97 Ford Ranger, weird drivetrain vibration

I know some people on here are Ford mechanics, I figured I'd ask before taking the truck to a shop.

The truck is a 97 Ranger supercab, 4x4, 4.0L V6 with 5spd manual tranny.

120,000 miles. Stock except for a single piece driveshaft from a later model Ranger

What's happening is that the truck makes a rumbling noise/vibration at speed, but only under power. If I take my foot of the gas it goes away. It is worse when the truck is cold and when driving at low RPMs. The truck still drives fine other than the vibration.

I've ruled out tires being out of balance because the noise isn't consistent with speed, The U joints feel fine, and I don't think it is wheel bearings because the noise isn't consistent with speed.

Anyone have any thoughts?

Thanks in advance

call cartalk!

pinion angle with the new driveshaft

pinion angle with the new driveshaft

I would look real close at the orientation of the new shaft. If backwards on some Toyota's, this will happen.

i would research and find out if the pinion angle is the same on the older truck as it is from the 98+ trucks you took the shaft from.

also, i know on my shaft that the driveshaft and pinion flange are marked from the factory so when it is removed and re installed that you can line up the marks so that it is in the same postion. if it is off, this may be causing an issue for you. do you have a mark anywhere on your pinion flange?

As far as I know the pinion angle is the same on all Rangers with the 8.8" rear end. The single piece shaft has been on the truck for 50,000 miles, no issues, ran smoother than the 2 piece unit it replaced. The rumbling/vibration I'm speaking of is a relatively new problem.

How long has the driveline been installed? Any way to put the old one on and drive it for a few miles? It sounds like to me that your are experiencing drivline issues. Sounds like you checked u-joints so you may have an unbalanced driveline. I would take the driveline to an axle/driveline shop and have them balance it for you. They should be able to do it pretty quick.

Ford Technician here. Have you pulled the driveshaft and actually felt if the u joints are stiff or loose??? Sometime they will fool you when everything is together. If you want to narrow the vibration down, remove the rear driveshaft, stick it in 4 wheel high, and see if it goes away. If it goes away, you have at least narrowed it down to the rear driveshaft. Also check the front flange where it enters the trans. Could be loose splines. Check the pinion bearing in the rearend for play also. PM me if you need any thing. Good Luck, WD

thanks everyone for your ideas.

I dropped the rear driveshaft and the U joints feel fine, but the slip yoke has a very small amount of play in it. I drove it around in 4wd (it does NOT like driving fwd only), and the vibration seemed to go away. I think the slip yoke is the problem.

Replacing it tommorow

Check out rangerpowersports.com if that doesn't fix it you should be able to find anything you need there. Great Site!

I also have seen bad pinion angles from the factory. since your under it, check them with even a small level

edit: rephrase, most of the time it is do to saggy springs, or when someone has beat on it a bit, and leaf wrap occurs

Greased up Slip yoke and replaced U joints, vibration is gone:ride:

Greased up Slip yoke and replaced U joints, vibration is gone:ride:

thats how gm "fixes" thier issue with slip yoke vibrations on thier 1/2 tons (which comes back after a few thousand miles), Hopefully your issue was just with the "U" joints

Heck, greasing the slip yoke every month or two on an old truck seems like a cheap fix to me.

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