Wilwood Dual-Caliper Rear Drag Conversion, Olds/Pontiac 2.81-Inch Offset, Chevrolet/Oldsmobile/Pontiac/Buick Chevelle/442/Beaumont/Camaro/Apollo (1964–1974)

Wilwood's dual-caliper rear package mounts two four-piston Dynapro calipers around each drilled Super Alloy rotor. The selected lug-drive hats and brackets are for an Olds/Pontiac housing end with 2.81-inch axle offset and half-inch studs. The preserved model applications need confirmation against the rear axle, since their front-spindle options do not establish this housing-end interface. Wilwood Engineering was founded by Bill Wood in 1977 and is based in Camarillo, California. The company designs and manufactures disc brake systems and components, including calipers, brake rotors, master cylinders, valves, fittings, and brake lines for motorsport, street-performance, and specialized applications.

Technical Details

• Manufacturer part number: 140-12554-D
• Type: Dynapro Dual SA Lug Drive Dynamic Rear Drag Brake Kit
• Calipers: Dynapro Lug Mount; 4 pistons per caliper; Type III Anodize.
• Caliper quantity: four total, arranged as two four-piston calipers at each rear wheel.
• Caliper bore sizes: 1.38, 1.38 inches. Piston type: Stainless.
• Included pad compound: BP-28.
• Rotors: 11.44-inch diameter × 0.35-inch thickness; Drilled; Super Alloy; Plain surface; solid, unvented.
• Rear housing end: Olds/Pontiac.
• Required axle flange offset: 2.81 inches.
• Wheel bolt circles: 5 X 4.50; 5 X 4.75; 5 X 5.00 inches.
• Included: four rear calipers, pads, rotors, mounting brackets and assembly hardware, rotor hats.
• Hydraulic lines and fittings selected separately. No master cylinder, booster or spindles are supplied.
• Conditional wheel screening size: 15 inches. Use the installation clearance diagram to verify the actual barrel and spoke profile.
• Wheel-stud selection: half-inch wheel studs as specified by the installation drawing; the selected hat has 0.520-inch clearance holes.
• Axle-flange limit: 6.29-inch maximum outside diameter with the specified 0.050-inch × 45-degree chamfer. Match the register and stud configuration to the exact installation drawing.

Fitment & Compatibility

Treat this as an Olds/Pontiac housing-end package with two calipers per wheel, not a vehicle-model-specific original-axle replacement. The listed Chevelle, 442, Beaumont, Camaro and Apollo applications require independent rear-end confirmation because their front-spindle entries cannot establish the flange. Use DS916 and the worksheet to record upper/lower horizontal bolt spacing, vertical bolt spacing, bearing/register diameter and wheel-side axle offset. The required 2.81-inch offset must place the drilled ring centrally between the paired calipers. This selected hat arrangement is for half-inch studs with 0.520-inch clearance holes. Check flange outside diameter and the specified chamfer before assembling the dynamic ring mounting. Hydraulic hoses, circuit design and master-cylinder displacement must suit all four rear calipers and the front brake package; verify wheel clearance at both calipers before use.

Match the individual model, year, submodel and brake configuration in the fitment table below.

Wilwood installation documents: Installation instructions; Technical bulletin.

PMB Performance has over 20 years of brake-system experience. Contact us with your vehicle details and installed brake hardware for help confirming the correct arrangement.

California Proposition 65 warning, brake pads only: 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.