The Moto Guzzi brake system incorporates two independent systems — one for the right caliper on the front wheel operated by a right hand lever, and one for the left caliper on the front wheel and the rear wheel caliper operated by a right foot pedal.
Most of the system will not be used since the cyclecar’s fully integrated braking system for the rear and both front wheels with a single master cylinder requires a significantly modified design and new components.
Brake light circuit
Two brake light switches are wired in series to trigger the rear brake lights from the right hand lever (front right caliper) and/or the right foot pedal (front left caliper and rear caliper).
The rear brake light wires pass through a 6-way Molex and then the red/blue lead attaches first to the brake switch on the brake proportioning valve using a 2-prong connector (a ground connection is also made through the valve mount that has a lead to the negative battery terminal).
A second lead goes to fused positive power, while the third lead continues to the front brake light switch on the handlebar via a 10-pin connector.
To remove the rear/front system, first unfasten the harness leads on the brake proportioning valve.
Brake proportioning valve
To help balance the complicated dual brake system, the California 1100 deploys a proportioning valve that gradually shifts hydraulic pressure to the front left caliper (presumably along with pressure on the front right caliper from the handlebar lever, too!) during hard braking.
At maximum pressure, this valve distributes about three-quarters of the pressure to the front brake, and the balance to the rear. This is mostly to prevent a lockup of the rear wheel that could result in a skid or loss of control.
To remove the front/rear segment of the brakes, first bleed the system. Disconnect the proportioning value components and then remove the rear brake caliper and hose.
Brembo brake caliper
Between 1974 and 1997, Moto Guzzi fitted Brembo P2 F08 dual calipers on the front and rear wheel (part 28653001). The F08 model uses 38mm pistons and is one of the most successful caliper designs of all time fitted to countless Benelli, Bimota, BMW, Ducati, Guzzi, Laverda and other European cycles during the last quarter of the 20th century.
Repair parts and replacements are readily available, including the sliding guide pins on floating calipers, hex head fasteners, dust covers, piston seals, and pistons.
Brake foot pedal
The right foot brake pedal assembly is attached at a pivot point to the frame, with a long extension link fastened to the master cylinder.
This pedal operates the left front brake and the rear brake simultaneously; the right front brake is separately activated by a right handlebar lever.
The brake rotor assembly is composed of an outer disc (P/N GU30635860) connected to a flange (P/N GU30613760) with five cylindrical bushings (P/N GU28613560) secured with special Belleville spring washers and circlips. The flange is then bolted to the wheel hub with five special flat head Allen hardware (P/N GU30611460).
The rear rotor diameter is 270mm and the dual front rotors are 300mm.