My '06 Frontier 22k mi. dog legs to the right above 50 mph. How is an alignment done? I think they put it on a rack w/lasers but how do they correct the misalignment? - i.e. do they loosen and retighten bolts somewhere? Thanks.
I’m assuming you mean the truck pulls to the right. Have the tires been rotated front to back or side to side? I have a 93 Caprice that pulled to the right when I got it in 2002. Two alignments and a front to back tire rotation later it was still pulling to the right. Out of frustration I switched the two front tires side to side and the car has tracked straight ever since.
If you look under your truck, you’ll see where the tie rods attach to each steering knuckle. In essence, these are the rods that push and pull each wheel left or right when you turn the wheel. They are threaded rods with pinch nuts to keep them from turning on their own. The wheel alignment people will use the alignment computer to determine how far out of spec things are, and make the appropriate adjustment by threading or unthreading the tie rod in to the tie rod end. This is your toe alignment.
Camber and caster are also looked at (depending on suspension design.) Camber is the angle of the face of the wheel in relation to a perpendicular plane (ie the ground). Its adjustment depends on the style of suspension that you have. If you have upper and lower control arms in the front, either the upper or lower will have adjustment where it attaches to the frame that will allow for lateral movement.
Caster is a little trickier to explain (for me, anyway). Caster angle is the pivot angle of the steering knuckle. Changing the caster angle changes the angle of the axis around which the tires pivot when steering. If you have neutral caster (prone to wander), the tires pivot around a perfectly vertical axis. Some cars have an actual caster adjustment, some cars attain caster adjustment through adjustment of other suspension components, some cars just have factory-specced caster which can’t be adjusted. (If my caster description is clear as mud, here is a better description: http://en.wikipedia.org/wiki/Caster_angle [wikipedia.org])
So what is the tire pressure currently at?
At this point you’re assuming a pull is caused by the alignment.
You’re right, caster is hard to explain. Two good analogies come to mind.
One is the thing that allows a bicyclist to let go of the handlebars and still have the bicycle track straight is the positive caster. In this case it’s the imaginary line drawn between the top of the fork (where it pivots) and where the fork is secured to the axle. Since that imaginary line goes forward, it’s positive caster.
A good example of zero/negative caster is the front wheels on a grocery store shopping cart. Those wheels have no directional stability because the imaginary line drawn between the pivot point on the fork and the axle is straight up and down (or slightly negavive).