Not to sure what it is.....was thinking it was that Driveshaft/Vibration thing that has been going around.

Freeway speeds...ESPECIALLY at 70mph, gets better or goes away at below 65 and over 75-80mph.

Sometimes, it SO hard riding that you cant even hold a conversation without it sounding like and McDonalds drive thru.

Tires....balanced...running around 60lbs front, 50 lbs rear air pressures
Engine Speed makes no difference

Truck has 24200 miles on it.

If I get three or so people in the truck its a little better, but its still hard as hell.

 

sounds like a universal joint going bad. I would slide under the truck next time your parked on level ground and see if the drive shafts move, especially in a side direction.

Also, check for dirt build up or missing balance weights on the drive shaft and related components.

 

Does it do this all the time, or only some of the time? Mine does this, it shakes the whole truck. It feels like a lot of bumps in the road, but only coming from the rear. But I only notice on certain road. So I don't know if its driveshaft or shocks, but I'm going to start looking for problems this weekend.

 

Is your truck 4x4? What kinda tires are you runnin. Give us some more info in your Sig. Sounds like the 70mph vibration bug goin around.

 

2wd long bed 6sp....stock tires

Some roads...smoooooth.
Other roads....hang on....your going for a riiiiiide.

But thats pretty much it Aggie.....just like that.

 

Mine has started doing it ever since I rotated my tires!! I did a modified X for the first time and I think I'm going to have to switch the fronts side to side and see if that helps. Mine feels like it's the front though.....

 

Mines in the shop now for rear ujoint.Same symptoms as you.45000 miles

 

Mine does the same thing at various speeds on various roads. I think its the suspension not being able to keep up with the bumps and your truck is pretty much just bouncing from bump to bump. When I drive on I-10 just west of Palm Springs I about loose all of my teeth at 70mph. Go just a few miles an hour up or down it is relatively smooth. I can drive 70mph just about anywhere else and all is fine. The best way to describe this bouncing to me is that my truck is harmonicing over the bumps. Hit the right frequency and you loose you teeth.

Joe

 

Same basic symptoms as what you are stating and it was all fixed by replacing the rear universal joint. Night and day difference after the replacement.

 

I had the same symptoms.

rear ujoint had to be replaced at ~ 60K. Was much better, but still had a slight vib. Dealer replaced the rear drive shaft. Fix the problem. Now it is amazingly smooth.

I think the rear drive shaft was out of balance from the factory. The dealer claimed it had thrown a weight, but I had the vib from the 1st day. I think the constant vib from the drive shaft caused the rear ujoint to fail.

The new drive shaft looks a little beefier then the original.