Looking for some wisdom.

I have a vibration coming from the rear end of the truck. Its recently started; but I don't drive the truck much. I swapped out wheels/tires to eliminate that variable - no change.

Truck has 85K miles, and sits more than its driven lately. Short bed, no carrier bearing. All U-joints etc are factory. Fluids levels in diff's, xfer case and transmission are good, and have about 7,000 miles on them. Front brakes/rotors are new, and rear brakes look good. The dealer did the front pads and changed out the right front u-joint a few months ago; I did the rotors this weekend, and had slight hopes that the new rotors would make the vibe go away. Nada...

The vibration makes itself noticeable around 65-70, but its not too bad, but my gf made a comment today "whats that noise?". It gets alot worse when I lift the throttle and decel, then it gets real noticeable. The vibe remains when I push the clutch in, so its not the transmission or engine or the tires.

The vibe disappears as I slow down through 60, but re-appears as I start coming to a complete stop (2-3 mph'ish) as a slight shudder.

Lying under the truck and checking the drive shaft etc, the u-joints and pinion bolt seem to be ok and not loose etc. 3 of us looked at it. There is no clicking etc. when I'm driving the truck. Its coming from the back of the truck, not the front, and not in the steering wheel.

I jacked up the rear end, ran it through the gears, and didn't notice anything except felt a "shudder" when the clutch was depressed and the wheels were slowly rolling to a stop. It did the same with other wheels/tires on it.

I was hoping it was the wheels/tires, but it is not. I don't think, or want to think its the rear diff or bearings going south.

Is it something so simple as u-joints?

And I hate to start throwing money at it easter egg'ing it - but will if I have to.

Thanks.

 

You live in rust country so I have to ask if it is garage kept or outside? The reason is you may have some rust build up in the rear rotors or rust causing the e-brake shoes to stick. Not real likely but I have seen stranger things. If driving at speed and the vib starts, try tapping the brake pedal to see what happens. Most of this is a long shot but it's free to check it!!

Next I would replace the rear drive shaft u joints. Not too expensive and could easily cause the problems you describe.

 

She is parked outside. The ebrakes are a bit loose right now so I don't think that's it. Not much difference when applying the brakes, unless its in that speed range when slowing down. I just talked to my son and he thinks I should change out the rear drive shaft ujoints.

Sent from my DROID RAZR using Tapatalk

 

Yup. I agree with your son! I think that is where the problem is.

 

Yes, I think it's u-joints too. There may not be a loose one, but if you remove the shaft and try to articulate each joint through its range, I'd bet you will find one that's seized.

 

torquefan, yep that's what it was. We replaced both of the rear driveshaft u-joints, but the rear one was very, very tight.

The front shaft u-joints were still good.

 

Great, glad you found it!

 

Mud in the rims