Since I've owned my truck I have been chasing a vibration problem. Here's the scoop, It only occurs at 60 to 70 MPH and it is constant with speed. I can shift it to neutral and the vibration doesn't change, just gets a little worse. If I carry any load, even 50 LBS in the bed the vibration goes away although I can feel the vibration ever so slightly on the transfer case shifter. It is not a big vibration like it used to be but it's there. (I carry 2 20 LBS sand bags with me near the tailgate to help my ride)

Here's what I have done so far to rid this problem. Some things worked a little while others did not.

-Added lift kit (No change)
-Replaced rear driveline and U joints (Helped a little)
-Replaced tires and rims (Helped a little)
-Tightened everything on the drivetrain and frame (Helped a lot)

I got rid of most of my vibration by doing those things but it's still there.

I checked the rear pinion bearing for movement and its solid. I also checked the transfer case output bearing and it seems to be good as well however I have some minor leakage there. I checked the driveline for proper phasing. When I replaced my brakes I did not notice any play with the rear drums and the bearings where not worn.

I'm at a loss here, the only thing I can conclude is since the vibration goes away when I carry a load it must be my rear wheel bearings but I check those when I did my brakes. I have D60 front and rear and they seem to be working properly. I have the stock ford "Trac Loc" so when I get both wheels off the ground they spin freely the same direction by hand.

Did I miss anything? What else should I do to troubleshoot this problem?

 

Bad wheel bearings or out of balance wheels. Rotate your tires front to back and see if it goes away. If not it's probably your bearings.

 

Tried that already. No luck.

 

Anybody?

Do I need to title this tread "Smok'n hot Babes with Dentside"? or add a photo of my hot wife with a tank top wrenching on my truck?

 

I got 973 hits by doing that but no answers to my problem
Sorry I can't help and I'm chasing a take off from stop vibration myself.
Wait a minute you did a lift, was it a body or suspension and if it was a suspension are the rear blocks tapered and are they in backwards causing a drive line angle problem that goes away with a load in it cause it squats with the load and therefore changes the drive line angle?

 

The vibration was there before I did the suspension lift. I was hoping that the lift would change the pinion angle slightly to rid the vibration but that wasn't the case.

I have blocks and they are orientated correctly. (I will replace with springs later.)

 

It kinda sounds like the driveline is out of balance to me. can you put a hose clamp on the driveline to use as weights and see if it gets worse or better? If it gets worse possition the screw on the opposite side and try again? Just a thought.

 

That was my primary suspect years ago so I had a new driveline custom made with new U joints. That helped a little and fixed some of my other driveline issues I had at the time.

I have an appointment this week with my driveline specialist to build a new custom front driveline (Another non related issue). Perhaps I'll have him try to troubleshoot this problem too.

 

How are the kinpins on front axle? Jack up the front and try lifting tire up and down while looking at the kingpins for play. If they are original u may wanna replace. If you have a divorce t case you should run a brace but I think yours is married. How are your cab mounts? Are they in decent shape and tight?
You installed a lift? Are the spring eye bushings new?

 

Nice and tight. No play.

Perfect condition for being 32 years old.

Yes, New from Skyjacker.

I have a married T Case and the vibration is coming from the rear.

 

You should have the D60 rear axle? Ive broken axle shafts before when running detroit lockers in them, is it possable to bend them? Maybe a bent or out of balance axle shaft? It wouldnt be hard to put them on a lathe and spin them.

 

Warped brake drum?

 

Yes I have D60 front and rear. The axle shaft is something I haven't looked at yet. I'm not new to wrenching but troubleshooting the D60 is something I have never done before. Since I don't have a lathe is there another way to check the axles? Framing level???

 

Roll the axle on a flat surface. The D60 rear is easy to work on, no clips holding the shaft in either, just pull the screws from the floater and pull the axle out. even after breaking an axle I didnt need to remove the differ. cover. just pulled the axle out and slid the new one in.

 

Unless someone corrects me, you could pull both axles out and then run the drive line up to the speeds your getting your vibrations and see if the vibration is still there. Without the drivelines installed the vehicle wont go anywhere.
I dont know if the differ. fluid will come out through the ends though.

Since youve got a locker/limited slip you will have to remove both axle shafts!