Need Alignment Specs

What are the magic numbers as far as alignment settings for my '92 4X4?
I am going to get the alignment done soon and want to see what is recomended here and why it differs from the 'factory' specs. My ride is bone stock with the exception of 235/75/15 tires. In fact, what are stock specs supposed to be? Why are the 'new' specs better than factory? I have been a jeeper for life (Had many CJs,Wranglers, an FSJ,etc) but this is my first XJ and I am trying learn all of its 'tricks'. I already tightened the track bar bolts and personally rotated and balanced the tires to get rid of a shimmy that wont go away(that happens at 55mph). I have never had a vehicle to react so adversely to a balance issue which makes me suspect there is more to the problem. When I tightened up the track bar the front end is tighter but the alignment is way off now and the steering wheel is crooked. Any other suggestions would be greatly appreciated as well. I love my Cherokee and need to work out the bugs, the alignment and 55mph mystery shimmy being the last two items on my long list.

The closest factory service manual I have to your year is 1994. Those specs should work fine for you.

Camber (not adjustable) = 0 degrees (+1/2 to -3/4 acceptable)

Caster = Manual tranny +6.5 degrees, auto tranny +8 degrees (5 to 9 acceptable)

Toe-in = 0 (+/- 1/32" acceptable)

If you have shimmy at 55 MPH the tires aren't balanced. Doesn't matter if you just paid the best shop in town $5000 to do it, if it shimmies at 55 MPH the tires aren't balanced.

Rather than just out of balance, you may have a tire that is out of round, or even comming apart at a ply seperation. Jack up the jeep then spin the tire. Watch the tread as it rolls, it should seem to go nice and stright. If you have a "snake" in the tread you need to replace that tire before going any further. That will make you sit up and take notice at the steering wheel.

Eagle said:

If you have shimmy at 55 MPH the tires aren't balanced. Doesn't matter if you just paid the best shop in town $5000 to do it, if it shimmies at 55 MPH the tires aren't balanced.

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First off, Thank you for the numbers. I really appreciate the reply. Secondly, I would like some theories about about why balance is such a critical issue on the XJs. I don't, however, appreciate such an ostentatious and non-helpful remark such as the quote above. I have been in the car repair business for better than twenty years and have seen the effects of different problems cause such an issue but do not have much experience with the XJ. I know a tire can be 'balanced' but still be out of round. Some vehicles can handle this problem better than others. What I need to know is what else could possibly be making this problem worse, other than the obvious worn tie rod ends, ball joints, etc. I realize it might start as a tire/wheel problem but something else might be contributing to the problem. Could alignment make it seem worse? I appreciate the fact that everyone has opinions and knowledge but I need a more detailed or technical insight to my problem. YMMV

pressurerat said:

First off, Thank you for the numbers. I really appreciate the reply. Secondly, I would like some theories about about why balance is such a critical issue on the XJs. I don't, however, appreciate such an ostentatious and non-helpful remark such as the quote above. I have been in the car repair business for better than twenty years and have seen the effects of different problems cause such an issue but do not have much experience with the XJ. I know a tire can be 'balanced' but still be out of round. Some vehicles can handle this problem better than others. What I need to know is what else could possibly be making this problem worse, other than the obvious worn tie rod ends, ball joints, etc. I realize it might start as a tire/wheel problem but something else might be contributing to the problem. Could alignment make it seem worse? I appreciate the fact that everyone has opinions and knowledge but I need a more detailed or technical insight to my problem. YMMV

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I've been "playing" with cars and trucks for a lot more than 20 years -- closer to 45. Shimmy that has its onset at 50 to 55 MPH and disappears when you get up to 60 or 65 MPH is ALWAYS caused by improper tire balance. ALWAYS
It's been that way since before I got my driver's license, and they haven't changed the laws of physics. That comment is not "ostentatious and non-helpful," it's Gospel. You can take it to the bank.

Why is it more noticeable on an XJ? Because an XJ has a solid axle. It doesn't have 'A' arms or leaf springs on each side that keep the axle centered under the vehicle, it relies on the track bar for that, and the track bar has a bushing on one end that can wear or get loose, and a tie rod end and bracket on the other end that can wear or get loose. Plus, a solid axle is simply more prone to transmit shake than an independent suspension.

However, I drove around for about 6 months with a track bar that was severely worn, and I had no shake problems. (Tracking problems, you betcha, but no shake.) Shimmy caused by tire imbalance may be more noticeable with worn suspension components, but the root cause remains tire balance, and the other parts just help cover up the symptoms. If the onset of the shimmy is 55 MPH, the cause is tire balance.

As to what makes the EFFECTS of the imbalance worse, I would start with the steering damper, and also look at anything that contributes to looseness, including but not limited to tie rods, track bar and ball joints. Worn ball joints can cause negative camber which combines with the tendency to toe out, and wears the tires on the inside. Anything that contributes to uneven tire wear will combine with the effects of imbalance to cause more nibbling and cupping. Remember too that the zero toe-in spec is a compromise between the tendency of undriven wheels to toe out and of driven wheels to toe in under power. If your Jeep is used mostly on the highway, and is getting a little long in the tooth, you may be better off erring on the side of toe-in than out.

I've had wheels with new tires dynamically balanced by reputable tire dealers that wobbled, and stopped wobbling only when I took the weights off and did it carefully on my own static bubble balancer. I think many people doing this just trust the machine implicitly and don't check their work. They also often don't clean the mud and crap off the wheel before they do it. As so often happens in the technological world, too many people confuse precision with accuracy. You're better within a half-ounce of the correct weight than within a hundredth-ounce of the wrong one.

A tire that's seriously out of round, or a bent wheel, won't wait until you hit 55 to start wobbling.

Now we are getting somewhere! I will post the results for my alignment soon and thank you all for the insight. I will also soon be getting some different tires soon and cannot wait to see the result.

oh, yes....Eagle, this is just for you :kissyou:

Sorry if I come off as "ostentatious and non-helpful" to you. Itend toward the pedantic in trying to give complete responses and I guess that can come off as being ostentatious, but I try never to be "unhelpful."

Matthew Currie said:

Remember too that the zero toe-in spec is a compromise between the tendency of undriven wheels to toe out and of driven wheels to toe in under power. If your Jeep is used mostly on the highway, and is getting a little long in the tooth, you may be better off erring on the side of toe-in than out.

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Back in the old days of 2WD, rear wheel drive cars, the factory manuals would tell you to check toe-in "dynamically" for that reason. The rolling resistance of the tires would tug at anything loose (like tie rod ends) and make the tires toe-out more than they showed on the alignment rack. "Dynamic" toe-in meant putting a spring-loaded rod between the leading edges of the front tires to spread them the same as they would be when driving on the highway. If they were set to zero that way, the un-loaded "static" reading was generally between 1/16 and 1/8 of an inch, toed in.

As Eagle stated above, Mercedes still requires the spring loaded bar to set the toe angle properly.
I have been performing alignment service for nearly 14 years and have never solved a vibration problem with an alignment. It is almost always wheel balance.