Billet Superlite 4R/ST Caliper Highlights:

The Billet Superlite 4R/ST is an extremely rigid, four piston, radial mount design that incorporates Wilwood's latest technology in brake system heat management. With its small piston volumes and large pad capacity, it is ideally suited for rear brake applications in severe duty oval track and road course competition.

The BSL4R/ST body is a product of FEA design and stress analysis technology. It is configured for use with 1.25" thick rotors and the substantial pad volume of the7420 style brake pad. The fully CNC machined, two piece, billet body features a closed bridge with grade 8 thru-bolts. It is the perfect balance between high strength, low deflection, and overall lightweight. Each caliper is fitted with stainless steel bridge plates to reduce wear and provide the smoothest pad operation. A center bridge bolt adds to overall caliper strength and gives easy access to the top loaded pads.

Mounting Dimensions

Bracket Mounting Dimensions

Superlite 4R/ST Caliper Pads

Thermlock^® pistons are used to minimize the direct heat transfer from the brake pads. This configuration has been documented to reduce caliper temperatures by more than 30% without the need for fluid recirculation systems. Fluid temperatures are already reduced, seal life is extended, and caliper service life is prolonged with less distortion and reduced wear in the piston bores. Cooler temperatures translate into maximum performance and ultimate reliability over the longest run. Use EXP 600 Plus racing brake fluid to guarantee trouble free performance in all extreme conditions.

BSLR bracket kits are used to install the BSL4/ST calipers in place of most 3.50" tab mount calipers. Radial mounting simplifies service in the field and the bracket kits provide two planes of adjustment for precise alignment over the disc.

Bore Size

Disc Width

Front Mount
RH - Part Number - LH

Rear Mount
RH - Part Number - LH

1.38/1.12"  44,5/28,4 mm

1.25"  31,8 mm

120-6541-FS  120-6542-FS

120-6541-RS 120-6542-RS

1.25/1.12"  31,8/28,4 mm

1.25"  31,8 mm

120-6543-FS  120-6544-FS

120-6543-RS 120-6544-RS

1.25/1.00"  31,8/25,4 mm

1.25"  31,8 mm

120-6545-FS  120-6546-FS

120-6545-RS 120-6546-RS

1.12/1.00"  28,4/25,4 mm

1.25"  31,8 mm

120-6547-FS  120-6548-FS

120-6547-RS 120-6548-RS

Non-Differential Bore: