Help: Vibration from rear progessively worse over 70

[BigTex1968]

Okay ya'll, I am the FNG here and this is the first time posting. I have been reading Posts for some time and can't seem to get the right info for MY truck. I would ask ya'll to be patient with me on this and I'll try to get it all out. 09 LMM 2500hd SLT 4X4 Crewcab with 80,000 miles. Good tires on it and it's been leveled, no lift. DPF Delete done and EGR Delete done. I removed the other Part. Filter and hollowed it out and reinstalled. Cold Air intake installed and I have the Super Chips Programmer on. I have recently found that I am getting a vibration from the back at around 70mph and progressively gets worse the faster I drive. Tires were rotated, good to go. I have beads in them instead of wieghts but this started well after they were put in. Drive shaft U Joints seem to be good considering there is NO play in them at all. I can't find where the driveshaft has lost any balancing weights anywhere either. Now there is, what I have been told, a damper or a "bi balancer" on the end of the driveshaft before third member. I don't see rubber anywhere but I don't anything about this thing. It seems that this is my problem from the deducing I have done but the "Beaming" issue is something I am going to look into next. Is there something I am overlooking? This is getting very annoying considering I use the truck daily. Any help would be appreiciated.
Thanks Tex

 

[Ne-max]

The rubber is hard to see. Its between the round part and the yoke itself.

Get the truck up to 75 and throw it in Neutral and see if it goes away. Does it do it when you let off the throttle?

 

[BigTex1968]

To tell the truth I have not tried that. I notice it bad when passing 18 wheelers and I get on it pretty hard but never threw it into N... I will do that right now. How do I know if it is that balancer then if I can't see the rubber? What is it called so I can even look the crazy thing up?
Tex

 

[BigTex1968]

To tell the truth I have not tried that. I notice it bad when passing 18 wheelers and I get on it pretty hard but never threw it into N... I will do that right now. How do I know if it is that balancer then if I can't see the rubber? What is it called so I can even look the crazy thing up?
Tex

Oh by the way, when I get off of it when passing its still vibrating but never threw into N.

 

[Ne-max]

Hope this don't get me in trouble since there not a sponsor. Using this link for the Pictures.
http://www.merchant-automotive.com/115pinionyoke-1480seriesujoint.aspx

 

[BigTex1968]

Thank You so very much. At least now I have something to go on. I could never get a strait answer as to the name of it.
Tex

 

[BigTex1968]

Okay here I am still with the vibration going on with this truck. I took it on a very long trip and this vibration has me dumbfounded. It actually goes away!!!! On its own!!! I have not heard of this yet anywhere and my mechanics have not been able to come up with anything as of yet. I jacked the back up with floor jack and had someone run it up to 65+ and I can feel it in the bed but I dont see a damn thing out of whack anywhere. HELP please!!!!

 

[S Phinney]

Have you actually removed the drive shaft and inspected the needle bearings? I just had a truck that you wouldn't have thought there was a problem with it but the needles were completely gone.

 

[dirtydmax]

U joints,dont trust just because they look ok,I had the same thing to a t and 20 bucks for a u joint and presto,no more teeth chattering.:thumb:

 

[cat_dr.]

I'm also saying u joints had similar issues awhile back and driveshaft didn't have any play but up removing u joints I found this

Roll Tide!

 

[MACKIN]

With a bad joint I'm surprised it would take 70 MPH to show it's worn out vibration. Plus he said it goes away.

Usually ,just saying, at that speed it's usually in the tire. I don't believe in balancing beads. If the u-joints turn out good balance the tires with exterior weights.

 

[dirtydmax]

maybe lost a drive shaft weight

 

[Andrew]

maybe lost a drive shaft weight

I can't find where the driveshaft has lost any balancing weights anywhere either. Already been stated :thumb:

 

[Ridin'GMC]

I'm having the same issue now. Just had my tires rebalanced a week ago and does that at 60-75 mph. Before I had a loose rear axle wheel bearing that wiped out my seal and it did that. I noticed it when gear oil was leaking on the rear brakes. I'll have to check out my u joint this weekend and fix the leaking axle seal.

 

[MACKIN]

Many have cracked the housing on the Allison do to bad U-joints so beware!