Racers in the Wide-5 hub equipped categories are now able to utilize the proven performance advantages of dynamic or "floating" mount rotors. Why Float Mount?Cast iron, steel, and aluminum have measurable differences in their thermal expansion rates. Rotors and hubs also operate in vastly different temperature ranges based on their proximity to the brake pads and cooling air. In sustained high heat competition, these thermal variances can create potentially damaging stresses at the rotor mount tabs and rotor bolt stands when the rotor is rigidly attached to the hub. Thermal distortion, uneven pad build-up and rotor wear can all lead to pulsing, excessive pad knock-back, or other undesirable pedal feedback to the driver. By "float" mounting the rotor, these negative characteristics can all be eliminated. The results are felt with truer running, smoother engagement, extended reliability, and consistent pedal feel after every lap. Wilwood's dynamic rotor mounting system is simply the most accurate and durable method of damping pad engagement harmonics, controlling pad knock-back, and isolating the thermal stresses that can occur between the rotor and the hub mounts. Dynamic Mount System Features: Hubs for use with dynamic mount plates feature specially machined bolt stands that compensate for the plate thickness and position the rotor at the standard offset location. This eliminates any need for caliper relocation when changing to the dynamic rotor mount system. The Starlite "55" series hubs feature 5 bolt rear drive flanges with Snap-Cap front hubcaps. They are the strongest lightweight hubs in the industry. The Starlite "V" series hubs use traditional 8 bolt rear drive flanges and bolt-on front hubcaps. High strength steel, dynamic mounting plates bolt solidly to the hubs and place the float between the plate and the rotor through the special mounting bolt and t-nut system. (#WIL300-8431 sold separately)Square faced t-nuts bolt solidly to standard 5/16" mount hole rotors and float within the slots on the mount plate. T-nuts provide a substantially larger load bearing area as compared to the round pin and bobbin type dynamic mounts that require slotted hole rotors. An assembly tool is provided with each bolt and t-nut kit to correctly position the t-nut during installation to assure bind-free operation. (#WIL230-8454 sold separately)Use with any standard 8 on 7. 00" mount pattern rotors with 5/16" bolt holes. This provides a wide range of rotor choices with a substantially more cost effective and durable mount as compared to slotted hole rotors.Pit Stop USA offers Wilwood Starlite "55" Wide 5 Rear Hub for Use w/ Dynamic Rotor Mount System - 5 Bolt - Standard 5/8"-11 Coarse Studs (Requires #WIL300-8431 Rotor Mounting Plate & #WIL230-8454 Rotor Bolt Kit Sold Separately) 270-8435C at low everyday prices. Be sure to check out all of our products from Wilwood Engineering including Wilwood Engineering Wide 5 Hubs and Wilwood Engineering Hubs.