Steering angles and wheel alignment
1 When reading this Section, reference should also be made in respect of front and rear suspension arrangement.
2 Accurate front wheel alignment is essential to good steering and for even tyre wear. Before considering the steering angles, check that the tyres are correctly inflated, that the roadwheels are not buckled, the hub bearings are not worn or incorrectly adjusted and that the steering linkage is in good order.
3 Wheel alignment consists of four factors:
Camber is the angle at which the roadwheels are set from the vertical when viewed from the front or rear of the vehicle. Positive camber is the angle (in degrees) that the wheels are tilted outwards at the top, from the vertical.
Castor is the angle between the steering axis and a vertical line when viewed from each side of the vehicle. Positive castor is indicated when the steering axis is inclined towards the rear of the vehicle at its upper end.
Steering axis inclination is the angle, when viewed from the front or rear of the vehicle, between the vertical and an imaginary line drawn between the upper and lower suspension swivel balljoints or upper and lower strut mountings.
Toe is the amount by which the distance between the front inside edges of the roadwheel differs from that between the rear inside edges. If the distance at the front is less than that at the rear, the wheels are said to toe-in. If the distance at the front inside edges is greater than that at the rear, the wheels toeout.
4 Due to the need for precision gauges to measure the small angles of the steering andsuspension settings, it is preferable to leave this work to your dealer. Camber and castor angles are set in production and are not adjustable. If these angles are ever checked and found to be outside specification then either the suspension components are damaged or distorted, or wear has occurred in the bushes at the attachment point.
5 If you wish to check front wheel alignment yourself, first make sure that the lengths of both tie-rods are equal when the steering is in the straight-ahead position. This can be measured reasonably accurately by counting the number of exposed threads on the tie-rod adjacent to the balljoint assembly.
6 Adjust if necessary by releasing the locknut from the balljoint assembly and the clamp at the small end of the bellows.
7 Obtain a tracking gauge. These are available in various forms from accessory stores, or one can be fabricated from a length of steel tubing, suitably cranked to clear the sump and bellhousing, and having a set screw and locknut at one end.
8 With the gauge, measure the distance between the two inner rims of the roadwheels (at hub height) at the rear of the wheel. Push the vehicle forward to rotate the wheel through 180° (half a turn) and measure the distance between the wheel inner rims, again at hub height, at the front of the wheel. This last measurement should differ from the first one by the specified toe-in/toe-out (see Specifications).
9 Where the toe setting is found to be incorrect, release the tie-rod balljoint locknuts and turn the tie-rods by an equal amount. Only turn them through a quarter turn at a time before rechecking the alignment. Do not grip the threaded part of the tie-rod during adjustment and make sure that the bellows outboard clip is released, otherwise the bellows will twist as the tie-rod is rotated. When each tie-rod is viewed from the rack housing, turning the rods clockwise will increase the toe-out. Always turn the tie-rods in the same direction when viewed from the centre of the vehicle, otherwise they will become unequal in length. This would cause the steering wheel spoke alignment to alter and also cause problems on turning with tyre scrubbing.
10 After adjustment of the tie-rods check that the exposed thread portion of each is equal and does not exceed 28 mm. Also check that the steering wheel position is centralised, with the front roadwheels in the straight-ahead position.
11 If the steering wheel angular position is incorrect, but the tracking alignment of the front roadwheels is correct, proceed as follows:
12 Where the steering wheel misalignment is less than 30° then the wheel can be left in position.
13 Where the steering wheel is misaligned by more than 60°, turn the steering onto full lock then move it back to centralise it in the centre point of the lock-to-lock travel. You will now need to remove the steering wheel and refit it in the correct alignment position.
14 To correct further misalignment between the position of the steering wheel and the roadwheels when in the straight-ahead position, you will need to raise and support the front of the vehicle on safety stands (see “Jacking and vehicle support”).
15 Mark the relative positions of the tie-rods to joints, loosen the locknut and the outer steering bellows clip, then rotate each tie-rod an equivalent amount in the same direction to correct the steering wheel misalignment. Note that 30° of tie-rod rotation equals 1° of steering wheel angular correction. Rotate the rods clockwise (viewed from the left-hand side of the car) to correct a clockwise misalignment of the steering wheel. Rotate the tie-rods anti-clockwise to correct an anticlockwise misalignment (also viewed from the left-hand side of the vehicle).
16 After the steering wheel and tie-rod adjustment is complete, recheck the wheel alignment (paragraphs 5 to 9 inclusive) and retighten the locknuts without altering the positional settings of the tie-rods. Hold the balljoint assembly at the mid-point of its arc of travel (flats are provided on it for a spanner) while the locknuts are tightened.
17 Finally, tighten the bellows clamps.
18 Rear wheel alignment is set in production and is not adjustable, but when dismantling any part, it is essential that all washers are refitted in their original positions as they control the wheel setting for the life of the vehicle.