CS Owners: What Are These???

[CanAutM3]

Originally Posted by Kief

Then why doesn't every F8x come with them?
Like I mentioned earlier, my CS is my 4th F8x, and this is the first I'm seeing these discs. And others have confirmed never seeing these discs either.

I think only the CS comes with them from the factory. But BMW also has them listed to fix issues under PUMA cases for non-CS models. What's interesting is that the CS has only one installed between the brake rotor and wheel while the PUMA listing shows two installed, one between the hub and brake rotor and one between the brake rotor and wheel.

[jdgamble]

They put these on my M240 to remedy a clicking noise while turning. They worked.

[gunsmoker]

Originally Posted by Kief

Then why doesn't every F8x come with them?
Like I mentioned earlier, my CS is my 4th F8x, and this is the first I'm seeing these discs. And others have confirmed never seeing these discs either.

Because they are not standard. It's a mitigation solution to the creaking while turning for whoever complains about that. Mine didn't have them either. After the dealer root caused my problem and it turned out to be something else, they had already installed the friction disks on the passenger side front wheel and left them there. Oh, and they changed both front rotors and brake pads while trying to find the cause.

[r0wr]

Originally Posted by gunsmoker

It's not a CS thing.
I had a creaking noise when turning and my dealer tried these, but they did not help. The installation procedure also requires sanding the rotor and the hub with a specific grit sandpaper. In my case the culprit ended up a play in the knuckle assembly where the strut is attached to the hub. They changed that clamp bolt and cleaned up the knuckle.

Wrt to the friction disks, due to the suspension stiffness and geometry, turning causes a lot of pressure on the hub assembly. You can see how the front end of the car raises up as you wind up the steering wheel. The disks create extra friction between the hub, the rotor, and the wheel to prevent a slight slippage that makes a creaking noise. There has to be one disk on each side of the rotor.

I had a clicking noise in my suspension at some point so they may have added it to try and aid.

[visi107]

Originally Posted by Kief

tom @ eas Thanks Tom for the quick reply...do I need them? Or better yet, any advice on how can i keep them in place when remounting the wheel?

You could install studs to make the wheel swapping easier.

[Poiseuille]

on multiple previous BMWs i've used something that sure looks like that except that the ones i used were very thin high density cork. purpose was to prevent corrosion causing the wheel to seize to the hub. BavAuto probably still sells them in which case there will be a description of their function in the catalog. if the one OP is showing here is maybe Teflon coated then I bet it does the same thing. if it's ordinary sheet steel then I have no idea what it does.
anyway, we had the same problem holding them in place, solved with a very thin smear of anti-seize compound.

Edit: my garden-variety M4 did not come with those.

[Signature Wheel BMW]

When I had an F85 X5M, the brakes / hub area were clicking excessively. BMW replaced the hubs, brakes, and pads which didn't help. The service bulletin suggested these plates to be installed, it didn't help. Not sure if it's mostly theory of it actually works.

[KGYLL]

I have the friction discs om my 2018 M4 CS!

Didn`t have it on an older M4 Competition!

[Kief]

Originally Posted by KGYLL

I have the friction discs om my 2018 M4 CS!

Didn`t have it on an older M4 Competition!

I take it you swapped out wheels which made you aware you have them...what did you use to keep them in place when remounting the wheel?

[CanAutM3]

Originally Posted by Poiseuille

on multiple previous BMWs i've used something that sure looks like that except that the ones i used were very thin high density cork. purpose was to prevent corrosion causing the wheel to seize to the hub. BavAuto probably still sells them in which case there will be a description of their function in the catalog. if the one OP is showing here is maybe Teflon coated then I bet it does the same thing. if it's ordinary sheet steel then I have no idea what it does.
anyway, we had the same problem holding them in place, solved with a very thin smear of anti-seize compound.

Edit: my garden-variety M4 did not come with those.

These "friction discs" have the exact opposite purpose of what you describe. Their purpose is to increase the shear friction when the wheel/brake-rotor/hub assembly is clamped together.

[Kief]

Just finished swapping on my winters for my now SMB M3CS, and my fronts had these friction discs as well...same as my first AW M3CS. Interesting how some CS owners have them, and some do not.

[Diljee]

Originally Posted by Kief

Was just swapping out my wheels for my winters, and found these "spacer-like" very thin metal discs on my two front hubs. Have no idea what they are. This is my 4th F8x and I have never seen these before. They were only adhered to the hub face by the wheel (my wheel pin is the only reason they didn't fall to the ground when I removed my front wheels). If I tried to place back, they would move and block the lug holes as I tried to mount my winter wheel. I gave up and kept them off.

Is my car going to blow up (joking), but seriously, anyone know what they are? Were they mistakenly left on at the factory?? CanAutM3 help...

Ok, this is what the disk is for. The upgraded brake package includes carbon ceramic 2-piece brake disks called the outer ring (eiter carbon fiber or steel composite) and the mounting part made of aluminium (called the hat) which are kept together by screws (also known as bobbins). People have been complaining about a noise occurring when cornering. Because of this, BMW designed this ring placed between the hat and the hub as a means to eliminate the noise and address complaints.

[CanAutM3]

Originally Posted by Diljee

Ok, this is what the disk is for. The upgraded brake package includes carbon ceramic 2-piece brake disks called the outer ring (eiter carbon fiber or steel composite) and the mounting part made of aluminium (called the hat) which are kept together by screws (also known as bobbins). People have been complaining about a noise occurring when cornering. Because of this, BMW designed this ring placed between the hat and the hub as a means to eliminate the noise and address complaints.

As shown in the various pictograms, these friction discs are installed between the disc and the wheel on the CS.

[nbennettksu]

Originally Posted by Kief

Interesting...so this looks to be related to a SIB?
Because my previous 2018 M3ZCP 8/8/17 production did not have these discs

I've put spacers on 18 m3's and 18 m3 cs; only the cs ones had them. You prob do on yours.

[Kief]

Originally Posted by nbennettksu

I've put spacers on 18 m3's and 18 m3 cs; only the cs ones had them. You prob do on yours.

For me, all 3 of my M4/3 civic and ZCP did not have them, but each of my 3 CS's did

Btw, cracks me up how some of these old threads come back from the dead, especially once the issue has been solved

[Gpatleet]

Originally Posted by Kief

Was just swapping out my wheels for my winter

Interesting thread. Sorry to be semi-off topic, but what winter wheel set ups do you (guys) use/recommend? Preferably what is a good warmer alternative to the Pilot Sport Cup 2s during cold weather?

[imperialgrunt]

Originally Posted by jdgamble

They put these on my M240 to remedy a clicking noise while turning. They worked.

How many did you put per wheel? I see diagrams for 1 and 2 per wheel. I got a 340i and have the same issue with my “upgraded” Zimmermann dimpled rotors.