Excessive Body Roll & Self-steer Over Bumps After Front End Overhaul

[89Suburban]

Look what I did here. See how the rear of the arm is 1 notch/peg further in than the front? That's what gives me some positive caster. Once you have that dialed in you adjust them equally in or out to set your camber.

What did you do to your NNBS GMT900 Tahoe/Yukon Today?

Strut under arm flip with the GR9 hardware.

www.tahoeyukonforum.com

 

[Fless]

Did you fully remove the center link/relay rod/drag link when you did all the front end work?

Great question, and a common issue when re-assembling the center link is to mis-orient it.

Also, do the front jounce (bump) stops contact the lower control arms at ride height? If not, they should.

 

[Doubeleive]

probably your first answer was most likely, if the keys are not where they normally should be set it will not ride right period.
that is the primary problem with the gmt800's and handling issues.
once the keys are set stock then you can add some stiffer sway bars and tighten it up a bit

 

[squeeler642]

For negative caster comparison, think of a shopping cart wheel and how it looks when you push forward. The right should have at least .3 degree more positive caster than the left, to allow for road crown and they both should be in the positive range. Why did you not change the sway bar frame bushings? Did you tighten all components while was suspended in air or after putting weight on ground?

Good to note on the caster being slightly asymmetrical. Makes sense on road crown, etc.

Great question, and a common issue when re-assembling the center link is to mis-orient it.

Also, do the front jounce (bump) stops contact the lower control arms at ride height? If not, they should.

To address all the re-assembly related questions:
- I did a loose assembly of each side, put the torsion keys back in it, and then on each side used a jack to achieve the approximate hub position as it would be when loaded with the weight of the truck using the running board as a reference... likely got it to within ~1", measured it before disassembly with the wheels on. Then I tightened the UCA/LCA bolts. I only have one jack, so I left the sway bar links until the truck was back on the ground, which you want to do anyways.
- With the truck back at approx. factory ride height as I described using my approximate fender well measurement, the bump stops hover about 1/8" above the LCA contact point.
- I didn't ever have the drag link entirely removed from the truck. I did all the suspension stuff first, then went back in and replaced idler/pitman arms the next day. The drag link is in the same orientation it was originally.

 

[Fless]

If you're going to leave the keys cranked up, maybe you can find some longer jounce stops so they properly contact the lower control arms.

How about a couple of pics of the center link, from a few different views?

 

[nonickatall]

Side note: how do you even measure caster on these trucks?

You set the wheel upright and measure the angle to the ground, i.e. how the wheel stands in relation to the road. Then you turn the wheel 20 degrees outwards and measure the changed angle. The angle between the straight and 20° position is the caster.

But about your problem,. Have you adjusted the middle tie rod? I don't know if this works with our cars, but I know from BMW's, that if you replace or remove the middle tie rod, you have to adjust it by adjusting the height of the auxiliary steering lever.

The tie rod must be exactly parallel to the ground, because the angle between the tie rods and the wheel must be the same on both sides.

If these are unequal, the wheels steer differently when compressed and that can lead to your phenomenon...