Alignment: Description and Operation

TOE-IN
The toe-in value is the difference between A and B, as illustrated.
If the wheels are exactly parallel, with the dimensions apart equal, the toe-in will be O.
The toe-in value must always be positive, that is to say, dimension B must be greater than dimension A.
B minus A = a positive toe-in value
Toe-in is adjusted by either lengthening or shortening the track rods. Correct toe-in contributes to directional stability.
The toe-in value on the rear wheels is always measured in relation to the vehicles symmetrical alignment. The symmetrical alignment is an imaginary line between the middle point of the front and rear wheel axles.
Incorrect toe-in or toe-out produce vibrations that increase tire wear. The tires slip side ways.
Excessive toe in often produces wear on the outer shoulders.





CAMBER (WHEEL INCLINATION)
Camber (B) refers to the angle formed between the wheel and the vertical (A), No. 1, as shown. If the wheel leans outwards, the camber angle is said to be positive (+), if it leans inwards, the camber angle is said to be negative (-). The Saab 9000 has a negative camber angle.
The camber angle is not adjustable on Saab 9000.

CASTER (AXLE INCLINATION)
Castor angle (C) is the angle at which the swivel pin deviates from the vertical (A) when seen from the side, given in degrees. When the swivel axle is inclined rearwards, No. 2 as shown, the castor is said to be positive. When it is inclined forwards, the castor is said to be negative. The Saab 9000 has positive castor angle.
The castor allows the wheel to be braced when moving directly forwards and to be relaxed when steering. Also, large castor improves the steering wheel return action.
The caster angle is not adjustable on the Saab 9000.

KING-PIN INCLINATION (KPI)
King-pin inclination (D), No. 3, as shown, is an imaginary line that passes through the centre of the bail bearing at the top of the MacPherson strut and the centre of the ball joint on the suspension arm. This inclination is measured against the vertical (A) and given in degrees.
Inclination inward is positive inclination and outwards is negative.
A correct king-pin inclination produces lighter steering and the wheels return to a correct position when the car returns to a straight heading.
King-pin inclination is not adjustable on the Saab 9000.





STEERING ANGLE
The ideal steering angle for perfect rolling of all wheels when cornering varies with the speed of the car and the tightness of the turn, owing to the suspension movement and deflection of the tires.
Since the track arms are turned slightly inwards in relation to the direction of the car, the angle of the inner wheel when cornering will be slightly greater than that of the outer wheel.
A - B = positive