Vibration

[pete m]

Now I have a new problem, hoping someone here has seen this and has a fix, as I and my mechanic do not.
2006 2500HD crew cab long bed truck, transfer case was leaking pretty bad from the rear seal, noticed the carrier bearing rubber was ripped and not in good shape between the 2 driveshafts, ordered both items from GM dealer, marked the driveshafts for phasing before removal, changed the carrier bearing, checked everything on the shaft, all u-joints look to have been changed recently, all appear in very good shape, no binding anywhere, installed the new oil seal. Drove the truck, has a bad vibration from 35 to 55 MPH, is not noticeable below or above that speed, and makes the vibration if slowing down to below 55, this is running empty with no load. Took truck back to shop, he took out the shaft and inspected everything, nothing wrong, put truck on the lift and ran in gear to inspect shaft while running, nothing wrong, looked perfect, shut truck down and placed a 4 foot straight edge along shaft to check to see if bent anywhere, nothing. Another mech. said maybe bad wheel or rim, so we took the front tires and put them on the rear, same thing, rear balancer on the shaft is in good shape, not damaged or spun. Any ideas????????????????????, thanks.

[DmaxMaverick]

This usually happens with a modest load. It's more rare empty, but can happen. It will eventually be called "frame beaming", by GM (there's a bulletin on it, and it's mostly hogwash, IMO). Not a lot you can to about it. This happens occasionally with the really long trucks (with 2 piece shafts), of all brands. Try indexing the rear U-joint 180° on the pinion. If no change, return it, and do each joint (rear to forward) one at a time, testing after each. A time consuming PITA, but it works, sometimes.

If nothing improves, return each joint to original. The problem is likely in the TC, or less likely in the rear diff.

[pete m]

I was hoping you would respond Dmax, you seem to have experience with this sort of thing from what I read.
Forgot to mention that before I had these items changed, there was no vibration at all running empty, when I was towing 8000 lbs. I felt it a little, but no where near as bad as it is now, thats why I started looking at the shaft and found the bad carrier. Today he did move the rear joint 180, maybe a little better, not a lot, he says he is out of ideas. I don't want to just "live with it" like this, as I feel it will cause some damage either in the TC or rear. Is it possible that the vibration was there all along with the ripped carrier rubber and I just did not notice it?, and now with a new bearing it is more noticeable? Truck has 95K, 1 previous owner, and no heavy towing or reported accidents, HELP!!!!!!!!!!!!!!!!!!!!.

[christophersond]

I had a GMC 2500HD,long bed, with the same vibration. The problem is with the dual drive shafts on the truck. The dealership tried to work the vibration problem out of the truck, but were unsuccessful. They finally said there wasn't anything they could do as the problem was inherent to the truck. GM, and the dealership worked with me, and I traded the 2006 in on a 2009 GMC 2500HD, short bed truck--got a heck of a deal. Life is good.:)

[dually2002]

I have a crew cab long box dually that had the same problem that you are describing. I also had drive train slack or a clunk when almost to a full stop and when starting from a dead stop. Changed the carrier bearing and it cured both problems. Not that the bearing portion was bad but I think the rubber support portion compressed enough to cause a problem in the in the geometry of the shafts. There was a noticeable difference in the rubber portion of the carrier between the new and old assemblies.

[NutNbutGMC]

In early 2001 - 2002 days, there was a similar issue of low-end shudder on the two-piece shafts. Under a TSB directive, they replaced it with a solid one-piece. Done deal. I had this replacement done to a 2001 model and it fixed any and all shudder and vibration problems.

[npauli]

I wouldn't rule out beaming as a possibility. Sure, there's a lot of driveline issues that could cause a vibration, but that's not the only possibility.

I believe the "beaming" explanation isn't all hogwash (though other problems have probably been incorrectly diagnosted as beaming).

GM didn't put enough technical details in the beaming TSB to satisfy me, but it sounded like:
1) the frame has a vertical bending mode (alternatively smiles and frowns) at some frequency
2) that frequency gets excited at certain road speeds - I think the TSB said it had to do with the wheel rev frequency, not the drive shaft frequency, but I could be remembering wrong.

