Whole lotta shaking goin on...

Thursday night I developed a nasty little vibration that is causing me some concern. At about 30-35mph, the dually starts shaking like I'm doing 90mph down a washboard road. It doesn't subside with increasing speed. It will only stop if I slow to under 25mph, or so.

My initial thought was that the harmonic balancer went bad, but when I got home and checked, it was a-okay. So I just parked it until I figure out what's going on. I have a few ideas, but I want to keep them to myself so as not to suggest the problem.

So how 'bout it? Anybody have any ideas on what the culprit may be?

very possible that it could be u-joints.

yea get it up to speed put it in neutral see if its still there that way you can start to isolat it also check tires for bad spots I've seen them brake belts and ballon up in one spot or even delaminate. if it goes away when its in neutral rev it up and see if it comes back that will tell you its in the engine/trans

Can you feel it in the steering wheel? I had a 3/4 ton square body suburban that would shake at about that same speed. Speeding up wouldn't stop it, you had to slow way down to make it quit. It ended up being the idler and pitman arms were wore out.

Maybe your gut starts wobbling around making the whole truck shake.

Eff you.

No, it's not in the wheel. I rebuilt the front end this summer, so I'm pretty sure it't not anything up there. It's not death wobble, mind you, it's a vibration.

I was thinking it might be the carrier bearing.

Had an issue like that once turned out it was a bad Carrier Bearing

Lost a weight off a driveshaft once and it would start in around 35 or so and just kept getting worse; pulled the shaft to have it balanced and also noticed previous owner hadn't pressed the u-joints in all the way!

Richard

It could also be the fan. I threw a blade on the freeway once and it causes the motor to be out of balance making the whole truck shake.
I would also check the u-joints on the driveshafts too. They could be broke but not all the way out.

10-4. Thanks Guys.