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The Importance Of Front-End Alignments - Front-End Alignment Basics
Understanding Alignment For A Better Driving Mustang
You may Not realize it but front-end alignment has the greatest effect on how your Mustang feels to steer and drive. When alignment is spot on and your Mustang is tracking properly, it yields a confident feeling. By the same token, when alignment is off, it can make your Mustang driving experience miserable and unsafe. What is front-end alignment and why is it so important?
Front-end alignment is an old term. These days, most reputable shops do what's known as a computerized four-wheel alignment to check tracking in all four corners. This is performed by a sophisticated computer alignment system where all four tires/wheels are called into accountability. All four should be tracking in concert for the best vehicle stability. Because Mustangs have a live rear axle (except late-model Cobras with independent rear suspension), there's not much you can do with rear axle alignment except check installation and integrity. If you have a rear end alignment problem, it means something's amiss with the leaf springs, axle housing, or unit body.
Marlon Mitchell of Marlo's Frame & Alignment in Chatsworth, California, has been in the alignment business most of his life. When a customer delivers a car, Marlon test-drives it first to get a feel for how the car is tracking before making adjustments. What may surprise you is his technique. Marlon does not have modern computer-aided alignment equipment. He does it the old-fashioned way with bubble alignment fixtures and a preset rod for checking toe. This approach, coupled with experience, enables Marlon to achieve exceptional alignment results. He is also able to check rear end alignment with his equipment.
There are three basic alignment elements-caster, camber, and toe-that affect a Mustang's relationship with the pavement. Camber is the tire angle as it relates to the pavement from a 12/6 o'clock perspective. In other words, is your Mustang bow-legged or knock-kneed? When alignment is correct, a Mustang will have just a pinch of negative camber (knock-kneed), usually around 1/2 degree, because the tread should remain in full contact with the pavement in turns. Racers and canyon cutters want even more negative camber to keep the tread solidly in contact with the pavement during hard turns. If there is positive camber, or bow-leggedness, you're going to get into the tire sidewalls in turns. As a rule, automakers design a certain amount of positive camber into the cornering process to induce understeer to help keep motorists out of trouble.
Caster is the spindle angle as it relates to upper and lower ball joints, just like a caster on a rollaway tool chest. This is known as the steering pivot axis. If the axis is tipped so the upper ball joint is ahead of the lower, this is known as negative caster. If the upper ball joint is behind the lower, this is known as positive caster. Mustangs need only a small amount of positive caster to perform nicely in a straight line. If this doesn't make sense to you, think about what happens to the casters when we push a rollaway tool chest across the garage. Which way do the casters articulate? They tend to trail the pivot point, or steering pivot axis, which becomes positive caster.
Through the years, Ford has improved how front-end alignment is performed. First generation '65-'66 Mustangs are antiquated, using shims of various thicknesses between the upper control arms and shock towers to achieve caster and camber. Today's front-end alignment technicians dread to see these dinosaurs arrive because they know they will have to earn their bacon. Classic Mustangs are more time consuming for alignment shops because shims have to be added or taken away to adjust upper control arm angle, thereby changing camber and/or caster.
You can eliminate this ancient shim process with some of the aftermarket performance suspension systems from Total Control Products, Global West, Ron Morris Performance, and Heidt's. All have adjustable Heim joints that do away with shims entirely. These systems stay in proper alignment and improve handling.
Toe is a fundamental of your Mustang's steering linkage. To steer precisely and predictably, your Mustang should have a very minute amount of toe-in, meaning both front tires pointed ever-so-slightly inward with the wheel centered, which allows the steering wheel to return smoothly to center after a turn. With too much toe-in, they will return too quickly to center. By the same token, toe-out has the opposite effect. Return to center in a turn will be sluggish to the point that you have to help the wheel return to center. That takes the pleasure out of your driving experience. Either way, with too much toe-in or toe-out, tires will scrub and wear increases proportionally. Excessive toe-in causes heavy wear along the tire's outboard edges. Too much toe-out causes wear along the inside.
If toe-in or toe-out causes tire wear, why isn't a Mustang's toe neutral? The reason is stability. There is a finite amount of toe-in, expressed in degrees from parallel, to improve a Mustang's stability while going in a straight line. With a small amount of toe-in, steering input feels confident and sure without being too sensitive. In fact, toe-in makes steering more predictable because the steering wheel wants to remain centered. When toe is dialed in to factory specifications, there should be no wandering whatsoever unless there's a significant crown in the road or high wind.
Toe-out is another story. With toe-out, your Mustang wants to steer right or left and steering becomes very sensitive. Racers tend to like toe-out for this reason. They know they're going to get quick response in turns with a certain amount of toe-out.
Before an alignment is performed, have your alignment technician check ball joints, tie-rod ends, idler and Pitman arms for excessive wear. Upper and lower control arm bushings, plus spring perch bushings, must also be checked for wear. When these items are excessively worn, your Mustang will not remain in alignment. In fact, alignment settings will change the minute you hit the road.
Caster and camber for '74-'78 Mustangs are adjusted by moving the upper control arms. The strut rods are fixed and cannot be adjusted. Instead of shims or eccentrics, Ford got smarter by having an upper control arm that can be adjusted, then locked down. The upper control arm angle can be changed to adjust caster. Move the upper control arm in or out to change camber.
When the Mustang switched to a McPherson strut front suspension in 1979, alignment changed forever because it eliminates the upper control arm. McPherson struts are fully adjustable on top, so caster and camber angles can be changed by moving the strut and control arm. Once the strut is properly adjusted, it's locked down. Toe is adjusted the same conventional way as first generation Mustangs despite the use of rack and pinion steering and adjustable rod ends.
For complete '65-'09 Mustang alignment specifications, go to our website at www.mustangmonthly.com.