Uncontrollable Bounce

[afrantom]

I am new to gmc trucks and just purchased an '84 K2500 for the ranch... When driving down the highway, at about 35 mph, the truck starts to bounce uncontrollably. I have replaced the shocks, sway bar bushings, and am about to do the steering stabilizer. Can anyone help me figure out what else it can be? I am not planning on doing any trips in it, but would like to drive somewhat safely to and from the farm. Thanks in advance

[GMstrong]

Probably worn u joints.

[GMstrong]

Forgot to say get the alignment checked then the tie rods and suspension parts

[ChevyTech77]

Bounce? Like a tire bounce?

[cliobogger]

please be more vague. lol. front end, back end, cab?

[afrantom]

Sorry. Front end. Seems the truck is constantly moving in the front end. The steering wheel moves slightly from side to side. At 35 mph, the truck starts to "bounce" from side to side, mostly in the front end. If you speed up to about 45-50mph, it will go back to a slight shimmy. Or, you can brake and it will stop at 15-20 mph. Just seems like the whole front end is loose or something. Ball joints? Tie rod ends?

[cliobogger]

you can replace all the front end components for fairly cheap if you do the work yourself. and by all the front end components, i mean tie rods, ball joints, pitman arms stuff like that.

[thebandnerd03]

make sure you have no bulges in your tires or bent rims. if they are out of balance this will also cause the front end to wobble

[Doug_Scott]

Is the truck at stock height? You are describing something like an alignment issue, but not a front wheel alignment, a front end component alignment. The drag link and the track bar should be close in angle. Changing the steering stabilizer will probably fix the shimmy, but only because it is a bandaid fix, you are not fixing the issue, you are merely covering it up until the steering stabalizer wears out from doing its job.

You can also test to see if when you hit a dip in the road, does the truck tend to bounce to one side, or feel like the you are being pushed to one side? That is bump steer, and is essentially the trucks front end turning the wheels when compresed one way, the turning the other way when uncompressed due to unequal length track bar and drag link. When they are at different angles they change in length differently when moved through their arc.