[Tag]

Don't know if person who made this video is a member here, but didn't see this posted anywhere. If you want to learn all about the 2NH “M Sport Brake” kit that's made by Brembo for the M2C watch this excellent and very informative video overview.

[Poochie]

Originally Posted by Tag

Don't know if person who made this video is a member here

His handle is listed in the video details; @FaRKle!

[FaRKle!]

Originally Posted by Tag

Don't know if person who made this video is a member here, but didn't see this posted anywhere. If you want to learn all about the 2NH “M Sport Brake” kit that's made by Brembo for the M2C watch this excellent and very informative video overview.

I'm delighted you found it interesting, and thanks for the share!

[Bumpinjeep]

Dude, excellent video. A lot of cool knowledge shared. Thank you.

[stormi.m2c]

Wow this is great, thank you!!

Originally Posted by FaRKle!

I'm delighted you found it interesting, and thanks for the share!

[stormi.m2c]

Does anyone have the correct part number for the front brake pads? I always see 34-11-2-284-969 online but they look way too small and I don't trust most websites' car selectors for the newer models.

[FaRKle!]

Originally Posted by stormi.m2c

Does anyone have the correct part number for the front brake pads? I always see 34-11-2-284-969 online but they look way too small and I don't trust most websites' car selectors for the newer models.

34112284869 is the right PN per RealOEM.

[Artemis]

Originally Posted by FaRKle!

I'm delighted you found it interesting, and thanks for the share!

Good job, FaRKle!.

[NISFAN]

Great video.

And confirms my decision to not go for 2NH ( we have a choice in EU), those things are heavy.

[CSBM5]

Nice video! Didn't you say in the video you thought the rotors were not floating? They are full floating rotors in that the iron rotors are "attached" to the aluminum hat via all those pins you can see. The rotor is constrained in two dimensions by the pins of course but in the third dimension, radial, it is free floating, and the iron is free to expand and contract in the radial direction along those pins. If it was actually fixed to the aluminum hat it wouldn't be for long -- the coefficient of thermal expansion for aluminum is more than twice that of iron.

[GarageMadness]

Thanks for sharing info on the brakes. Nicely shot video. Interesting how much weight is attached to them. Is your new system considerably lighter?

Ps. You're brave in placing all of your heavy brake materials on your hood. I would have gotten a folding table for display purposes.

[T1313]

Agreed, nice video!

[FaRKle!]

Originally Posted by CSBM5

Nice video! Didn't you say in the video you thought the rotors were not floating? They are full floating rotors in that the iron rotors are "attached" to the aluminum hat via all those pins you can see. The rotor is constrained in two dimensions by the pins of course but in the third dimension, radial, it is free floating, and the iron is free to expand and contract in the radial direction along those pins. If it was actually fixed to the aluminum hat it wouldn't be for long -- the coefficient of thermal expansion for aluminum is more than twice that of iron.

You can have a two piece rotor that's not fully floating. For example, the 345/370mm rotors on the F2x/F3x have aluminum hats and iron rings, but the rings are coupled to the hats via rivets. No float.

For the F8x rotors you have pins that are cast into the aluminum hats and iron rings. It does separate the ring and hat more than conventionally, but I'm not sure it's really floating since there's additional stress (concentrated in the pins) when the materials expand/contract.

[CSBM5]

Originally Posted by FaRKle!

You can have a two piece rotor that's not fully floating. For example, the 345/370mm rotors on the F2x/F3x have aluminum hats and iron rings, but the rings are coupled to the hats via rivets. No float.

For the F8x rotors you have pins that are cast into the aluminum hats and iron rings. It does separate the ring and hat more than conventionally, but I'm not sure it's really floating since there's additional stress (concentrated in the pins) when the materials expand/contract.

It's pretty much a full floating design similar to other BBK designs. From the horse's mouth too:

According to Klaus Dullinger, the BMW M Engineer responsible for the development of the new standard BMW M Compound Brake system:

“M compound brakes have a grey-cast friction ring in a floating arrangement that is connected by pins to the aluminum brake cover. The pin assembly means that as the temperature increases, it can expand freely in a radial direction and subsequently cool down again without any residual deformation.”

[M2Cmtl]

Originally Posted by NISFAN

Great video.

And confirms my decision to not go for 2NH ( we have a choice in EU), those things are heavy.

I love the look of the 2NH, but I wouldn't have paid for them if they where an up charge.

[Poochie]

The M2C calipers are exactly twice the size, weight, and price (pads cost) of the standard blue setup and in my humble opinion, is really an overkill.