If it is beaming, and not other driveline issues, it should be improved with:
1) few hundred pounds in the bed - this changes the resonant frequency to be lower, so it happens at a lower road speed and probably isn't as bad. I think the TSB said to put 500 lb in the bed to diagnose if this is the problem or not.
2) add a tuned absorber somewhere near the center of the truck, tuned to the same frequency to absorb energy from this vibration. I've heard that some trucks do this, but haven't seen one with my own eyes.
3) Redesign the new trucks to used boxed in frames and/or hydraulic cab mounts. Multiple OEM's are doing this.


Mine vibrates sometimes at ~ 40-45 mph at light load.

[DmaxMaverick]

In early 2001 - 2002 days, there was a similar issue of low-end shudder on the two-piece shafts. Under a TSB directive, they replaced it with a solid one-piece. Done deal. I had this replacement done to a 2001 model and it fixed any and all shudder and vibration problems.

Doesn't apply to CC/LB trucks. They must have a 2 piece shaft (it's just too long). Shorter chassis trucks were updated with the 1 piece shaft.

[DmaxMaverick]

I wouldn't rule out beaming as a possibility. Sure, there's a lot of driveline issues that could cause a vibration, but that's not the only possibility.

I believe the "beaming" explanation isn't all hogwash (though other problems have probably been incorrectly diagnosted as beaming).

GM didn't put enough technical details in the beaming TSB to satisfy me, but it sounded like:
1) the frame has a vertical bending mode (alternatively smiles and frowns) at some frequency
2) that frequency gets excited at certain road speeds - I think the TSB said it had to do with the wheel rev frequency, not the drive shaft frequency, but I could be remembering wrong.

If it is beaming, and not other driveline issues, it should be improved with:
1) few hundred pounds in the bed - this changes the resonant frequency to be lower, so it happens at a lower road speed and probably isn't as bad. I think the TSB said to put 500 lb in the bed to diagnose if this is the problem or not.
2) add a tuned absorber somewhere near the center of the truck, tuned to the same frequency to absorb energy from this vibration. I've heard that some trucks do this, but haven't seen one with my own eyes.
3) Redesign the new trucks to used boxed in frames and/or hydraulic cab mounts. Multiple OEM's are doing this.


Mine vibrates sometimes at ~ 40-45 mph at light load.

I agree. Frame beaming, in itself isn't hogwash. The bulletin, diagnostic process, and GM's general approach to it is the hogwash. They stopped short of what I consider an acceptable diagnosis and solution. Beaming can be eliminated, or at least minimized, and/or compensated. This is not a new chassis configuration, or a new condition. Long chassis have had multiple segment prop shafts for a century. The problem should have gone back to the engineers, not a complaint department (which is where the bean counters hang out). Most of these chassis length/configuration do not have this issue, so it is absolutely avoidable or correctable. Frame beaming is the effect, not the cause (which current mfg's seem to get lost).

[DmaxMaverick]

I was hoping you would respond Dmax, you seem to have experience with this sort of thing from what I read.
Forgot to mention that before I had these items changed, there was no vibration at all running empty, when I was towing 8000 lbs. I felt it a little, but no where near as bad as it is now, thats why I started looking at the shaft and found the bad carrier. Today he did move the rear joint 180, maybe a little better, not a lot, he says he is out of ideas. I don't want to just "live with it" like this, as I feel it will cause some damage either in the TC or rear. Is it possible that the vibration was there all along with the ripped carrier rubber and I just did not notice it?, and now with a new bearing it is more noticeable? Truck has 95K, 1 previous owner, and no heavy towing or reported accidents, HELP!!!!!!!!!!!!!!!!!!!!.

I'm not sure what to tell you at this point. I suggest replacing the carrier bearing assy with another new assy. Your condition is probably NOT beaming, as you didn't experience this before the replacement, and it happens with little/no cargo load. I mentioned the frame beaming because that is the ultimate conclusion you should expect from GM (not because I think that is what it is).

If you begin replacing U-joints, I have had excellent service from the "Brute Force Heavy Duty" joints (Autozone). They are non-grease zerk type, which I prefer for heavy duty use. If your current joints have grease zerks, ditch them at your soonest convenience.

[NutNbutGMC]

Doesn't apply to CC/LB trucks. They must have a 2 piece shaft (it's just too long). Shorter chassis trucks were updated with the 1 piece shaft.Thank you.

Indeed. Mine was not LB.

