So here is the story.

03 F250 7.3 with 8" superlift

Truck had a vibration/humming noise at highway speeds.
Broke transmission mount
Replaced mount
Broke new transmission mount in 2 days
Found Carrier Bearing to be bad
Replaced carrier bearing
Replaced bad Trans mount

Go down road and a tremendous amount of vibration from low speed acceleration. I can feel the vibration at higher speeds but not nearly as bad as low speed or dead stop acceleration.

I just bought all new U Joints. I don't have a whole lot of confidence in this fixing the issue but the truck does have 170K miles on it and they don't appear to have ever been changed.


Thoughts?


Thanks

 

Based on what you've said already, I think your vibration is related to your lift, but that is just a shot in the dark.

Tell us more about the vibration. Do you feel it in the seat of your pants or more in the steering wheel? Does the frequency increase with speed, amplitude, or both? Does the vibration change more with vehicle speed or engine speed?

When was the lift installed?

What was the last thing done to the truck?

 

Hey thanks for replying.

Here is the thing. I've only had the truck for 3 months.
When I first got the truck it did not shake or anything but I did have the loud bearing noise, which I can now confirm was indeed the carrier bearing was bad.

About a month into ownership the transmission mount broke. So I simply just replaced it. It broke again 2 days later. Going on the advice of the shop I used, we replaced the engine mounts and the transmission mount.

I still had the loud bearing noise. Climbed up under the truck and found the carrier bearing to be bad. I replaced the carrier bearing and that is when all hell broke loose.

The truck now vibrates/shakes violently when accelerating from a dead stop or low speed accelerating. You can feel a small amount of vibration at higher speeds but not nearly as bad as lower speed. The vibration is obviously related to the rear driveline.

My suspicion is that there was a problem before but after replacing everything it stiffened up and now has made the vibration very pronounced. The last thing I did to the truck was replace the carrier bearing and the transmission mount at the same time. If I drive the truck without the rear driveshaft, I have ZERO vibration or noises.

 

Get the rear driveshaft balanced at a good shop and make sure the u-joints are ok.

 

OK, no worries. This probably isn't as bad as you might think.

Vibration or shudder when you take off is caused by your pinion angle being too large. Ford actually has a TSB for this.

05-17-6***DRIVE-AWAY SHUDDER OR VIBRATION

The short version is that you need to shim the new carrier bearing to lessen the pinion angle. The geometry on the new bearing must be off just enough to cause you these issues, or the shims that were there were not reinstalled when the bearing was changed.

 

Wait could new tires cause this? I installed new tires the same day all work was done.

 

UPDATE!!!! I climbed under the truck and pressed up on the rear section with the slip yoke. There is a tremendous amount of play in the spline. I removed the boot and found some type of blue plastic in a million pieces that looked like it fit inside the splines. Called a local shop and they said that this is to reduce vibration. Exactly the problem I am having. He also informed me that the plastic piece is not sold separately. Any idea what my options are? I would think a new shaft from ford would be quite expensive.

Btw my friend that was helping with all of these repairs informed me that while I was at the parts house he separated the spline on the drive shaft and that it was seized up. I would think that this would also be the cause of my broken transmission mounts.

Thoughts, ideas, criticism???

 

I too have vibrations on my 1999 f250 with 165000 mi. I too replaced carrier bearing and rear u-joint. I have a 6" lift and no shims when I bought it.I am experimenting with nylon shims made from a 1/2" cutting board. Easy to cut on a table saw and to drill. One shim(1/2") helped alot , two not so much. I am going to cut one in half and see if 3/4" is the size. I also believe a traction bar set-up is needed to reduce rear end wrap up under low speed tourqe. I run 38.5x14.50x17 tires and blame some of the high speed vibes to the knobby tires. Hope any of this helps. Go to driveline 101 for more info.