Wheel Alignment diagnosis, Adjustment, and Repair

Question 1

How would you diagnose vehicle wandering, darting, pulling, drifting, shimmy, and steering effort problems?

Answer 1

_Perform a vehicle road test to confirm customer complaint.
_Determine if the load carried is a cause of the complaint.
_If necessary, repeat the road test with the load in place.
_If load alone is not the problem, perform the following steps:
1. Weigh vehicle with and without load.
2. Confirm load rating for the vehicle type.
3. Determine if the installed suspension is of sufficient load-carrying capacity.
4. Confirm that the suspension has not been modified; that is, new springs increase or decrease in the spring rates.
5. Inspect front and rear suspension mounting, shackle pins and bushings, and torque arm pins and bushings for wear.
6. Inspect vehicle for proper tire/rim type and air pressure.
7. Confirm suspension height specifications.
8. Check for binding or loose steering components.
9. Check for frame damage; that is twists, bends, cracks.
10.Determine if alignment is within specifications (especially caster).
11. Measure steering box and column bearing preload specifications.
12. Check shock-absorber function.

Adjust, repair, or replace all necessary components to return vehicle to the manufacturer’s specifications. Repeat road test to confirm repairs and that complaint is corrected.

Question 2

What is camber?

Answer 2

Camber is a setting that determines the inward or outward tilt of the top of the wheels when viewed from the front of the vehicle.
_ It is referred to as either negative or positive camber.

Question 3

What is positive camber?

Answer 3

Moving the top of the wheels out from a neutral (vertical) position provides positive camber movement.

Question 4

What is negative camber?

Answer 4

Negative camber is the inward tilt of the wheel.

Question 5

What is a visual indication of out-of-specification camber?

Answer 5

A visual indication of out-of-specification camber is that the inner or outer edge of the tire shows accelerated wear in comparison to the remaining tread.

Question 6

What are KPI (kingpin inclination) or SAI (steering axis inclination)?

Answer 6

KPI or SAI is the inward tilt of the kingpin at the top viewed from the front of the vehicle.
_KPI is measured in degrees from the center line of the ball joints or kingpin to true vertical (0)
_It is a directional control angle with fixed relationship to camber settings.
_It is also nonadjustable.

Question 7

What is one purpose of the inclination?

Answer 7

Is to reduce the need for excessive camber.

Question 8

What is a road test indication of out-of-specification SAI/KPI ?

Answer 8

Is that the steering wheel does not return properly.
_Check steering wheel movement, using a tension gauge first to confirm correct pre-load or binding.
_All specifications should be confirmed using available alignment equipment after a visual/mechanical and road test inspection.

Question 9

What is caster?

Answer 9

Caster is the forward or rearward tilt of the kingpin or the forward or rearward tilt of the upper ball joint in relation to the lower ball joint as viewed from the side of the vehicle.

Question 10

What does positive caster indicate?

Answer 10

Indicates that the kingpin is tilted rearward.

Question 11

How is determining caster settings most accurately performed?

Answer 11

Bu alignment-measurement equipment and is adjusted by using angled axle shims between the front axle spring seat and front spring assembly.
_Caster is a necessary engineered component as it allows manufacturers to build into the vehicle directional stability.
Most vehicles are designed with some degree of positive castor.

Question 12

What can too little castor cause?

Answer 12

Wheel instability, wandering, and poor steering wheel recovery.

Question 13

What can too much castor result in?

Answer 13

Can result in hard steering, darting, oversteer, and low-speed shimmy.

Study page 35 for illustrations.

Question 14

How do you check toe measurement?

Answer 14

Usually is performed by alignment machines, trammel bar, measuring tape, or string.
_A visual inspection of the tier tread area will allow the technician to determine out-of-specification settings.

Question 15

How is toe setting engineered?

Answer 15

Toe setting is engineered into the suspension to provide longer tire life.
_Vehicles having rear-wheel drive will usually have toe- in settings.
_As the rear-wheel drive will pushes the vehicle forward the to-in will become a zero toe measurement due to deflection in tie rods.
_the measurement is determined as follows: The front tire tread is closer together than the rear tread (toe-in) or the rear tread area is closer together (toe-out) when measured at the forward and trailing horizontal tread areas.

Question 16

What will incorrect toe angles do?

Answer 16

They not only accelerate tire wear but also can have an adverse effect on directional stability of the vehicle.
_Too much toe-in produces scuffing, or a feather edge along the inner edges of the tire ribs.

Question 17

How are adjustment achieved?

Answer 17

Is usually achieved by rotating a threaded sleeve on the tie rod or center link or rotating the tie rod (cross tube).
_Although adjusting toe will not affect other alignment angles, camber settings will affect toe.
_If toe measurements are radically different from the OEM specifications, a measurement of the camber settings may be in order.

Study illustrations on page 36.

Question 18

What happens when a vehicle’s rear wheels track directly behind the front wheels?

Answer 18

The vehicle has a proper thrust-line.
_This prevents dog tracking or abnormal Ackerman effect.
_In addition, improper rear axle alignment may cause excessive scrubbing of the front steer tires.

Question 19

How would you inspect the rear suspension and axle alignment components for wear, loose or broken parts, or distortion?

Answer 19

_Replace components as required.
Adjustments to rear axle alignment may be accomplished through the use of shims or by rotating the adjustment eccentric bushings in the front spring hanger.
_Refer to the OEM service manuals for prosper alignment procedures.

Question 20

What happens when a vehicle turns a corner?

Answer 20

The front and rear wheels must turn around a common center with respect to the turn radius or angle.
_On a single rear axle, this common center is located at the center of the rear wheels.
_On most front suspensions, the front wheels pivot independently at different distances from the center of the turn, and therefore the front wheels must turn at different angles.
_These are called the Ackerman angles, and they are controlled with the steering arms.

Question 21

Compared to the outside wheel, how must the inside front wheel turn?

Answer 21

Must turn at a sharper angle.
_This action is necessary because the inside wheel is actually ahead of the outside wheel.
See illustrations on page 37.

Question 22

How is toe-out-on-turns checked?

Answer 22

Is checked using two turning plates equipped with angle scales and pointers.
_Prior to checking the Ackerman angle ensure the toe-in settings are set to OEM specifications.
_Mount the wheels on the turntables in a straight ahead position.
_Make sure the pointers are set at 0 degrees.
-Turn the left-front wheel inward to a 20 degree angle and read the right wheel outside angle.
_Repeat the process for the right wheel and note the left wheel outside angle.

Question 23

What should you do if the outer wheel angles from sided to side vary more than 1 degree?

Answer 23

Further inspection is indicated.

Question 24

What should you do if the front-end alignment angles and toe settings are correct and the toe-out measurement is grossly different or incorrect?

Answer 24

One or both steering arms are bent.

Question 25

How is maximum turning radius maintained?

Answer 25

By the steering stops located at each front wheel.
_If the steering angle is too tight, the vehicle could dangerously lock up.
_The technician should check the steering stop adjustment any time the front axle is replaced, replacement of the spring assemblies, or when the front-end alignment requiring a setting change.
_If the unit is equipped with power steering, the power steering gear pressure relief should be checked for proper setting and operation.