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Alignment Problems

imp

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West-Central AZ along the Colorado River
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59 Ranchero F250 D'Line
The following thread start is quite old. However, it's premise is important to every Explorer, of any age or generation. Thus, the first 2 posts introduce the circumstances; the third is my own reflection regarding the "straight pointing" steering wheel problem.

BY: LOREN (2002 Explorer)

Hello,
To introduce myself, I'm a technician working in the automotive industry. I do not own a Ford product myself but I do lots of work on Ford cars and trucks. I apologize ahead of time if I'm asking a question that has already been covered elsewhere but I did not find it right away and I don't have time to wade through the entire forum. In any event, the last two Ford Explorer's I have done alignments( and suspension work ) on have still ended up with a slightly off center steering wheel. All angles will be in the green, the suspension is verified to NOT be loose, I will "split the tow" and jounce the vehicle, verify correct ride height, etc. etc. I'm starting to wonder if the Hunter DSP 300 that I use has the correct specs for the caster angles.
Has anybody run into this problem and do you know what the caster angles should be?

BY: CORNCRASHER

The only thing that is going to effect steering wheel alignment is toe. If the car is driving straight and the wheel is off the toe is off. Are you doing 4wheel alignments or 2 wheel? If you are doing only two wheel and the rearend is off one way or the other it can cause the wheel to be off even if the machine says the steer ahead is right on.

BY: IMP

First, a "****eyed" steering wheel when moving forward in a straight line adds the possibility of improper or no turn signal cancellation, for small turns.

Second, if the wheel must be manually held in the "not straight" position, the front end is "pulling" the vehicle to one side, and the driver is forcing it to move in a straight line.

Third, if "hands off" the wheel allows it to locate "not straight", but the vehicle moves straight forward, without "pulling", this suggests alignment is OK, as far as caster and toe-in are concerned, but the wheel needs to be relocated.

CORNCRASHER is not entirely right, in that given a vehicle with ZERO toe-in, but equal and acceptable amounts of caster angle, it will "track" in a straight line, regardless of steering wheel position. The KEY to smooth, straight tracking is that both front wheels must have as nearly equal caster as possible. If unequal caster angles are present, the wheel having the GREATER amount of caster will tend to face straight ahead, overcoming the caster influence of the other wheel. Thus, since absolutely EQUAL caster angles are very difficult to achieve in reality, and due to structural flexing within the suspension system, TOE-IN is added to further stabilize the straight-ahead motion of the vehicle; that is, it "plows" the pavement as each wheel attempts to drive the vehicle toward the center-line of it's motion.

Now, given that the above description "fits" for a non-driving wheel front end, it DOES NOT for wheels which drive the vehicle forward (i.e., front-wheel drive, or 4WD). Pulling the vehicle forward by driving it's front wheels causes deflections in the suspension which PULL the front of the wheels toward the center of the vehicle. Thus, many FWD vehicles actually have TOE-OUT put in place, to compensate for this effect; otherwise, the wheels would run in excessively toed-in condition, and greatly affect tire life.

To sum up regarding the "crooked steering wheel" problem, once caster angles are established as correct in amount of angle, AND being equal, side-to-side, and toe-in(or out) is set to specs, then the steering wheel may be "scoshied" (spelling?) by adjusting rod ends in EQUAL amounts but opposite directions, to keep toe-in unchanged, but relocate the steering wheel's straight-ahead position.

Lots of words, but not really complicated! imp ;)

(this might be better located under another category)
 






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