My wife keeps hitting curbs (she says not hard by the alignment gets knocked out every time)… This is the 3rd time in a year I have had the Van aligned. I have it done at work where I know all of the techs, and today they gave me the print out of its final specs. EVERYTHING is right now except the caster which they say they can’t adjust, so my question is how do you adjust caster?? What sets it?? Currently my Left Front is 4.4 degrees out my right front is 4.3 out, left rear is -0.6 degrees out but my right rear is -1.2 out… I just put $700 worth of tires on this van 3,000 miles ago (got almost 60k out of the originals) and I don’t want to do that again anytime soon.
I would have to believe there is an error some where. 4+or-30’ degrees of caster is is normal but you said yours is off by 4 degrees meaning it is at zero or 8 degrees? That would indicate some noticeable suspension damage or more likely the measurement wasen’t done correctly.
Basically, the vertical angle of the strut, as measured from the side, from top to bottom. Camber is the vertical angle of the tire, measured as looking from the front, I think we all know what toe is.
Normally, caster is set by the suspension components, and isn’t adjustable except for some higher end vehicles, and a few SUV’s. The suspension arm that goes from the floorpan underneath your feet to the bottom of the strut controls your caster. You can examine those components and see if any are damaged. If they are, you can try replacing them. Bushings can also get damaged and cause that problem.
The chart is from Alldata, the Hunter machine shows the front caster to be 3.77 +or- .5 degrees. You’ll have to chech a Kia service manual to see witch is correct. From the alignment machine values your only off by .2 degrees and the is little benifit in correcting it.
Your rear camber should have been adjusted, do they charge extra for adjustments? -1.2 degrees of camber is way of of spec.
I find it funny that the alignment techs where the OP works couldn’t explain how to adjust caster, so the OP came to us!
Having said that, I am not so concerned about the caster as I am about the rear camber. In my opinion, anything over a degree is going to cause wear issues. This needs to be fixed and the OP’s alignment techs ought to be able to tell him how to do that - and if they can’t, he should go somewhere else. This is basic stuff and every competent alignment tech ought to know what to do.
The rear camber would seem to be the only critical deviation. And although I am unfamiliar with that vehicles chassis there is surely some way to correct the problem. Certainly a frame shop can put things in order.
The rear camber might be affected by any extra weight in the rear. If its an independent rear suspension, and there was some extra weight back there, it would throw off the camber settings.
As for the caster, I would not be too concerned with the specs as they are right now. Its not going to affect your tire life very much. In fact, if you tend to corner hard, it will actually improve your tires life a little.
Caster has nothing (ok, very little) to do with tire wear. If the car steers straight, does not wander, is not hard to steer and returns to center after a turn, the caster being out of spec here is inconsequential. There is also no way to adjust it–short of replacing fault components–on many cars, I believe yours is one.
As others have said, I’m more worried about the rear camber readings. Those are also not easily adjustable, but should be corrected.
I would definitely be worried about that rear camber being so far out. In fact, if this alignment machine requires a “caster sweep”, correcting the rear camber and doing another caster sweep may bring the caster measurement into the green. It’s not off by much.