Truck wobbles side to side when hitting expansion joints at highway speed...
 

Ok, I have been meaning to post this up for a while now, but my truck will wobble side to side if I hit any sort of bump at any angle other than head on. we have a lot of bridges on the interstate around here and if the expansion joints are not totally perpendicular to the road my truck will start wobbling or rocking pretty bad. I have to take my foot off the gas to get it to settle down.

at one point I was told shocks were shot, so I pulled out the rear shocks but while dirty and ugly, they were working just fine. Haven't done the front ones, but thought I would get a second third fourth and fifth opinion here.

Any thoughts or ideas? Thanks in advance.

I would have to say shocks or idler arm.

When I had this issue it was a combination of shocks,idler arm,pitman arm an upper & lower control arm bushings.Also check the condition of your sway bar link kit bushings!

Sounds similar to "bump steer" which is when the vehicle changes direction over bumps without driver input to the steering wheel, (Google it). The center link not being level is the most common reason for it. Raise the front end off the ground and remove the wheels. Steer straight ahead, measure up to the frame from each end of the center link. Must be within 1/16" side to side. To adjust, loosen the idler arm mounting bolts and move the center link up or down. Sounds like you may have "other issues" as well.... loose/worn steering and or suspension parts.

when I first got the truck it wandered all over the road. The guy I bought it from said it needed new bushings. I had a shop look at it and they said the idler, pittman and one of my hubs were shot, So I got that changed out. night and day difference. It tracks fine, but the rocking thing is starting to annoy me...

I will look into the center link thing, and eventually I plan on getting new bushings and ball joints in the front. I just dont want to dump a ton of money into this thing as I only paid 1000 for it.

Keep in mind that if you adjust the idler arm, it WILL affect toe, which means you'll need an alignment afterwards. Might as well wait and do all that stuff and only get one wheel alignment ;)

The vibration only happens when I hit a bump, at a wide range of speeds, and has happened with 3-different sets of tires, so I don't think that's what's causing it. I've never seen the hood vibrate & it feels latched tight. when i hit the bridge expansion joints the vibration feels like it's under, or close to the floor.