Wilwood Front GM Six-Lug 4x4 SRP Conversion (1971–1991) — Black Superlite, 12.88 x 1.25-Inch Rotors

Black six-piston Superlite calipers pair with 12.88 x 1.25-inch SRP rotors in this GM 4x4 front conversion. The drilled-and-slotted configuration is documented consistently for this variant, with BP-10 pads supplied for the calipers. The manufacturer is Wilwood Engineering, founded by Bill Wood in 1977 and based in Camarillo, California. It designs and manufactures disc brake components and complete systems, from calipers and brake rotors to valves, master cylinders, fittings and brake lines. Motorsport, street-performance and specialized installations each require those components to be matched to the complete brake system.

Technical Details

• Manufacturer part number: 140-18155-D
• Rotor specification: Spec-37 Iron, SRP Drilled & Slotted, vented; 12.88 x 1.25 inches
• Caliper specification: 6-piston Forged Narrow Superlite 6R in Black Powder Coat; radial mount
• Included service pad compound: BP-10; Stainless pistons
• Caliper body material: Forged aluminum
• Hydraulic inlet: 1/8-27 NPT
• Rotor/hat wheel-stud clearance pattern(s): 6 x 5.5 in; 6 x 139.7 mm; match the installed hub/axle pattern
• Hydraulic brake hoses: not included; select the correct application-specific lines/fittings
• Wheel clearance: 17-inch wheels may fit; verify the manufacturer’s complete caliper/rotor template for the installed wheel
• Supplied as one kit with mounting hardware; spindles, hubs, master cylinder and booster are not included

Fitment & Compatibility

Select this 12.88-inch Superlite conversion by the installed six-lug front hub and the exact GM 4x4 listing. The supported group spans specific 1971–1991 K-series pickups/Suburbans, Blazer/K5 Blazer and Jimmy versions, with no blanket coverage across the entire date range. Verify rotor and caliper clearance using the installation drawing.

DS1671 requires hub stud-hole preparation. Hydraulic planning is also essential: Wilwood specifies a recommended 15/16-inch master cylinder when retaining the factory pedal and vacuum booster, rather than the 1.12-inch OE bore that produces very high pedal effort. Where rear drums remain, follow the recommendation for a 10-pound residual valve plus a proportioning valve in their circuit. Hoses are not supplied.

Check the complete application table below, including its model-year splits and configuration notes.

Manufacturer Resources

• Exact Wilwood kit specifications and wheel-clearance information
• Installation instructions and component list

WARNING: This product can expose you to chemicals including Arsenic, Cadmium, Chromium (Hexavalent compounds), Lead, Nickel, Cobalt and Antimony Trioxide which are known to the State of California to cause cancer or other reproductive harm. For more information go to www.p65warnings.ca.gov.

Ask PMB Performance to help confirm the configuration before ordering if the vehicle has modified brakes or running gear. We have over 20 years of experience with parts and fitment; a VIN plus the installed component details gives us the best starting point.

Vehicle Applications

Application Notes

1. Caution: A 15/16” bore master cylinder is recommended for proper brake function when installing this brake kit with the factory brake pedal and vacuum booster.
2. Wilwood offers a 15/16” bore tandem master cylinder suitable for this application, p/n 260-18184
3. Using the OE 1.12” bore master cylinder is not recommended and will require very high pedal effort to stop the vehicle.
4. Line kit included (manufacturer): None
5. Front line-kit reference: 220-18356