Goofy alignment question
08-02-2011, 12:21 PM
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Goofy alignment question
Ok, guys/gals. This question has been bothering me for a while. It may be stupid to some, but it's a real head-scratcher to me:
I have seen many front alignment specs for my truck posted, showing the caster for left and right sides to be different (ie, 4.7 left, 5.0 right), to correct for the right pull of the crown of the road. Now as I have looked under the front-end of my truck (see signature), I see a big ol' AAM front axle, that is pretty darn stout. I also see that the caster is set by means of an eccentric on the end of an arm on each side. The eccentric is rotated to move the bottom of the axle forward and back, which rotates the knuckles to adjust for caster. This arm is attached to the axle and frame with a bolt running through rubber bushings. Now, I can't see where there is any possibility of actually twisting that big ol' axle by rotating the eccentrics to different positions on the left and right sides when the end of the arms have rubber bushings! As far as I can see, changing the setting of the eccentric from side to side only moves one entire end of the axle forward or backward a little, but cannot possibly change the caster from side to side. The only way I can see the front end having a different caster from side to side is if the axle were welded together with a slight variation in the angle the knuckles were welded onto the tube, which would not be adjustable. The other possibility is slop in the alignment machine.
Question: Well? Am I stupid or what? Can you really adjust separately the caster on a 4wd Dodge front axle?
I have seen many front alignment specs for my truck posted, showing the caster for left and right sides to be different (ie, 4.7 left, 5.0 right), to correct for the right pull of the crown of the road. Now as I have looked under the front-end of my truck (see signature), I see a big ol' AAM front axle, that is pretty darn stout. I also see that the caster is set by means of an eccentric on the end of an arm on each side. The eccentric is rotated to move the bottom of the axle forward and back, which rotates the knuckles to adjust for caster. This arm is attached to the axle and frame with a bolt running through rubber bushings. Now, I can't see where there is any possibility of actually twisting that big ol' axle by rotating the eccentrics to different positions on the left and right sides when the end of the arms have rubber bushings! As far as I can see, changing the setting of the eccentric from side to side only moves one entire end of the axle forward or backward a little, but cannot possibly change the caster from side to side. The only way I can see the front end having a different caster from side to side is if the axle were welded together with a slight variation in the angle the knuckles were welded onto the tube, which would not be adjustable. The other possibility is slop in the alignment machine.
Question: Well? Am I stupid or what? Can you really adjust separately the caster on a 4wd Dodge front axle?
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