The four-piston equal bore configuration provides balanced loading for even pad wear in sustained high heat environments. The standard F/BNSL4R calipers feature one-piece stainless steel pistons. Stainless is used for its slow heat transfer properties and high resistance to corrosion. Calipers can be upgraded with Wilwood's exclusive Thermlock pistons. This multi-part piston design creates a highly efficient thermal barrier to further reduce heat transfer from the pads to caliper body, seals, and fluid. Cooler temperatures translate to longer service life and less chance for heat induced pedal fade.

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In addition, each F/BNSL4R is equipped with SRS bridge plates. SRS plates eliminate all bridge wear caused by pad gouging and extend the service life of the caliper. The spring-loaded action of the SRS plates also eliminates pad rattle and dampens the harmonic vibrations that contribute to pad squeal. Two piece bleed screws on each end and internal fluid crossovers prevent damage from track debris and other potential damage sources. High temperature, square faced bore seals provide the largest possible sealing area and controlled piston retraction on release. The full range of Wilwood pad compounds is available to match the brake response and heat range of any competition or sports driving application.

• Narrow body designed specifically for tight clearance applications
• Stainless steel pistons are utilized (where noted) for their low heat transfer properties and high resistance to corrosion
• Thermlock short track pistons are utilized (where noted) for even more protection against heat related seal crystallization and localized fluid boiling
• Internal fluid passages - no external tubes