Squaring up axles?

LONGJP2

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I'm trying to verify my rear axle is square to the frame.
I realize the control arms will not necessarily have matching lengths.
Although, they shouldn't be too far off considering they were fixed length from the factory.
So is there any good measuring point to check from.
I've seen posts mentioning the middle skid bolt.
What about the rear crossmember?
Or is an alignment check the only real way to know?
 
You need a reference point- like hold a level from the rear bumper to the floor and measure each side to the axle , or measure from the skid to the axle on each side

Then you need the axles square to each other and centered.
 
I'm trying to verify my rear axle is square to the frame.
I realize the control arms will not necessarily have matching lengths.
Although, they shouldn't be too far off considering they were fixed length from the factory.
So is there any good measuring point to check from.
I've seen posts mentioning the middle skid bolt.
What about the rear crossmember?
Or is an alignment check the only real way to know?

I would use the skid bolts or the frame may have some holes in it that were used on the assembly line. I would assume the skid bolts would be within allowable tolerance.
 
Best method I have found is to run a plane laser down the centerline of the rig, then snap a chalk line along that line on the shop floor. Then use the laser to sight a line perpendicular to the chalk line at the axle. Site where the laser hits the axle, and then make your adjustment.

I’ve done it this way for both the front and rear when setting up the suspension. Works well for me. I believe I posted how I did it over on my build thread. Starts on post #505.
 
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I'm trying to verify my rear axle is square to the frame.
I realize the control arms will not necessarily have matching lengths.
Although, they shouldn't be too far off considering they were fixed length from the factory.
So is there any good measuring point to check from.
I've seen posts mentioning the middle skid bolt.
What about the rear crossmember?
Or is an alignment check the only real way to know?

Easy way? With the rig on level ground side to side, get a straight length of something like 2" x 3/8" aluminum bar stock that will reach from the rear axle to the middle skid bolt. Butt the end of the bar into the axle tube. Grab some vise-grips or similar and a framing square. Clamp the framing square to the bar stock so that the end of it on one edge hits the center of the skid bolt. You are basically making a long legged L with the long leg roughly parallel to the ground. When you are happy that you have the center of the bolt indicated and are butted into the tube, carry that to the other side and check it. Note roughly where you stuck the bar stock on the tube and do it the same on both sides.

Takes less time to do it that it took me to type all that.
 
Best method I have found is to run a plane laser down the centerline of the rig, then snap a chalk line along that line on the shop floor. Then use the laser to sight a line perpendicular to the chalk line at the axle. Site where the laser hits the axle, and then make your adjustment.

I’ve done it this way for both the front and rear when setting up the suspension. Works well for me. I believe I posted how I did it over on my build thread. Starts on post #505.

That will center your axle left to right under the frame, what about making sure your thrust is straight ?
 
Easy way? With the rig on level ground side to side, get a straight length of something like 2" x 3/8" aluminum bar stock that will reach from the rear axle to the middle skid bolt. Butt the end of the bar into the axle tube. Grab some vise-grips or similar and a framing square. Clamp the framing square to the bar stock so that the end of it on one edge hits the center of the skid bolt. You are basically making a long legged L with the long leg roughly parallel to the ground. When you are happy that you have the center of the bolt indicated and are butted into the tube, carry that to the other side and check it. Note roughly where you stuck the bar stock on the tube and do it the same on both sides.

Takes less time to do it that it took me to type all that.

Do you (or anyone else) happen to have that measurement on a stock TJ?