[pete m]

What could be wrong with a new GM assemby?, this part alone cost me $170. The u-joints were replaced by the last owner within the last year, all look perfect. I don't think thats the problem since I drove this almost 5000 miles as it was with the leaky seal and bad carrier and with no load it made no noise or vibration. I kept checking and filling the TC about every other week, would be down about 1/2 a QT. or less. After changing the seal and carrier the problem started.
On a positive note, I have about 200 miles on it and the seal does not leak a drop.

[DmaxMaverick]

What could be wrong? Any number of things. They are still made by human hands. There could have been a design change or two, and you got one that should have been purged from the system. I dunno. I've bought several new products bad right out of the box (albeit, less OEM's than aftermarkets).

You had a smooth driving truck. You changed something. Now, it is not smooth. You must go back to what changed. I don't suggest reinstalling a leaky seal. If you were located close to me, I'd be happy to get hands on (I do that often for TDP members and others).

[pete m]

Dmax, do you have the part number for the current bearing?, I want to compare that to the one i was given from the dealer, he did not have it in stock, he had to order it from the warehouse, maybe it was the wrong one??????????.

[DickWells]

A couple of things come to my mind. First, when I drove my 04 CC-LB, empty, used, the day I found it, I had frame beaming, and didn't know it. I asked that the wheels be balanced before I picked it up. They showed me the TSB the next day. Upshot is, when I put my tool boxes in the bed, the vibration went away!
When I changed to air suspension, in back, in 07, I got a shim, about 5/8 thick to put between the mid carrier bearing and cross-member. Again, no vibration. Don't know if you've changed that carrier bearing or not, but if you have, it seems that it is possible to install it backwards???? Not sure. There are two. Your's is likely the larger one. Interesting that my rubber isolater has looked "shot" ever since I bought the truck, but still not ripped out, so I haven't changed it. You might try droping that block, say, 5/8" or so, and see how it works. That's IF DMAX's plan of rotating the U joints doesn't work out. He has to be right in his assumptions. No way around it, if the thing was smooth before.
Good luck.:)

[DmaxMaverick]

Dmax, do you have the part number for the current bearing?, I want to compare that to the one i was given from the dealer, he did not have it in stock, he had to order it from the warehouse, maybe it was the wrong one??????????.I don't have the part #. I'd have to look it up, and that wouldn't help you any. The part # hasn't changed, that I know of, but that doesn't mean they haven't changed the design, materials, or you just got a bad one.

[pete m]

Both shafts were marked with paint marker before removal, this guy has done a lot of big truck repairs and was well aware of shaft phasing. He is positive they were re-installed the way they came out, the seal would not cause this problem, so it must be the carrier. I drove the truck almost 5000 miles before the repair, and he borrowed the truck to move something the day before, so he too drove it and agreed there was no vibration at all. For that reason, we do not want to take the shafts apart and rotate u-joints since they were recently replaced and were not a problem before the last repair. He says the carrier can't be installed backwards, however, he did mention trying to shim it down because of the angle from the transfer case is pointing down, and shimming it down would maybe help, so we are trying that next week, not sure what could be wrong with the new bearing, it does not have any tight spots or binding, and he said it was fairly easy to install, we will see.

Dmax, was asking for the part number to see if maybe there was a change on the bearing that included a different part number.

Hey Mark R., you reading this dilemma?, figured with all your millions of miles towing you would of run across something like this, feel free to chime in anytime.

[pete m]

Tried 1/2" of shim under the carrier, seemed a lot better, so we are making an aluminum block for a spacer and will need new mounting hardware to accommodate, and will be 2 or 3 different sizes to see what works best, its a band aid fix to cover-up a problem, but with everything else replaced, and $350 spent so far, I will not drive the truck with this NEW vibration, mech. says he doubts there is anything wrong with the new carrier, and dealer will not replace it unless it is visibly defective they said, and the mech. says he wants to be paid for labor to remove and replace the carrier, well over $200 with another bearing and no guarantee. I will try the shim, if I am not happy, I'll just sell the truck, and never buy another one with a carrier. I finally get a loaded up diesel with the HO motor, under 100K, and I now hate to drive it because i tried as usual to stay ahead of a problem by replacing a worn part. I believe, the original bearing probably had bad vibration too, and ripped the rubber out along with damaging the rear seal on the trans, after the rubber tore out it stopped the shake.