Marlon Mitchell of Marlo's...
Marlon Mitchell of Marlo's Frame & Alignment in Los Angeles begins his alignment regiment with ride height measurement in all four corners. Ride height, especially in front, has a certain effect on alignment. Marlon is one of the rare technicians who performs alignments the old-fashioned way-without computers and lasers.
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?
Marlon Mitchell of Marlo's...
Marlon Mitchell of Marlo's Frame & Alignment in Los Angeles begins his alignment regiment with ride height measurement in all four corners. Ride height, especially in front, has a certain effect on alignment. Marlon is one of the rare technicians who performs alignments the old-fashioned way-without computers and lasers.
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.
Positive caster is when upper...
Positive caster is when upper ball joints trail the lowers. This is what you want, although not as extreme as this illustration.
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 an element of steering...
Caster is an element of steering spindle angle between upper and lower ball joints. Negative caster is when the upper ball joint leads the lower. This is what you don't want. You want just a little bit of positive caster per factory specifications.
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.
Caster/Camber Adjustment
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.
This is an extreme example...
This is an extreme example of negative camber. You want just a pinch of negative camber (see specifications for your particular Mustang) for good cornering, which keeps the tire tread in full contact with the pavement.
Your Mustang's two front axle...
Your Mustang's two front axle spindles operate on two basic dimensions-camber and caster. Camber is the spindle's 12/6 o'clock angle between the fender and pavement. Caster is the relationship between upper and lower ball joints.
With '65-'66 Mustangs, shims...
With '65-'66 Mustangs, shims are added to push the upper control arm outward to move toward positive camber. Although most alignment specialists use pry bars to adjust the upper control arms, there are Ford-recommended specialized tools designed to screw the arm in or out, taking the violence out of a front-end alignment. That's what is shown in this and following illustrations. This jackscrew adjustment tool enables a technician to get Mustang alignment spot-on without abusing the shock towers.
The upper control arm is moved...
The upper control arm is moved inboard by removing shims to get negative camber. Strut rods on '65-'66 Mustangs are fixed and not adjustable.
Caster is adjusted by added...
Caster is adjusted by added or subtracting shims to move the upper ball joint fore or aft to place it either ahead or behind the lower ball joint. When adding shims to the front or rear control arm bolt, the arm angle is modified, which moves the upper ball joint forward or backward.
For '67-'73, Ford came up...
For '67-'73, Ford came up with a better idea-lower control arms that adjust via an eccentric to move the lower arm in or out. Move the arm out to achieve negative camber. Move it in to get positive camber. The downside to this eccentric is movement when you hit a pothole. It could move, causing an unwanted change in camber.
Ball joints should be checked...
Ball joints should be checked for wear by supporting the Mustang at the framerail and applying pressure by moving the tire upward. If you feel clunking (play), the upper ball joint is most likely the culprit. Upper ball joints wear out much faster than lowers. Lower ball joints are always replaced with the lower control arm, which must be serviced as a unit.
Caster is adjusted on '67-'73...
Caster is adjusted on '67-'73 Mustangs by moving the strut rods fore or aft, which moves the lower control arm fore or aft to position the lower ball joint ahead or behind the upper ball joint. Instead of moving the upper control arm like '65-'66, the lower is moved for '67-'73. The use of urethane bushings may stiffen up front-end alignment, however, you risk breaking the strut rod. This is why polyurethane or rubber bushings are suggested.