Hayes Dominion A4 Disc Brake Kit

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sku: 154580

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Hayes Dominion A4 Disc Brake Kit

With the 4-piston Dominion A4, Hayes has developed a new disc brake especially for trail, enduro, downhill and E-MTB applications.
High braking power with 4-Piston: Disc Brake Dominion A4 from Hayes
Dominion’s master cylinder is factory tuned for the shortest dead stroke possible and a crisp bite point. The Dominion A4 caliper utilizes four pistons in the most structurally rigid design possible. It features a cold-forged caliper and KingPin structural pad retention bolt that increases stiffness.


  • With a motorsports-inspired Two-Stroke dual port bleed system, industry-leading DOT 5.1 fluid and Kevlar hose, the hydraulic system is engineered for ultimate performance across all temperatures and easy maintenance.
  • Features - Dominion A4
  • 4-Piston Caliper
  • Cartridge-bearings used in the brake lever
  • Aluminum piston operates smoothly across operating temperatures
  • Piston glide ring - technology pioneered in suspension forks
  • Patented Crosshair caliper alignment screws
  • Allows mechanics and end users to quickly and accurately set brake caliper with no rubbing of the rotor on the pads
  • Eliminates guesswork and trial and error


  • Use: MTB, E-Bike
  • Model: Dominion A4
  • Brake type: Disc-Brake
  • Lever length: 2-Finger
  • Open clamp: Yes
  • Caliper: 4-Piston
  • Brake mounting: Postmount
  • Brake pads: T106 Semi-Melalic and T100 Sintered Metalic
  • Brake hose length: front 1000mm / rear 1800mm (shortable)
  • Brake fluid: DOT 5.1
  • Recommended brake rotor: D-Series