The link below will provide a reasonable explanation of toe-in, relating it to camber as well as to the advisability of loading up the springs as I'd suggested, with sandbags to simulate driver (and possibly passenger) weight. This will "normalize" the axle-to-body position of the car. Body ground clearances at each corner as well as spring deflections and shackle positions should be close to where they'd be while driving. Clearly, any play from kingpins, bushings, et al will be somewhat neutralized if toe-in is consistently measured that way.
http://en.wikipedia.org/wiki/Toe_(automotive)
Camber in solid axles is, of course, determined by the condition of the axle itself together with the stub axles and their bushings that determine the vertical angles of the kingpins with respect to the ground when the steering is pointed straight ahead. The laser device I illustrated on our website can only determine whether the camber angle is within acceptable limits, because it cannot be adjusted on solid axle designs like the TC. This device will also compensate for caster, because the laser level itself can be rotated to simulate kingpin verticality in the side view of the car so as to read camber angle only (which is the outward skewing of the tire tops that is so apparent from the front view of our cars). Measuring camber may at least indicate the need to correct a bent axle, and will show any difference in camber between the driver and passenger side. Caster angle is another non-adjustable parameter, but has often been modified (rotated) by axle shimming in some innovative ways by our list members.
With regard to toe-in, because I completely distrust across-the-tire devices, and more particularly over-the-rubber-mounted-on-a-wobbly-19"-wire-wheel, I much prefer to go directly to the stub axle for an accurate place to start. That is why I'd like someone to build a pair of threaded wheel nuts to attach (and rotate) laser levels that can be used with tires that do nothing more than hold up the car.
Lest there be an endless thread over this, I would submit that there is no magical number nor method for setting-and-forgetting a proper value for toe-in angle. As others have suggested, it is dependent upon many things when the car is at speed, including all the elements that contribute to steering control. By far, the best setting is that which gives the best feel and control in a variety of steering positions (straight ahead, cornering, etc.) which will vary from car to (old) car depending on the condition of all of the elements outlined above.
The best method is that which enables the user to measure and set toe-in starting from the same, reproducible base line, without any influence from varying tire pressure, spoke tension, and all the other indirect consequences of marking lines on the floor or clamping to a tire or rim, etc., in an unlimited combination of tire rotations and bulgy sidewalls. By simply measuring the outer dimension of the stub axle ends across the car (including the custom wheel nuts I proposed), the dimension for zero toe-in would be where the laser light beams (with the lasers set to the horizontal position) are spaced to the same distance where they hit the garage wall. That way, zero toe-in can easily be restored. One can then keep records and re-adjust toe-in from there at will, but always with the idea that a test drive is part of the adjustment procedure, and that the ideal toe-in is the one that feels best. A target angle can be determined with a little trigonometry based on the distance from the stub axles to the wall.
An alternative for those that object to the "feel-good" method is to see which adjustment gets the best gas mileage after a few thousand miles. Point is, there just isn't a "one-size fits all" adjustment.
Austin TC 8362
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