Preparation: In preparation to performing chassis adjustments the fuel tank should be half full with fuel, an equivalent amount of weight to the driver & passenger should be placed upon the seats and floorboards, and the tires should be filled to the appropriate air pressure.
Front Tire Pressure: a tire's diameter and the inflation air pressure are the two biggest factors determining its load capacity, its temperature, and the shape and size of its contact patch. If the front tires are approximately 25 inches diameter it is probably best to start at the factory setting (28 psi) and adjust up or down from there to achieve equal wear across the tire. If the front tires are approximately 24 inches diameter it is probably best to start at the later factory setting for the European GTS (31 psi).
Front Caster: The front caster spec for the Panteras assembled during the Ford era is +3° to +4° for Pre-L versions, and +2-3/4° for the Pantera L. The spec for Panteras assembled in the "Post Ford" era is +3-1/2° to +4°.
This is an ADEQUATE amount of caster for providing directional stability so long as the front toe-in is adjusted properly. Directional stability is not an issue ... but there is undeniably room for improvement. The Pantera (and other mid-engine cars) needs more positive front caster than other cars you may be familiar with due to the weight distribution of the chassis. Some owners prefer to increase positive front caster; they may be doing so to improve directional stability or their goal may be to improve dynamic camber.
Dallara intended for the Pantera to have 6° positive caster. Positive caster causes the outside front tire to lean inwards when the steering wheel is turned off-center, thus increasing the negative camber of the outside front tire in corners. The more the steering wheel is turned, the more the outside front tire leans inward. Positive caster also causes the inside front tire to lean outwards (towards the inside of the corner) when the steering wheel is turned off-center, thus decreasing the negative camber of the inside front tire in corners to such an extent that the inside front tire is cambered in the positive direction. The more the steering wheel is turned, the more the inside front tire leans outward.
The change in camber based upon steering angle is an integral part of the camber change characteristics engineered into a chassis, known as dynamic camber. Ford reduced positive caster to +3° in order to create understeer, and slow the car's response to driver input. The change in dynamic camber is why reducing caster achieved Ford's goal, and why reducing caster impacted more than just directional stability. Ford reduced caster by bending the upper front control arms so as to move the upper front ball joints about 1/2 inch forward. This is the second way in which Ford upset the dynamic camber engineering of the Pantera's chassis. There was a cosmetic downside to Ford's alteration as well, the front tires were no longer centered in the fender openings, they were shoved forward.
The earliest Panteras had no adjustability for front caster, later a small amount of adjustability was added. If caster is adjustable then stack all the adjustment shims in front of the upper ball joints and set it for as much positive caster as you can squeeze out of its adjustments, +4° may be attainable in some chassis. Every 3/16 inch (4.7mm) the upper ball joints are moved rearward should increase positive caster by 1°. Caster up to +6° is desirable, but it is not realistically attainable unless the upper front control arms are modified. Front caster should be the same side to side.
Front Camber: Adding negative front camber is the major way in which modern Pantera alignment varies from Ford's specification.
The static camber applied to the suspension was originally specified taking into account the "dynamic camber" engineered into the chassis. Dallara originally specified -1/4° front camber (-0.250°), and therefore this is my recomendation. Negative camber means the tops of the tires are tilted inward towards the middle of the car. Adding negative front camber restores some of the excellent cornering grip the Pantera's chassis is capable of having, and allows the chassis to respond more quickly to driver input.
Additional negative front camber can be added, but the car may not benefit from extra negative camber "if" the chassis is set at the European ride height and "if" front caster has been set around +5° or +6°. However additional negative camber is a universal "band aid" for cars in which the dynamic camber is unknown or "out-of-whack". Keep in mind the front camber setting must also take the rear camber setting into consideration, the two settings MUST complement each other, in as much as the balance between the two impacts the chassis' balance in corners. It is reasonable to limit the amount of negative front camber to not exceed the amount of negative rear camber (i.e. -1/2° or -0.500°). As with other chassis settings the amount of negative front camber should be the same side to side.
Front Toe: The Pantera needs a certain amount of toe-in to achieve directional stability, for most chassis only a small amount of toe-in is required. The indications of insufficient toe-in and too much toe-in are the same, the slightest movement causes the car to wander or dart left or right, the steering can be described as nervous or twitchy, the driver has to "focus on direction" an unusual amount to keep the car going straight.
