Component Tests and General Diagnostics

PROPER TEST CONDITIONS
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, oily, or covered with loose dirt. These conditions prevent the tires from gripping the road equally. A crowned roadway 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 affects 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 show 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

Tires - Tires with unequal contact and grip on the road will cause unequal braking. All tires must be of the same size and have identical tread patterns. They must also be inflated to the proper specification.

Vehicle Loading - When the vehicle has unequal loading, the most heavily loaded wheels require more braking power than the others.

Front Wheel Bearings - Loose front wheel bearings allow the rotor to tilt and have spotty contact with the linings. This causes erratic braking action.

Front End Alignment - Misalignment of the front end, particularly with camber and caster, will cause the brakes to pull to one side.