At DMG Motorsports, we present the All Balls Racing Rear Master Cylinder Rebuild Kit (21-81151) — a direct-fit rebuild solution engineered to restore a leaking or soft-feeling rear brake master cylinder on applicable Harley-Davidson Sportster XL models back to like-new performance. Rather than replacing an entire master cylinder assembly, this kit lets you refresh the internal wear components at a fraction of the cost, getting your rear brake feel firm, consistent, and reliable again. Every component is manufactured to meet OEM specifications, so fitment and function match what came on the bike from the factory.

Features:

• Complete rebuild kit contains all parts needed to re-seal a leaking rear master cylinder
• Includes cup seals, copper washers, o-rings, and replacement screws where applicable
• Cross-references to OEM part number 42810-07A for correct fitment
• Designed as a direct, bolt-in replacement for worn or leaking internal components
• Manufactured to OEM specifications for reliable braking performance
• Cost-effective alternative to purchasing a full new master cylinder assembly
• Straightforward installation using factory mounting points and hardware