Shake or Vibration Issues

07Softail · October 17, 2016

I can tell you it's not the body mounts! PEOPLE IT'S THE DAMN DRIVESHAFT FOR GOD SAKE!!! Have any of you even read my post!

RT

Newell33 · October 18, 2016

I can tell you it's not the body mounts! PEOPLE IT'S THE DAMN DRIVESHAFT FOR GOD SAKE!!! Have any of you even read my post!

RT

There are a lot of pages in this thread. I'm guessing you haven't read all of them. There have been plenty of others that have taken their driveshafts to specialty powertrain shops to have them checked. A very small percentage have had driveshaft issues. Most have mentioned that theirs have checked out ok for both runout and balance. The consensus is that it's not one single issue with these trucks, there are multiple reasons for the vibrations.

Brianibew · October 18, 2016

I can tell you it's not the body mounts! PEOPLE IT'S THE DAMN DRIVESHAFT FOR GOD SAKE!!! Have any of you even read my post!

RT

If you go back and read the 600+ pages, you'll find other people have done the same thing you have done but it didn't have an effect on the vibes.

07Softail · October 18, 2016

There are a lot of pages in this thread. I'm guessing you haven't read all of them. There have been plenty of others that have taken their driveshafts to specialty powertrain shops to have them checked. A very small percentage have had driveshaft issues. Most have mentioned that theirs have checked out ok for both runout and balance. The consensus is that it's not one single issue with these trucks, there are multiple reasons for the vibrations.

If you go back and read the 600+ pages, you'll find other people have done the same thing you have done but it didn't have an effect on the vibes.

I am part of the 600 pages if you would read them you would see that!

RT

slopra · October 18, 2016

I am part of the 600 pages if you would read them you would see that!

RT

That makes you sound even more ridiculous for saying and yelling over and over that the driveshaft is the issue. If you were part of the 600 pages then you would know, as Newell33 and Brianibew have already pointed out, that checking for runout/balance and then balancing or replacing accordingly has only fixed a small percentage of vibration issues in these trucks.

Congrats on finding the source of vibration with your truck and thanks for sharing. But quit trying to shove it down people's throat and then getting upset when people don't acknowledge you. You haven't contributed anything by just yelling DRIVESHAFT in this and every other vibration thread you bumped.

It's very obvious that there are many many things causing vibrations in these trucks. I think the goal here should be to simply give everyone the knowledge to properly diagnose which is exactly what I've been trying to do.

abominable z71 · October 18, 2016

I can tell you it's not the body mounts! PEOPLE IT'S THE DAMN DRIVESHAFT FOR GOD SAKE!!! Have any of you even read my post!

RT

If the PICO is picking up a T1,T2 or T3 vibration. Its not possible for it to be the driveshaft for a T1 or T2. The angular velocity is too low to coincide with a driveshaft. A T3 vibration is a possible driveshaft vibration but only for a truck with a 3.08 ring and pinion because the shaft is spinning at very close to 3x the tire angular velocity. However if the truck has a 3.42 or 3.73 gear set the drive shaft is spinning too fast to be mistaken for T1,2 or 3 vibration. It's just not physically possible for a dive shaft rotating at say 43 Hz at 72 mph to induce a vibration reading at 13 26 or 39 Hz. Congrats on getting yours figured out though too bad most are not so lucky. The body mounts on these trucks have been suspect since the beginning, the real question would be why only a handful of them have resonance issues.

Willyone · October 18, 2016

I'm not buy'n the body mount thing at all, or the frame thing either. I guess new & improved mounts could help in some cases. But I believe back in the day cabs and beds were just bolted to the frame? I've been driving GM 1/2 & 3/4 ton 4x4s for 35 years or more and never had a vibration problem like what I and allot of others here have now. At least nothing that a tire/wheel balance wouldn't cure. I'm pretty sure it's drive train related. My '16 Z71 goes back to the dealer on 10/25 which will be it's 2nd vibe visit. Of course I'm hoping they find/fix the issue, but I'm not overly optimistic. I'm think'n on this one, Murphy's law has a hold on my Z, and me. But I will post any positive results if there are any.

