[stressdoc]

Following an idea suggested in another thread by marconi118, I ordered Z435is Aluminum hat 2-piece rotors as replacements for my E90 335. About $30 more than the OEM rotor, 3 lbs lighter, better thermal properties.

[tres]

is it front and rear ? and have you tested it yet because my rears will be needing replacements soon

[subieworx]

Nice. I need new fronts.

[Gavin@MMW]

Nice find, +1 to the front and rear question.

[stressdoc]

Only available for front. I used regular 335 rotors for rear.

[ianbiz]

less dust too?

[The HACK]

Those might be "2 piece" to save weight but they're not floating rotors.

Here's what true BMW floating rotors look like:



Notice how the rotor ring is separate from the actual hub with pins? The Z43.5is rotors are the same as what came on E60 545i. The hub itself are two piece with aluminum inner hub, but the outside hub and rotor are still attached...

While it does serve to lighten the load, it has little to no performance benefit in comparison to floating rotors wrt heat transfer and management.

[stressdoc]

Not the same as floating rotor, but heat transfer via Al hub is reduced a bit compared to grey iron.

[marconi118]

these are not real floating rotors, but yes the pins prevent heat transfer and lighten up the disc. E92M3 has the same, but not a direct replacement for the 335i

extra bonus of centre aluminium is no RUST no need to paint it

[stressdoc]

In summary:

Benefits = Lighter weight, slight improvement in heat transfer, no rust. Very reliable, no worries about warping or cracking. Low cost, especially if you are getting brakes replaced under warranty; BMW will not foot the bill for non-BMW aftermarket parts or install, but they will cover installation of these and most of the part cost (amount of regular OEM replacement rotors). Keeps BMW warranty. Great option for daily driver.

Cons = Heat transfer not as good on track as full floating 2 piece rotors. Have to replace entire rotor -- disk not removable/replaceable. Not available for rear.

[The HACK]

Originally Posted by stressdoc

Not the same as floating rotor, but heat transfer via Al hub is reduced a bit compared to grey iron.

But it doesn't have all the heat dissipation benefit of a true floating rotor design. While it gives a little benefit in weight reduction and some protection to the bearing hub, it doesn't provide true tangible benefit in proper heat management that a true two piece floatie would.

Just pointing out some of the obvious. It's still a good alternative upgrade to say, drilled or slotted traditional one piece. It's still not as good as using a floatie like the Motorsports Euro Floaties on the M3 ZCP/CSL. But those floaties are a lot more expensive too.

[lpphreakx06]

I want these for my coupe

[marconi118]

The euro M are not real floaties, the pins are hard fixed to the center cup and the ring.

In a real BBK floating rotors have screws + plates to let the rotor really float, because the caliper is fixed

have a look at the AP racing or Brembo BBK pictures on this and the M3 forum

[The HACK]

Originally Posted by marconi118

The euro M are not real floaties, the pins are hard fixed to the center cup and the ring.

In a real BBK floating rotors have screws + plates to let the rotor really float, because the caliper is fixed

have a look at the AP racing or Brembo BBK pictures on this and the M3 forum

Actually they are. The rotors are free to "float" on the pins therefor making them true "floating" rotors per the definition. They're just designed differently to allow open access to air for the rotors from both inside and outside of the hub, instead of like typical BBKs where the hub is mounted from outside therefore a slightly smaller volume of air is available (and typically the air near the outer surface of the rotor is the cooler of the ambient air).

The definition of a floating rotor, is the ability of the rotor to expand independently of the hub. The BMW ///M Floaties fits that description nicely. In fact, if you're ever at a track with an E46 M3 with ZCP, you'll hear the tell-tale "pop" when it comes off the track, it sounds like a bunch of pin-drops as the rotor cools down and contract around the fastener. In terms of pure performance of the rotor, the BMW ///M Floaties are actually superior to the typical AP Racing/StopTECH/Brembo design.

And the floating rotor design has little to do with the fixed caliper.

p.s.: If you want to see some REALLY impressive floating rotors, take a look at Performance Friction Direct Drive rotors. They're the BEST OF ALL WORLDS. The mounting hardware attaches to the rotor from the centerline of the flat plane, thus has the benefit of the center-mount floaties of the BMW ///M rotors, but the hat/hub is re-usable thus it has the benefit of typical BBK floaties in that you can re-use the hub. It's the pinnacle of performance rotor "design". There are only two aftermarket companies that I know of that offers a center mount hub design, that's Performance Friction and RacingBrake.

[aus]

stressdoc, did the dealer bill BMW for these and you just picked up the difference?

[ianbiz]

how is the pedal feel and overall braking difference?

[Bakeme521]

What is the weight of a oem 335i rotor?

[The HACK]

Originally Posted by ianbiz

how is the pedal feel and overall braking difference?

Pedal feel is a function of caliper design and brake line stiffness. Rotors do not alter that. Overall braking difference is a function of tire grip and coefficient of friction for the pad material. Once properly bedded in rotors do not alter that, if it's the same size rotor.

What rotor design will affect, is 1) cooling properties for repeated use and 2) unsprung weight. Anyone telling you that changing their rotors made the pedals feel different, or bettered their single stop braking distance...Probably should not be trusted to provide subjective feedback.

[Bakeme521]

anyone?

[stressdoc]

Originally Posted by aus

stressdoc, did the dealer bill BMW for these and you just picked up the difference?

The dealer will bill BMW for the regular, authorized warranty service. Anything outside of that is my responsibility. In this case the dealer would get credit for regular rotors, and I will cover the difference in the cost of the alu hat rotors. There is an extraordinarily sensible Service Manager at the local dealership here, not sure if others would be as accommodating.

[firechicken99]

anyone know part numbers for these at the dealer??

[yakev724]

Originally Posted by firechicken99

anyone know part numbers for these at the dealer??

34116782593

(Fronts)

The F10 uses the same rotors...maybe one of the F10 rears has the same size (336mm) as ours?