How to align your Jeep Wrangler TJ

I am done arguing with you. If you want to do your toe-in differently than recommended in this thread because you refuse to believe it will produce accurate results, be my guest.
 
Instead of reacting, you can simply answer me with a yes or no.

Did the alignment rack showed the results that you have 0.3 degrees?

Also, I understand why you are facepalming me, since I am a newbie here, asking questions. But, would you facepalm post #149 of @mrblaine in this thread?

I am literally saying the same thing.
I thought this was pretty interesting to question or prove out why what is accepted is. I even went back to read the FSM on how they recommend we align. Doing it with the vehicle running is a nice trick to avoid needing to bother with following up by centering the steering wheel (assuming you get it good and straight when you stop).
 
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I am done arguing with you. If you want to do your toe-in differently than recommended in this thread because you refuse to believe it will produce accurate results, be my guest.
Actually, I am not even arguing. What I am saying is simple math. No one can dispute that.

I admire the method. I am following the method. Anyone should follow the method, if they want to work on their rig.

Since it is a how to thread though, it should be mentioned that there are two options as far as the measurement of the toe in go:

1) Follow the consensus, 1/16" toe in, which many use over the years.
2) Calculate the 0.3 degrees, which the Jeep Wrangler TJ Factory Service Manual indicates.

*There is nothing wrong to have the desire to be precise, and do the extra step.
 
I thought this was pretty interesting to question or prove out why what is accepted is. I even went back to read the FSM on how they recommend we align. Doing it with the vehicle running is a nice trick to avoid needing to bother with following up by centering the steering wheel (assuming you get it good and straight when you stop).
I simply believe, as I explained in post #286, 1/16" should have started by something calculating the .30 degrees at 12" ( Size of rotor).
 
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Wrong is still wrong in math.
Years ago someone posted up the toe angle for a stock tire which was around 1/16" closer at the front. I laid out my aluminum sticks at 30" and measured the toe to be 1/16" at that pair of points. Then I measured the marks I made at 35" which turned out to be 3/16" closer at the front. The angle did not change, but the distance between the marks got shorter due to the taller tires.
 
Doing it with the vehicle running is a nice trick to avoid needing to bother with following up by centering the steering wheel (assuming you get it good and straight when you stop).
I am totally doing that next time I align. That's a good find too.
 
If tire diameter doesn't matter, then this sentence in the OP doesn't make sense.

"Center and hold the square tubes to the rotors with spring steel clamps after marking them at points equal to the diameter of your tires."

Two non-parallel lines will move closer together in one direction until they cross and away from each other in the opposite direction. By necessity the larger the tire diameter the more toe will show up as long as factory 0.30* is maintained.

If you set your 35" tire at 1/16" toe in then the angle will be 0.10*
 
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Years ago someone posted up the toe angle for a stock tire which was around 1/16" closer at the front. I laid out my aluminum sticks at 30" and measured the toe to be 1/16" at that pair of points. Then I measured the marks I made at 35" which turned out to be 3/16" closer at the front. The angle did not change, but the distance between the marks got shorter due to the taller tires.
1643761510819.png


That's exactly what this photo shows. Thanks!
 
If tire diameter doesn't matter, then this sentence in the OP doesn't make sense.

"Center and hold the square tubes to the rotors with spring steel clamps after marking them at points equal to the diameter of your tires."

Obviously two non-parallel lines will move closer together in one direction until they cross and away from each other in the opposite direction. By necessity the larger the tire diameter the more toe will show up as long as factory 0.30* is maintained.
As a matter of fact, marking them at points equal to the diameter of your tires has no value to find the correct angle.

Just marking both tubes at the same points. So, if you mark it at 15", 20", 40" or 60" has no difference, whether you are running 27" tires or 40" tires.

You just have to add the distance that you marked on the tubes to the calculator to tell you the toe in measurement at the specific distance. Am I making sense?
 
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As a matter of fact, marking them at points equal to the diameter of your tires has no value to find the correct angle.

Just marking both tubes at the same points. So, if you mark it at 15", 20", 40" or 60" has no difference, whether you are running 27" tires or 40" tires.