When toe is measured the old fashioned way as the difference of the distances between the tire centerlines at the front of the tires and the back of the tires, it is specified in inches. Measured this way toe will vary "slightly" with the diameter of the tires. Tire diameter does not impact toe when it is measured in degrees with modern equipment. Toe measured in degrees should be the same for both the front and rear tires. Toe measured in inches is slightly less for the front tires because the front tires are smaller in diameter than the rear tires.
The Pantera does not settle to ride height after being jacked up to adjust camber. When toe-in is set to spec after the car has been jacked up, it becomes toe out as soon as the car is driven a short distance and the front suspension settles.
0.14° toe-in is a good place to start. Measured in inches that would be 0.122 inch (just under 1/8 inch) for front tires that are approximately 25 inches diameter , and it would be 0.117 inch for front tires that are approximately 24 inches diameter. Bounce the front of the car after making this adjustment, due to the stiction in the suspension. Adjust it until the 0.14° toe-in setting is maintained before and after bouncing. If the car feels "twitchy" afterwards the toe-in adjustment will need to be changed. Changes should be made in small increments because too much toe-in is just as bad as insufficient toe-in.
Rear Tire Pressure: If the rear tires are approximately 27 inches diameter it is probably best to start at the European factory setting (31 psi) and adjust up or down from there to achieve equal wear across the tire. If the rear tires are approximately 26 inches diameter it is probably best to start at the later factory setting for the European GTS (34 psi).
Rear Caster: is not adjustable.
Rear Camber: Trailing throttle over-steer is a potential problem with mid-engine cars. Rear camber contributes to preventing over-steer. A setting of -1/2° (or -0.500°) is consistently recommended in the various Pantera alignment specifications, for versions which have rear tires varying in width from 215mm, 255mm, 285mm, and 345mm! However -1/2° (or -0.500°) was the maximum setting for Panteras equipped with the widest tires (Pirelli P7s). I assume this amount of rear camber was specified taking three criteria into account: the needs of the chassis based upon dynamic camber, the trailing throttle forces which cause over-steer, and tire wear. The rear camber should also be the same side to side.
If you're having trouble eliminating excessive negative rear camber, this is due to the inner wheel houses folding or flexing inward where the upper control arms mount. This is a common problem with the Pantera. The solution is to install adjustable upper rear control arms which are commercially available. Some owners will attempt to "spread" the inner wheel houses apart with an adjustable chassis brace, which is commonly referred to as a spreader bar. However, the design and attachment of the original rear chassis brace and the spreader bar which replaces it is inadequate for stabilizing the wheel houses structure. If it were adequate, the wheelhouses wouldn't fold-inward as they do.
Excessive negative camber will cause accelerated rear tire wear. There is a tendency to over-compensate for the excessive camber caused by wheel house flexing by setting the rear camber at zero in the hope that the camber adjustment will "settle' into an acceptable (BUT UNKNOWN) amount of camber as the car is being driven. However, it would be better to resolve the problem than to compensate for it by setting the rear camber at zero. The best solution shall be to take steps to eliminate wheel house flex ... such as more substantial bracing, welding seams, adding gussets, etc. Stiffening the wheel houses will have the added benefit of eliminating the nasty habit of the rear tires to loose traction suddenly instead of progressively.
Other aspects which impact rear tire wear include tire width, spring rate, and chassis height. The more the suspension compresses when the driver and passenger sit in the car, the more the car leans in corners, or the wider the rear tires are, the worse rear tire wear shall be. The solutions to these possible issues are obvious, limit the width of the rear tires (275mm to 295mm), set the chassis at its European ride height, and/or increase the spring rates. If achieving the chassis' best handling performance is your goal, it is better to have a 285mm rear tire and a small amount of negative camber, than to have 335mm rear tires and no rear camber.
Rear Toe: As with the front tires 0.14° toe-in is a good place to start. Measured in inches that would be 0.132 inch for rear tires that are approximately 27 inches diameter, and it would be 0.127 inch (just over 1/8 inch) for rear tires that are approximately 26 inches diameter (bounce the suspension as you did for the front). Toe measured in degrees should be the same for both the front and rear tires. Toe measured in inches is slightly greater for the rear tires because the rear tires are greater in diameter than the front tires.
