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TYRE WEAR
Center Tread Wear= Over Inflation
Outside Tread Wear= Under Inflation
Feathered or Sawtooth Wear= Toe or loose steering parts
Single Shoulder Wear= Camber problem
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CAMBER
The tyre may lean towards the car, or away from the car, or it may be straight vertical. Camber is measured from a straight up (true vertical) angle. Negative is the top of the tire in, positive is the top of the tire out, and zero is straight up and down.
Why its important to have proper camber.
1. It maximizes the amount of tread in constant contact with the road surface.
2. It helps to establish the proper load point on the suspension.
3. If incorrect, it can cause a pull or lead in the car.
4. It is used with another angle to diagnose bent suspension components.
The side with the most POSITIVE camber will cause a pull if both sides arent even. If the camber is within spec but to far off both sides then it will pull.
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CASTER
Caster is to aid proper steering stability. When the top hat/mount is mounted further back then straight up its positive caster, when its mounted more forward the straight up then its negative caster. The main function of caster is directional steering stability.
Increasing caster toward positive will increase directional stability and increase steering effort. Decreasing caster will reduce directional stability and decrease steering effort.
Caster is generally not a tyre wearing angle. Caster helps stabilize the vehicle and make turning away from the straight ahead position easier or harder.
The vehicle will pull to the side with the most POSITIVE caster if there not close by generally .5degrees.
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SAI (Steering Axis Inclination)
Sai is the angle between the line going straight up and down the ball joint compared to the strut angle. SAI helps provide dynamic stability (when the vehicle is in motion) and steering wheel return.
Check SAI very carefully if there are problems with pulling or handling that normal alignment doesn't correct.
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TOE
Important: Toe is the biggest tire wearing angle of all.
For every 3mm of incorrect toe its the same as dragging the tire sideways 8.5meters for every mile.
Toe is always completed AFTER the camber and caster have been adjusted.
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Thrust Angle
Is the angle between the geometric centerline of the car, and the difference between front and rear toe. A wrong thrust angle will cause dog tragging, crooked wheel and pulling.
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An alignment should always be done this way:
Rear toe.
Rear camber.
Front Caster
Front Camber
Straighten the steering wheel with the engine running so there is no pressure in the rack. Lock the steering wheel, turn off the car then adjust toe.
Center Tread Wear= Over Inflation
Outside Tread Wear= Under Inflation
Feathered or Sawtooth Wear= Toe or loose steering parts
Single Shoulder Wear= Camber problem
----------------------------------
CAMBER
The tyre may lean towards the car, or away from the car, or it may be straight vertical. Camber is measured from a straight up (true vertical) angle. Negative is the top of the tire in, positive is the top of the tire out, and zero is straight up and down.
Why its important to have proper camber.
1. It maximizes the amount of tread in constant contact with the road surface.
2. It helps to establish the proper load point on the suspension.
3. If incorrect, it can cause a pull or lead in the car.
4. It is used with another angle to diagnose bent suspension components.
The side with the most POSITIVE camber will cause a pull if both sides arent even. If the camber is within spec but to far off both sides then it will pull.
----------------------------------
CASTER
Caster is to aid proper steering stability. When the top hat/mount is mounted further back then straight up its positive caster, when its mounted more forward the straight up then its negative caster. The main function of caster is directional steering stability.
Increasing caster toward positive will increase directional stability and increase steering effort. Decreasing caster will reduce directional stability and decrease steering effort.
Caster is generally not a tyre wearing angle. Caster helps stabilize the vehicle and make turning away from the straight ahead position easier or harder.
The vehicle will pull to the side with the most POSITIVE caster if there not close by generally .5degrees.
----------------------------------
SAI (Steering Axis Inclination)
Sai is the angle between the line going straight up and down the ball joint compared to the strut angle. SAI helps provide dynamic stability (when the vehicle is in motion) and steering wheel return.
Check SAI very carefully if there are problems with pulling or handling that normal alignment doesn't correct.
----------------------------------
TOE
Important: Toe is the biggest tire wearing angle of all.
For every 3mm of incorrect toe its the same as dragging the tire sideways 8.5meters for every mile.
Toe is always completed AFTER the camber and caster have been adjusted.
----------------------------------
Thrust Angle
Is the angle between the geometric centerline of the car, and the difference between front and rear toe. A wrong thrust angle will cause dog tragging, crooked wheel and pulling.
----------------------------------
An alignment should always be done this way:
Rear toe.
Rear camber.
Front Caster
Front Camber
Straighten the steering wheel with the engine running so there is no pressure in the rack. Lock the steering wheel, turn off the car then adjust toe.