opinions on vibration issue

[ab2625]

Starting about a month ago I get a vibration in the floor board and hear a whining and slight grinding noise when above 60mph but only when I let off the throttle and only for a few seconds each time. I can hear and feel it the most when I let off most of the way but keep a little pressure on the pedal putting the driveline in a neutral position, this makes it last longer. I cant feel it in the steering wheel. It seems to get worse the faster I go past 60. I pulled the drive line and replaced the one U-joint that was bad, but that was not it. Carrier bearing feels good. Sounds like its coming from up front somewhere but not sure. Could this be wheel bearings? Any thoughts or suggestions would be appreciated.

Thanks

[ShawnCT450R]

Check where your downpipe makes the turn from coming down to going towards the back of the truck. It should go over a crossmember right after the turn, and if your downpipe joint has drifted a bit and is close to the crossmember, it can touch it and make the noise you described in various circumstances. Mine did it only at idle, but not above.

[husky74]

I would double check carrier (steady) bearing and u-joints again, had the same issue changed rear u-joint and steady bearing.

[superjet701k]

subscribing --- i have a high speed vibration also

[eberlestock]

Do you guys have CV joints on your rear shafts? If so have you checked them. Just had mine re built but it was vibrating and loud.

[ab2625]

I think I'll replace the other two u-joints and see if that helps. After replacing the one that was leaking a little it seems to have gotten slightly better.

[superjet701k]

Originally Posted by ab2625

I think I'll replace the other two u-joints and see if that helps. After replacing the one that was leaking a little it seems to have gotten slightly better.

There are no cv joints in superduty, my front drive shaft has a double cardion joint

[K9-K141]

what was the verdict?

[ab2625]

I had a single piece rear drive shaft made and the vibration is almost gone. When they built it they didn't have the end plates to ballance, so I need to get it all rebalanced and I'm confident that it will be all good.

[K9-K141]

i will be driving down the highway, everything is great, go to let off the throttle and a violent noise sounds like something spinning in a worn bearing race under my feet for a couple seconds or until i give it more throttle. I sware this truck is biggest pile of ****