Brakes

General Information

Cleaning of components

The components of the hydraulic braking system must be cleaned in clean brake fluid or denatured alcohol which does not contain benzene (benzole).

Although brake fluid is an excellent cleaning agent, it is also expensive. Denatured alcohol is, therefore, the most suitable cleaning agent.

Petrol, naphta, trichloroethylene or alcohol containing benzene must not be used for cleaning purposes since the slightest trace of mineral oil in the system will attack the rubber seals and cause them to swell.

It is extremely important that no cleaning agent remains in the system when filling with brake fluid. Traces of substances such as alcohol will lower the boiling point of the fluid, causing vaporisation and impairing operation.

After cleaning, the components should be wetted with brake fluid and assembled. The complete system should then be filled with fluid.

Brake fluid

Only top-quality brake fluid complying with the DOT 4+ standard should be used in the system. Use only genuine Volvo brake fluid. Never re-use brake fluid. Always store the brake fluid in the original container and seal tightly.

Do not mix brake fluids

Maximum cleanliness is essential to prevent the entry of dirt into the system when topping up the master cylinder and carrying out similar operations. Use only fresh, new fluid. Fluid drained from the system, for example when bleeding the brakes, must not be re-used.

Even top-quality brake fluid will deteriorate gradually due to absorption of moisture and minor impurities after a long period of use.

Compared with new fluid, a brake fluid which has deteriorated is recognisable by its darker or altered colour, relative lack of odour and watery appearance. The fluid should be replaced if any of these signs are present.

The recommended brake fluid replacement interval is every second year.

Brake fluid, replacement

The recommended brake fluid replacement interval is 40,000 km or every second year. The fluid should be replaced more often in climates of high humidity.

Tightening of wheel nuts

The following applies to fitting and tightening of the wheel nuts:

Ensure that the brake disc and wheel mating surfaces are clean. Lubricate the wheel locating pins on the hub with rust inhibitor, P/N 1 161 038-3.

Finger-tighten the nuts and then tighten diagonally to 85 Nm (63 ft lb) using a torque wrench or torque socket 981 4031-2. The torque socket is designed for tightening wheel nuts with a standard, pneumatic, impact-type nut runner delivering a torque of 250-350 Nm (184-258 ft lb).

Diagonal tightening/torquing is important to prevent stressing of the brake disc.