Edited October 18, 2016 by Willyone

Smickie500 · October 18, 2016

Anyone ever research Sorbothane for use as a cab mounts. This stuff is the cat daddy for absorbing vibrations..

07Softail · October 18, 2016

If the PICO is picking up a T1,T2 or T3 vibration. Its not possible for it to be the driveshaft for a T1 or T2. The angular velocity is too low to coincide with a driveshaft. A T3 vibration is a possible driveshaft vibration but only for a truck with a 3.08 ring and pinion because the shaft is spinning at very close to 3x the tire angular velocity. However if the truck has a 3.42 or 3.73 gear set the drive shaft is spinning too fast to be mistaken for T1,2 or 3 vibration. It's just not physically possible for a dive shaft rotating at say 43 Hz at 72 mph to induce a vibration reading at 13 26 or 39 Hz. Congrats on getting yours figured out though too bad most are not so lucky. The body mounts on these trucks have been suspect since the beginning, the real question would be why only a handful of them have resonance issues.

You didn't read my post either! It was a SHAKE not a vibration more like a tire being oval....not like driving over rumble strips in the road. Body mount theory is bullshit and if they come out with new ones it's just going to mask the real problem. Go ahead and discount my finding but the shop I went to said he has fixed a ton of them and Dodge trucks also which have AAM driveshafts as well. They did not have to balance it either they only straightened it and it was pretty much bent in the middle a 1/16 of an inch which throws each end of the shaft off severely. Take a straw and slightly bend it and look at each end (not 90 degrees anymore) to see how that will affect the trans yoke and the pinion end of the the rear axle and would also support the issue of a lot of pinion bearings and pinion nuts being lose or ruined and having to be replaced. BTW the dealership put that pico meter on the truck and found nothing even when I took him for a ride and the cab felt like it was going to shake off of the chassis so I have ZERO faith in the service dept or GM to find this issue. Have fun looking elsewhere

RT

Edited October 18, 2016 by 07Softail

slopra · October 19, 2016

You didn't read my post either! It was a SHAKE not a vibration more like a tire being oval....not like driving over rumble strips in the road. Body mount theory is bullshit and if they come out with new ones it's just going to mask the real problem. Go ahead and discount my finding but the shop I went to said he has fixed a ton of them and Dodge trucks also which have AAM driveshafts as well. They did not have to balance it either they only straightened it and it was pretty much bent in the middle a 1/16 of an inch which throws each end of the shaft off severely. Take a straw and slightly bend it and look at each end (not 90 degrees anymore) to see how that will affect the trans yoke and the pinion end of the the rear axle and would also support the issue of a lot of pinion bearings and pinion nuts being lose or ruined and having to be replaced. BTW the dealership put that pico meter on the truck and found nothing even when I took him for a ride and the cab felt like it was going to shake off of the chassis so I have ZERO faith in the service dept or GM to find this issue. Have fun looking elsewhere

RT

Shake, vibration, shimmy, jiggle, whatever you want to call it, it's all the same thing. The oscillating component that's causing you to feel something is producing a frequency. That frequency directly correlates to whatever you're feeling. You then measure that frequency and can use the speed you were traveling/what gear you were in, to determine what could have produced that frequency. If I'm feeling a 10-14hz frequency at highway speeds, I know that it simply isn't possible for that to be coming from the driveshaft. That can only be coming from something in the wheel assembly.

No one is discounting your findings, we have no idea what the frequency of your shake was anyway. (the dealership definitely found something with the pico meter, they just didn't know what to do most likely. that or they didn't install it right) The issue is you arguing the fact that every one of these trucks with a vibration issue is having a driveshaft issue...that's a ridiculous claim.

