How are the wheels aligned?

[DOCTORBILL]

My '93 Metro front tires show some wear on the inside, so it looks like it is
time to get the wheels aligned.

From replacing my own front wheel bearings, I know about the ball joints on
the steering arms (don't remember the jargon for naming it).

By rotating the threaded ball joint portion, one controls where the tire is "aimed" as it
rolls - that's called "toe-in" (no?)

However, alignment also has to do with the vertical angle of the tire as it rolls
when going straight forward - what is that called?

Anyway - how do they adjust that angle on the wheel? What is moved or
adjusted to do that?

THEN - if they also align the rear wheels - how is that done?

Normally, I used to go in and watch the mechanic working to learn how things
are done, but now almost all shops won't let people do that "for insurance reasons"...

DoctorBill

[JustSayGo]

The threaded ball joints are called tie-rod ends. Turning them will adjust the "toe" which is usually set in. Radial tires roll straight so toe is set close to "0"

Camber is the vertical angle of the top of the tire compared to the lower. Positive camber is when the top of the tire is out farther than the bottom. Wear on the inside of tires indicates a need to increase camber. Caster is another vertical angle that is adjusted.

Caster is the angle of an imaginary line that passes through the centers of the upper and lower steering pivot points.

Alignment begins with inspection of worn parts and measuring ride height. Your Metro very likely may have lost camber in both sides because the springs are collapsing a little over time and the body will flex inward a bit.

Repair shops use alignment machines that use laser beams analyzed by a computer to measure alignment. You can measure and adjust toe using a string and a tape measure. Find a reference point toward the rear of the body (frame) and take a measurement on both sides as a string is pulled across the side of the front tire. Measure as the string just touches the rear of the front tire. Accuracy is improved by using a board that is longer than the tire diameter between the string and the sidewall of the front tire.

Camber can be measured more accurately than one might think using a straightedge, bubble level, and a plastic protractor.

Many cars use aftermarket camber kits to allow adjustment of camber and caster.

Many rear axles use cams or adjustable aftermarket links like the front tie-rods that move the caster.

Looks to me like Metros use rear camber kits to adjust rear alignment.