Ok, I've got a weird one and I need some help diagnosing the culprit. At any given speed - when I lift off the throttle, I get a rumbling in the front end. Almost sounds like someone put some mud terrain tires on the front wheels, but I'm running BFG ATKO's. I checked the tire pressures and they are all right on the money so that's not it. Truck does not wander and I've got even tire wear (usually rotate every 5-7K). I've got some vibration at certain speeds 65-70 mph but that seems to be the only time I get it. I've tried putting it in nuetral, shutting the truck off and coasting and it always happens when I lift off the throttle. Any ideas? Any input would be greatly appreciated.

 

i have seen worn carrier bearings and u-joints cause these problems and sometimes lots of playin diff will cause vbration good luck

 

DID YOU LAY UNDER THE TRUCK AND TRY TURNING THE FRONT DRIVE SHAFT BY HAND ......IT SHOULD SPIN FREELY .....MAYBE YOUR STUCK ENGAGED IN 4WD.....WHEN YOUR ON THE PEDAL ITS UNDER LOAD THEN WHEN COSTING ITS DRAGGING ......AZ REDNECK HAS GOOD POINT WITH A WORN CARRIER BEARING....GOOD LUCK

 

Bad u-joint or slip joint in your front drive shaft... Could be bent or out of balance too. Are you sure the truck is in 2wd? Bad axle u-joint?

You can unbolt the front d-shaft and drive around to see for sure if that is the problem (unless you can see an obviously bad u-joint or something...)

Are you sure it isn't the rear drive shaft making the noise? The noise could transfer through the powertrain and maybe feel like it is coming from the front... Check the rear u-joints and carrier bearing while you're at it.

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3rd gen trucks don't have hubs or CADs, so if the front wheels are on the ground, the drive shaft won't turn unless the truck is rolling...

 

Well, I know I'm not stuck in 4 wheel drive just by checking my mpg - definitely in 2 wheel drive.