Wilwood 260-8555 High Volume Aluminum Tandem Master Cylinder 1.00in Bore Manual

Vehicle Fitment

• Semi-Universal - Compatible with most domestic cars and trucks from the mid-1960s to present using a standard mount flange with 3.22 in. to 3.40 in. center-to-center bolt spacing
• Suitable for street rods, customs, muscle cars, trucks, and competition vehicles requiring a lightweight tandem master cylinder for manual or power-assisted brake systems

Fitment Notes

• Mount flange centers must be between 3.22 in. and 3.40 in. - measure your firewall or pedal box mount before ordering
• The 1.00 in. bore is suitable for both manual and power-assisted (vacuum or hydraulic booster) brake applications - does NOT include a pushrod
• Pushrod Kit #330-13914 is available separately and recommended for manual pedal applications where no booster pushrod is present
• Tandem (dual-outlet) design provides split front/rear circuit braking - primary and secondary chambers operate independently for safety
• Outlet ports on both sides of the bore accept multiple inverted flare fitting sizes - four line adapter fittings and two hex plugs are included for flexible brake line routing
• Also available in ball burnished/polished (260-8555-P) and black e-coat (260-8555-BK) - order the correct suffix for your desired finish
• Combination proportioning valve kit #260-13190 (with brackets and stainless lines) available separately; retrofit kit #220-13189 also available

Features

• High-pressure die cast aluminum construction weighs approximately 3 lbs - approximately 75% lighter than a comparable cast iron OE master cylinder
• Machined billet lid with integrated pressure-balanced bellows gasket provides 100% sealing against moisture intrusion and fluid leakage
• 1.00 in. bore with 0.780 in² area delivers correct hydraulic output for a wide range of disc/drum and full-disc brake systems
• 1.10 in. stroke with 2:1 primary-to-secondary volume ratio - larger primary chamber feeds the front brakes, smaller secondary feeds the rear
• Dual integral reservoirs (8.0 oz primary / 4.8 oz secondary) mounted directly to the body for a clean, compact installation
• Fluid outlet ports accept 3/8-24 IF or 1/2-20 IF fittings on both outlets for maximum brake line routing flexibility
• Tandem safety design maintains partial braking in one circuit if the other develops a leak or failure
• Compatible with Wilwood proportioning valves, residual pressure valves, and No-Bleed Quick Disconnect fittings

Specifications

• Type: High Volume Aluminum Tandem Master Cylinder - Dual Outlet, Integral Reservoir
• Fitment: Semi-Universal (3.22 in. - 3.40 in. mount flange centers)
• Bore Size: 1.00 in.
• Bore Area: 0.780 in²
• Stroke: 1.10 in.
• Outlets: 2 (Tandem)
• Outlet Size 1: 1/2-20 (accepts 3/8-24 IF or 1/2-20 IF)
• Outlet Size 2: 1/2-20 (accepts 3/8-24 IF or 9/16-18 IF)
• Overall Length: 8.76 in.
• Flange to End Length: 8.15 in.
• Reservoir Type: Integral (Dual Bowl)
• Reservoir Size: 8.0 oz / 14.4 cu in. (primary), 4.8 oz / 8.7 cu in. (secondary)
• Material: Aluminum
• Finish: Bare (Natural) - see 260-8555-P for polished, 260-8555-BK for black e-coat
• Pushrod: Not Included - see #330-13914 (sold separately)
• Weight: ~3 lbs.
• UPC: 889545067958

Included Components

• 1x High Volume Aluminum Tandem Master Cylinder - 1.00 in. Bore, Bare Finish, Dual Integral Reservoirs
• Line Adapter Fittings: 9/16-18, 1/2-20, and two 3/8-24 inverted flare (shipped loose inside reservoir - remove lid to access)
• Two Hex Head Plugs for unused outlet ports

Product Description

The Wilwood 260-8555 is a high volume aluminum tandem master cylinder designed for manual and power-assisted brake systems on a wide range of domestic cars and trucks. Its 3.22"-3.40" mount flange center spacing matches the standard firewall mount found on most domestic vehicles from the mid-1960s to present, making it a clean bolt-in option for street rods, muscle cars, trucks, and custom builds. The 1.00 in. bore is sized for both manual and boosted applications and delivers a 1.10 in. stroke with a 2:1 primary-to-secondary volume ratio for balanced front/rear hydraulic output.

At approximately 3 lbs, the high-pressure die cast aluminum body saves significant weight over cast iron OE replacements, while the machined billet lid and pressure-balanced bellows gasket ensure 100% sealing of the dual integral reservoirs. Outlet ports on both sides of the bore accommodate multiple inverted flare fitting sizes for flexible brake line routing. A pushrod is not included - order kit #330-13914 separately for manual pedal applications. This unit is also available in polished (260-8555-P) and black e-coat (260-8555-BK) finishes.