HIAORS Rear Disc Brake Master Cylinder & Caliper Assembly for 50–125cc ATVs — DOT3 Filled, Spare Pads Included

HIAORS rear disc brake master cylinder and caliper assembly is a complete replacement kit designed to restore hydraulic braking performance on many 50–125cc Chinese and compatible ATVs and quads.

If your ATV’s rear brake is worn, leaking, or no longer responsive, this HIAORS kit bundles a master cylinder, caliper, DOT3-filled reservoir, and one extra pair of brake pads to get you rolling again. Built to fit a long list of popular Chinese 4-wheelers — including TaoTao, Coolster, Kazuma, Roketa, Lifan and many others — the assembly arrives pre-assembled and includes commonly needed mounting and tubing dimensions so you can confirm fit before buying.

Which ATVs will this rear brake assembly fit?

This assembly is made for many common small-displacement Chinese ATVs and compatible models. Check your vehicle model against the provided fitment list and the mounting measurements to ensure compatibility.

• Common fits: TaoTao, Coolster, Apollo, Peace, Vitacci, Baja, Kazuma, Roketa, Lifan and similar models.
• Displacement range: designed for 50cc, 70cc, 90cc, 110cc and 125cc 4-stroke ATVs.
• Confirm: compare master cylinder and caliper hole spacing and tubing length with your bike.

How do I confirm the brake will mount to my quad?

Measure the mounting hole centers on your vehicle and compare them to the kit’s dimensions. The listing provides specific central spacing values for both the master cylinder and caliper so you can quickly validate fitment before installation.

• Master cylinder mounting hole spacing: 35–56 mm (1-3/8" to 2-3/16").
• Brake caliper mounting hole center spacing: 63 mm (2.5").
• Brake tubing length: 550 mm (21.5"), ready for most rear routing positions.

What comes in the box and what condition is the kit in?

The kit ships as a ready-to-install rear brake assembly with one pair of brake pads pre-installed and an extra pair included as spares. HIAORS supplies DOT3 fluid in the master cylinder so the unit is assembled and filled, reducing bench bleeding work during installation.

• Included: 1 rear master cylinder with caliper assembly and reservoir.
• Pads: 1 pair installed + 1 spare pair included for future replacement.
• Fluid: DOT3 brake fluid pre-installed; check and bleed after fitting per vehicle manual.

What should I expect during installation and maintenance?

Installation typically requires basic hand tools and some brake-bleeding to remove air after mounting. Routine inspection of pads, fluid level and hose condition helps maintain consistent braking performance.

• Tools: wrenches for caliper and master cylinder bolts, brake-bleeding kit recommended.
• Maintenance: inspect pads for wear, change fluid as manufacturer recommends, and check hose fittings for leaks.
• Support: HIAORS offers after-sale messages for sizing or installation questions.

Who is this for? Riders and mechanics who own small-displacement Chinese-style ATVs and need a cost-effective, drop-in rear brake replacement will find this HIAORS assembly useful. It’s aimed at owners of 50–125cc 4-stroke quads who want a complete hydraulic rear brake package that includes pads and fluid, with clear mounting dimensions to verify fit. If you’re restoring a stock brake, replacing a leaking master cylinder, or upgrading worn caliper parts, this kit provides the core components to get your rear braking system back to reliable operation. Always confirm fitment with the listed measurements and follow safe installation and bleeding procedures specific to your vehicle.