Hello all, I have been dealing with this vibration when accelerating the truck (2003 DII) around the 40 MPH for some time now.
I have read a lot about it in this forum but I can't find a straight fix for it. Everyone is changing something different and getting different results.
I have done:
1.- Changed drive shafts (front and Rear) including flange.
2.- Changed nylon nuts
3.- Balanced front shaft (even though it was brand new)
4.- Balanced the tires including rotation.

Please help!!

 

might try to single out if its front or rear or worse both. remove one shaft at a time engage cdl and test drive both front wheel drive and rear wd
also how are your hubs?

 

Does the steering wheel wobble in sympathy? Or is it strictly a vibration of the vehicle body?

I test drove one Discovery with a nasty "death wobble" through the steering wheel, from 40 to 50 mph.

The problem with ordinary balancers is that they don't measure runout. They would balance a square wheel quite happily, but would it give you a smooth ride? A good result on an ordinary balancer does not eliminate the wheels/tires, unfortunately.

A Roadforce balance, with the Hunter Roadforce balancer, applies a load with a roller and measures runout. This can then be minimised with a process called ride matching where they try to mount the tire and wheel so as to reduce the runout. It worked very well on a previous Audi of mine, with chronic vibration issues.

 

If the wobble is low frequency - tires have a broken belt or loose suspension.
If wobble is high frequency - drive shaft may need attention again.
Driveshaft noise is more like a buzz.

 

Yeah honestly I think you've already gone over the problem area(s)

In my experience, my wheel vibrations (lower frequency, felt more through seats etc) is at 55 in the Disco.

However, the driveshaft is a harsher vibration, chattering almost - close to your feet / the floor, and is almost always 40-45mph.

I've gone through this a couple times with various driveshafts. My original (well, from when I got the DII one was about to die, harsh at this speed.. rebuilt with new ujoints/centering ball and it was much better but still noticed vibration at this speed. That driveshaft was stolen and I went around w/ center diff lock RWD while I was getting a new one. VERY SMOOTH driveline, no vibration. With the snows here I threw on an old (intact) front driveshaft for the rest of winter while I save up for new one in spring... THAT one also has a vibration at 42-45mph.

I'm almost starting to think that the double cardan design is inherently unbalanced due to the awkward angle of the driveshaft. It's not BAD but it's never going to be perfect - it'll always be worse than if you remove the front driveshaft and lock center diff for testing purposes.

If it's new, balanced, etc.. I'd leave it.