Pulling after 3 alignments

HACK BLOCK said:

when measuring ride hight you need to measure from the fender to the center of the wheel to not the ground

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This guy must be kidding, right? Anyone understanding the dynamics of automotive suspension should know that how the body hangs on a car or truck has nothing to do with how it drives down the road. It doesn't mater if they used laser equipment, Strobe or did a totally manual alignment, the numbers and dynamics are the same. OP truck trended to the right before the brake swap so it is doubtful that brake drag is causing it, but it is surely easy to confirm. I've been aligning and setting up chassis since 1978 to a high degree of precision (Usually race cars and sports cars). I did three Corvettes, a 56 F100, a 2010 K3500, a 63 Chevy II SS, 06 Tahoe and a 66 Buick Grand Am last week, so I have some experience in this subject. In the USA, most of our roads slope to the right for rain drainage. Cars like Porsche and Corvette need about 0.2 degrees more positive caster on the right front than the left in order to counter act typical road crown. Full size trucks and SUVs like between 0.7 and 1.0 more positive caster on the right front to counter act road crown. Most crappy alignment techs look at the camber and caster numbers and if they are in the "Green", they just set the toe and go. On trucks and SUVs, it is a pain in the ass to adjust camber and caster, but it is part of a good alignment. A toe set is not a complete alignment. A lot of techs get paid flat rate so they make the same amount of money doing a full alignment as they do for a simple toe set, as long as everything is in the green. That would never fly in my shop. You want left and right camber to be within 0.10 degrees of each other. You want 0.7 to 1.0 degrees caster split (more on right than left) and you want 0.10 degrees toe in on each front corner. If it still pulls right on a reasonably flat road (2 to 4 percent slope to the right), then I would start looking at worn suspension parts, corner weight (failing or mis-adjusted spring or torsion bar), rear axle thrust angle, brake drag on right side, tire stagger. Lately I been seeing high mileage GM trucks where the torsion bars are beginning to fail.

First of all, yes, measuring from the fender lip to the center of the wheel is absolutely the correct way to measure ride height because it measures only the suspension and takes the variable of tire and wheel diameter out of the picture. "How the body hangs" absolutely does have an affect on how the car drives because if the right front is 3" lower than the left that would indicate a suspension problem. It's a good thing the vehicles you mentioned are all old because if you align anything newer it will drive like crap. You align to spec and if that isn't achievable, the cross-spec (which is why the spec has tolerance). You don't arbitrarily set caster to 0.7-1.0 split and toe to 0.1 just because that's the way it used to be. Every vehicle has particular specifications for a reason. Most newer vehicles including trucks run no caster split or only a couple tenths of a degree (some of the GMT-900s run the right side caster a couple of tenths LOWER than the left and they drive straight). The design of the suspension has changed a lot in the last 20 years and electric power steering keeps the car driving straight with the help of the yaw sensor and others.

Any other ideas? Tired of fighting this thing for the last 3 years.

I just changed my intermediate shaft too.

When a GM truck chassis pulls to the right and only the right, the first thing I look at is the idler arm. If the idler arm is loose it will cause pulling to the right. Easiest way to check it is jack right front tire just off the ground to where it isnt touching. Have someone grab tire at outside edge at 9 and 3 oclock and rock it inward and outward (toe in and toe out). You lay underneath and watch idler arm closely. It will have a very noticeable bounce up and down if it has wear. These chassis and the generations before will eat up idler arms, even the expensive OEM type. If the suspension is not regularly greased then they will die a premature death and your tires will pay for it.

AN292 said:

Any other ideas? Tired of fighting this thing for the last 3 years.

I just changed my intermediate shaft too.

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We need to see the alignment measurements.

rockola1971 said:

When a GM truck chassis pulls to the right and only the right, the first thing I look at is the idler arm. If the idler arm is loose it will cause pulling to the right. Easiest way to check it is jack right front tire just off the ground to where it isnt touching. Have someone grab tire at outside edge at 9 and 3 oclock and rock it inward and outward (toe in and toe out). You lay underneath and watch pitman arm closely. It will have a very noticeable bounce up and down if it has wear. These chassis and the generations before will eat up idler arms, even the expensive OEM type. If the suspension is not regularly greased then they will die a premature death and your tires will pay for it.

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I am sure you meant to say, "look at Idler arm" and not pitman arm but I would also have all weight down on ground and move steering wheel, engine running, from 3 to 9 and also watch for the idler arm movement and the sector shaft movement at steering gear where pitman arm mounts. While under there, look at the rest of the steering linkage. I would also look at the steering gear mount area. Also, post the before and after alignment readings. Needs right caster lead to offset road crown.

OR VietVet said:

I am sure you meant to say, "look at Idler arm" and not pitman arm but I would also have all weight down on ground and move steering wheel, engine running, from 3 to 9 and also watch for the idler arm movement and the sector shaft movement at steering gear where pitman arm mounts. While under there, look at the rest of the steering linkage. I would also look at the steering gear mount area. Also, post the before and after alignment readings. Needs right caster lead to offset road crown.

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Fixed it.

this may sound stupid but check to make sure all hardware is tight

Any progress on this issue? My 03 Denali XL is pulling hard and the alignment shop suggested a new steering gear box. I'm kind of dreading having to swap that out but if I end up doing it I'll swap the pitman and idler arms as well. Hope you got it figured out.

I would also be looking at the camber in the rear. if they dial in the front, but your rearend is bent and has neg camber on the driver side it will pull to the right also. you need a full printout.