good day everyone, i am trieing to find a problem with vibration that starts at 55mph and ends at 70 on that f250 sc i just got so far i have replaced all the wheels/tires with new,balanced, re and re the spring packs the pass side ubolts were finger tight,driver side not much better,po replaced or rebuilt 2pc drive shaft,re and re to assure there is no binding ujoints,and play for length center bearing is new and tight new moter/trans mounts the ? i have is how do i know if the drive shaft is "phased" as my manual is missing this part? the tag shows it came from a very good shop in edmonton and i have had work done there in the past but want to double check one thing i noticed is when i " look down" the drive line it seems the rear drive shaft is not straight but angles to the left the trans mount/center bearing looks to be in the right spot as factory bolts/rivets were used is this normal? thanks for your help regurds joe

 

Hmmm... you already covered all the bases. :)
You missed something. ;)
Or assumed something. ;)

Maybe this will work... ?
Put the pickup up on blocks and start the sucker up and run it so the
speedometer reads 50 to 70 mph? :) Try not to get run over ok? ;)

BTDT and showed me right away that there was no fixing my vibration
problem with two flimsy little screw-type hose clamps, like they show
in the books! :/

Dangged drive shafts warp from hard use.
Ever'so many years they need to be re-straightened and re-balanced.
...at least that's been my experience.

Sounds like something's is wrong with the drive shaft to me.
"new" or not.
in phase or not.

My scanner's not up and running or I'd scan off the page you need.
Easier tho is for you to find a picture on the internet.

First, the drive shaft needs to -not- be perfectly lined up. That's bad. ;)
Almost as bad as running yourself over with your own pickup. ;)
The drive shafts need to be "out of line" so the u-joints "work" just a little.

The only place for my u-joints to not line up is in the slip-joint.
The ends need to line up like this...
>< (side view ;)
-- (top view ;)
Not...
>-
-<

Something I've noticed is... steel wheels ain't straight!
They are "good enough" usually but not always even "good enough".
But -never- all-the-way-straight like alloy wheels that are turned on a lathe.

Alvin in AZ

 

Jack up the wheels and turn the tires by hand to make sure a brake is not dragging. This can cause a high speed vibration.

 

Ooops...
Ok? :)

 

good day i changed out the radius arm bushings today as they were totaly soft cracked loose end nut and half tight frame brackets vibration has changed from 60mph and up now never thought of this till a buddy said he had the same problem with a ranger getting better but i will take your good advise alvin and jack it up and run it and see what happens talked to a shop today and they said to start from the back and work up [1] run with wheels turning [2] remove axels [3] remove rear drive shaft if its in the drive line you will find it this way thanks for the help regurds joe