FSLI4 and FSLI4/ST calipers provide the pad wear performance advantages of differential bore pistons with the option for ultimate heat protection using Thermlock® pistons in the ST models. Differential piston bores compensate for leading-edge mechanical loading and temperature variances across the pad face to reduce pad taper wear in sustained high temperature applications. Thermlock® pistons in the ST models block heat transfer from the pads and reduce temperatures in the caliper, fluid, and seals by up to 25% over standard stainless steel pistons. These are the go-to calipers for all types sustained hard braking on dirt and asphalt ovals and a wide range of off-road, rally and road course applications.
These new FSLI4 and FSLI4/ST models use the latest innovation to the Superlite family of calipers. They have been redesigned with internal fluid ports that eliminate the external fluid cross-over tubes, along with any potential problems that could arise from a damaged tube. The transfer tube has been replaced with two additional bleed screw assemblies which allow this group of right and left hand oriented differential piston bore calipers to be mounted in either a leading or trailing position.
The most noteworthy feature of all the FSLI caliper models is the exceptional strength and reduced weight of the forging. With assembled weights just at 4.4 pounds, the caliper body design in itself is a product of computer generated solid modeling and stress analysis technology. Each caliper features closed end bridges with a radial transition down to the main body and piston bore housings. The elimination of machined steps and sharp shoulders in this critical critical area provides a measurable increase in overall body strength and resistance to deflection under load. Every FSL body is stress-flow forged from a premium grade aluminum alloy billet. Stress-flow forging realigns 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.
Additional Notes
FSLI calipers use high strength steel main bridge bolts in tension and a supplemental center bridge bolt to provide maximum resistance and strength against deflection and body separation under load. The center bridge support also provides positive pad retention with quick access when it’s time for service. Clamping force, structural deflection, and volume displacement tests have proven the superior strength and efficiency of the FSL. Simply stated, there is no better way to build a stronger or more efficient one or two-piece aluminum caliper body at equal or lower weight. FSLI calipers feature all of Wilwood’s latest refinements and proven performance features including replaceable SRS stainless steel bridge plates. SRS plates extend caliper life by preventing wear at the bridge abutments otherwise caused by pad edge gouging. Spring tension in the SRS plates also eliminates pad rattle and helps to dampen the vibration harmonics that can contribute to squeal under braking. Other standard Wilwood features include high-temperature, square faced o-ring seals for positive sealing, controlled piston retraction, and long service life in high heat conditions. Machined stainless steel pistons are used in the standard models to resist corrosion, retard heat transfer, and eliminate backside deflection under pressure. Two-piece bleed screw assemblies provide long, reliable service life and are easily replaced if necessary.
About Wilwood Engineering
Wilwood Engineering designs and manufactures high-performance disc brake systems. Since the company’s inception in 1977 by Bill Wood, we have developed a substantial matrix of brake components and engineering techniques that allow us to quickly and reliably create brake systems for almost any application. Our core ability is the rapid development of custom engineered brake systems using a combination of off-the-shelf and custom components. In addition to designing and manufacturing brakes for all types of competitive motor sports, Wilwood also manufactures brake systems and components for agricultural equipment, industrial applications, utility vehicles, snowmobiles, quads, motorcycles and military vehicles.
With headquarters in Camarillo, California, Wilwood employs approximately 250 people. We have on-shelf stock of more than 300 different brake calipers, 200 rotor designs, 100 master cylinder designs and a wide assortment of brackets, fittings, valves and brake lines. Our off-shelf brake calipers range in size from tiny calipers used on go-carts and light duty industrial equipment, to heavy duty original equipment brakes for the U.S. military Humvee.
Wilwood's engineering department uses the latest computer-aided design and manufacturing techniques in conjunction with finite element analysis, dynamic test and cycle test equipment, to find high-performance and reliability solutions for the most difficult braking tasks. Our extensive inventory of proprietary on-the-shelf components allow us to provide cost-effective solutions for unique brake applications.
Wilwood is ISO 9000 compliant and has extensive experience maintaining quality levels of 100ppm or less for original equipment manufacturers.
