Ryan Thompson
Active Member
put new tires on the o4 ST about a month ago already wear on inside of tire. will new shocks fix this from becoming worse. already had an aligment job when tires were installed
new rubber
- Thread starter Ryan Thompson
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Chad Merry
Well-Known Member
Your camber is off. Fords are terrible for this and you need to watch it closely.
Chad
Chad
What settings did the shop set your alignment at?
Tom
Tom
Ryan Thompson
Active Member
not sure what setting it is at. what im thinking about doing is getting some new shocks and getting it aligned again. what should i say to the tech. align the truck to the spec or just align it??
Set it to prefered specs.
Tom
Tom
Jeff C
Well-Known Member
Caymen, what are the preferred specs for the ST?
I personally do not know this since I do not do alignments for a living. A shop that does alignments does know this information.
Tom
Tom
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0.0 toe
0.0 camber
Slightly (+) Caster
Todd Z
TOE ALIGNMENT
Toe is the most important wheel alignment angle because it has the greatest effect on tire wear. Toe refers to the parallelism between the wheels as viewed from above and is usually measured in inches or millimeters. When both front wheels are aimed straight ahead and the distance between the leading edges of both front tires is exactly the same as the distance between the trailing edges, the wheels have "zero toe" and are theoretically aligned. We say in theory because toe alignment changes when the vehicle is being driven.
Toe-in means the front edges of the tires are closer together than the rear edges. Most rear-wheel drive cars and trucks have alignment specifications that call for a little bit of toe-in (say 1/16th of an inch or so). This will produce zero rolling toe as the vehicle is being driven down the road because the natural tendency for the front and rear wheels is to toe-out due to rolling resistance and compliance in the steering and suspension.
Toe-out is when the front edges of the tires are farther apart than the rear edges. This may occur if the tie rod ends are worn, or if the control arm bushings have collapsed. Toe-out is a bad condition to have because it causes the tires to scrub as they roll along. Only 1/8th inch of toe-out will scrub the tires sideways 28 feet for every mile driven. At this rate, it doesn't take long to wear down the tread.
Strange as it may seem, on some front-wheel drive cars and minivans, a slight amount of toe-out (up to about 1/16th inch) may be specified when aligning the wheels to compensate for toe-in that occurs as the front wheels pull the vehicle down the road. Drive torque more than offsets the compliance in the steering and suspension allowing both front wheels to toe-in slightly when accelerating. This is also what causes "torque steer" (a sudden steering pull) in some FWD cars that have unequal length halfshafts. Under hard acceleration, the left wheel with the shorter halfshaft experiences more toe-in than the right wheel with the longer halfshaft. The result is unequal toe changes and a steering pull to the right. Vehicle manufacturers have reduced or eliminated torque steer in many FWD cars by using equal length halfshafts and/or stiffer control arm bushings.
CAMBER ALIGNMENT
The next important wheel alignment angle you should know something about is camber. Camber refers to the tilt of the wheels as viewed from the front or rear. Camber is the inward (negative) or outward (positive) tilt of the wheels. It is usually measured in degrees.
As with toe, zero camber (perfectly perpendicular to the road) is the ideal alignment setting. But like toe, camber changes as the vehicle is being loaded and every time the vehicle encounters a bump or dip in the road. The up and down motions of the suspension change the geometry of the control arms and struts, which causes camber to change. So many static camber alignment specifications may allow up to a degree of more of positive or negative camber depending on the design of the suspension. As a rule, camber settings should usually be within half a degree side-to-side.
If camber is out of specs, a tire will wear unevenly on one shoulder and the vehicle may pull toward the side with the most camber. Camber usually only affects one wheel, so if only one tire shows unusual shoulder wear it is usually a symptom of camber misalignment.
Keep in mind that camber applies to both front and rear wheels, though only vehicles with independent rear suspensions typically have rear camber alignment specifications. Most rear-wheel drive cars and trucks with solid axles do not have rear camber specifications because there's no way to change it (even so, a bent rear axle can cause a camber problem!).
