Hydraulic System: Testing and Inspection

CAUTION: If the vehicle pulls to one side during braking, make sure the front end alignment is correct before assuming the condition relates to a brake system malfunction.

Brakes should be tested on a dry, clean, reasonably smooth, and level roadway. A true test of brake performance cannot be made if the roadway is wet, greasy, or covered with loose dirt. These conditions prevent the tires from gripping the road equally. A crowned roadway also affects brake testing by throwing the weight of the vehicle toward the wheels on one side. Roadways rough enough to cause the wheels to bounce also affect this test.

Test the brakes at different vehicle speeds with light and heavy pressure. Avoid locking the wheels and sliding the tires on the roadway. Locked wheels and sliding tires do not indicate brake efficiency. Heavily braked turning wheels will stop the vehicle in less distance than locked wheels. More tire-to-road friction is present with a heavily braked turning tire than a sliding tire.

External conditions that affect brake performance include:
^ Tires: Tires with unequal contact and grip on the road will cause unequal braking. The inflation and tread pattern of the right and left tires must be about equal.
^ Vehicle Loading: When the vehicle has unequal loading, the most heavily loaded wheels require more braking force than the others.
^ Front Wheel Bearings: Loose front wheel bearings permit the rotor to tilt and have spotty contact with the linings. This causes erratic braking.
^ Front End Alignment: Misalignment of the front end, particularly camber and caster, causes the brakes to pull to one side.