That is one thing I forgot to post initially. I had seen this issue come up when searching my problems before and I am going to check on this when I do the rear wheel bearings. Parts in today, hoping to get to it this weekend. I have read about this before and good to know this fixed your problem! Hope you didn't spend as much time as me trying to track that down. Thank you!

 

Wanted to give an update from this weekend:

Thanks to GregN and sammie0126 for their walkthroughs for the rear wheel bearings! This made the job quite easy and pretty enjoyable. If there is a way to "officially" thank them in the forum, please let me know how. I'm kinda new to this.

No change in the vibration unfortunately, but I did solve the whine from the rear end. The emergency brakes were in good order, very clean actually, and moved freely. Just cleaned them up some. I also did the test inthedirt recommended and this was also negative. Absolutely no vibration from the drivetrain with the driveshaft removed from transfer case...smooth as silk.

While I had the truck on jack stands from the rear bearings, I reconnected the driveshaft and left the rear wheels in the air and repeated that part of the test. One of my rear tires, not wheels, was wobbling side to side, not up and down. This movement was probably 1/2-3/4" each way and I felt a noticeable shaking in the cab from about 30 to 60 mph. The other tire was very consistent. Just to restate, the rims were NOT wobbling, just the tire. Anyone know what an acceptable, if any, amount of side to side movement is? Again, none of the 3 tire shops ever brought this up.

I'm 95% convinced this is all just tire related. Don't want to belabor it much more, but perhaps the info in the thread will help others. I just needed to feel more confident before dropping a grand on new tires if it was something else I was missing. I would also like tire recommendations from you guys. I have no mods, tunes, lifts, etc. This is my family hauler and highway runner, with very occasional towing/hauling needs. I want a good riding, quiet tire, that can handle the occasional load, but also not one that will dryrot before the tread wears. I've had that happen to me with Michelin (can't remember what kind) and Firestone Transforce (last tires I had on my Yukon XL). I probably put 10-12,000 mi per year on them.

 

I wouldn’t think any side to side movement is acceptable; if the other tire isn’t moving side to side, that basically confirms that.

If it were me, I’d switch the rear tires just to make sure the problem follows the tire. If it does, might be the belts inside are coming apart.

 

I chased a highway vibration for almost 2 years..... it shook from around 60-65 on up. Had a reputable driveline guy rebuild the drive shaft. He doesn't balance but trues the shaft...(I thought that was weird) Mine has a front cardan joint too.
I put it up on rear jackstands, removed the rear wheels and then spun it up to 75 and you could see the driveline hopping (took the wheels off so the hopping didn't get out of hand)
The Only Way I fixed it was to take it to Lances Driveshafts in Portage (NW) Indiana and have them balance the shaft....the vibration was gone...... I went there as it is big truck country and they fix all the big mill trucks and haulers. He made half shafts for a old 280z for me years ago.
Having the right guy fixed my problem....Not saying your knoxville guy isn't good but just my story.

 

Sorry you’re having such trouble chasing the ghost vibration. I’d hate to see you give up on the Ex after all you’ve done so far.

I’ve read through your thread and have some additional ideas for you to consider.

Do you have a good spare? If so, swap it for the tire with the side to side wobble. If no change, swap it with the next tire till you’ve checked all four.

Does anyone on the forum live near you? Would they be willing to swap tires on a Saturday so you can rule in/out tires and rims?

Could one or both of your front axle half shafts be binding? Even with the hub lock set to free, a stuck joint on the front will grab, bind, spin and bounce inside that knuckle. Periodic binding would cause the 90/10 sometimes vibration you have. My Ex made an awful racket when the front joints were binding. Only happened intermittently at speeds over 55 mph and in 2WD. Would drop it into 4HIGH and the noise went away. I replaced the joints and swapped to Warn manual hubs. After that it seemed to have significantly reduced vibrations on the freeway.

Have you tightened your steering box? Any play (very common with age) could be allowing your front suspension to have a party under there and it wouldn’t necessarily equate directly to a steering wheel, drivability issue. Does the vibration reduce or change on long, slow freeway curves where there’s a continuous light pressure turning the wheels and keeping consistent pressure on all the suspension components?

have you changed the front axle fluid? If it’s thick and gummy, it could be a stuck axle joint in combination with bad fluid causing all sorts of drag, spinning, flopping of the axle joints. Just replacing my rear able fluid with Royal Purple eliminated a highway vibration for me. You’ve done the rear, consider doing the front pumpkin too.

Does the vibration exist in 4HIGH and with hubs locked on the freeway? There’s usually added vibration from the extra moving parts but is the vibration the same?

**WARNING** not sure of the safety risks on this item so I’ll leave it to others to confirm efficacy. Consider removing your rear driveshaft and running down the freeway in 4HIGH using only the front axle. That would remove rear driveshaft concerns.

Well, that’s what I’ve got. I hope it helps or at least gets the brain juices flowing and looking at other possibilities.

Good luck man!
Jasonodsky

 

One other thing the Guys at Swamps diesel suggested......swap a driveshaft with someone with no vibration.....it's all of 8 bolts....then see if the vibration changes..

 

I had my driveshaft rebuilt and balanced. It made a huge difference, drove like a new truck.

 

First, taking out front driveshaft will NOT help diagnose anything.

