*UPDATE* - It's Definitely a Drive Shaft Vibration...

Had a loud tinging couple months back that turned out to be a rock that had worked its way into one of the heat shields on the exhaust!

Someone suggested tires, doubt they'd cause that much shudder but could always pay a little extra and have them road force balanced!

 

I had the same problem and traction bars solved them. Stops the axle from rotating and then causing the vibrations from the axle missalignment. The aal doesnt stop axle wrap it as much as some would think. Other members here have had similar results.

 

My vibrations were from the factory. A well known defect, and lift kits are known to increase the issue or bring it about if it wasnt there before. Mine would occur when accelerating from a stop and up to 15mph is driven normally, up to 25mph with the agressive acceleration. You may be able to fix it with the carrier bearing drop, but if not everyone who has put traction bars on has eliminated their acceleration vibrations. Ask around.

 

+1 My traction bar project was, as referenced by WOODEX M.E., because of very slight factory vibration, on stone stock suspension. (dealer said "normal") After recording about 20 minutes of video of the rear suspension, watching pinion movement and spring distortion, I concluded that limiting my pinion gear "rise" to about 12 - 15 degrees - under mild acceleration, would "fix" it. And in fact it did. My contact or "slapper" traction bars, limit pinion gear movement to about a 12 degree rise. The bars are angled up at 13 degrees from horizontal from the spring perch, following the spring contour, and contact the front spring eye. Are bolt on, adjustable, silent, and have no effect on ride quality. The most dramatic improvement came under aggressive acceleration and crawling over obstacles, where the axle really wants to "wind" up. FYI

 

I'm definitely going to take the time to measure my drive angles this weekend and decide if dropping the carrier bearing will be worth it. If my drive line angles are within spec or close to within spec I'll probably start researching custom (i.e. affordable) traction bar solutions. Because this issue doesn't bother me nearly enough for me to justify spending $400-$500 on a traction/ladder bar made for serious off road use.

 

y'know the tread pattern on your tires could cause vibration that "goes away" as it smooths out at speed.

 

I feel like if that were the case I'd feel it in the steering wheel and as I've mentioned the "shudder" I feel on takeoff is felt more in my seat or the floor. This is what makes me think it's coming from the rear of the truck. Either the drive line or the axle.

 

If you want proof for yourself if it is axle wrap, use a go-pro or borrow one and mount it under the truck. When you go to accelerate you'll see the axle wrap and the drive shaft start to run out. It is a large/visible amount and you'll feel it at the same time when you go back to look at the video. I saw a couple videos of people doing that, don't know if it belonged to jbrnigan or not, but it was all the same result. Plus it will cost you nothing to try.

 

https://www.youtube.com/watch?v=ozF3KsHBFB4

https://www.youtube.com/watch?v=r-qy0qzdl6E

 

I can almost guarantee the axle in my 2009 look very similar to the first video posted. Even at slow start speeds. And if the drive line angle changes that much during takeoff I can understand why I feel the shudder...

 

You can see in the back he has 2 leaf springs and an overload you have far more than that.

 

That is a correct statement. I now have 6 leafs plus the overload...

And I just got back from a short trip in the truck. I was driving with no AC and no radio on with both front windows down. It does appear that the "shudder" I feel at takeoff is present to a lesser extent at almost any speed up to 40 mph. It's not nearly as consistent and it seems to vary depending on the road surface but the truck is definitely much smoother over 40 mph than it is under. This leads me to believe the drive line angles are the cause of my shudder more so than axle wrap. I even tried to stomp on it on one or more takeoffs and the "shudder" doesn't seem to be any worse when I do that which all but eliminates axle wrap as the cause...

 

If its not shuddering more when you accelerate hard, especially with all those leafs it may not be axle wrap. adjusting the carrier bearing is super cheap and may be your solution.

 

Just curious, when you installed the AAL, what did you do with the OEM shims?

 

If there were any, the OEM shims are still installed. I just crawled under the truck and I didn't see anything that looked like an axle shim though.

 

Another vote for carrier bearing drop.

I had the same/similar shudder on takeoff after getting an AAL installed. $10 part, five minutes of work. Mine is probably 95% cured. If I'm focused on looking for it, I can still barely feel it. It's subtle enough now, that if this thing was installed at the same time as the lift, I would have never noticed it.

 

They're hard to see. I left mind out in order to get s better driveline angle. I don't have any issues with my lift.

 

As far as I know there are no shims from the factory.

A side note as well - I wouldn't go with the ATO/4X trac bar unless you plan to change out the studs in the rear axle as well, they will sheer right off.

 

Have about 25 bucks in my tractions bars - primarily the snubbers, tried urethane but went with a softer durometer "equipment isolater" for the contact point. Square tubing and mounting plate was scrap from other projects. I'm not sure what "serious" off road use is, but, my "custom" bars have been very effective in "moderate" situations (no sliders on my truck) and was the "fix" for street use.

 

I was referring to the Bud Built and other bars that are readily available and don't have to be custom built. I don't have the ability to weld so custom traction bars would become expensive by the time I found someone to build them for me. That and after driving my truck more and more with the lift I'm beginning to think the "shudder" I'm experiencing isn't axle wrap and is in fact a driveline vibration that's only noticeable at very low speeds. I've turned my attention towards finding time to measure driveline angles and will likely be doing a CB drop or installing axle shims.