Bad Vibrations

[agallant]

When I accelerate once I get past 30mph or so the truck starts shaking it gets really bad at around 70(it is loud as well). but the strange thing is that when I let off of the gas it goes away. Any one know what this could be? It is getting really bad.

 

[Blee1099]

Could be a number of things, tires out of balance, alignment issues, etc.

 

[agallant]

Yeah but it goes away when i take my foot off of the gas. If it was an alignment or the tires wouldn't it do that all of the time?

 

[falls guy]

Bent driveshaft? Bad u-joint. Cracked flywheel? Motor or tranni mount?Good luck
Peace

 

[rookieshooter]

Just an idea, check all the universal joints. Sounds like its only doing it under load. Can u tell if its in the front, rear or middle?

 

[agallant]

I herd when U-Joints go they make noise when there is no load then it goes away with load. How do you check them?

-AG

 

[351wExplorer]

i know my driveshaft is slightly bent and it causes vibrations

 

[rookieshooter]

You can at least try to move it from side to side at the u joints not running of course. Put it on a lift, start it up and put it in drive and see if you can find it that way. You can also check the tires for any play while its up off the ground and all associated steering links.

 

[falls guy]

Put the truck in neutral, with E brake on and block it off so it doesn't roll over you and get under it in front of the back wheels. Try to rotate the drive shaft by hand. It shouldn't move at all in comparison to the rear yoke or front yoke(the part that sticks into the tranni or rearend). If there is no play found this way, they're probably good.
I'd check the motor and tranni mounts too.