Alignment problem

[sloth454]

Hey all thanks for the help in advanced. So ive got a 72 C20. I rebuilt the front end, used the original control arms with new bushings, did all the ball joints, ect. My problem is I'm running a 255/70R16 tire, I personally have done the alignment and another guy has done it after me. When I am turning through a corner/ turning around in a coldasack/ U-turn. The tires scrub and hop like as if I was in a 4x4 that's locked in. Any advice and help would be great. Just looking for ideas so I can stop burning up the outside edges of my tires.

[Ironangel]

If you havent disturbed the steering wheel, (removed it) or the pitman arm on the steering box shaft. Jack both wheels up and scribe a line with a nail or awl down the center of each tire while rotating the tire. This gives you a line to measure from on each tire, then center the steering wheel up and lower the wheels back down while the steering wheel is held center. Measure the distance between the front tires at the front of the tires and the distance between the rear of the front tires. You should measure about a 1/16th to an 1/8th inch narrower at the front of the tires...Take a look at the front tires (while the steering wheel is centered) to see any noticeable misalignment of one or the other tire in relation to the rear tires...Thats how I align my front ends and I'm running 275/70/16's on one of my 72 C-10's with zero scrubbing and very little wear on two year old tires with 20K miles on them. I dont get any scrub or wheel hop like you described when I turn in either extreme...Wheres your steering wheel when your tracking straight down the road, is it centered?

[Grumpy old man]

We used to just use a string taped to the back side of the rear tire then pulled forward with the string just touching the front and rear sides of the rear tire and the rear side of the front tire you should have about 1/16th to 1/8th as described above . just a different method but you can also get a hint of how it's tracking front to rear .

old school mechanics !

['68 Newtricks]

interesting
My '01 S10 does this "scrub/hop" during the same scenario. I always figured the damn A arm bushings are bad again. 155k miles and they have been worn out and replaced 3 times now.

[sloth454]

So I took some time this morning and jacked the truck up. Measured out the front tires and they are about 1/8th of an inche towed in in the front. I jacked the rear of the truck up set it on jack stands as well. pulled the front wheels off and used my camber guage to check ccamber. I'm sitting about 1 to 1.5 degrees cambered in. While driving down the road the truck tracks straight ahead (on a flat road) with the steering wheel centered and straight. I have also followed my wife driving my truck and it has no sighns of catwalking/dogwalking. so I know the rear tires are tracking true to the fronts.