vibration issue narrowed down

[Codymunlin]

Since my post about vibration issues I have done some diagnoing myself. The F-450 has 19.5 inch rims which require a special adapter to balance. I went to a big truck shop where my tires were out of balance a little since 4000 miles from the last balance. The tires were rebalanced and installed back on the truck. The test drive prooved that the balance was not the issue, at 72 MPH my teeth still were rattling out of my head. We put the truck on jack stands to run the truck at the 70-75 MPH range to inspect the drive shaft etc. The vibration was still there. we took off all of the back tires, ran the truck on the stands and the vibration was still there. We then put it in 1st gear to see at what rpm the vibration was happening and to see if it was consistent through all the gears, it was. The vibration while the truck was on jacks was happening at 1600 to 1900 rpm. We then left the tranny in park and ran it up to the rpm range in which the vibration was occuring and it was still there in park and in neutral. We also noticed that while in park, running the truck at the rpm range, and then hitting the brake, the torque converter did not seem to let go and killed the engine. The conclusion we are drawing is that the vibration was coming from the transmission and we are assuming it is the torque converter and bearings in the tranny. After making some calls to buddies, a Ford mechanic said that on the 2008 6.4L engine the fan clutch has a tendency to go out and cause this vibration issue as well. If anyone knows for sure it sure would be helpful. Warranty on the drivetrain is expired and for now I am going to drop the tranny to see what is going on.

[cam31]

I am having this exact same problem. At those RPMs and speeds. I have a 2008 F350 with a 4" lift, and 35" BFG A/T. I have been over EVERYTHING. No matter what I do, I cannot get rid of this vibe.

By any chance, while you're driving, can you feel the converter unlock? Does it seem like it releases abruptly or rough? Im going to try your test on my truck tomorrow to see what happens.... It feels like I have a bad u-joint or bad tire, but everything is new, balanced, and in good shape.

[canada6.0]

Just picked up a 2008 F450 last night.
on my way home I noticed the same vibration.

Took it back to the dealer, they sent me to a truck tire store and basically told me that they would cover half the cost of new tires or the full cost of used.
They checked the front tires, and showed me that they were out of round. I put new tires on the front with dyna beads. (dealer installed brand new rears yesterday)

The problem is still there.

I am told that 19.5s will never be as smooth as regular tires, But I really can't belive that the shaking like I am experiencing is normal.

Let me know what you find.
I am going to take it to my buddy's shop tommorows and see if he can figure it out and post up what he finds.

Real kick in the *** because other than the vibration its an amazing truck.

[canada6.0]

Ok so since my last post..

Did a roadforce balance.. no Dice

The dealer had my truck for 5 days and changed a wheel bearing, upper/lower ball joint.. no difference

Had another shop spend 4 hours going over the front end .. they couldn't find anything.

Pulled the axle and checked the U-joints.. not that either

Did a spin balance where they balance the wheel on the truck...money wasted

Found an out of round rear tire...Tire shop replaced at no charge..no difference

Did the shim thing on the driveshaft.. Nothing.

Today I noticed that when i put the truck into 4wd on the fly there is a huge clunking noise. Once its engaged there is a loud whining noise. mainly when I am coasting.

I am really starting to HATE this truck.

My old F350 SRW with 450,000 miles never had issues like this.

I'm also being told now that some Superduty's just have a HOP and that is normal?????

Any ideas on any of this guys?