Excessive camber can be caused by a bent spindle, mislocated strut tower
0.0 camber
Slightly (+) Caster
Todd Z
TOE ALIGNMENT
Toe is the most important wheel alignment angle because it has the greatest effect on tire wear. Toe refers to the parallelism between the wheels as viewed from above and is usually measured in inches or millimeters. When both front wheels are aimed straight ahead and the distance between the leading edges of both front tires is exactly the same as the distance between the trailing edges, the wheels have "zero toe" and are theoretically aligned. We say in theory because toe alignment changes when the vehicle is being driven.
Toe-in means the front edges of the tires are closer together than the rear edges. Most rear-wheel drive cars and trucks have alignment specifications that call for a little bit of toe-in (say 1/16th of an inch or so). This will produce zero rolling toe as the vehicle is being driven down the road because the natural tendency for the front and rear wheels is to toe-out due to rolling resistance and compliance in the steering and suspension.
Toe-out is when the front edges of the tires are farther apart than the rear edges. This may occur if the tie rod ends are worn, or if the control arm bushings have collapsed. Toe-out is a bad condition to have because it causes the tires to scrub as they roll along. Only 1/8th inch of toe-out will scrub the tires sideways 28 feet for every mile driven. At this rate, it doesn't take long to wear down the tread.
Strange as it may seem, on some front-wheel drive cars and minivans, a slight amount of toe-out (up to about 1/16th inch) may be specified when aligning the wheels to compensate for toe-in that occurs as the front wheels pull the vehicle down the road. Drive torque more than offsets the compliance in the steering and suspension allowing both front wheels to toe-in slightly when accelerating. This is also what causes "torque steer" (a sudden steering pull) in some FWD cars that have unequal length halfshafts. Under hard acceleration, the left wheel with the shorter halfshaft experiences more toe-in than the right wheel with the longer halfshaft. The result is unequal toe changes and a steering pull to the right. Vehicle manufacturers have reduced or eliminated torque steer in many FWD cars by using equal length halfshafts and/or stiffer control arm bushings.
CAMBER ALIGNMENT
The next important wheel alignment angle you should know something about is camber. Camber refers to the tilt of the wheels as viewed from the front or rear. Camber is the inward (negative) or outward (positive) tilt of the wheels. It is usually measured in degrees.
As with toe, zero camber (perfectly perpendicular to the road) is the ideal alignment setting. But like toe, camber changes as the vehicle is being loaded and every time the vehicle encounters a bump or dip in the road. The up and down motions of the suspension change the geometry of the control arms and struts, which causes camber to change. So many static camber alignment specifications may allow up to a degree of more of positive or negative camber depending on the design of the suspension. As a rule, camber settings should usually be within half a degree side-to-side.
If camber is out of specs, a tire will wear unevenly on one shoulder and the vehicle may pull toward the side with the most camber. Camber usually only affects one wheel, so if only one tire shows unusual shoulder wear it is usually a symptom of camber misalignment.
Keep in mind that camber applies to both front and rear wheels, though only vehicles with independent rear suspensions typically have rear camber alignment specifications. Most rear-wheel drive cars and trucks with solid axles do not have rear camber specifications because there's no way to change it (even so, a bent rear axle can cause a camber problem!).
Excessive camber can be caused by a bent spindle, mislocated strut tower
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Jimmy Lavoie
Well-Known Member
Todd - Thanks for the detailed description. It is the most clear I've read yet.
Gavin Allan
Well-Known Member
Here's a few more measurements a good alignment shop will check:
Thrust Angle:
The angle between the thrust line and centerline. If the thrust line is to the right of the centerline, the angle is said to be positive. If the thrust line is to the left of center, the angle is negative. It is caused by rear wheel or axle misalignment and causes the steering to pull or lead to one side or the other. It is the primary cause of an off-center or crooked steering wheel. Correcting rear axle or toe alignment is necessary to eliminate the thrust angle.
If that is not possible, using the thrust angle as a reference line for aligning front toe can restore center steering.
Included Angle:
The sum of the camber and SAI angles in a front suspension. This angle is measured indirectly and is used primarily to diagnose bent suspension parts such as spindles and struts.
Steering Axis Inclination (SAI):
The angle formed by a line that runs through the upper and lower steering pivots with respect to vertical. On a SLA suspension, the line runs through the upper and lower ball joints. On a MacPherson strut suspension, the line runs through the lower ball joint and upper strut mount or bearing plate. Viewed from the front, SAI is also the inward tilt of the steering axis. Like caster, it provides directional stability. But it also reduces steering effort by reducing the scrub radius. SAI is a built-in nonadjustable angle and is used with camber and the included angle to diagnose bent spindles, struts and mislocated crossmembers.
