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Suspension and Steering Auto Service Tech Tips
These Tech Tips are provided courtesy of autoclassroom.com, an online training resource for automotive instructors, students, and technicians.
Play it safe: Disconnect the air bag
Whenever working on or around the steering column or dash, it is wise to disconnect the air bag to avoid the possibility of an accidental deployment of the bag(s). While the exact methods recommended by vehicle manufacturers vary, most include the following steps:
Step 1: Disconnect the air bag fuse. This fuse (or fuses) is usually labeled with yellow
to mark their location.
Step 2: Disconnect the connector at the base of the steering column and under the dash
on the passenger side if the vehicle is equipped with a passenger-side air bag.
Again, the connector(s) are yellow in color. These two steps will help prevent the possibility of an accidental air bag deployment.
The hydro-boost accumulator test
The accumulator stores hydraulic fluid under pressure to provide a reserve in the event of a failure of the power steering system. The accumulator is designed to provide three or more power-assisted stops with the engine off. If the accumulator fails, it does not hold pressure. To easily check to see if the accumulator has lost its charge, simply grasp the accumulator with your hand and try to twist or move it. The accumulator should have so much pressure on it that it does not move or wiggle. If the accumulator moves, it has lost its ability to hold pressure and the hydro-boost unit should be replaced.
The killer Bs
The three Bs that can cause steering and suspension problems include bent, broken, or binding components. Always inspect each part under the vehicle for each of the killer Bs.
Jounce/rebound test
All steering linkage should be level and "work" at the same angle as the suspension arms. A simple test to check these items is performed as follows:
Park on a level, hard surface with the wheels straight ahead and the steering wheel in the "unlocked" position.
Bounce or "jounce" the vehicle up and down at the front bumper while watching the steering wheel. The steering wheel should not move.
If the steering wheel moves while the vehicle is being bounced, look for a possible bent steering linkage, suspension arm, or steering rack.
Caster angle tire wear
The caster angle is generally considered to be a non-tire wearing angle. While this statement is true, excessive or unequal caster can indirectly cause tire wear. When the front wheels are turned on a vehicle with a lot of positive caster, the front wheels become angled, which is called camber roll. (The caster angle is a measurement of the difference in camber angle from when the wheel is turned inward compared to when the wheel is turned outward.) Many vehicle manufacturers have positive caster designed into the suspension system. This positive caster has increased the directional stability of these vehicles. However, if the vehicle is used exclusively in city-type driving, the positive caster can cause tire wear to the outside shoulders of both front tires. |
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