Hi, all, im back, seems like the rear end bouces some in between 40-55 mph. then it quits, it happens anywhere in that speed range, and only happens for a couple seconds untill you speed up a little more then its gone. Only seem to notice it while accelerating a suppose. Would old shocks cause any of this? I got 80,000 on the truck and i dont think they have been changed in a long time. I just put new rubber on 2 weeks ago. Had the bounce before that too.

Only seems to do it on smooth roads. It actually looks from the sideview mirror that the bed is bouncing up and down and you can feel it in the whole truck. Pulled the emergency brakes and levers on saturday and cleaned them really good and anti-seized them. Tire pressure is at 35.

 

Yeah shocks would definitely cause that especially if you have an unbalanced tire.

 

Tires were balanced two weeks ago.

 

It's possible that the bouncing is stated from torque when you accelerate and then your shocks are note absorbing the oscillation of the rear end. Do you have a lot of body roll back and forth when you come out of turns?

 

I do sort of notice some decent amount of body roll, when i go threw some long tight turns you can feel the truck roll per say.

 

Body roll is normal (its a big heavy truck) but it should recover to center after the turn but my guess would be your shocks are going. Check your sway bar on the front end too make sure everything is connected.

 

Well it does recover to center and everything is good up front (just spent a while at the dealership for front end problems a couple months ago) So bad shocks would cause a bouncing in the rear. I do notice when i hit other bumps or holes in the road that it feels like it bounces a little after the bump. But would bad shocks make it feel like bouncing during a certain speed on a nice smooth road? Thanks for you help so far!

 

Well it might be low tech, but since I was a kid we would start bouncing the shocks let go and if it kept bouncing they were shot. I'd imagine these days a good tire store has some type of test equipment.

 

Im going to try some new shocks, my father inlaw owns a NAPA, so ill get them for a good price. Thanks!

And as far as i know the shocks are original at 80,000 miles.

 

What does anyone think about the bed or frame dampeners? Where can i get them and do they fix vibes for real?

 

Tire balancing machines are not always calibrated well. I would still primarily look at tire balance and roundness. Take it to a different shop--maybe one that does race cars or high end work--and have the balance and tire roundness and wheel straightness checked. Ideally, having them balanced *on the truck* will also make certain that the brake discs are not causing a balance issue. Make sure the disc surface that the wheel contacts is totally clean as well. Again, even though you've had them balanced, you can not always assume that the balance has been done well.

Worn out shocks may exaggerate the problem, but I've found that with tires that are a bit out of balance, they often seem fine until I'm on a road surface that causes them to start a small oscillation, at which point.

With perfectly balanced and perfectly round tires, you should have virtually no bouncing even on worn shocks in a steady state cruise on a smooth road.

George

 

Some of the 150s '04-? had dampeners put on in ref to a TSB. You may want to check into that.

 

Im going to have the balanced checked on the tires after work today. If that checks out fine then new shocks tommorow. it almost feels like the bed is shaking the whole truck.

 

If your rear shocks have 80,000 miles on them they dont owe you anything but they are done. I do agree with one of the posts though, if tires are not in balance it will bounce maybe more with weak shocks. Do your fronts have the same mileage? If so might as well change them too.

 

Got my tires balanced after work (my uncles shop so i was right there to watch) all tires were out a little. One rear tire needed 1.00 (whatever the measurement is grams or ouces) on the inside. All the others needed anywhere from .25 to .50 on both inside and outside. I dont understand i just had the tires put on 3 weeks ago and were balanced at the tire shop, but it was a late friday afternoon, so we all know what that means. Im going to put new rear shocks on tommorow night. As far as i know the fronts are the same although they are a different color than the rears, what color are motorcraft, orange? if so the front are probably original as well. And i hear that cause they are coil over they are hard to get out without taking the coil off. I didnt drive far after the balance, my uncles shop is close to home so ill be able to tell if the balance help tommorow morning on my way to work. Thanks for the help again guys.