You just have to add the distance that you marked on the tubes to the calculator to tell you the toe in measurement at the specific distance. Am I making sense?
A nice thing about this is you could mark at lengths that are really easy to measure. Meaning that 0.15" is much harder to measure than 3/16" (at least on my measuring tapes) - assuming you want to be precise, so mark your bars at that distance for when you measure. The manual for the 06 says 0.25 degress +/- .05 - so maybe it doesn't really matter.
 
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As a matter of fact, marking them at points equal to the diameter of your tires has no value to find the correct angle.

Just marking both tubes at the same points. So, if you mark it at 15", 20", 40" or 60" has no difference, whether you are running 27" tires or 40" tires.

You just have to add the distance that you marked on the tubes to the calculator to tell you the toe in measurement at the specific distance. Am I making sense?
Yes, you're making sense.

Of course, the marks don't help you find the right angle. We have to have the engineers baseline in the FSM. From there we extend out the diameter of the non-stock larger tire. A simpler way to do it with the tires off is to simply make the marks at 29" (or whatever the stock tire size), and measure it there 1/16" toe in (but it's actually 5/32's, so it's not simpler unless you have 32's on your measuring tape). Then you're toe in will be correct no matter the tire size.

Whatever the case, 1/16" is not enough for any stock size tire or larger, and barely falls within the percentage of error in the FSM you cited.
 
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A nice thing about this is you could mark at lengths that are really easy to measure. Meaning that 0.15" is much harder to measure than 3/16" (at least on my measuring tapes) - assuming you want to be precise, so mark your bars at that distance for when you measure. The manual for the 06 says 0.25 degress +/- .05 - so maybe it doesn't really matter.
0.25 degrees for front?
 
Yes, you're making sense.

Of course, the marks don't help you find the right angle. We have to have the engineers baseline in the FSM. From there we extend out the diameter of the non-stock larger tire. A simpler way to do it with the tires off is to simply make the marks at 29" (or whatever the stock tire size), and measure it there 1/16" toe in (actually it's 5/32's). Then you're toe in will be correct no matter the tire size.
You definitely could do that. But since we want degrees over a distance. A little algebra and you can get round numbers from the formula, mark the center and the distance (radius from the middle). You're in the money for any tire size.

0.25 degrees for front?
I guess 0.30 total +/- 0.12 (total)?

1643762472733.png
 
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Yes, you're making sense.

Of course, the marks don't help you find the right angle. We have to have the engineers baseline in the FSM. From there we extend out the diameter of the non-stock larger tire. A simpler way to do it with the tires off is to simply make the marks at 29" (or whatever the stock tire size), and measure it there 1/16" toe in (actually it's 5/32's). Then you're toe in will be correct no matter the tire size.

Whatever the case, 1/16" is not enough for any stock size tire or larger.
No, if you mark at 29", you should measure around 0.15".

for 1/16", which is 0.0625" you should mark roughly at 12".
 
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No, if you mark at 29", you should measure around 0.15".

for 1/16", which is 0.625" you should mark roughly 12".
Right, that's what I said, which is 5/32's. We're on the same page. 😉 I did make some edits, so there could have been some confusion!

P.s. you know, but so it's clear, 1/16" is 0.0625.
 
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You definitely could do that. But since we want degrees over a distance. A little algebra and you can get round numbers from the formula, mark the center and the distance (radius from the middle). You're in the money for any tire size.


I guess 0.30 total +/- 0.12 (total)?

View attachment 306518
If everything in that column is Total, then yes, +/- 0.12, so 0.18-0.42 would be acceptable. That brings 1/16" back into spec since the angle would be about 0.246* for a 29" tire.
 
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Right, that's what I said, which is 5/32's. We're on the same page. 😉 I did make some edits, so there could have been some confusion!

P.s. you know, but so it's clear, 1/16" is 0.0625, which will never be enough toe even on stock tire size.
ooh okayy! right! Sorry, my bad. I typically use metric system due to location, so I didn't convert 5/32.
 
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