I've got a 2000 E-250 Regency conversion van. Was a killer when we towed a 30 ft. camper--now we just use it occasionally when we have more than 4 in the party. Great van, great equipment but just one problem--it's got a vibration that we can't get out. I've put on a new set of wheels (2 of originals were bent), new set of tires (Dunlop's), had it on a front end machine 4 times since January and NO ONE can figure out where it's coming from. Drive shaft has minimal amount of play, nothing looks bent, nothing warped.......steering wheel begins to twitch about 50 mph and escalates into a vibration about 70 and just keeps on going......

Where can I find an E-series forum or have you got any ideas?

 

Actually, we have a forum just for that and I've moved your thread to it. It's the 1968 - Present Full Size Van forum and the folks down here are great. Lots of knowledge and it's a very active forum. They'll help you out for sure.

 

Thanks! and I forgot to mention the wheels and tires have been balanced at least 6 times since April (when all this started). We've also installed 2 different sets of tires--one Mastercraft and one Michelin--with the same results!

 

because of the speed involved, it sounds like a balance issue. i've heard of 4x4 drive axles having their joints seizing up and having a very aggressive wobble, but i doubt you're a 4x4, so this wouldn't relate.
again, with the speed, this sounds unlikely, but its possible its an issue with the engine being out of balance, but only if its at engine RPMs above whatever and builds from there, if revving lower gears up doesn't produce it, this doesn't apply.
is it possible that your hubs/brake rotors are out of balance somehow? i've never heard of this being an issue, but doesn't hurt to think about
as for driveline, you should inspect it by lifting the rear tires off the ground, supporting it well on jackstands or blocks, and with the wheels spinning, get under the van and inspect the driveline from there for any hints of being bent. after inspecting it at low speeds, get back in the cockpit and spin the tires up to high speed, and notice if any vibrations are present. if they are, the problem lies somewhere in the greater drive train, but if not, the problem lies somewhere in the front end.

this should be enough to point you toward an answer, and we'll be happy to answer any further questions with the results from this

 

Josh is certainly onto something here---same thoughts I had.

There simply has to be some indication or "feel" for where this vibration occurs. Front end the steering wheel would visibly shake, back end there should be an overall feeling of it being transmitted into the frame and body, drive line only will feel as though its coming from underneath. Mind you those terms and descriptions are my own and not technical terms at all!

It concerns me you say there is minimal vibration in the driveshaft----that might be the issue there. U-joints, the forward mounted driveshaft vibration damper---all could be issues and should be checked as Josh recommends.

If you do this yourself for cripes sakes keep safety first!!