driveline vibration starts at 23 mph. U joints look good
 

I bought a 2003 recently. It has a pronounced vibration that comes on at about 23 mph. The frequency of the vibration feels more like driveshaft than wheels. Its a higher frequency than a wheel and tire would be at 23mph and it feels like it is coming from under the floor (although I do get some vibrations in the steering wheel).

I definetely need a new steering tie rod. Both tie rod ends are loose on it. I will replace it and see if any vibes are reduced.

Ive taken a look at the driveshafts, and the front u joint on the front drive shaft,....and the forwardmost u joint on the rear driveshaft,..both have grease/zerk fittings and there wasnt any discernable slop when I grabbed the driveshafts and tried to move them side to side and up and down at the u joints.

any thoughts on this.

Do you have this little spud atop the transfer case, which you could trunk with a wrench to engage CDL and allow the truck to be driven without a shaft to be sure?

Does your truck have the rubber flex coupler at the rear shaft?

RE: Front driveshaft - the centering ball that is inside the double cardan joint is prone to failure and could generate vibrations. I don't think there's any good way to check it.

Also, if it's an aftermarket shaft or if it's been rebuilt it could need a balance.

You can't tell if a u-joint is bad or not just by trying to shake the propshaft, especially if it's causing slight vibration. A seized u-joint won't be loose, it will be tight, and the only way to tell is remove the propshaft.

Rebuild or replace it ASAP or very soon it will fail and can take out your tranny at the same time.

Buzz, I tried looking at the top of the transfer case with a mirror and flashlight last night,......couldnt get a good angle to view. Then tried just reaching up and blindly feel the top of the Xfer case,......couldnt tell if there was anything up there for certain,....thought I might have felt it,.....or it could have just been a bolt.

Looks like your pic is from above with the xfer case still in the vehicle,.....is there a panel that I can remove to direct view it? Also, Yes, I do have the flex disc at the rear of the rear driveshaft.

No panel to remove, would be whole console. Pix from another member. But please understand that the results of the shaft coming apart will be severe. Shaft seems to break at the big end, which is then a war club wielded by the front differential with considerable force against the transmission.

Some early D2 had the spud, but linkage can be added to make it a locking CDL unit.

It is item 33 in attached pages from the RAVE shop manual.

BC, here is a picture of what to look for. Look for the round plate held down with 3 bolts that has the shift nipple in the center.

I would still get the tires checked to make sure they are balanced. 23 mph is low for tire vibration, but if the vibration starts at that point and stays with you above that speed, a tire might be the cause.

Thanks guys. I do understand about the front driveshaft destroying the tranny, My third Disco and have been here (on this site) for 5+ years now sorting out various issues on my Discos. Think I will pull the driveshaft down for a look. Will be a busy day in the Texas heat. Also pulling the radiator and headliner today.

BTW, I did get my new front tie rod in yesterday. Big improvement.