Thrust angle

[Jeepr]

About a year ago and many miles ago, I put on the Kore Recon lift, got it aligned, etc... all was well.



Well, several weeks ago, a friend borrrowed it, and was backing up with the wheels turn hard left and smacked the mirror on a tree, and stopped when the tree hit the front tire (so luckily didn't get the fender!).



Well, right after that, I was towing on about an 8 hour round trip, and when I got back, I noticed bad "chunky" wear on the front tires. And, the truck just doesn't seem to handle as well to me. Now, maybe this wear is the usual problem we all have with these trucks and I'm crazy about the handling... .



So, I took it to have the alignment checked. They said everything up front is in spec with no changes needed. They did note I need ball joints



But, they said the rear thrust angle is "way" out of spec. The spec was like . 20 (or . 020?) and mine was twice that (. 40 or . 040). Of course, there isn't much to adjust in the rear of our trucks.



I don't have an adjustable track bar on front with the lift, so I know my axle isn't centered. I called the alignment shop back and mentioned that, and said that will make the front and rear axles be on a different track, and asked if that could have caused the reading they saw. They claimed that was not it.



So, do I worry about this thurst angle spec? Short of unbolting the u-bolt and trying to pull the axle and rebolting, I don't know what I could do. And, even if I did that, I'd think it would find it current position again. Or is it really just a false reading because of the front track bar.



Oh, and the thrust angle doesn't explain the front tire wear and what I consider to be poor handling, but maybe I'm just crazy on that.

 

[snuff]

go find a differnet alignment shop. it does not matter if the axles are centered or not but they due need to be straight for tracking. it could cause problems with towing and handling down the road. depending where they measured it the rear should be ok, the tree hit the front so that axle will out of track.

 

[sag2]

That is not that far off, but you really want it as close to zero as you can. There is not much to play with so you want to mark the current position, and measure it as well to a good solid reference point. Then drop the U bolts and grind out the spring pad in the direction you need to move it. Unfortunately there is no way to know how much . 2 degree is without being at the alignment shop, but at least if you hog out the holes slightly (1/8-3/16) on both sides the shop can then make the adjustment while they have it on the rack. The U bolts will hold it in position if torqued properly. The through pin or alignment nubs are just there to keep it from moving way out of position if the bolts ever get loose.

 

[Matt400]

A few things come to mind-



I worked on an 08 the other day that took a hard enough hit to the wheel & no body damage that it caused the lower strut bushing holes to egg shape which caused the bushings to become unseated. The only way it was found was by grabbing ahold of the strut bar and you could rattle it.



On another one. . an 03 it took a hard enough hit to the wheel & again no body damage to shove one frame rail back and caused a thrust fault in the rear.



You may not know all that really happened if you were not there, don't mean to point fingers but its possible.



Your alignment shop most likely checked your truck measurements under different conditions than with your 8hr towing venture so loads can make a difference in the front toe settings especially if you are still using the old style steering linkage.



You might want a second opinion from another shop and to get a "set-back" measurement. Thats the measurement of front to rear axle on both sides compared.