I was driving down the interstate the other day, and all of a sudden, I started getting a vibration in my seat and pedals. It happens from 70-80, worse in the lower 70's. I had the tires rebalanced and I rotated them. Still a vibration in seats and pedals, now starting at like 68 and going until 75. Above 80, no vibrations at all. Any ideas? Thanks.

 

Welcome to the forum, Merry Xmas

Knowing what vehicle you have will be helpful

Ranger year and engine, manual or automatic
2WD or 4x4
Regular or extended cab

Most likely drive shaft lost a balance weight since you don't feel it in the steering wheel

Inspect drive shaft and look for a "bare spot"
If you have extended cab, carrier bearing may be going out
If you have a 4cyl engine then vibration damper may be failing

 

Sorry, thought it said in my bio. 02 Ranger XLT 4x4 automatic, 4.0 SOHC if that helps

 

CV joints on front axle of 2001 and up 4x4 can do that BUT.............you would feel it in the steering wheel first

U-joints on rear drive shaft, of course, and the slip joint
Check them all for play

A tire defect, in rear tire, can do that
Spin balancing can NOT detect this, road force balancing can
When the weight of the vehicle is on the tire a small defect in a belt will cause a vibration at speed, road force balancing is like spin balancing but tire is spun with road force(weight) pressing against it as it spins
Tire is replaced if defect is found

 

The balancing was with a road force. I saw the machine and saw the road force wheel under the hood of the machine. It just all of a sudden happened. I'll start by checking U-Joints. As a side note, I had that clunk from the rear driveshaft slip-yoke. As per the TSB, I packed it with grease and reinstalled. Interestingly, it only clunked when it was hot outside, during the summer. Once the fall started, and the temps dropped, the clunk went away. Decided to grease it anyway. This was a while before the vibration though, maybe a month or 2. Any ideas other than the joints? Should I start with that?

 

I would start there

What about mud in one wheel, that can happen suddenly and then not remembered, lol.

The rear seal on transmission isn't leaking is it?
Just replied awhile back to someone that had a failed slip yoke, looked fine but after two new rear seals failed to stop the leak he changed it and no more leak or vibration

 

So, it's been a while. I just got around to doing the u-joints 2 weeks ago. Both front and rears. Still vibrating, but it's not as harsh in the pedals, more of a consistent vibration. Hard to explain. I did notice on the driveshaft that there was a circular area recessed a little bit below the rust line towards the transfer case end of the driveshaft. Could there have been a weight there that flew off? How would I go about rebalancing it? I don't have the money to dump on a new driveshaft, and I just put new u-joints in. I can try and get a picture of it tomorrow if it helps.

 

Generally speaking you should mark a driveshaft before taking it off the differential so it goes back on at the same place, and then mark joints/knuckles so they also go back on in the same orientation with new u-joints installed, this can keep balance better

Google: balance driveshaft with hose clamps

Several videos and articles on how to do this, cheap, oops, inexpensive, lol, and works well

Article here on a front drive shaft balancing but method is the same for front or rear: https://www.therangerstation.com/for...-shaft.165506/

 

I did mark the driveshaft before I took it off for the u-joints. I crawled under and took a look at the suspecting area. Does it seem like at one point there was a weight or something in this spot? Seems too coincidental that rust would form around a nearly perfect circle.

 

No, that just looks like it might have been hit by road debris

Try the hose clamps

 

So, since the last post, I did the u-joints, nothing. After that, I diagnosed deeper. I took off the tires, vibrates. Took off the drums, vibrates. I took the driveshaft off completely and ran it, no vibration. That rules out anything in front of the driveshaft. I took the carrier out of the diff, checked the carrier bearings, no play. Checked the pinion, no play. I sent the driveshaft off to get balanced, seeing as I narrowed it down to that. They said it was out-of-round and bent. Went to the junkyard and picked up a used one. Had all the weights. Installed it, vibrates. Even worse now actually. I wonder if the driveshaft shop just made that up. I'm at a loss of what else could be causing it, Any ideas?

 

Did you have this junkyard driveshaft checked out by the driveshaft shop?

Good chance the junkyard bent the driveshaft when moving the truck with their forklift.

 

No I didn't. I figured I'd try absolutely everything before sending another driveshaft to get a balance check. Could anything else cause a vibration?