by Dave Zeckhausen
StopTech AeroRotors are attached to lightweight, billet aluminum AeroHats with hardware that allows them to expand freely as they are heated. Thus, they are known as "floating rotors."
StopTech AeroRotor (also called "friction ring") attached to aluminum AeroHat
Although you can't see it in the photo, the hardware passes through oval slots in the AeroRotor, rather than circular holes. Since iron and aluminum expand at different rates, the slots allow the hardware to slide and the AeroRotor to expand and contract, unconstrained by the aluminum AeroHat. This reduces stress at high temperatures and extends component life and improves pedal feel under heavy racing conditions. Conventional rotors can distort into a cone shape during race conditions, leading to tapered pad wear, stress cracks, and spongy pedal feel.
Each new StopTech AeroRotor comes with a hat mounting kit, consisting of 10 each of the following: 4mm Allen screws, Inconel (Nickel alloy) Belleville washers acting as anti-rattle springs, drive pins. Also included is a packet of Loctite 290 thread locking compound, and an instruction sheet.
All mounting hardware should be replaced at the same time as the rotors. For this reason, StopTech AeroRotors are sold with mounting hardware INCLUDED.
AeroRotor Replacement Instructions
Remove rotor and hat assemblies from vehicle.
Spray the mounting hardware with penetrating oil and allow to soak for about 10 minutes.
Remove the Allen screws from the drive pins with a 4mm Allen wrench. To avoid stripping the screws, be sure the end of Allen wrench is not rounded from excessive use.
Loctite 290 is strong and occasionally a bolt may strip while being removed. Carefully applied heat from a propane torch may be used to soften the Loctite. In some cases, it may be necessary to use a vise grip to grab the head of the bolt and break it loose or even to drill out the old hardware. Just take reasonable care not to damage the aluminum hat.
Remove used drive pins from hat and discard.
It may be necessary to tap out some of the pins with a hammer. Insert one of the used 4mm Allen screws into the drive pin a couple of turns and strike the screw head until the drive pin is pushed out of the hat. Be careful not to drive the head of the screw into the hole.
Lay new rotor face down with mounting flanges facing up.
Place hat on top of rotor
Install new drive pins into hat. They should slide in, but light tapping with a hammer is not uncommon.
Flip rotor over and install bolts and washers finger tight. The concave surface faces downward, making the washers appear as small domes.
After installing all bolts finger tight, lay the rotor, hat-side up. Place a drop or two of Loctite 290 into the ends of each drive pin. This special Loctite is designed to wick into the threads. Loctite should be applied BEFORE you fully tighten the bolts. Allow assembly to sit for a few minutes, while Loctite flows into the threads.
Tighten the bolts with a torque wrench to 72 in/lb (6 lb-ft). A torque wrench with the proper range must be used to avoid under or over-tightening the fasteners. This is very important! Do not use a torque wrench that STARTS at 10 lb-ft and goes higher. Torque wrenches are very accurate in the middle of their adjustable range, and very inaccurate at the extremes of their range.
After final tightening of hardware, rotor assemblies can immediately be installed on the vehicle and bedded in.
NEW ROTORS MUST BE BEDDED IN.
The proper break-in procedure is documented here: Bedding in new pads and rotors
If you have questions about rotor installation or any brake related issues, please call Zeckhausen Racing before taking things apart.