by Dave Zeckhausen
Theory of Operation
Some race cars with advanced ABS may have difficulty with floating rotors. The tiny amount of radial play between rotor hats and float hardware can be detected, during cyclic braking events, as "noise" superimposed on the signal from wheel speed sensors and can trigger unwanted behavior by the ABS. StopTech's patented Wedge Lock drive pin design helps solve this problem by eliminating any radial play between drive pins and hats. When tightened, the 2-piece drive pin expands and firmly locks into place in a specially machined depression in the hat. In addition to solving this ABS issue, the StopTech design extends the life of rotor hats by eliminating wear in the hat's drive pin holes.
View complete patent details here: https://www.google.com/patents/US8733518
Each wedge lock hardware assembly consists of a 2-piece drive pin, bolt, flat washer, and nut. Components are sold as a kit containing 10 assemblies, for rotors and hats with 8mm mounting flange thickness. Order here: Wedge Lock AeroHat Mounting Kit p/n 89.000.0030
Wedge Lock Components
Assembled Wedge Lock Hardware
IMPORTANT! Wedge lock drive pins are directional, with proper orientation indicated by a machined depression on the upper portion. For LEFT side rotor assemblies, the machined dimple must face outward, as shown below:
LEFT SIDE ROTOR ASSEMBLY
For RIGHT side rotor assemblies, the machined dimple must face toward the center of the rotor, 180 degrees opposite the LEFT side assembly. Failure to orient the drive pins properly may result in accelerated pin wear, hat wear, and reduced effectiveness at controlling unwanted ABS behavior.
To install, place the lower half of a drive pin through the hat and rotor mounting hole. Place a washer onto the bolt and insert the bolt from the rotor side, through the drive pin. Install the upper drive pin half and orient the depression poperly (facing out for a LEFT rotor assembly, facing in for a RIGHT rotor assembly). Install the nut on the end of the bolt and tighten to 7.1-8.1 Newton Meters (63 inch pounds - 72 inch pounds). No thread locking compound is required.