DIAGNOSIS CHECKLIST
Assuming your tire psi is 28-30, your tires/wheels have been balanced and rotated to make sure the wobble doesn't move with the rotation, here would be my order:
The last ditch thing if there is a non-DW, speed dependent range wobble, I would borrow a different set of wheels and tires to see if it changes, and I would try driving it with no front driveshaft to see if that changes anything.
Although it is always a good idea to inspect your axle shaft u-joints, they will not cause DW.
The most common sources of full on DW are:
Assuming your tire psi is 28-30, your tires/wheels have been balanced and rotated to make sure the wobble doesn't move with the rotation, here would be my order:
- Remove the steering stabilizer.
- Have someone turn the engine on and turn slowly from full lock to full lock while I visually, manually (with my hands on the components), and auditorily inspect for any play in the tie rod ends, drag link ends, sector shaft, trackbar ends/bolts/brackets, and trackbar bracket welds.
- Then, do the same thing but with short, sharp, quick back and forth turns of the steering wheel between the 10 o'clock and 2 o'clock positions, instead of the slow, lock to lock approach.
- Then, I would remove the front trackbar to inspect the axle bracket bolt holes for ovaling and inspect the trackbar bushings for separation or cracking with a long screw driver through the bolt sleeve and the trackbar in a vise to leverage against the bushing in all directions. I would also inspect the frame side bracket for damage and the frame side end of the trackbar for up and down play using a channel lock pliers. If all is good, I would reinstall the trackbar with the tires on the ground at ride height to 55 lbs at the axle side and 65 lbs at the frame side.
- Then, I would inspect the drag link end joints by using a large channel lock pliers that gave me enough leverage to check for up-and-down play in the drag link ends. There should not be any meaningful up and down play. If there is, the ends should be replaced, or a new drag link with heavy duty joints should be installed. After, I would check the torque of the drag link ends. Taller lifts magnify the problems of bad drag link ends.
- Then, I would inspect the tie rod ends with the channel lock pliers for up-and-down and in-and-out movement. There should be no meaningful play. There should only be rotational movement in the joint ends.
- Then, I would put the front axle on jack stands with the tires about 2" off the ground and check the front ball joints by using a long pry bar as a lever under the front tires to lift them up to inspect for up and down play in the lower ball joints. There shouldn't be more than maybe 1-2 mm.
- Then, I would use the prybar/lever against the frame or just my hands on the top and bottom of the tire to inspect for lateral movement of the top ball joints. There shouldn't be any. If you have a lighter tire/wheel combo, you can do this by hand.
- Then, I would remove the front tires/wheels and remove the front tie rod--one knuckle at a time. Then with a large wrench or vice grips, I would inspect the end for side to side play. Then I would reinstall the end and torque to spec (20 ft. lbs.) and repeat on the other side.
- Then, I would remove the brake calipers and brake disks to inspect the unitbearings for play.
- Then, I would reinstall the discs, brake calipers, and tires/wheels and set the axle back on the ground.
- Then, I would support, but not lift, the front axle with a floor jack and loosen the front lower control arm bolts. One at a time, I would drop the lower control arms to inspect the bolt holes and bushings (similar to with the trackbar), reinstall without torquing, and do the next one. Afterwards, remove the floor jack so the suspension is at ride height, vigorously rock the vehicle side-to-side and front-and-back, then torque to spec. (LCAs frame side 130 ft lbs, LCAs axle side 85 ft lbs, and upper CAs 55 ft lbs.
- Next, I would inspect the sector shaft that comes out of the steering box for cracking or twisting of the splines.
- Then, I would take a test drive without the steering stablizer to feel for any wobbles.
- Finally, I would reinstall the steering stablizer or spring $40 for a heavy duty steering stablizer.
- I would use adjustable lower front control arms to set my caster spec between 4 and 5 degrees--with a cross caster that has less on the driver side than the passenger side. I would personally not do more or less, with a target around 4.5-4.7 degrees caster.
- If my camber is out of spec, but it is not due to failed ball joints, I would install offset ball joints to get my camber in spec.
- I would set my toe-in to spec on the machine--which is about a 1/16" to 1/8" toe-in.
- If my front to rear alignment is off, I would install rear lower adjustable control arms to fix this.
The last ditch thing if there is a non-DW, speed dependent range wobble, I would borrow a different set of wheels and tires to see if it changes, and I would try driving it with no front driveshaft to see if that changes anything.
Although it is always a good idea to inspect your axle shaft u-joints, they will not cause DW.
The most common sources of full on DW are:
- Improperly torqued trackbar bolts
- Damaged trackbar and control arm bushings because bolts were torqued on a car lift or while the vehicle was not at ride height with the tires on the ground. When you torque trackbar and control arm bolts, the bracket pinches the bolt sleeve in the bushing, as well as the bushing itself. If this is at a geometry other than actual ride height, the bushings are twisted/bound/pre-loaded, and they will eventually fail/separate/etc. If you have a flex joint end, this does not apply for that end.
- Ovaled out trackbar bracket holes due to DW episodes from loose bolts.