If a hub is locked that hub will rotate axle joints and differential even if driveshaft is out. So reach behind tire and make sure axle joints rotate freely when in 2wd. If they don't than this could be your issue.

Don't discount a torque converter issue.

Push and pull up and down on rear driveshaft. Look at pinion for any movement.

MAKE SURE REAR YOKE ISN'T WORN. Sometimes they are and need replaced. There should be plenty of grease in rear yoke and no movement. New ujoints don't mean rebuilt driveshaft necessarily if yoke isn't new too.

If springs sag than the rear yoke to driveshaft angles may be off. Non cv driveshaft angles MUST be the same at transfer case and rear end.

 

I agree, that tire has me feeling like I'm just going to have to bite the new tires bullet earlier than I wanted to...frustrating when I've got a set that would last me many years. I was thinking of swapping out my spare with the one questionable tire, but they are different sizes. I went up to 285/75's and the factory spare is 265/75...would this still be suggested and a good/safe test?

The driveline shop did a full rebuild, new slip yoke, both ujoints, and a "high speed balance." I am pretty confident with his work, and with the rear wheels on stands test I did last weekend, the driveshaft seemed very smooth.

Swapping parts was one of the first things I thought of and is a great idea, and I agree, very easy...driveshaft, wheels, etc. I had mentioned earlier in my posts that in my circle of friends and family, I'm the only one with a SuperDuty

 

See reply to Seville009...any opinions? I'm new to these trucks, diesels and just getting my feet wet with repairs. If anyone is close to Knoxville, TN, I would be grateful for any help...hate to even ask, weekends are valuable time off. I would gladly pay/repay anyone if it's an option.

This is where my knowledge is lacking. rock2610d also brought this up for to consider. I'll ask more specifics in my reply to that post. Feel free to add anything more on this.

This is interesting, as I could swear that on the interstate, 75 or so, if I took a sweeping turn, enough to kind of pull you to one side of the seat, the vibration changed. It didn't go away completely, but I felt it less in the wheel. I will search how to tighten the steering box. I had mentioned somewhere in my posts that I have some/a lot of play in my wheel, maybe an inch each way? This is WAY different than what I'm used to in the BMW's, but I just assumed it was a truck thing...what is normal, if any?

Yes, we did this when we replaced the ball joints and I recently did the rear too.

I have tried this on a highway near my house, 50 mph or so, using the autolocking function. Is this the same as your suggestion or should I manually lock them? How fast is acceptable in 4 high? I think my Yukon was 55?

I read this a long time ago, but as you warned, I was also skeptical of the safety risk as well. Anyone done this before?

 

I have no idea what is normal and anything related to 4wd is where my knowledge most lacking. Under the truck just now...not running, in park, flat driveway, 2wd, hubs in Auto. I cannot turn the ujoints inside either side of the front wheels, nor can I turn the front driveshaft. But, I don't know what this tells me. It is not locked in 4wd, i don't think...no binding when turning and last week my rear end fishtailed out during rain pulling onto highway when the turbo kicked up. You may have to dumb it down for me

This is something I ran across early on, but I'm leaning away from it. I have a guy, friend of a friend, who does transmissions at his home shop, he's retired from a trade school where he taught transmissions for decades. He has done a rebuild on my Yukon and about 6-8 other vehicles, cars, trucks, vans, of friends and guys who work for me. Based on my detailed description of my issues, he didn't think it was TC. His main line of thinking is that a shudder/slip would be temporary when locking in in overdrive and most likely would not "shudder" from here to Orlando, FL when I called him during that trip. I have tested for changes in Drive and Tow/Haul unloaded, as well as pulling a very heavy load of firewood in both Drive and Tow/Haul. Please, feel free to add any add'l info and I'll call him to ask/confirm. He lives a little far away, so he didn't drive it, but would be happy to if I took it to him.

No movement. I had the rear driveshaft completely rebuilt with new slip yoke, greased and new boot, new ujoints, and "high speed balanced." It is tight. I originally had this done to cure a clunking at stop/start and was hoping it was the cause of the vibration too. The vibration was there before and after, no change, but no more clunking.

It's a 1 pc driveshaft, no carrier bearing. The angles would be the same regardless of sagging if my thinking is correct? As to the sagging, how do I know this? The truck looks nice and level, measurements from ground to bottom of fender is F-39" R-41", so a bit higher in the back. Here's my truck, very slightly down hill at rear end, but pretty flat.

Thank you for the info and let me know what you think further. These are good suggestions, some I have been wondering about for a while when I ran across them in researching this.

 

Yes all excursions have 1 piece driveshafts.
BUT some have 2 u joints.....1 by differential and one by transfer case. Others have 3 u joints....1 by differential and 2 up by transfer case.

On 2 u joint systems both angles need to be the same. 3 ujoint systems need a zero degree angle at differential and all angle is at cv joint.

 

should be fine to use to test; wouldn’t want to run different tires permanently of course.

Regarding spinning the front axles, you should be able to move them by hand as long as the front hubs are unlocked and it is in 2wd. Note that they don’t turn easy (can’t do it with one finger); takes some muscle

 

to I can turn mine very easily. I just went out and did it just to be sure. One hand very easy. No clunking.

 

Ive had some vibration issues and every time I replace a few things in the front end mess with drive shaft no change. Then replace tires and Bingo all vibration gone.