Automotive Technology/Suspension and Steering

This page is written for those taking the ASE A4 test


 * Always mark the placement of any part before removal

Steering
Always disable the ../Air Bag/ system before any change to the steering column.

../Steering Columns/ should be locked into place to preserve timing and prevent overextending the clock-spring.

Replace ../Bushings/ when they no longer hold the part in position. Replace ../Bearings/ when they have any visible play, or have a turning torque outside of specification.

Adjustments can affect front wheel toe

Diagnosis
Bump steer can be caused by
 * Loose idler arm
 * Loose rack mountings
 * Loose or damaged mounting

Steering wheel free play can be caused by
 * Worn couplings
 * worn u joint
 * Loose mounting

Steering problems are sometimes subframe alignment problems

Manual Steering Gears
Also known as worm gears

Noises, binding, looseness, hard steering point to bearing and lubrication problems.

Other parts
Air bag Steering wheel Clock spring

Worm gear Idler arm Rack and pinion

Tie rods

Power Steering Units
Power steering uses hydraulic pressure to apply force to the worm gear or rack

Diagnosis
Weeping, or a slight fluid leak requires repair or replacement


 * inspect power steering fluid
 * Remove and replace power steering pump belt, tensioner, pulley
 * diagnose power steering pump problems
 * Remove and replace power steering pump
 * power steering pressure test
 * Remove and replace power steering hydraulics
 * Steering gear worm bearing preload and sector lash


 * Remove and replace steering gear seals and gaskets


 * Remove and replace rack and pinion unit
 * Remove and replace rack and pinion steering gear bellows/boots.
 * flush, fill, bleed power steering hydraulics
 * Diagnose, Remove and replace variable-assist steering systems


 * Rack and Pinion Steering:can provide assistance by applying pressure to one side

Steering Linkage

 * Inspect and adjust steering linkage geometry



Pitman arm
Pitman arm is only bent in collisions, and wears on other parts. These are pressed on, and are difficult to separate from the splines.

Center link
If bent, will affect front wheel toe

Idler arm

 * Remove and Replace tie rods
 * Remove and Replace steering linkage damper

Remove and Replace

Frame

 * Frame

Springs
You should understand spring frequency, even if you never measure the frequency of the spring. Most spring are made of a chrome-vanadium alloy. Very tough stuff.


 * Leaf spring
 * Coil spring
 * Torsion bars


 * Constant-velocity joint:Usable in torque transfer

Suspension

 * Kingpin
 * MacPherson Struts
 * Short/Long Arm

Glossary

 * Aspect ratio


 * Bead:The lip of the tire that seals the rim flange
 * Belt:Material under the tread


 * Center section AKA Spider:Center of a steel wheel


 * Conicity
 * DOT tire code
 * E-metric tire
 * High flotation tire
 * Inner liner
 * Load index
 * Lug nuts
 * Major splice
 * Offset
 * Ply steer
 * Rim width
 * Run-flat
 * Sidewall
 * Speed rating


 * TPC


 * Tread


 * Unsprung Weight:Weight below the spring in a vehicle


 * Uniform Tire Quality Grading System (UTQG):Tires sold in the USA are rated in Tread wear, Traction, and Temperature Resistance as per NHTSA.

Automotive Diagnostics
 * Wear bars:raised features located at the bottom of the tread grooves that indicate the tire has reached its wear limit