Wilwood 120-12603 FNSL4R Universal Radial Mount Caliper 4 Pistons

Forged Narrow Superlite 4 Radial Mount

FNSLR/ST forged billet calipers, with four Thermlock pistons, deliver championship proven performance with piston sizes to provide matched rear braking bias for use with the Aero6/ST or other larger piston front calipers. FNSL4R/ST calipers incorporate race technology into a radial mount body design with widespread adaptability. Including competition update options for all FNSL4R rear Big Brake kits. Thermlock pistons, high-temp seals, SRS bridge plates, and two-piece bleed screw assemblies are standard in all calipers. Four high-temp race only brake pad compounds in the 7416 pad type allow precise tuning of the brake response, friction requirements and temperature range.

The key to the superior performance of the FNSL4R comes from the extremely durable and efficient body design. Starting at 4.9 pounds it is the product of computer generated solid modeling and FEA stress analysis technology. The most noteworthy feature of this new caliper design is the forging. Each body is stress-flow forged from premium grade aluminum alloy billets. Stress-flow forging re-aligns the metal's internal grain structure to flow within the contour of the caliper body. This process eliminates the stresses and interruptions to the internal grain structure that occur when machining a straight block billet. Simply stated, there is no better way to build a stronger aluminum caliper body.

Available in diiferent piston bore sizes, provides braking as either a front or rear caliper. FNSLR/ST calipers are 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.