I totally agree with you that new body mounts is only going to mask the real problem. It could reduce the vibrations transferred to the cab in theory, but the oscillating component is going to keep on doing so, which is only going to damage other components on the truck. With the many many different vibration symptoms owners are reporting I truly believe that GM just has a QA problem. The part manufacturers could have poor QA or poor tolerances, or GM could be installing parts wrong, but at the end of it all GM QA should catch any of it, or a good chunk of it at least.

abominable z71 · October 19, 2016

You didn't read my post either! It was a SHAKE not a vibration more like a tire being oval....not like driving over rumble strips in the road. Body mount theory is bullshit and if they come out with new ones it's just going to mask the real problem. Go ahead and discount my finding but the shop I went to said he has fixed a ton of them and Dodge trucks also which have AAM driveshafts as well. They did not have to balance it either they only straightened it and it was pretty much bent in the middle a 1/16 of an inch which throws each end of the shaft off severely. Take a straw and slightly bend it and look at each end (not 90 degrees anymore) to see how that will affect the trans yoke and the pinion end of the the rear axle and would also support the issue of a lot of pinion bearings and pinion nuts being lose or ruined and having to be replaced. BTW the dealership put that pico meter on the truck and found nothing even when I took him for a ride and the cab felt like it was going to shake off of the chassis so I have ZERO faith in the service dept or GM to find this issue. Have fun looking elsewhere

RT

Shake or Vibration is merely semantics. Periodic displacement of a rigid body regardless of how high or low the frequency may be is a vibration. Call it a "shake" if you like. I never discounted your finding, I believe GM allows .020" of run out on their drive shafts which 1/16 is way out of spec. I gave a little more thought to your straw analogy and you make an excellent point regarding the ends not being perpendicular to the shaft or parallel to one another but the shaft still showing to be balanced. You can balance anything even a square tire but anyone knows the ride would be terrible but as long as the CG is inline with the rotational axis it will balance this can compensate for the bend in the shaft especially if you chuck the drive line around the main tube itself as opposed to the u joints (which I believe is how the typically do it) to perform the balance but once you connect it to the the u joints on the pinion flange and slip yoke in the truck the CG will move and you now have an imbalance causing a shake or vibration. Whats really odd is this should have showed on a vibration analysis, although my experience is most dealerships don't have any idea how to use the equipment properly, it's like they invest in the equipment not in the training to use it properly. I don't doubt this fixed your issue but I don't believe it to be the only thing on these trucks out of spec causing NVH issues. Many have noted that trucks vibrate worse in the heat and less or not at all in the cold, Rubber and plastics are the most susceptible to changes in their physical properties under moderate temperature swings a slight change in these properties can be enough to cause resonance especially if the were designed real close to the natural frequency. That being said a lot of people have mentioned a change in the body mounts would just masking the real issue, this is not necessarily true everything that rotates vibrates proper damping is why you don't feel it and these body mounts might not be properly designed. Case in point some motor mounts required a 3 mm shim because customers were feeling motor vibrations at idle. No one ever said well they're just masking the real problem that the motor just vibrates too much at idle and that something must be done to fix the engine, build a motor that doesn't vibrate and you don't need motor mounts at all.

07Softail · October 19, 2016

Oh Brother! You guys are something else, you all have fun chasing it all you want glad I figured it out see ya!

RT

C6Bill · October 19, 2016

Glad you got your's fixed Robert, happy trucking to you

Newell33 · October 20, 2016

Oh Brother! You guys are something else, you all have fun chasing it all you want glad I figured it out see ya!

RT

I love it... 600 pages of people trying all kinds of fixes. Some work on some trucks, and some don't. A guy reads 10 pages, tries a driveshaft fix, and holy moly he's got the whole thing figured out! Congratulations on your fix, and on how you've so eloquently communicated it!

Snoringbear · October 20, 2016

I love it... 600 pages of people trying all kinds of fixes. Some work on some trucks, and some don't. A guy reads 10 pages, tries a driveshaft fix, and holy moly he's got the whole thing figured out! Congratulations on your fix, and on how you've so eloquently communicated it!

Well, I must say I have found this thread entertaining reading, even informative on occasion. My take-away is that the problems and subsequent solutions offered are very varied (all over the map). And, consequently, vibration/shake is not and will not ever manifest itself as a recall or class action suit. Adding to the mix is the fact that a considerable number of the posters are DIY guys driving modified vehicles and thereby their experiences and problems just muddy the water so to speak. But, I wish no one ill will for sure. Just saying that if you're waiting for a mass bailout on this generation truck you're going to wait a long time. Calf Rope, I'm through