Yes, aesthetically, they sure do indeed look stout but there isn't much call for them on a street car, since it adds unnecessary weight and for the track, the additional surface area just makes it tougher to dissipate a massive amount of heat generated by frequent hard usage.

Even if there is a minut reduction in brake fade by having a larger sweeping area, it will just get offset by the increased unsprung mass, significantly degrading the efficiency of the suspension and ironically, the braking effectiveness.

BMW should of instead invested some resources to develop a proper ram air plumbing, in order to decrease thermal heat buildup and by extension, brake fade and maybe throw on some braided lines.

Of course all that would add to the R&D cost, so why not instead just go scavenging through the parts bin, throw on the M5 calipers, paint them to a gray bespoke and call them the Competition BBK.


Regardless, very informative video OP. 👍🏻

[CSBM5]

Originally Posted by Poochie

Yes, aesthetically, they sure do indeed look stout but there isn't much call for them on a street car, since it adds unnecessary weight and for the track, the additional surface area just makes it tougher to dissipate a massive amount of heat generated by frequent hard usage.

This is completely backwards. The additional surface area of the rotor, both internally and externally, increases heat transfer to the environment via forced convection (and radiation heat transfer on exterior rotor surface). The convective heat transfer coefficients would likely be very similar between the two designs, so for a given delta-T, the increase in heat transfer is directly the A1/A2 ratio. The added mass of the rotor also significantly increases transient heat capacity (i.e. massive braking at end of high speed straight) since it is a larger thermal mass which can absorb more energy with a smaller temperature rise.

They are clearly a better thermal solution on track by a significant amount. A set of Ti shims coupled with full race pads and SRF fluid, and you're good to go for 10/10ths tracking with R-comp tires.

I agree with them being unnecessary for a street driven car, but when has that stopped BMW from using stuff like this as a marketing tool?

[Poochie]

Originally Posted by CSBM5

The added mass of the rotor also significantly increases transient heat capacity (i.e. massive braking at end of high speed straight) since it is a larger thermal mass which can absorb more energy with a smaller temperature rise.

I agree with you that a larger rotor surface area means a better offset of heat buildup, before fading but that comes with its own baggage.

The fact that they actually used a smaller size rotor but with better cooling, for the CS Racing pretty much speaks for itself and supports my theory that the BBK is more so for show, than actual practical substance.

[CSBM5]

The needs for a pure race brake setup are different versus a street car. For example, one concern is overcooling the brakes and/or allowing too much moisture onto the surface of the brakes (i.e. directed cooling ducting into the center of the rotor inside). One real BMW example was the E39 M5, which if any BMW needed better brakes it was this one (I owned one for 15 years and tracked it hard in the early days quickly upgrading to Stoptech BBK). However, compared to the E39 540i, BMW blocked off the brake ducts which direct flow from the front through the fender liner solely due to concerns of too much cooling on cold and wet conditions. We had to buy the 540i ducts and either cut holes in the liners or use the 540i liners along with either using sink drains or drilling holes in the grill to open up the brake ducting.

Also, pure racing brake rotor setups are designed with forced cooling through ducts into the rotor inside center, and hence the entire balance of thermal mass versus thermal surface area is a completely different calculation versus a street driven everyday car. What works best for a pure race car is not practical for a street car especially when you factor in wear and replacement costs not to mention up front costs. If you drove one of those low thermal mass heavily forced convection cooled brake setups on the street in cold, wet or winter conditions, it would be "interesting." Particularly if you did a massive panic stop from high speed with that huge transient thermal input into a low mass 25F rotor. Not something it is designed to accomplish.

What ended up on the M2C was a parts bin plus design a new iron rotor solution...min cost to BMW, max marketing payoff.

[Poochie]

Originally Posted by CSBM5

What ended up on the M2C was a parts bin plus design a new iron rotor solution...min cost to BMW, max marketing payoff.

We're on the same page, for the most part... Nevertheless, I appreciate your additional insight 👍🏻

[warrenw]

Originally Posted by Poochie

I agree with you that a larger rotor surface area means a better offset of heat buildup, before fading but that comes with its own baggage.

The fact that they actually used a smaller size rotor but with better cooling, for the CS Racing pretty much speaks for itself and supports my theory that the BBK is more so for show, than actual practical substance.

This was mainly so they could run 18" wheels.

[wavyyyy]

I wish blue brakes were an option in the USA. Would've been able to run the wheels I really wanted to lol. I'm not a track guy and these are definitely overkill for the streets.