Excellent write up thanks for taking the time. I vote to add this to the end all alignment thread.

 

That's a good write up. I do mine very similar except I only have one tape measure so I have to go back and forth a few times. It looks easier with two for sure.

 

Nice write up & pics...I do the same with two old hockey stick shafts(nice and straight)use bungee cords to hold to tires/rims and measure across...definitely looks easier to measure without tires in the way, but more work jacking and removing..

 

Yep, I tried the bungee cord on the outside of the tire method too and found it to be not as accurate due to tire sidewall variance. This method, with the bar under the rotor hat, is easy to duplicate. When you're trying to hold tight dimensions every bit counts, this method seems to be accurate and repeatable. To get that, I don't mind a little extra work.

Thanks for the comments, glad to help.

 

awesome! thanks! I see you are targeting 3/16" for your toe-in. Is that on 35's? Does anybody have info on what toe-in to use for different size tires?

 

Typically 1/16" to 1/8" but through trial and error I use 3/16" toe-in for my 35's. I know some jeeps seem to handle/drive better with toe-out too.

You're welcome!

This is something most folks can do, in the driveway, with a couple of tools, some jack stands, and this kit. Also, you can check it as often as you desire and experiment with different settings without another trip to the alignment shop.

 

Nice write up. Thanks!

 

Clear and concise write up! I think I am gonna tackle this today... Just got new tires and. Want to make sure they wear in properly!

 

Very good writeup...thanks for taking time to shoot some pictures

I think I saw something similar written up by Jerry or stu maybe? Not as comprehensive and detailed as this writeup though

 

I drilled holes in my bars and tighten them down on the lugs with spacers to clear the hub. Easy to get level and keep centered. I check it every time I rotate. It takes maybe 10 extra minutes.

 

I use the tire seam method,don't even lift the Jeep and never had any wear problems, robncar.I'm too lazy to remove my tires to do your nice alignment as long as my tires wear evenly.Really nice write-up though.:thumbsup: Moderators put it in the sticky!

 

Moderators put it in the sticky!

Then it will never get read.

 

Robncar,
I'm assuming your pulling both measurements roughly 17-1/2" from the center of the hub?

 

Yep, that is correct, see table below...

If you guys want a visual, I'll make a drawing in my CAD software at work. I can show fractions in 1/64" increments. It's really just trigonometry.

Damn math, it always gets in the way of a good story... :teehee:

Here's a table that shows what happens when you set the bars for 35" tires at 3/16" toe-in for the other common Jeep tire sizes.

Now, I know we can't likely even hold a 32nd of an inch and I used generous rounding, but here you go...

 

Nice write-up :cheers:

I use some aluminum I bought from home depot & hop back & forth with one tape measure :rofl:

Measuring off the tread seems like it'd be way harder/less accurate....at least for me

Sent by a messenger bird

 

Excellent write up! Simple and precise.

 

This is a great write-up, thanks for taking the time.

 

I have gotten lazy in my old age and prefer a little less work also.

 

I have an exercise in creative thinking for you. Set your straight edges and mark them for 35's, use that dimension with the 3/16" difference to set the toe in, assume that is in fact correct for 35's. What would change it for 33's, 32's, 31's or any other tire size as long as that is correct for 35's and you used those marks?

I suspect that it would be linear,meaning the toe in would decrease an acceptable amount as the tire size decreased, and the angle front to rear hasn't changed

 

I suspect that it would be linear,meaning the toe in would decrease an acceptable amount as the tire size decreased

What's more important when determining toe: the difference in the distance between the front and back of the tires or their angle relative to each other?

 

What's more important when determine toe: the difference in the distance between the front and back of the tires or their angle relative to each other?

I could be wrong here, but I think what Blaine's saying is that if you used the marks for 35's and set to 3/16", you would find it acceptable with 31's, the angle would be the same, but the toe in would be less with a smaller diameter

 

No, we use 3/16" toe-in for 35's because we don't have a fancy angle finder and that dimension at that distance sets the ANGLE.

If we assume the angle is correct for 35's, then we can mark the same straight edges for any size tire and the angle doesn't change, just the distance between the pairs of marks will. Angle is what we are after, not a dimension.

If you want to know the dimension, set the straight edges for 35's and then lay them out for what ever size tire you want under that, make the marks and measure between them. That will give you what you are after, but it won't be any more accurate than doing it for 35's.

 

What's more important when determining toe: the difference in the distance between the front and back of the tires or their angle relative to each other?

I think we are talking about the same thing, if the angle stays the same, toe in would increase with diameter, say at 1/8" with 31's to 5/32" with 35's (or 3/16" as the op used)

 

Where you are confusing everyone is using the term "toe-in" as in it changes and it doesn't. The dimension to describe the angle of toe in changes with diameter, but the angle does not.

 

I think we are talking about the same thing, if the angle stays the same, toe in would increase with diameter, say at 1/8" with 31's to 5/32" with 35's (or 3/16" as the op used)

like the point of a triangle

 

I think we are talking about the same thing, if the angle stays the same, toe in would increase with diameter, say at 1/8" with 31's to 5/32" with 35's (or 3/16" as the op used)

I think so too. I just read and quoted your post before you added more to it.

Robncar: I use a similar method to set toe with just a few differences. The main one is that I support the tape measure body at a height just a hair lower than the height of the bars clamped to the rotors. This helps keep the tape more level and aids in reading the measurement IMO.

It should also be noted that the same tape measures should be used when doing it the way you outlined. Using one that is wider than the other can cause one tape to bow more than the other, creating errors in the measurements.

 

If you guys want a visual, I'll make a drawing in my CAD software at work. I can show fractions in 1/64" increments. It's really just trigonometry.

 

Ok, no visual, but I'll chart it out.
Factory alignment spec is 0.30° +/- 0.06°, toe-in.

28": 0.117 - 0.176 or 4/32 - 6/32
29": 0.121 - 0.182 or 4/32 - 6/32
30": 0.126 - 0.188 or 4/32 - 6/32
31": 0.130 - 0.195 or 4/32 - 6/32
32": 0.134 - 0.201 or 4/32 - 6/32
33": 0.138 - 0.207 or 4/32 - 7/32
34": 0.142 - 0.214 or 5/32 - 7/32
35": 0.147 - 0.220 or 5/32 - 7/32

You can use the Law of Cosines to figure this out for yourselves.

0.188" is within spec for a 30"-45" span, and perfect at 36". For a driveway job using a tape measure, 3/16" is within spec for a 25"-52" span.

 

I think so too. I just read and quoted your post before you added more to it.

I realized it wasn't very articulate, often the case this time of day

 

I used the same method aligning mine after installing my lift. Great write up.

 

Great write up good way to save a little dough. Charge 50 for a thrust angle alignment and my shop and have 20 off coupon good for alignment. Plus 6 month warranty. Guess its what your times worth/ how much they charge in your area. Plus other angles checked also (camber caster thrust angle)

 

Where you are confusing everyone is using the term "toe-in" as in it changes and it doesn't. The dimension to describe the angle of toe in changes with diameter, but the angle does not.

Precisely what I was trying to articulate, I wrote the angle hasn't changed, and that toe in has because prior to this thread, we had always referred to our toe in value in inches not degrees. . Therefore with a constant angle, toe in value (inches) would indeed increase as tire size increased if all that was changed was tires. Reading back through my post, I can definitely see where my posts weren't clear.