Questionable SLK55 Brake Rotor Design?

[slk55er]

The SLK55's brake rotors are both drilled and slotted. FYI -- I have been having e-mail dialogue with AMG (without satisfactory answers) regarding the following situation:

From my experience installing slotted Brembo rotors on my BMWs, it appears to me that the slots in the SLK55's brake rotors may be incorrectly, or at least not optimally, angled on the driver's (left) side of the vehicle.

For example the Tire Rack's Website page at

http://www.tirerack.com/brakes/brake...+Slotted+Rotor

states the following:

"Brembo Sport slotted brake rotors are sold in axle pairs and the easiest way to verify correct usage is to install the rotors on the side of the vehicle that results in the end of the slot nearest the outer edge of the rotor always contacting the brake pads first."

This is the situation on the passenger side, but not on the driver's side of my SLK55 where the slots are oriented in the wrong direction from that suggested in the above instructions. On the SLK55, it appears that the same rotor is used on both the left and right side at both the front and rear axle. Normally with slotted rotors, the rotors are designed and manufactured uniquely for each side.

I have asked AMG if this was intentional, an oversight or perhaps a cost savings measure to preclude the need for separate right-side and left-side rotors?

I am hoping that in the future, separate left-side and right-side rotors would be available.

AMG has not provided a satisfactory answer and my impression is that they do not want to address this issue. In fact, it appears that they are not aware that the rotors are slotted, focusing instead on the "perforations." In their latest message, they suggest I check with my local service manager to determine if the brakes are functioning as designed. I suggested that the brakes are functioning as designed and that I would expect that my local service manger would not have a clue if the design was proper.

Now I must say that my experience with the SLK55's brakes during my on-track time was very satisfactory -- no sign of fade and only minimal pad wear. However, it seems that if AMG is going to go to the trouble of making these special rotors, they would want to do it right and provide separate rotors for each side of the car with the slots angled optimally.

I will keep you posted on any additional info I receive.

[Duo-Art]

This sounds like the same situation with the Turbine Wheels where the angle is the same on each side of the car.

[fredfromny]

The brakes are parted out and made by brembo. The big issue here is heat dissipation. Hard to say if it really matters. The bright side is that one side vents properly away from the car. I'm not sure whether the Kleemann kit uses a bidirectional set up, either.

[slk55er]

My understanding is that the function of the rotor slots is to provide an escape path for the gases that build up between the rotor and pad. This allows more direct contact between the rotor and the pad and therefore provides more effective braking force and less fade. The sweeping action is most effective when the slots are oriented in a specific direction WRT the rotation of the rotor.

Re. turbine wheels -- BMW does provide on some models turbine wheel design that is side-specific. This was the case with the "Throwing Star" wheels on the '95 540i M-sport (V8, 6-speed) that I owned and sold prior to buying my SLK. I installed side-specific slotted Brembo rotors on this car.

These wheel covers (shown in the photo) are designed for installation on a specific side of the car so that they act as a fan to blow cooling air onto the rotors.

[JJones]

The vanes inside the rotor should face towards the rear. Note that on nearly all AMG cars the driver's side has holes facing towards the rear, while the passenger side has holes facing forward - which is the wrong direction. The idea is to bring air from the hub outwards - not to try to scoop air and push it towards the hub. So the passenger side will heat up faster than the driver's side. This may not be a catastrophic issue, but it is irritating that on a car this expensive, the rotors are technically backwards on the passenger side. The direction of the slots probably doesn't matter.

[SIlver_Lana]

All AMGs are like this.
I have personally verified this "problem" on an E55, SL55, C32, C55 and SLK55 AMG.

I guess MB decided to save money by ordering and using two left side rotors instead of a left and a right pair.