Vibration at high speeds

[AdamDude04]

Truck drives/shifts normal.

However, at high speeds, 65mph or higher, I get a loud (simular to drone from exhaust type deal), vibrating comming from under me. Not exactly sure if it's motor/tranny vibrations or driveshaft/rear end vibrations.

Only hear/feel it with the gas NOT applied, or if I'm giving it gas to maintain speed and not go faster. If I give it gas, enough to power it to go faster, it'll stop. And again, only at 65mph or greater. I'd love to do 75mph (CO speed limit)..but the vibration noise is just way too unsettling and the vibration doesn't help out at all either.

Havn't checked for movement on the driveshaft, it's dark outside. But if anyone has had this issue, let me know so I can take the correct amount of action!

About to go on a 2,500 road trip in a couple weeks..hate to break down in the rocky mountains in the middle of the night <_<

Thanks!

 

[AdamDude04]

Also I can't feel it in the steering wheel..so it's not front-end related. Got manual hubs, and they are locked in FREE position

 

[Krafty]

have a very close look at your drive shaft and rear end. it doesn't sound like bearings, transmission or transfercase. its only coming from moving parts, bearings would be constant, when your coasting or cruising thats when there is almost equal force rotating from the engine, and resistance returning from the wheels, when the force is greater coming from once direction or another (Acceleration and deceleration) the u joint is hard against its internal parts. if it is worn and the forces are almost equal thats when worn ujoints will " float " between contact causing vibrations.

the longer you drive with bad u joints the more obvious the damage when you inspect it visually.

 

[AdamDude04]

Well it was tearing me up inside LOL

so I went out and the drive shaft is solid. No movment at all. However, to my understanding a u-joint can still be bad, even tho a physical inspection (trying to rotate the shaft by hand) shows no loose movement or issues, it can still be bad somehow?

At $8.99 x 2, it's worth just replacing anyway I suppose.

 

[Krafty]

yeah always a safe investment. look at your rear end where the yoke bolts up. make sure there is no play in that part either. as long as the nut and yoke turn together and only about 1/8 rotation. also do the same with the yoke on the transfer case, if it is all locked up there should be next to no play, 1/8 again or less rotation., lastly have a really good look at the splines on your slip yoke drive shaft, if it has a grease fitting, then grease the living **** out of it,

hope this helps

 

[AdamDude04]

yeah always a safe investment. look at your rear end where the yoke bolts up. make sure there is no play in that part either. as long as the nut and yoke turn together and only about 1/8 rotation. also do the same with the yoke on the transfer case, if it is all locked up there should be next to no play, 1/8 again or less rotation., lastly have a really good look at the splines on your slip yoke drive shaft, if it has a grease fitting, then grease the living **** out of it,
hope this helps

Awesome. Looks like we tackle this issue on Wednesday. I'll check out the rear end too..

actually last night, got me thinking: I want a posi rear end, so in the near future I may just rebuild the rear end to convert it to a posi with the same gearing (3.55 I think)

but I am hoping this is just a u-joint issue... I have noticed it getting worse in the last two years. Before I had to drive 75-80 mph on the highway for about 10 minutes every day. Never really had an issue. A slight one..but nothing major. The most my time is in city driving. Starting to get a clunk when going into reverse, and noticed when I get out of the 55mph city speeds.. it starts to occure around 65-70mph now. Really bad at 75 mph..so bad, I just do 65 in a 75 zone