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by Dave Zeckhausen
Brembo 2-piece rotors use lightweight, billet aluminum hats connected to iron rotors (also called "friction rings") by hardware that allows them to "float" and expand or contract freely.  Thus, they are known as "floating rotors."

Brembo Rotor Ring and Hat

Rotor (friction ring) attached to aluminum hat by two types of fasteners

Although not visible in the photo, the hardware passes through oval slots in the rotor, rather than circular holes.  Since iron and aluminum expand at different rates, the slots allow the hardware to slide and the rotor to expand and contract, unconstrained by the aluminum hat.  This system reduces stress on the rotors at high temperatures and extends their life.  Conventional 1-piece rotors may distort into a cone shape during race conditions, leading to accelerated rotor cracking, soft pedal, and tapered pad wear.

To allow expansion and contraction of the rotors as they heat and cool, the attaching hardware must allow the parts to move relative to each other.  However, the resulting rattle is unacceptable for a street car.  Brembo developed an anti rattle system for the McLaren F1 Supercar, which is now used in many of their street kits.  Every other hole location utilizes McLaren anti-rattle springs and spacers to eliminate noise.

The retaining screw passes through a washer, then a spring clip, then a square spacer and, finally, into the threaded "float bushing" which is inserted through the hat and rotor from the outboard side.  The flat edge of the bushing fits against a raised feature on the hat, which prevents it from rotating as the screw is tightened.

It is normal for the five screws without spring clips to seem loose.  Do not try to tighten them!

McLaren Anti-Rattle Assembly

McLaren Anti_Rattle Hardware

Exploded view of the retaining devices used on each rotor assembly. 

Note that a longer screw is required when the McLaren anti-rattle clip is used and a shorter screw is required otherwise.  Each rotor/hat assembly is held in place by 10 fasteners, five of each type.  The brass float bushings are shown on the right side of the photo and they are the same, regardless of which type of fastener is used.

Assembly Instructions

  1. Remove old rotor from hat by unscrewing each fastener with a 5mm allen wrench.  Note the proper orientation of the McLaren anti-rattle clips so you can install them properly later.  Avoid using an Allen wrench with a worn tip, lest you strip some of the screws.  If a screw head does strip, remove it with vice grips and discard, replacing it with a new screw.  Remember, there are two different lengths of screws.

  2. It is strongly recommended that you replace the hardware each time you change rotors.  If you must reuse the hardware, clean the threads of the screws with a wire brush to remove any old Loctite or corrosion.

  3. If the new friction ring is not plated (gold colored), then use a brake cleaning spray and wipe it off with a rag to remove the anti-corrosion oil that was applied at the factory.

  4. Place the new friction ring on the hat and insert a brass float bushing, flat side toward the hat's center.  The bushing should pass through the hat first and then extend through the slot in the rotor.

  5. Place a drop of high strength thread locking compound (e.g., Loctite 262 or Vibra-Tite 137) on the tip of a short retaining screw.


Just enough thread locking compound is used to fill the bottom 5 or 6 threads

  1. Place a round washer on the screw, insert it into the brass float bushing and tighten with your fingers.  You may tighten VERY gently with an Allen wrench, if it doesn't turn easily with your fingers.  Do not tighten fully yet.

  2. Skip a hole and install a second bushing, washer, and screw.  Don't forget the thread locking compound.

  3. After you have installed five of the short screws, it's time to start with the McLaren anti-rattle assemblies.  Insert a bushing through the hat, place a washer on a long screw, then a spring clip, then a square metal spacer.  Screw this assembly into the bushing, keeping the same orientation that you observed when removing the old rotor from the hat.

  4. In case you forgot the proper orientation, the rectangular metal tab that hangs down from the spring clip faces the center of the rotor/hat assembly.  The two wings that contact the rotor are oriented on either side.

  5. Tighten each screw with a torque wrench to 62 inch-pounds of torque.  This is the same as 5 foot-pounds or about 7 Newton-meters of torque.  It is a tiny amount.  Do not over tighten!  The screws that do not have spring clips under them will seem loose, even after being tightened to the proper torque.  This is normal.

Torquing Brembo Rotor Mounting Hardware

Tightening the rotor screws to 62 inch-pounds of torque


NEW ROTORS MUST BE BEDDED IN. The proper break-in procedure is documented here: Bedding in new pads and rotors

If you have any questions about rotor installation or any brake related issues, please call Zeckhausen Racing before you start taking things apart.

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