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Sequential Alignment Fault Diagnostics

 

by Tony Bones

 

Condition                                                                    Possible cause

Premature tyre wear                                            Incorrect tyre inflation

                                                                                Wheel alignment out of tolerance

                                                                                Suspension components worn

                                                                                Incorrect ride height (1)

                                                                                Distorted wheel

                                                                                Incorrect torsion bar adjustment

                                                                                Loose or worn wheel bearings

                                                                                Worn shock absorbers

                                                                                Tyres out of balance

 

Pulls to one side                                                 Incorrect tyre inflation

                                                                                Brakes binding (2)

                                                                                Mismatched tyres (3)

                                                                                Broken coil spring (1)

                                                                                Power steering valve not centred (4)

                                                                                Wheel alignment out of tolerance (5)

                                                                                Defective wheel bearings (6)

                                                                                Damaged anti roll bar drop links

                                                                                Incorrect castor angle (7)

                                                                                Wear on nsf tyre (8)

 

Heavy steering                                                     Drag link seized

                                                                                Ball joint seized

                                                                                Steering linkage seized (9)

                                                                                Power steering fluid low (10)

                                                                                Power steering belt loose

                                                                                Power steering pump defective (11)

                                                                                Incorrect wheel alignment (12)

                                                                                Damaged steering rack

                                                                                Damaged suspension components (13)

 

Vehicle wandering                                               Worn or damaged suspension

                                                                                Worn track control arm or tie rod (14)

                                                                                Loose or worn wheel bearings (6)

                                                                                Incorrect tyre inflation

                                                                                Anti-roll bar drop link defective

                                                                                Wheel alignment out of tolerance (5)

                                                                                Broken coil or sagging coil spring (1)

 

Method of Testing

(1) Measure ride height from mid wheel arch to the centre of the hub, except no more than 10 mm difference across any given axle, a broken or sagging coil spring can cause a pull even from the rear.

(2) If checking when cold, look for hot spots or blued discs.

(3) Rotational/ directional/ asymmetrical/ mismatch bias.

(4) Check track rod threads are even, ignore the position of the steering wheel, may prove steering wheel has been re-set.

(5) Will need to be in excess of 1 degree/ 6 mm normally negative/ toe out.

(6) Worn tapered rear wheel bearings will change the camber angle and cause a pull/ front wheel bearings are harder to test cold/ hold the coil spring and spin the wheel, if you feel a rumble then the bearing is worn.

(7) In most cases will only go wrong by an impact, telltale sign, the wheel alignment will be a long way out, if a full wheel geometry is not available, check to see if the wheels have excessive set back, measure mid-wheel to mid-wheel, front to rear, ns and os, if the lowest is the direction the vehicle is pulling, then the castor is probably wrong, avoid setting just the wheel alignment as this will not resolve the pull and probably generate a complaint.

(8) Due to the road layout (UK) the nsf tyre has a smaller turning radius than the osf, this will cause the outside of the nsf tyre to wear more than the osf, this pattern of wear is unavoidable, if the vehicle is pulling left and the nsf is showing signs of wear, move the front wheels side to side, or front to rear, then test and adjust wheel alignment, noncompliance is a common reason for an after adjustment complaint.

(9) Common on Fiesta/ Escorts, jack up front wheels and turn steering, if (terminology differs) the steering column/ linkage/ coupling/ joint, is seized it will go tight 180 degrees, ½ turn.

(10) The more the steering is turned, the more the pump will scream.

(11) Jack up front wheels, start engine and rev to about 2500 rpm observe if the steering wheel moves, also manually check the steering's resistance by moving the steering wheel from left to right.

(12) Will need to be in excess of 1 degree/ 6 mm positive/ toe in.

(13) Disconnect track rod from strut, turn strut from side to side, and feel if metallic bush is seized.

(14) If front wheel drive the wander will deviate left/ right under acceleration/ deceleration, beware a worn engine mount on a front wheel drive vehicle can also cause this, by offsetting the drive shafts, rear wheel drive will deviate mainly under braking, or coming of bumps.

 

 Tony Bones and Jason Saunders of Wheels in Motion (http://www.wheels-inmotion.co.uk/index.php) have developed somewhat of a cult following as alignment experts in England.  Although their articles are amazingly complicated and there may be a little bit of a language barrier, we asked to reprint these gems for your benefit. Tony Bones did ask us to please advise readers that this information is a global overview of alignment principles and actual practical application to specific vehicles should be left to the professional alignment technician or shop.

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