Quote:
Originally Posted by Terry, NJ
Sighting Rods are known to have been used by ancient "Primitive" people for whatever surveying they did! They work! However, one question, looking at that axle in the picture, It will come out of the process with no caster. Shouldn't or wouldn't it be better to add the caster angle now while it's out of the car? It seems like it would or does the car's weight etc. change it somehow?
Terry
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The pix is of a Model T axle which happens to be the pix used by Victor Page in his Model A Book. I think he was demonstrating use of the rods (and only two of them) I'm not familiar enough with the Model T axle to make a statement about Model T caster.
The Model A News and Restorer articles had FOUR rods IIRC - which to my mind will give more positive and repeatable results.
As to caster, that is controlled entirely by the condition of yoke end, wishbone rods or physical positioning of the wishbone. At least one in this thread mentioned damage to the wishbone as a possible cause of front end misalignment. I mentioned positioning with reference to the aftermarket wishbone ball seat which lowers the back end of the wishbone a smidge (technical term) and will increase caster. Fortunately not to any noticeable change in steering in my experience.
I am not aware of any standard or method to measure one's wishbones and assure correct caster. But how to apply this number to either an axle assembly or a wishbone out of the car? A number DOES exist. I think that was discussed earlier. BUT - technology to the rescue - don't most modern alignment machines measure caster? It is adjustable on modern cars, unlike the Model A with its limited defined by structure adjustment. One imagines the Model A caster number was a sort of "discovery" item found when someone actually put a Model A to an alignment machine?
IIRC, the front control arms on the VW Golf had "shims" at their inner pivot which could be moved front to back to change caster. The top of the McPherson strut was fixed on the car. The camber was adjustable at each strut to bearing housing connection. Toe was done on the rack & pinion tie rods.
Of course finding caster "out of spec" on a Model A would involve bending (straightening?) the wishbone to correct it.
And yes, caster will be modified as the front spring compresses and relaxes while driving.
Maybe just adding to the "dynamic experience?"
Joe K