Kingpin Offset/Scrub Radius:
Is the distance from the center of the wheel contact face to the intersection point of the kingpin extension. The line through the center point of the spring strut support bearing and the control arm ball joint corresponds to the "kingpin". The scrub radius is influenced by camber, kingpin angle and wheel offset of the wheel rim. This is set at the factory and is not adjustable.
Set Back:
The amount by which one front wheel is further back from the front of the vehicle than the other. It is also the angle formed by a line perpendicular to the axle centerline with respect to the vehicle's centerline. If the left wheel is further back than the right, setback is negative. If the right wheel is further back than the left, setback is positive. Setback should usually be zero to less than half a degree, but some vehicles have asymmetrical suspensions by design. Setback is measured with both wheels straight ahead, and is used as a diagnostic angle along with caster to identify chassis misalignment or collision damage. The presence of setback can also cause differences in toe-out on turn angle readings side-to-side.
Ride Height:
The distance between a specified point on the chassis, suspension or body and the ground. Measuring ride height is an indirect method of determining spring height, which is important because it affects camber, caster and toe. Low ride height indicates weak or sagging springs. Ride height should be within specifications before the wheels are aligned.
Thrust Angle:
The angle between the thrust line and centerline. If the thrust line is to the right of the centerline, the angle is said to be positive. If the thrust line is to the left of center, the angle is negative. It is caused by rear wheel or axle misalignment and causes the steering to pull or lead to one side or the other. It is the primary cause of an off-center or crooked steering wheel. Correcting rear axle or toe alignment is necessary to eliminate the thrust angle.
If that is not possible, using the thrust angle as a reference line for aligning front toe can restore center steering.
Included Angle:
The sum of the camber and SAI angles in a front suspension. This angle is measured indirectly and is used primarily to diagnose bent suspension parts such as spindles and struts.
Steering Axis Inclination (SAI):
The angle formed by a line that runs through the upper and lower steering pivots with respect to vertical. On a SLA suspension, the line runs through the upper and lower ball joints. On a MacPherson strut suspension, the line runs through the lower ball joint and upper strut mount or bearing plate. Viewed from the front, SAI is also the inward tilt of the steering axis. Like caster, it provides directional stability. But it also reduces steering effort by reducing the scrub radius. SAI is a built-in nonadjustable angle and is used with camber and the included angle to diagnose bent spindles, struts and mislocated crossmembers.
Kingpin Offset/Scrub Radius:
Is the distance from the center of the wheel contact face to the intersection point of the kingpin extension. The line through the center point of the spring strut support bearing and the control arm ball joint corresponds to the "kingpin". The scrub radius is influenced by camber, kingpin angle and wheel offset of the wheel rim. This is set at the factory and is not adjustable.
Set Back:
The amount by which one front wheel is further back from the front of the vehicle than the other. It is also the angle formed by a line perpendicular to the axle centerline with respect to the vehicle's centerline. If the left wheel is further back than the right, setback is negative. If the right wheel is further back than the left, setback is positive. Setback should usually be zero to less than half a degree, but some vehicles have asymmetrical suspensions by design. Setback is measured with both wheels straight ahead, and is used as a diagnostic angle along with caster to identify chassis misalignment or collision damage. The presence of setback can also cause differences in toe-out on turn angle readings side-to-side.
Ride Height:
The distance between a specified point on the chassis, suspension or body and the ground. Measuring ride height is an indirect method of determining spring height, which is important because it affects camber, caster and toe. Low ride height indicates weak or sagging springs. Ride height should be within specifications before the wheels are aligned.
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Gregg Freshcorn
Member
Gregg Freshcorn
Member
the '04 Factory vehicle has NO CAMBER ADJUSTMENT! You need to get on E-Bay and buy a camber adjust kit, abot $5 for both sides. It consits of 2 bolts and 2 washers with off centered holes for the bolts. When you rotate the bolt, the washer adjusts the camber. Park you Trac on a flat level surface and note how the tops of the tires lean in. It is not the shocks, it is lack of camber adjust with OEM parts.
