Hi, I have a continued problem with vibration with my '99 F250 4x4 ext cab short bed. I've checked alot of the forums and have seen a few others with similar issues, but haven't seen a solution.

My issue is a vibration. I can feel it between 30-40mph, and then after 75mph you can feel and hear it to the degree where going any faster really feels like it will end up badly.

I've replaced all the ujoints last year in the rear driveshaft.
I've felt the ujoints after a ride to see if any are hot, and they are dead cold.
I've jacked up each wheel and they spin freely without any play.
I've driven next to the truck @ 75mph and heard no noticable abnormal sounds.

Now tonight, I decided to "road test" it in 4wd low (w the hubs unlocked).

Considering the transfer case ratio is 1:1 in high, and (i think) 2.72:1 in low, I would assume if;

1) vibration still at 30-40mph = something in the driveshaft, wheels, rearend, etc
2) vibration at 11-14mph = something in the transmission, torque converter, etc
3) no vibration = something in the transfer case.

I believe I felt option #3, nothing. I even tried holding the brakes on while at the 11-14mph to place a load on the drivetrain and heard/felt the same nothing.

What do you think? Bad gear or bearing in the transfer case?

 

could it be a bad tire, ball joints, hub.

 

I thought of that. I have one set of ball joints replaced last year, and the other side tested out fine. I also couldn't feel, hear, or see anything when i tested it out.

On the transfer case "test", My thoughts was if I still had the vibration at 30-40, then that would isolate the issue to something downstream from the engine, transmission, transfer case.

If the 30-40 vibration went away, then it would have to be something upstream.

??

 

What kind of tires do you have? How old are they? I had some mud tires on my jeep once that gave a hell of a vibration at about 20-25mph and above 55. Thought my jeep was falling apart. Tires finally wore down and when i changed back to an all terrain things straighten right out. My point being you could have an out of balance tire or a bad tire causing that vibration.

 

The tires are normal bfg tires, about 3-4yrs old, ~50% worn, nothing special.

I was thinking the same, until the transfercase test.

If it was tires, I would think there would be no difference between high & low.

 

Maybe drive shaft center carrier bearing?

 

Isolate the rear driveline by removing the drive shaft, locking the front hubs, leave the X-fer case in high, and re test. You said you replaced the U-joints, did you rebuild the double cardan joint?

While the D/S is out, check the play at the pinion. Side to side, and back lash.

How soon did this come on?

 

you feel it in the steering wheel or your seat? have you rotated the tires to see if the vibration moves ie frt to back?

 

I finally found my issue. The drive shaft threw a weight. $86.50 to balance the drive shaft. Just got it back yesterday and all is good.
I had a hard time finding the problem. 2 new tires on the front. They didn't balance properly the first time so that added to my confusion. rear most u joint was bad so I changed that first and thought I was good to go. Ended up replacing center support bearing and one more u joint while the drive shaft was out

 

To the replies;
My driveshaft is a 2 piece with no carrier bearing

I've replaced both the rear ujoint as well as the two in the cardan joint last year.

I can feel the vibration generally everywhere. In the body and in the steering wheel. I can feel it by touching the 4wd manual shift on the floor, which kinda supports my transfercase thought.

I've had random isolated vibration issues for a year or more (which is why I replace the ujoints), but the issue now is definete and predictable. it came on within the last month.

I was going to try removing the rear DS and running the front for the test, until I thought about my transfercase test. If I still had the vibration at 30-40 in 4W low (hubs unlocked), then I was going to drop the rear DS to see if its that. The vibration went away, which (I think) tells me its either in the transfercase or transmission.

 

back to the basics....alignment?

 

Yes, but not recently. When it was done last, the tech mentioned he very rarely sees these trucks go out of alignment.

Again, pointing to the transfercase test...if it still vibrated at 30-40 in low, then it certainly could be anything down stream (driveshaft,rear end, brakes, tires,body,alignment,etc)