I am trying to narrow down some vibraton which I believe may be coming from the driveshaft of my 98 F150 4.2L. I was reading some things in the Chilton book for this vehicle and one of the trouble shooting procedures was to " Remove the driveshaft and reinstall 180-degrees from original position, then retest."

Does anyone know if this is a 180-degree rotation then re-bolt, (countering the indicator marks) or a 180-degree flip (front to rear reversal) and re-bolt. It seems to me they're suggesting a reversal of the driveshaft but I wanted to check in to see if that's a bad idea or not. Has anyone done this before?

 

No, dont flip it, just rotate it 180. When you are doing that, inspect the u-joints carefully, that may be all that's wrong, worn joints.

 

A couple weeks ago I started noticing some shaking vibration coming from under the cab which seemed like possible u-joint issues. I ordered some Spicer u-joints and installed them last weekend and re-installed the driveshaft the exact way it was indexed. The problem is the same. Just after I posted this question, I crawled back under there add noticed a very small amount of play at the spline less than 1/32" I don't know if that's normal or if I should check the extension housing bushing

 

Of all those who are experiencing the "Vibration", how many have 157 inch wheelbase (carrier bearing two-piece shaft) and those with one-piece shafts? My vibration starts at 40 mph and is so severe, major wheel hop happens and it shakes the whole rearend of the truck. Also more evident when the truck is cold first thing in the morning.

 

My vibration started after I changed gears (3.55 to 4.10). Mine start at 80 when it first started and now starts at 73 and some times when slowing down. Also had to replace tail section of trans. I have had the gears in and out 20 or 30 times drive shaft indexed same, 180,180,180,180 and 180 again!!
Mine seams to be coming from the passenger rear.

 

I have a 139" wheel base. I'm working on it right now to check on the slight play at the slip yoke. Kragen ordered me an extension housing bushing that turned out to be too small in diameter so now I have to track one down while it's apart in my driveway. I'm not sure if the little bit of movement (up/down side to side) is normal on that shaft inside of the extension housing. Is it possible the bushing sleeve holds the slip yoke in place and is just worn? If that's the case that may be the issue, at least with some of us.

 

GLC,
What will happen if you do filp the driveshaft fron to back? What would be the signs on that has happened?

 

I don't think you CAN do that physically.