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Brembo Rotor Replacement
Brembo
2-piece rotors use lightweight aluminum hats connected to iron rotors (also
called "friction rings") by a combination of hardware which allows them to
"float" and expand freely. Thus, they are known as "floating rotors."
Rotor (friction ring) attached to aluminum hat by two
types of fasteners
Although
you can't see it 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 greatly reduces the stress on the rotors at high temperatures and
extends their life. Conventional 1-piece rotors tend to distort into a
cone shape during race conditions, leading to tapered pad wear and stress
cracks, especially at the outer edges. |
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In order to allow the expansion and contraction of the
rotors to take place, the attaching hardware must be loose. However,
the resulting rattle would be unacceptable for a street car. Brembo
developed an anti rattle system for the McLaren F1 Supercar which is now
used in most of their street kits. On every other hole location, these
McLaren anti-rattle springs and spacers are used to eliminate noise.
The retaining screw passes through a washer, then a
spring clip, then a square spacer and, finally, into the threaded brass
"float bushing" which is inserted through the hat and rotor from the
outboard side. The flat edge of the bushing prevents it from rotating
as the screw is tightened.
It is normal for the screws without the spring
clips to seem loose. Do not try to tighten them! |
McLaren Anti-Rattle Assembly |
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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
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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.
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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.
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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.
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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.
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Place a
drop of red Loctite 262 on the tip of a short retaining screw.
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Just enough Loctite is used to fill the bottom 5 or
6 threads
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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.
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Skip a
hole and install a second bushing, washer, and screw. Don't forget
the Loctite.
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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.
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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.
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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.
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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