What gets adjusted in an alignment?

I am having a shimmy problem since 2005, at 50+ mph, and my tires are visibly pointing outward, so I know I need an alignmet. What do they adjust? Im just imagining the mechanic coming out to me and giving me a santa-claus-list of parts that need replacing first.

The shimmy wont go away. Everything underneath is tight as can be, and the tires are tight with the 9-3 and 12-6 test. Ruling out TRE"s and balljoints.

Would an aligment cure my problems? What do they adjust when an alignment is performed?


I am also suspension illeterate, FYI...

Camber (the amount of tilt outwards or inwards as viewed from the top of a tire. This cause uneven tire wear and effects cornering ability.

Caster (the angle at which the balljoints point when a straight line is drawn through them), caster issues can be: Litlle to no self center, or Death wobble (it's the one shopping cart at the super market that rattles and shakes when being pushed down the aisle)....

Toe (the angle at which the tires point in or out as viewed from the front), this also causes death wobble, but usually just wears one tire more than the other. It can create a pull to one side or another....

poorboy_616 said:

Camber (the amount of tilt outwards or inwards as viewed from the top of a tire. This cause uneven tire wear and effects cornering ability.

Caster (the angle at which the balljoints point when a straight line is drawn through them), caster issues can be: Litlle to no self center, or Death wobble (it's the one shopping cart at the super market that rattles and shakes when being pushed down the aisle)....

Toe (the angle at which the tires point in or out as viewed from the front), this also causes death wobble, but usually just wears one tire more than the other. It can create a pull to one side or another....

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Excellent explanation. Are you an alignment guru? Cause I have uneven tire wear. I have checked all the above on a Bear machine and all seems perfect but the tires still wear unevenly. More tire wear on left than right.

Get the balancing checked on your wheels and tires. Sounds like a good dual plane balance could help.

On a XJ all you can truely adjust is the toe-in and steering wheel center, anything else will require parts replacement.

Caster is set by the upper and lower control arms, the later models can be adjusted at the frame bracket with shims. Or with adjustable lower control arms and/or adjustable upper control arms. You have to be careful there or you will give yourself a new problem by messing with the pinion angle and causing DS vibes. You can also get offset ball joints to correct caster. Generally speaking caster is over-rated on a XJ, if it comes back to center without having to force it it is probably ok. I run as little as 4* on one of my XJ's and as much as 8* on some of the others.

Camber is set by the axle "C's", knuckles, and ball joints.

Have you checked the ball joints?

The shimmy may be the track bar, check that and make sure it is tight and in good shape.

Have some one work the steering wheel back and forth while you lay under the front of the Jeep, watch for anything that is loose or anything that is attached to something and one part is moving while the attaching part is not.

OK, I got to this thread from a search. I am interested in the statement about Caster and DW.
I did a 2"BB and now when I am at 30 and am negotiating a slight turn with a bump in it , I get DW until I slow down. Could the caster contribute to this?

The issues I've had with death wobble, the caster was the culprit. It seems very unlikely for a 2" budget boost to affect caster significantly, though.

I would agree, but one never knows when you have a heep with 215K and no knowledge of when the last time alignment happend!

So judging by these, I should get an alignment?? Thanks for the responses guys. It is obvious I need it, just wanted to post these...

90Blue_XJ said:

Excellent explanation. Are you an alignment guru? Cause I have uneven tire wear. I have checked all the above on a Bear machine and all seems perfect but the tires still wear unevenly. More tire wear on left than right.

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I did get one thing worng though....

Camber as seen by looking at the front of the tire, not the top...

What kind of uneven wear?? When was the last time you rotated your tires??

By no means a guru....

I have a couple years in auto tech classes, four years in auto parts sales, a year as a technician, a year rebuilding engines for Detroit Diesel, all totalled that's 12+ years of wrenching.....

For some add reason, when we got to the Alignment part of the class, I soaked it in and aced all the tests.....

Maybe I am meant to do alignments??? Nahh....I actualy hate wrenching on other peoples vehicles.....

Everytime I have fixed DW is when I have found worn or loose parts. Too much or too little caster(as long as it is not excessive) will not cause DW but will enhance it.

Look for loose/worn parts first, fix any if you find them, then get the "toe" set to spec and see what happens.

xjtrailrider said:

Everytime I have fixed DW is when I have found worn or loose parts. Too much or too little caster(as long as it is not excessive) will not cause DW but will enhance it.

Look for loose/worn parts first, fix any if you find them, then get the "toe" set to spec and see what happens.

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Agreed. Best thing is to check for loose parts first as it's pretty quick. I like checking the track bar and tie rod ends by crawling under the front and having someone crank the steering wheel back and forth, looking and feeling for any play. It's common for the upper end of the track bar to develop slop which causes lots of problems. Some will disagree that it's a band-aid and doesn't fix the underlying problems (probably true), but replacing a shot steering stabilizer can sometimes take care of DW.

Do a quick search and you'll find plenty of writeups for measuring and adjusting the toe-in using nothing more complicated than a tape measure. You can get surprisingly close just measuring between the front and rear of the tire. I have a pair of 5' metal rods I clamp the the brake drums and measure side-side at the brake drum and the ends. Just get them to measure the same and you're at 0* toe-in.

Trivia question: Whats the definition of accuracy versus precision. Precision is the alignment machine reading out to 0.001 degrees. Accuracy is the fact that it's only within 0.1 degree due to slop in the equipment mounting to the wheel and other errors.

I was doing some searching and ran across this thread. I had an alignment done at Belle Tire a couple weeks ago before having a new set of tires put on. I was looking at my tires the other day and noticed that on my passenger front tire the inside inch of the tread isn't making contact with the ground when I drive judging by the road dust on the rest of the tire and still being black on that inside inch. The guy at the alignment shop said that either my ball joint or wheel bearing was going bad on that side so I replace the wheel bearing unit and ujoint since I had a new one in the garage already. The tire is still riding the same way. Would this be a sign of the balljoint going bad on that side?

Yes....

Bad Ball joint or joints, do them both on that side, just to be safe....

88XJSport said:

So judging by these, I should get an alignment?? Thanks for the responses guys. It is obvious I need it, just wanted to post these...

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Yes... you have a decent amount of toe-out... Which can cause pulling, rapid tire wear, and off-center steering wheel.

I would say do the alignment yourself. It really is pretty simple, and you can get pretty accurate setting the toe-in with nothing more than a tape measure. Do a search and you'll find tons of writeups.