Technical Description

of

the Rear Brake Disc Conversion Kit

BMW R65 / R80 / R100 Monolever

This set corresponds to a rear brake disc conversion kit for BMW Monolever motorcycles.

Its main function is to replace or improve the original braking system, providing greater braking power.

Better pedal feel and a more precise and safer response.

Main Components and Their Function

1. Perforated Brake Disc

This is the main circular component of the kit. It is mounted on the rear wheel and rotates together with it.

Function:
To receive the pressure from the brake pads through the caliper, creating a smoother and more precise braking feel, similar to that of a more modern motorcycle.

Visible features:
Cast brake disc with multiple perforations to improve heat dissipation, reduce weight, and help evacuate dust, water, and braking residue.

2. Brake Caliper

Metal component located on the rear right side of the motorcycle.

Function:
It houses the brake pads and applies pressure to the disc when the brake pedal is activated. It is one of the key elements that transforms hydraulic pressure into real braking force.

Importance:
A properly sized caliper improves initial bite, braking progression, and overall stopping performance compared with the original system.

3. Caliper Bracket / Adapter

High-performance cast black components located in the lower central and rear area.

Function:
They allow the brake caliper to be mounted onto the swingarm or the corresponding fixing point of the motorcycle.

Importance:
These are critical components because they ensure the exact alignment between the caliper, brake pads, and disc. Poor alignment can cause irregular wear, vibrations, or loss of braking efficiency.

4. Brake Pump / Master Cylinder

Metal component located on the right side, connected to the black hose and the brake fluid reservoir.

Function:
It converts the force applied to the brake pedal into hydraulic pressure. This pressure is transmitted through the brake hose to the caliper.

Importance:
It determines much of the braking feel: pedal travel, firmness, progression, and braking power.

5. Brake Fluid Reservoir

Small translucent reservoir located in the upper right area.

Function:
It stores the brake fluid that feeds the hydraulic circuit.

Importance:
It allows visual control of the fluid level and compensates for small variations caused by brake pad wear or maintenance.

6. Braided Stainless Steel Brake Hose

Blue curved hose located in the lower and side area of the image.

Function:
It carries hydraulic pressure from the brake pump to the caliper.

Advantage:
A braided stainless steel brake hose expands less than a conventional rubber hose. This improves pedal feel and provides a more direct braking response.

7. Auxiliary Hose / Hydraulic Connection

Black corrugated hose connected to the brake pump.

Function:
It forms part of the hydraulic supply or connection system, depending on the final installation configuration.

Importance:
It ensures proper brake fluid circulation between the reservoir, the pump, and the main hydraulic circuit.

8. Fittings, Bolts, and Washers

Small components located in the center of the image.

Function:
They connect the different elements of the system: brake hoses, pump, caliper, bracket, and disc.

Importance:
They are safety-critical components. They must be installed with the correct tightening torque and, where required, with new washers to prevent brake fluid leaks.

9. Wiring / Auxiliary Sensor

Small black assembly located next to the blue brake hose.

Function:
It may correspond to a switch, sensor, or auxiliary connection related to the brake light or the motorcycle’s electrical system.

Importance:
It allows the brake action to correctly activate the rear brake light.

General System Operation

When the rider presses the brake pedal, the brake pump generates hydraulic pressure. This pressure travels through the brake hose to the caliper. The caliper pushes the brake pads against the disc, creating friction and reducing the speed of the rear wheel.

The system improves the original setup by combining:

A higher-performance disc, a more effective caliper, a suitable brake pump, a braided brake hose, and specific machined mounting brackets.