All,
Sorry for the length of the initiating post, but want to be as informative as possible. Vehicle is a 2000 Ex. Limited 2WD 6.8, 3:73 rear, 135,000 miles purchased at the end of December (Merry Christmas to me!). When I purchased the vehicle it had some vibration at speed, that I chalked up to the completely worn tires, tire rod ends and ball joints, all that I knew about when purchasing. The vibration slowly builds up to 70mph, and then comes on like a light switch where it is nearly violent, then slowly dissipates over 80mph. First on the vehicle were new BFG TA/KO2's 285 75 16. No change in vibration. Next were ball joints and tie rod ends. No change in vibration. Next were new inner/outer front hub bearings, rotors, pads. No change in vibration. At this point I was scratching my head a little. I had the tire balance checked twice by two different shops. Alignment was also checked by two different shops.

The vehicle has 2" spacers under the front coils and an aftermarket 4" lift block in the rear of unknown manufacture. I decided that the vibration may be due to an incorrect taper on the block causing a pinion angle issue. I replaced the block with a stock F-350 block for the same wheelbase truck. No change in vibration.

At this point I figure all that is left is the driveshaft and I am very fortunate to have the great guys at Driveshaft Specialists about 2 miles away from my office here in San Antonio. They took it out for a drive and said "we'd love to sell you a new driveshaft, but we don't think that's it." They put it on the lift, jacked up the rear by the differential and ran it up to speed. By 50mph the rear wheels had VERY VISIBLE "hopping" at the hub. You would have thought there were 5lb weights attached to the inside of each wheel. It was vibrating like crazy. There isn't any noise or play to indicate bearings (and with the amount of wobble/hopping/vibration I was seeing the bearings would have to be reduced to dust). Their best guess is that somehow the axles are bent

They referred me to another shop where the Ex will be going today, for possibly new axles. Anybody ever heard of bending axles on an Ex? (how on earth?!) Anybody ever heard of something similar and what it might be other than axles? I am leaving for a 2500 mile round trip road trip Thursday and am at my wits (and wallets) end. Appreciate anything you guys have to offer.

 

Ive been chasing a vibration for a while now at approximately the same speeds. I have two sets of wheels I run for winter and other 3 seasons. I just had the spline yoke greased and new Michelin tires installed. Vibration gone. I had tires and driveshaft yoke greased at the same time so not sure what fixed it. I suspect the tires. Good luck.

 

I used to experience vibrating at about 80 kph that would disappear by 100 kph then come back with a vengeance at 110 kph.

In my case it ended up being the rear U-joint that was causing all the problems.

 

Check out the NVH thread link in the tech folder in the General Engine & Engine Compartment Threads section.

Stewart

 

Stewart,
Thanks. I have read the tech folder and searched until my eyes bled. I took the truck to yet another tire shop today, who told me all three tires were 3oz or more out of balance. Suddenly the phantom vibration is gone.... I'm not really pleased right now. I have a spent a lot of money and time chasing this vibration.... And it's what I thought it was to begin with. Moral of the story.... Trust your gut, and have local shops you trust.

 

Yeah, I wasn't sure where in the thread it was listed, that's why I ID'd the section for you. It's the last link in that section.

Stewart

 

Okay, resurfacing this. In two days of driving three of the four wheels spit off some of the balancing weights. Was back to vibrating today on the way to work, took it back in and sure enough, balance was off. After the guy balanced one of the wheels he pulled it off the machine, dropped it to the floor with a little bounce and one of the weights he just put on flew off!

BFG KO2's, 285 75 16, stock 16" wheels. Anybody else having this issue with this combo? Discount said they would static balance them if they flew off again, but that seems far less than ideal to me. This is a pretty common combo. Any suggestions/thoughts? I'm leaving on a 2,500 mile road trip tomorrow and I would rather not spend an hour in a tire shop every other day....

 

Are they the stick on weights with sticky backs, or the old school clip on weights?

Stewart

 

I had an issue similar with the general Grabber AT-2s I run. On my old Ram W-150 the rim guard of the tire was interfering with the new style of the old school clip or tap on weights. I had ONE tire shop that had already identified the same issue and these guys found the weight point, pulled the tire off the machine, deflated it, put the weights on by force, then reinflated and checked. In the next 4 years that I was running those tires on that truck I never once had one more pop off. Sometimes it takes a knowledgeable and dedicated shop to fix stuff right. Even if it took the owner of the shop and one of his more experienced guys almost 2 hours to balance 4 tires for me. Needless to say I am a near constant customer of that place.

 

Clip on the edge of the rim type, i was tempted to tell them to pull the tires and start over to see if that made a difference. Definition of insanity is to keep doing the same thing expecting a different result.

 

See above, might help

 

If not that, tell them not to use the clip on weights.

Stewart

 

So it went back to the same Discount Tire yesterday because it was vibrating again. They made adjustments to three of the tires AGAIN and it was WORSE!!! I took it to the Discount I bought the tires at (the other one is closer to my office) and the guy looked at the wheels and said "A discount store did this? Those are the wrong weights and they are not installed correctly" An hour later they said they had it...traffic was miserable this morning on my way in to work so I never saw real highway speed. Leave for the first leg of a 4,000 mile round trip in a few hours...guess I'll see how it rides then...

 

I don't have weights on mine anymore. The tire shop was having too much of an issue getting the balance correct so we went with dynabead.

 

Well, made it to Gulfport, ms after getting beat to death by vibration where I had a Firestone tell me that discount didn't know what they where doing and rebalanced the tires. Got it back on the road and all they did was move and change the vibration. It is violent around 75, smooth as silk over 80. Made it to Columbus, ga and heading to Spartanburg, sc now. Once I get to Spartanburg I will have someone else look at it again. This is making me crazy