October 29, 2012

Why does front-end alignment seem like black magic? Yet it’s nothing more than tire and wheel angle and how they relate to the road. Alignment is complex because of what happens to wheel and tire angle as our Mustang cruises down the road or round a bend. Road conditions, road crown, vehicle condition, tire and wheel size, suspension components, and a host of other issues affect alignment. During alignment, we have to plan for these changes and adjust accordingly.

What makes alignment even more involved today is four-wheel alignment. Not only do we need to check front-end alignment, but rear wheel alignment as well so all four corners track together. Not all Mustangs have adjustable rear wheel alignment, but you can check for the sake of accuracy, especially if the vehicle isn’t tracking true to mark. Aside from SVT Cobras with independent rear suspension, Mustangs have a fixed rear axle, which as a rule cannot be adjusted, although some aftermarket late-model rear suspensions can be tuned via adjustable links and panhard bar.

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Caster, camber, and toe are the basic staples of every chassis alignment. Think of alignment as preventative maintenance that prevents tire wear and aids in driving pleasure and safety.

An alignment should include a detailed chassis inspection where suspension and steering components are checked for abnormal wear. Ball joints, tie-rod ends, control arm bushings, spring perches, shocks, springs, stabilizer links and bushings, leaf springs, and bushings should all be inspected and replaced as necessary. When components have excessive wear issues, they should be replaced before doing an alignment.

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What Is Alignment?
Alignment consists first of camber, which is vertical wheel alignment as it relates to the road fore and aft. There are two types of camber—positive and negative. When a Mustang has positive camber, it looks bow-legged. When it has negative camber, it looks knock-kneed. As a rule, we want either zero camber, or just a pinch of negative camber, for better cornering. With minute negative camber (1⁄4 degree), the tire tread addresses the pavement with a good contact patch for turning. Avoid positive camber because your tires will tend to roll over onto the sidewalls in turns.

Either the upper or lower control arm is moved in or out for camber adjustment. For ’65-’66 Mustangs, shims at the upper arm attachment point are added or removed to adjust camber. For ’67-’73, the lower arm is moved in or out with an eccentric. For ’74-’78, the upper control arm is moved in or out with an eccentric. For ’79 and up with McPherson struts, all you have to do is adjust strut angle. For the most part, ’79-up Mustangs use a fixed position camber angle, though it becomes fully adjustable with an aftermarket caster/camber plate on top.

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Caster is the angle of the upper and lower ball joints as they relate to one another. This can also be seen as spindle angle. The easiest way to understand caster is to think about the caster wheels on a shopping cart. When the wheels trail the pivot, this is negative caster. When the wheel is ahead of the pivot and you have to jerk the cart to get it to turn, that is positive caster. It’s harder to steer a cart when the wheels are ahead of the pivot point. Most alignment specifications are negative caster for easier steering effort.

Caster angle on first generation ’65-’66 Mustangs is adjusted with shims. Add or subtract shims fore or aft on the upper control arm to change caster. From ’67-’73, adjusting the strut rod fore or aft moves the lower control arm forward or back to change caster angle. The Mustang II has caster adjustment on the upper control arm via eccentrics, which are also used to adjust camber. From ’79-up, the McPherson strut adjustment is on top, which is also used for camber.

Mustang Alignment Specifications

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
Model YearCaster In DegreesCamber in DegreesToe-In  
’65-’66  Power SteeringLeft: +1½  Right: +2 Left: -¼ to -½ Right: -1⁄4 to -¾ 1⁄8 to 3⁄16-inches
’65-’66 Manual SteeringLeft: +½  Right: +1 Left: -¼ to -½ Right: -1⁄4 to -¾ 1⁄8 to 3⁄16-inches
’67-’68 Power SteeringLeft: +2 Right: +2½Left: -¼ to -½ Right: -1⁄4 to -¾ 1⁄8 to 3⁄16-inches
’67-’68 Manual SteeringLeft: +1⁄2 Right: +1Left: -¼ to -½ Right: -1⁄4 to -¾ 1⁄8 to 3⁄16-inches
’69-’70 Power SteeringLeft: +2 Right: +2½Left: -¼ to -½ Right: -1⁄4 to -¾ 1⁄8 to 3⁄16-inches
’69-’70 Manual SteeringLeft: +1⁄2 Right: +1Left: -¼ to -½ Right: -1⁄4 to -¾ 1⁄8 to 3⁄16-inches
’71-’73Left: +2½ Right: +3Left: -¼ to -½ Right: -1⁄4 to -¾ 1⁄8 to 3⁄16-inches
’74-’78Left: +2 Right: +21⁄2Left: -1⁄4 Right: -1⁄4 to -1⁄21⁄8 to 3⁄16-inches
’79-’93Left: +2½ Right: +3Left: -3⁄4 to -1½ Right: -3⁄4 to -11⁄21⁄8 to 3⁄16-inches
’94-’98Left: +2½ Right: +3Left: -3⁄4 to -1½ Right: -3⁄4 to -11⁄21⁄8 to 3⁄16-inches
’99-’04Left: +2½ Right: +3Left: -3⁄4 to -1½ Right: -3⁄4 to -1½1⁄8 to 3⁄16-inches
’05-’13Left: +2½ Right: +3Left: -3⁄4 to -1½ Right: -3⁄4 to -1½1⁄8 to 3⁄16-inches

Alignment specifications can vary from manual to manual and from shop to shop. Marlon Mitchell of Marlo’s Frame & Alignment has been in the alignment business since he was 14. His area of expertise is Mustangs. These are Marlon’s own alignment specifications based on what works in the real world—road crown, rough pavement, V-8 versus six, manual versus power steering, performance driving versus grocery getting.

Marlon’s specifications work well in Southern California where road conditions are generally pretty good. They may not work in the hills of West Virginia. Although alignment specifications tend to be cast in stone in the manuals, what actually works varies from vehicle to vehicle, driver to driver, and road conditions. A well-worn steering gear or rack requires a different approach than new equipment. Larger tires and wheels mandate a different approach as do high-performance suspension components. When you rotate and balance your tires, expect to need a front-end alignment. When you have to fight the steering wheel, help return it to center, or have to keep correcting, front-end alignment needs to be checked. 


Source
Marlo’s Frame & Alignment/Fly-Ford Racing
818/341-0940
www.fly-ford.com