Steering and Wheel Alignment Diagnosis.docx

Steering and Wheel Alignment Diagnosis

Name: Mohamed Ashraf Sayed

Section: 3

Before getting into the diagnosis process, some information must be declared about camber, caster and Toe considering the benefit of each one.

Camber :

-Wheel camber is an important factor in the vehicle’s handling and stability.

-There are two camber angles utilized: positive and negative camber.

-Too much positive camber will cause the tyres to wear on the outside edges.

-Too much negative camber will create excessive wear on the inner edges of the tyres.

-If the camber angles are set differently on each side of the vehicle, this can create a problem with the vehicle pulling to one side – the vehicle will generally pull to the side of the wheel with the greater positive camber setting.

Caster:-Wheel caster is applied to enable the driver to ‘feel ‘the straight-ahead position so that they may steer a straight path.

-is the forward (negative) or rearward (positive) tilt of the steering axis as viewed from the side.

-too much caster produces hard steering, whereas too little causes ‘wander’.

-Vehicles have a small amount of positive caster to provide quick steering return and high speed stability.

-Applies to the front wheels because they are the only ones that steer.

Toe:-Toe refers to the parallelism between the wheels as viewed from above and is usually measured in inches or millimeters.

-Most rear-wheel drive cars and trucks have alignment specifications that call for a little bit of toe-in.

-Classic toe misalignment is a feathered wear pattern across both front tires. The direction of the feathering tells you if the tires are toed-in or toed-out.

-Toe-in will wear the outer rib while toe-out will cause wear on the inner rib. In both instances, wear can be aggravated even more if the tires are underinflated.

Steering systems and wheel alignment –routine maintenance

Steering wheel installationby moving the steering wheel in all directions, it is possible to check that the steering wheel has been correctly installed. This test will also check that the main shaft bearing is not loose and that the steering wheel is secured correctly to the main shaft.

Steering wheel free playwhile sitting in the driver’s position steering wheel free play can be checked. Place the steering wheel in the straight-ahead position and check that the front wheels correspond to the steering wheel. Now move the steering wheel slightly to the left or right without the wheels actually moving. Check the manufacturer’s specifications for the amount of free play allowed. If there is excessive free play, then one of the following problems may have occurred: -Worn steering linkage -Steering wheel not secured properly -Worn wheel bearings -Worn steering rack, or incorrect adjustment of steering gear and Loose main shaft joint

Wear in the steering linkageRaising the front of the vehicle off the ground and moving the wheels back and forth is the recommended method

for checking the wear in thesteering linkage. If there is excessive movement, then either wheel bearings or worn steering linkage are possible causes. To raise the front of the vehicle, either use a two-poster ramp or a trolley jack; if a trolley jack is used, then axle ramps must be used to support the vehicle.

Wheel bearing playAs with the steering linkage, the wheel bearing play can be checked by first raising the front of the vehicle off the ground and then gripping the wheel at the top and bottom and checking if there is any play in thewheel. If there is play, then the same task must be carried out with the brakes applied. If the amount of play is reduced and not eliminated totally, then it is probably not a wheel-bearing fault.

Steering joints and gaitersCheck around all of the steering linkages from the steering column down through the steering rack and to the rack rods and track rod ends. There should be little or no play in these areas. Check the dust gaiters located on the steering rack and the track rod ends, as any damage to these will cause water and dirt ingress, which will accelerate the wear of these components and lead to possible seizure.

Wheel alignment

Under normal conditions, it is not necessary to check the wheel alignment at every service interval, although it must be checked during the pre-delivery inspection. Wheel alignment does need to be checkedwhen a fault occurs, which will normally be evident due to abnormal tyre wear.

There are numerous components and systems that can affect wheel alignment. If a component is physically worn, then adjusting the wheel alignment will not solve the problem. The components that suffer fromwear and can affect the wheel alignment are: tie-rod ends steering linkage wheel bearings suspension components

Other factors that can affect wheel alignment are:

tyre pressurevehicle ground clearancetyre run outdifference between left and right wheelbase and wheel alignment being carried out on uneven ground

Diagnosis of steering faults

The following table summarizes the various steering faults that can occur:

Different conditions of Caster

Condition EffectHigh positive caster Makes the front wheels want to go

straight aheadNormal amount of positive caster Provides stability and makes the steering

wheel straighten out after turningToo little caster Can make steering unstable and cause

wheel shimmyExtremely negative caster and the related shimmy

Can contribute to cupped wear of the front tires

If caster is unequal from side to side The vehicle will pull toward the side with less positive (or more negative) caster

Different conditions of Camber

Condition EffectZero camber-a perfectly vertical wheel and tire

Causes the least tire wear

Positive camber Causes the outer tread of the tire to wear more than the inner tread;

negative camber Causes the inner tread of the tire to wear more than the outer tread

Normal camber angles Have little visible effect on tire wearExtreme camber(positive or negative ) Causes noticeably abnormal tire wear

and shortens tire life.

Different conditions of Toe

Condition EffectZero toe-wheels aimed straight ahead Causes the least tire wearExtreme toe-in or toe-out Causes feather-edged wear across the

tire tread.

Too much toe-in Wears the outside tread edges, with feathered edges on the inside of each tread row

Too much toe-out Wears the inside tread edges ,with feathered edges on the outside of each tread row

Common pull-related conditions along with their causes

Problem Probable Causes

STEADY PULL

This is a condition where the vehicle continually pulls or drifts to one side while traveling straight. The driver typically has to maintain steady pressure on the steering wheel to keep the vehicle on the road.

Uneven camber side-to sideA bent strut or dislocated strut tower, a bent spindle, collapsed control arm bushing, weak or broken spring, or a shifted cross member or engine cradle.

Uneven caster side-to-side.The underlying cause may be a bent strut, spindle or dislocated strut tower.

Rear axle steerThe underlying cause may be rear toe out of specifications, a bent rear axle, chassis misalignment or a stackup of assembly tolerances in the chassis causing rear axle misalignment.

Uneven tire wearThe uneven wear may be the result of incorrect camber, toe and/or failure to rotate the tires periodically to even out wear

MEMORY STEER

The steering wheel and wheels want to return to some position other than center. This may cause a steering pull or drift to one side after turning

Misalignment or improper installation of Ford rubber bonded socket (RBS) tie rod ends.

RBS tie rod ends do not swivel freely like conventional tie rod ends

Binding in upper strut mounts.upper strut mount is binding or loose

OFF-CENTER STEERING WHEELThis condition may accompany a steady pull or memory steer. But if the steering

Steering linkage not centered when toe was adjustedBinding in upper strut mounts.

wheel is off-center (crooked) but there is no pull to either side,STEERING WANDERThe vehicle lacks directional stability and wanders or drifts from side to side.

Loose or worn steering componentsLoose or improperly adjusted wheel bearings.Insufficient casterExtremely low tire pressure. Extreme toe misalignment.

BUMP STEERThe steering suddenly jerks or veers to one side or the other when the vehicle passes over a bump

caused by unequal toe changes that occur as the suspension travels through jounce and rebound. The condition can be confirmed by checking individual front toe with the suspension loaded (compressed)possible causes are listed as follows:

Parallelogram steering linkage not levelSteering rack not levelSteering rack not levelStructural damage

Front wheel Adjustment:

Rear wheel adjustment

Checking for worn parts before alignment

References

-Hiller’s fundamentals of motor vehicle technology

-Auto fundamentals

Websites :

www.aa1car.com