotors by error when I meant iron rotors)

[swamp2]

Originally Posted by CanAutM3

Why twice as much? I figure the equivalent mass factor for brake discs on the M4 would be in the 115-120% range. Am I missing something?

My numbers above are too generous. In fact the twice factor comes only from assuming that the rotating mass is basically all in a thin annular ring at a given radius. That approximation is much better met by a tire than by a wheel or a brake disc. For a disc brake assuming a solid disk is obviously a better approximation. In such a case losing a pound of unsprung mass is equivalent to 1.5 lbs of sprung mass. You can verify this by simply writing out the translational and rotational energies for a block with four spinning discs. Depending on how disc like or how annual like the wheels are one arrives at different ratios. Of course a constant power argument is needed as well...

[zosoboogie]

Originally Posted by ersin

PFC = Performance Friction Corp
BBK = Big Brake Kit


Cheers.

Thanks for the information. I am on the list here in Florida going with the steels then the StopTech Trophy Big Brake Kit later.

[gee-m-w]

Yeah I suppose "warp" is a misnomer. I really mean "when the rotor makes it so you can't drive the car any more". That can be a number of things. In my experience it has been a pad that wears to the backing and scores the rotor.

Carbon is going to take the longest sustained abuse at high temp. With any ferric rotor you're borrowing time when you run it on a track, and wearing away microns which add up to millimeters which mean you're out of spec and need a new disc.

[CanAutM3]

Originally Posted by gee-m-w

Yeah I suppose "warp" is a misnomer. I really mean "when the rotor makes it so you can't drive the car any more". That can be a number of things. In my experience it has been a pad that wears to the backing and scores the rotor.

As is mentioned previously in this thread, brake shudder is often attributed to warped rotors while in reality it is most likely coming from pad deposit. Running the proper pads will resolve the issue; hence my comment about the pads being the weak point.

My experience so far is that it is disc cracking that is causing me to replace the rotors (not light surface cracks, those are normal; but deep cracks than run from a cross drill hole to the outer diameter of the disc). You should pay closer attention to your pads as they wear if you end-up scoring your discs with the pad backing plate...

Originally Posted by gee-m-w

Carbon is going to take the longest sustained abuse at high temp. With any ferric rotor you're borrowing time when you run it on a track, and wearing away microns which add up to millimeters which mean you're out of spec and need a new disc.

My ///M is at 90 000km (56k miles) and is closing in on 100 track days. I am on my third set of front rotors and still running the original rears (albeit I will need a new set in the spring). The OEM fronts are costing me $800 a pair. So I am at $1600 spent so far. A far cry of $5000+ for the CCB option and not even considering replacements...

[karussell]

Originally Posted by gee-m-w

I will keep this car for 5 years or about 50k miles. If ceramics can last that long I don't care if I go through 5 sets of pads. But I don't want to eat a set of front discs for another $6k.

If you don't track the car that often then they should last the entire time you own the car.

Just keep careful track of the rotor thickness. i bought a nice dial caliper and measured my rotor thickness very often. once they are worn half-way they go very quickly. at that point i suggest switching to a steel rotor and shelving the ceramics. put them back on when you sell it.

gt3's with ceramics on used market sell for same as steel braked cars given all other factors. maybe in an M3 that will be different though. but interesting to note.

[karussell]

Originally Posted by gee-m-w

We're making a lot of assumptions about the price without looking at the scale. This is the first mass market application in an affordable car lots of people buy. The supplier could easily see an order for 100,000+ rotors over 5 years (6-8 per car inclusive of new cars and replacement disks). The economics could change a lot.

The M3 is not what i consider an affordable car that lots of people buy. I think this one with some options will touch $80k in the US market. wheels are mass produced and certainly cost less to produce yet there is still a significant profit margin on them. i think you will be waiting a while for the ceramics to become cheaper especially since their primary appeal is that they are expensive and rare. just wait until someone at bmw looks at porsches other ideas like wrapping ac vents in leather for $1000 and deviated stitching for $1500. i don' think string is made from carbon ceramic material. maybe it is...

[karussell]

Originally Posted by swamp2

Well they certainly can't be CSiC layered on cast iron or the weight savings would not be present. Are you saying that there is only a thin (wear) layer that is a suitable material for frictional pad contact?

yes link here to MCCB document for M5. Its same way its made for everyone else as well.

http://f10.m5post.com/forums/showthread.php?t=821498

[karussell]

i miss 5 lugs on the porsche too. thinking of switching to those if i keep the car longer. the center locks are a travesty. i'm glad bmw didn't copy that yet...