Truck Vibrating at 60+ MPH

Gravity

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I've searched for people having the problem elsewhere, and really haven't found much on it. At 60+ MPH my truck will start to vibrate/rumble like crazy. It usually is intense for a little while, fades more toward the back, then comes back up front and is intense again. Then kind of just continues like that getting worse with speed. I had this problem before and after I did the following:

1.5" lift with AC upper control arms
New torsion bars
New leaf springs
New shocks
New wheels and tires
New U-joints
New ball joints
New center link
New tie rods
Alignment (obviously)

Also I have manual hubs that always stay unlocked unless I'm offroad, so the front driveline isn't moving at all. Like I said it feels like it's mostly coming from the rear of the truck and then kind of varies in intensity. I really feel it in the seats, and sometimes it'll even shake the dash. The steering wheel is pretty much unaffected. Mechanic suggested wheel or tire problem, but for the same problem to carry over after new wheels and tires plus all of the above, I'm a little skeptical. Anyone have any idea what this could be and how to fix it? I'd like to do some longer road trips to experience some of the wheeling outside of my state. Even now some of the places I'll frequent are about an hour away and it's tiring dealing with the vibrating the whole way there.
 
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granitex

Skid Plates
Founding Member
Location
Columbus OH
Speed sensitive vibration is almost always tire or u-joint related.

when you had the u-joints replaced did you have both of them done, was the shaft put back in, in phase? Did it help for a short time when the joint, or joints replaced?

After that is there any chance that you have a bent axle shaft in the rear end. highly unlikely, but since I have one in the corner of my garage I do know that it can happen.
 

granitex

Skid Plates
Founding Member
Location
Columbus OH
The drive shaft might also be out of balance also. There is a counter weight somewhere on it, or should be at least, or posably a slight bend.
 

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It was at a shop when I got the u-joints in so I had them throw the new ones in. I took a look at their work and they match-marked everything, so I assume it was replaced in-phase. Given that this was happening BEFORE I had the new ujoints put in, I'm assuming it's likely not an out-of-phase driveshaft. This being based on the fact that my X was pretty neglected when I picked her up, so I doubt the ujoints were replaced at any point before I got it.

The driveshaft itself is pretty uniformly rusted, no dings, dents, or scrapes, so my best guess is it's intact. Unless a weight broke off when it was fairly new and it just rusted over and has been that way ever since. Another reason I'm really thinking it might not be the driveshaft is that I was under the impression the vibrations in a driveline are typically harmonic, correct? So it would kind of fade out after 60 and come in again later instead of getting worse and worse the faster I go. I could definitely be wrong here.

It sounds like an axle shaft might be my real problem... is there a good way to diagnose that beyond pulling them out? I'd love to be able to get a solid diagnosis before tossing money at the problem. This thing is starting to get expensive and I want to get into the "MORE MODS" phase rather than the, "welp, let's fix this now and hold off on the fun stuff" phase of my build.

Are you able to comment on what kind of vibration you had from the axle shaft being bent? Did it come in at a certain speed and just stay?
 

granitex

Skid Plates
Founding Member
Location
Columbus OH
You need to jack up the back of the truck and get the wheel spinning, you should see if there is any runout just by looking at it spin. you may have to spin it a lot faster than you think that you should.
 

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Great.... Well, I have access to a shop with nice lifts and an ASE Master Tech with a certification list as long as my arm to help out. Hopefully I'll be able to nail this problem down and post some details. There's an infuriating lack of information on anyone else having this problem, so I must just be lucky. Do you know if our driveshafts have foam or rubber balancers in them that can come loose? If it IS the driveshaft that would be the most likely issue since it's lived in the high desert all 15 years of its life and everything rubber and plastic has shrunk.
 

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That's good to hear, at least. There's a local machine shop that might be able to make me a new driveshaft with my existing yokes if it is the shaft that's bad.
 

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Haven't gotten around to checking this problem out more, but I'm really starting to suspect a bent axle is my mostly likely culprit. I'm going to attempt to check the run out on the rear wheels, then have the tires balanced (free with the tires, so why not?), then have the driveshaft checked. I'm hoping this will give me an idea of what's happening so I can get this problem fixed. If none of this provides any answers I'll start to suspect the bearing and seal on the tcase output shaft or something in the rear diff.
 

granitex

Skid Plates
Founding Member
Location
Columbus OH
If it the output seal on the transfer case is bad it will throw ATF allover the the driveshaft. They are pretty easy to change and cheap to buy, you have to drop the drive shaft to do it. If you have a vibration due to that being an issue would indicate that the transfer case would be shot.

Not that I think that is the case because you would have noticed all of the ATF covering the underside of your truck.
 

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And it ended up being a tire.... I'm pretty relieved it ended up being the second simplest thing for me to check and the easiest to get fixed. Still have some weird vibes and rumbles, but they very faint and for all I know could just be the roads around my area.
 
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