Another thread on it...
https://www.ford-trucks.com/forums/1...l#post11893602

 

Ok thanks! Just checked it. What about be out 180? Is there a way to check this besides removing the rear drive shaft?

 

Take the driveshaft out of the truck and drive around in 4WD with the front tires pulling the truck. This will quickly tell you if the driveshaft is the problem.

 

Going down to remove drive shaft now! Whish I would have thought of this sooner!

Thanks 89LX306 !

 

Just did a test drive. Seems to have the same vibration. I did not take out the first section though. It seems to pull funny side to side. Is this normal? Could it have something to do with the clutch? Or T case? Thanks.

 

Also just jacked up the rear. You can feel the vibration at 35 mph them also in the floor board.

 

Joe, this is not always true. When I installed my 2" front leveling kit, I also began to get vibrations at 45-55 mph. Even after changing the carrier bearing (which did have slop) and u-joints, the vibration remained, even though it was less extreme. Shimming the bracket resolved the vibration completely (one shim, 1/8").

 

OK these are the things I have done in order.

1. Got the rear tires off the ground. Put it ingear starting with 2nd going thru the gears to 4th Vibration happens at 35 MPH. Put in 5TH still there!

2. Remove the rear tires and put 2 lugs on to hold disc brakes in place. Again 35 MPH Vibration!

3. Leave tranny in Neutral. 35 MPH NO Vibration!

4. Put back into 4th Vibration is back!

5. Reamove rear drive shaft. Matched the RPM's that would be approx 35MPH. Vibration is Gone!

6. Checked the U-Joints on the rear drive shaft! fount that the one at the slip yoke had a tight spot in both directions.

This could be it according to a local shop that Helped me over the Phone. Im going to replace this U-Joint and re install the drive shaft and see if the vibration is gone. He did mention that if there is any play with a twisting motion at the slip yoke to the spline shaft that this could also cause this issue. He has always had to use force to get the drive shafts in and off. Mine seems to go on and off fairly easy with about a 1/6 inch play twisting motion.

UHH so much but is saving alot of money doing it myself. Hopfully this will help someone one day!

 

He is def right about using some force to slide back on!!! don't ask me how I know!!

Smokie

 

So could the blue stuff be worn down? He mentioned maybe need a new yoke.

 

If its sloppy IMHO I would say yes!!

Smokie

 

Well we will find out soon! The parts man is on his way! I really dont see much if any wear on the yoke splines. The blue coating does show some wear though. Can we just have these recoated?

 

I beleive the blue is the original Ford grease on the spline - You can just re-grease this with some good quality lube - Like F250 said I also had to shim mine 1/4" after doing my front leveling kit. Mine is a 2 wd truck though. But the shim took care of the shimmy shakes. Made a shim out of 1/4" aluminum stock.

 

Mine is also 2WD. The 1/8" shim didn't quite get 100% of the vibration out, but it can barely be felt now at all, so I've left it alone, and it hasn't gotten any worse in the recent 40K miles. Incidentally, I only felt mine shake when I let off the accelerator between 45 and 55 mph. While it was under load, there was no vibration at all even before adding the shim.

 

New U-joint installed. Drive Shaft installed. Tested Vibration is back. The new U-Joint did feel much smoother though. Going to say that this issue is due to the blue stuff with wear and maybe the slip yoke wear. I put the tires back on and took for a test spin just to see actual road feel. It is still there. So now I will be looking for a new slip yoke and pull the drive shaft and see if the new slip yoke fits any tighter.

At this point I not sure what else to try.

Thanks for all the imput. Keep it coming. I will try to find one tommorrow after work.