AUTOKAY Brake Master Cylinder for Hammerhead 80T / TrailMaster MID — Integrated Reservoir, Single Rear-Port Replacement

Autokay's Hammerhead 80T / TrailMaster MID master cylinder is a direct-replacement hydraulic brake master with reservoir designed for mid-size go-karts that use a single rear brake line.

This replacement master cylinder fits Hammerhead model 80T go-karts, TrailMaster MID models and many mid-size American Sportworks and comparable Chinese-brand karts. It ships as a complete reservoir-and-cylinder assembly engineered to mount in the original location on compatible karts and provides one port for a rear brake caliper. Measurements are provided to help confirm fit: an overall base length of 4 1/4" and mounting-bolt spacing of 1 3/4".

Will this master cylinder fit my Hammerhead 80T or TrailMaster MID?

Check two critical measurements and the brake port arrangement to confirm compatibility. If your kart matches the listed models and uses a single rear caliper line, this unit was made to replace the factory master cylinder.

• Fits: Hammerhead 80T and TrailMaster MID models.
• Also compatible with many mid-size American Sportworks and Chinese-brand karts.
• One brake port: intended for a single rear brake caliper.
• Confirm base length 4 1/4" and bolt spacing 1 3/4" before ordering.

How do the dimensions and mounting points compare to my existing master cylinder?

This replacement lists two measurable mounting features so you can verify a direct bolt-on fit. Measure the original part's base length and bolt hole center-to-center distance and compare them to the values below.

• Base overall length: 4 1/4" (108 mm approx.).
• Mounting bolt spacing (center-to-center): 1 3/4" (44 mm approx.).
• Single fluid outlet for rear brake caliper plumbing.
• Reservoir integrated with the cylinder for a compact assembly.

What’s included and what should I expect during installation?

The package includes one complete master cylinder with integrated reservoir as pictured. Installation generally replaces the existing unit using the same mounting holes and brake hose; bleeding the brake system after installation is required for proper brake performance.

• Package contains one AUTOKAY master cylinder with reservoir assembly.
• Designed for bolt-on replacement using 1 3/4" bolt spacing.
• Requires brake fluid, hose connection to the single rear caliper, and bleeding after fitment.
• Check hose fittings and banjo/flare orientation for leak-free sealing.

Are there special considerations for international or aftermarket variations?

Because this is an internationally sourced aftermarket part, labeling and minor fit or instruction details may differ from original factory parts. Always compare part measurements and brake-port orientation before purchase to avoid fitment issues.

• Aftermarket unit; packaging or instructions may vary by region.
• Verify model fit and measurements rather than relying on model name alone.
• May require common workshop tools and brake-bleeding equipment for installation.
• Sold as a single master cylinder; additional hoses or hardware not included.

Who is this for: This AUTOKAY master cylinder is made for owners, mechanics, and restoration builders of mid-size go-karts—specifically Hammerhead 80T and TrailMaster MID users—who need a single-port hydraulic master cylinder with integrated reservoir as a direct, measurable replacement. It’s best suited to DIYers comfortable measuring mount points, connecting brake lines, and performing a full brake bleed, or to professional shops performing routine brake repairs on compatible mid-size kart platforms.