wheel balancing and alignment

Symptoms of a car out of balance are recognised by vibration in the steering wheel also seats or floorboard at certain speeds. Even weight distribution is absent from mass produced wheels. Consequently when it rotates it tends to ‘vibrate’ this can be the biggest killer in any machine, an inherent imbalance which will get worse and cause un-even tyre wear. A tire is out of balance when one section of the tire is heavier than the others and if left untreated will cause steering ‘wobble’ at various speeds and ware of shock absorbers, suspension and chassis components. Popular misconception is that Wheel Balancing is required only for the front wheels, but if not done on front and rear wheels not only does the car user experience steering ‘wobble’ but can also kill wheel bearings prematurely. To balance a wheel, the technician will mount it on a balancing machine which spins the wheel to locate the heavier part and attach a lead weight on the opposite side. Symptoms of a car that is out of alignment are, uneven or rapid tyre wear and drifting away on a straight level road, also the spokes of the steering wheel are off to one side while driving on a level road. It is wise to have the alignment checked regularly, as uneven wear on tyres can become too bad to save the tyre. The best type of wheel alignment is a four wheel alignment this will allow the technician to identify any rear tracking problems and make the appropriate adjustments to the front. Tire balancing Despite advanced tire manufacturing processes and advanced rubber compounds used today, some weight imbalance can still be evident in new tires. Therefore they should be balanced with wheel weights to achieve smooth rolling of the tire. An imbalanced tire expresses itself as a wheel shimmy (rocking back and forth of the steering wheel while driving, usually at a specific speed). To balance a tire, it must first be mounted in the proper rim and then inflated to the proper air pressure and a new valve stem installed. Next, the complete tire/wheel assembly is affixed to a machine that is designed to spin the tire and identify the location and severity of the imbalance. The tech must then affix the proper weight to the rim in the location designated by the machine. Finally, the wheel is spun again to ensure that the tire is properly balanced. A tire is balanced based on the mass of rubber present at the time of its first balance. As the tire rolls down the road, rubber wears off, causing the tire to become imbalanced again. For this reason, when tires are rotated on the vehicle every 5-6,000 miles or 6 months, they should be checked and rebalanced if necessary. So how could you lose money by not having an alignment done? By significantly decreasing the life of your new tires. The steering and suspension of your vehicle has wear points. They are bushings, ball & socket joints, and miscellaneous mechanical links. When the steering and suspension system is new and adjusted according to factory specs, the rate at which the tires wear is minimized and the vehicle corners and handles smoothly. Over time, the steering and suspension systems are jostled and hammered (compliments of America’s highways). This produces wear in the parts listed above, causing the alignment to go out from factory specs. This results in poor cornering and handling, and a significant increase in tire wear. There are three alignment angles that must be in line for the vehicle to handle properly and for minimal tire wear. Carmakers have built adjustment points into the steering and suspension that allow for re-alignment of the front end. There are three alignment angles: Camber is the angle of wheel alignment that measures the tilting in or out in reference to the top of the tire. If a car’s camber angle on a tire is too positive then the top of the tire is tilting outward. If the camber angle is too negative then the top of the tire is tilting inward. This angle is adjusted mechanically. Conditions that cause excessive camber are worn ball joints, control arm bushings, strut bearings/mounts, or excessively worn wheel bearings. These parts must be ‘tight’ (not sloppy) to insure accurate alignment of the camber angle. Toe: The best way to explain how this angle affects wheel alignment is to look down at the tops of your feet. Imagine that you’re hovering above the hood of your car and you can see through the body of the vehicle. Your feet represent the tops of the tires. Now slowly turn your feet inward to an excessive degree. That’s what your tires look like when they’re toed-in. Now turn your feet outward excessively. That’s what your tires look like when they’re toed-out. This alignment angle is adjusted through the lengthening or shortening of a steering linkage part called a tie rod (found in both Conventional and Rack & Pinion Steering systems). Obviously when this angle is out or in too far, tires wear out quickly! This angle also affects whether your car’s steering wheel is straight. If the steering wheel is crooked, the toe’s probably way out. Excessive toe can be caused by worn tie rods, loose rack mounts, worn idler arm/s (some vehicles have two), pitman arm, drag link assembly, or a worn rack or steering box. Before you can accurately set the toe angle, you must have tight steering linkage parts. Caster is adjusted either by mechanical adjustment or by bending a suspension part. The caster angle can be best illustrated by the bicycle of your childhood youth. Remember when you rode your bike with “no hands?” Remember how the handlebars returned to the straight-ahead position when you leaned right or left to turn a corner? This is the caster angle expressing itself. The caster angle of your car expresses itself when the steering wheel returns to the straight-ahead position after making a turn. It is also expressed when the car wants to wander right or left. When having new tires installed, at the very least have the wheel alignment checked. If it’s out, have the vehicle realigned or pay the price of another set of new tires sooner than later.