tommyp

Driving an 06 3500 srw automatic 5.9 with a smarty dual feed lines fass pump ats torque converter intake and exhaust rolling on 35 in BFG mud terrains with a 3 inch leveling kit that just turned 56000 miles. truck has a vibration that starts exactly at 50 miles per hour and continues but doesnt worsen up thru highway speeds. vibration stops when you let off the go pedal and starts up again when back on it. truck makes great power but isnt beat on. any help would be much appreciated.

CatDiesel_762

Sounds like a ujoint. Possiblly, the carrier bearing if you have a long box. Otherwise, I am thinking transmission or transfer case. Next would be the ball joints. You might also be hearing and feeling your Mud Terrians Signing at that speed.

Jack up the truck up and put the truck on jack stands on all four corners. Then get in and start the truck up. Bring the truck up to speed while on the jackstands(50 MPH) and listen and feel for the vibrations. if the vibrations is gone then it is mostly your tires or ball joints. If the vibration is still there then it is in your driveline/powertrain. Start with your tires and have them balance and then work your way towards the engine checking every joint along the way.

Shawn

aborgardt

check the tires for cupping....that was my kulprit....had to replace the shocks and then rotate tires....

wesboyd585

is the vibration up and down or side to side?

tommyp

the vibration doesnt move??? it starts right when i hit 50 mph weather slowly coming up on it or accelerating hard. i can be at 52, 57, 70 anything above 50 and let off the throttle and the vibration ceases immediately even when above 50 then when im off throttle, above 50, no vibration occuring get on the go pedal ( above 50 ) and it starts again

Mindy

I had the exact same problem last year. Ujoint and a warped driveshaft...It was pretty much exactly at the 80km/hr ( which is 50 mph) speed...as soon as you accelerated or let up it disappeared.

Dealer fixed under warranty despite mods

GreyTD

My vote is u-joint. Mine just went this weekend pulling a t-trailer. Didn't feel it until after off loading the TT. Down the highway hit 80km/hr vibration starts, but time I hit 115km/hr I could not see out my rearview mirror.
Rear joint by diff gave up the ghost (needle bearings in one cup disappeared). front joint loose, but still intact. Changed both, back to quiet ride.
Block your tires, put truck N, mark the the shaft for placement, undo 4 bolts rear diff, check joints, 10 minute job.

goosepilot

rear u-joint is going bad. New u-joint=smooth