This is a classic description of a worn inner cv joint housing, usually the right one. To locate the problem, jack up the vehicle so the right front tire is off the ground. (Do the right one first because I found the culprit to be that one nine out of ten times). Remove the cotter pin, lock ring, anti-rattle washer, and the large nut on the end of the axle shaft. Never loosen this nut when the weight of the vehicle is on the tire because the wheel bearing will become noisy.
Push the axle shaft in toward the engine. It should push very hard, and spring back on its own. If it doesn't spring back, the internal spring is broken. They are available at the dealership for around $4.00.
Even if the spring is not broken, the inner joint must be disassembled to inspect the housing. There are six polished surfaces where the rollers run back and forth. The surfaces have to be perfectly smooth. If you can feel any slight bump, you REALLY have junk. If they feel smooth, wash all traces of grease from them, then shine a light in there and look at the reflections. Similar to looking at the ground reflecting in a car's body at a car show, you're looking for the slightest wave in any of the roller surfaces. If present, the housing must be replaced. It's less expensive now to just install a remanufactured half shaft.
This spring-loaded joint allows the length and angle to change as the shaft rotates. When a roller binds, the shaft pushes on the spindle and the lower control arm. The control arm is mounted with flexible rubber bushings that allow the movement to take place. The moving spindle tugs on the steering linkage which is why you see and feel the steering wheel move. When you let off the gas, the rollers can move freely so the steering wheel stops shaking.
A worn right joint will cause more shaking when turning right and accelerating, such as when leaving a parking lot, because weight transfer causes the right corner of the van to rise increasing the angle change and distance the rollers move as the shaft rotates.
When reinstalling the shaft, be sure to torque the nut to the specified amount before allowing the vehicle's weight to be supported by the wheel bearing. Typical value is between 150 and 180 foot / pounds, but on some cars it can be as high as 250 foot / pounds.
Tuesday, April 21st, 2009 AT 12:20 AM