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Posted

I am not an engineer by any means but I think you are heavily exaggerating saying it will be "detrimental" to the vehicle. In my line of work I am offroad on daily basis, more than 99% of the public who own 4x4 trucks. We beat the crap out of them, dent drive shafts, ride around with out of balance tires, warped rotors, etc. None of my work trucks ever stay vibration free for more than a few months but we ride them till about 150k miles or so (3 to 4 years) and then buy new and auction the old ones off. They look like crap when we get rid of them but the engine runs, tranny shifts, and front and rear diffs are still functioning. Unless the vibration is coming from diffs that are all screwed up, those of you with the vibrating trucks will be riding them with little to no problems till you decide to get rid of them. My truck also still vibrates but it comes and goes based on how long it has been sitting, temps, tire pressure, etc.

There is a huge difference between the user being off-road causing a causing the truck to rock, vibrate & shake that way and the truck itself being the source of the vibration. When off-road the truck my scrape, and rock, but the entire vehicle is doing it at the same rate, although the individual parts may have a different rotational and translational momentum, they are still bolted into place and are designed to be off-road. When the truck itself is causing the vibration, it can indicate parts being misaligned, excessive and not enough torque being applied to parts etc. not to mention the constant vibration will end up causing the interior panel clips to become loose, hurt the integrity of various shafts, can cause exterior panels and doors to become loose etc. the severity of the vibration has alot to do with the frequency that it is, how often it occurs etc. Remember off-roading is more bumps than vibration, which depending on the severity of the bump, can be just as detrimental, but they in most cases occur with a much lower rate.

Posted

I am not talking about the bumps and vibrations when I am off road, I am talking about how my work trucks vibrate and shake all the time. I cover a 5 hour radius from my home base so I sometimes drive for hours on the interstate till I get to a work site and then I am offroad for how ever long it takes me to do what I need to do. Those hours on the interstate my work truck (present and past) shake like crazy mainly due to out of balance tires but also includes wore out shocks/struts, drive shaft dings, etc. I usually try and get the tires rebalanced when I can but a month or more may go by before I get around to it. My work truck(s) can shake as bad as some of the videos posted in the vibration thread but as I mentioned before, we drive the trucks till they are beat up and go get new ones. I know we are talking about two different things but on these new trucks unless it is severe vibration I think it is just more of an annoyance than anything else.

Posted (edited)

Visited a Chevrolet dealer today with a magnet in hand.

Crawled under every Silverado 1500.

The models having a one piece aluminum material drive shaft are double cab with 6.5' box,

crew cab with 5.5' box.

The model having the two piece steel material drive shaft is the crew cab with 6.5' box.

The model having the one piece steel material drive shaft is the Z71 off road crew cab with 5.5' box.

Regular cab both 6.5 ft and 8 ft boxes have one piece aluminum material drive shafts.

Those models were the only models the dealer had on the lot.

 

Impacting my fingers on the 5" diameter aluminum drive shaft , the thickness of the tube seemed quite thin.

Edited by raven3
  • Like 1
Posted

Visited a Chevrolet dealer today with a magnet in hand.

Crawled under every Silverado 1500.

The models having a one piece aluminum material drive shaft are double cab with 6.5' box,

crew cab with 5.5' box.

The model having the two piece steel material drive shaft is the crew cab with 6.5' box.

The model having the one piece steel material drive shaft is the Z71 off road crew cab with 5.5' box.

Regular cab both 6.5 ft and 8 ft boxes have one piece aluminum material drive shafts.

Those models were the only models the dealer had on the lot.

 

Impacting my fingers on the 5" diameter aluminum drive shaft , the thickness of the tube seemed quite thin.

theres a shock lol

Posted (edited)

On a quality drive shaft the run out tolerance measured at each end should be no greater than .005".
The centripetal force caused by Excessive run out of the drive line tube will excite vibration, even if the
drive line is perfectly dynamically balanced.

The drive shaft can be heated with a gas torch and water cooled to reduce the run out using a drive line machine similar in appearance to bench type lathe and a dial indicator.
Noticed all the aluminum drive shafts have welded tube to yoke joint with a circumferential bead weld.
Welding will distort the tube.
Have an aluminum drive shaft removed from a 1989 ,non GM light duty truck, where is there no circumferential weld, as typically used on steel drive shafts.
The aluminum yoke is pressed into the tube with an external collar sleeve over the yoke to tube joint.
A pin is inserted through the joint connection. The aluminum pin has only a small tack weld on each end the collar
to secure it in place. Aluminum welds are sensitive to fatigue cracking caused from vibration.

A quality drive line is bench balanced using specialized drive line machine with counter weights tack welded on both ends of the drive line tube. The bench method uses a dial indicator.
The tolerance is only .002" run out for a quality drive shaft.

Of all the dozen 2015 Silverados I crawled under at the dealership , found no counter weights on any aluminum drive shafts.

Balancing the drive shaft installed on the vehicle has advantages.
The mass of the differential pinion shaft , housing, pinion gear are integrated into the balance as opposed to a bench method balance.
Stainless steel worm screw hose clamps secured the drive shaft tube maybe used.
The worm screw and cap weight approximately 1/2 ounce.
A small hand held vibration analyzer, strobe light and vibration sensor maybe used to balance the drive shaft.
The analyzer will indicate the frequency of maximum vibration amplitude and the level of amplitude.
In addition, the tubes are not perfectly straight and some are bowed more than others.
The straighter the tube the smoother it will run.

A quality drive shaft will have a .010" maximum run out tolerance at center of the shaft

compared to .005" run out tolerance at the ends.

Edited by raven3
Posted

My 2014 with the aluminum drive shaft does have a counter weight on it near the rear diff side.

Posted

Update,

 

Had the truck at the dealers yesterday afternoon and they did not fix the issue but here is what they did. Re-balanced all four tires, fixed weight issue on a few and they wanted to check the rims but their machine was out of service so I have to go back for another service call for that. Dealer could not guarantee that this would fix the issue because they could not drive the truck due to rain. They advised to call back if the issue continued. After the service call it seemed to be worse so I headed to my father in-law's to try his rims and tires from his GMC Sierra. His tires (Goodyear) and rims (steel) were the same size but different brand with almost 14k miles on them. After placing his tires on my truck I really noticed the vibration/shaking. So it seems, the more miles on a tire and lower PSI I notice the issue, the newer the tire with more PSI the less I notice the issue. I may be wrong in thinking it's the tires that's causing the issue. If it was the tires the vibration should have stopped with his.

 

Also, my father in-law drove his truck with my rims and tires and felt no vibration or shaking, smooth ride!

 

I will be calling the dealer back today to schedule another service call. I’ll update the post from my next visit.

 

I have the 20" wheels on my truck and we swaped out for some 17" wheels to see if the wheels and tires were the issue. I also found that it was not. The first dealer I took it to didn't want to go any further. The second dealer rebuild the rear diff. That seems to have fixed it. I am about 500 miles in on that repair that happened last week. Good luck.

Posted

Realize the forum is all about GM truck but made a comparison of drive shafts of 2015 Silverado vs 2015 F150.

The drive shafts are completely different in design and material.

Silverado uses a single section aluminum drive shaft for all configurations, except crew cab with standard box,

which incorporates a two section steel drive shaft with an intermediate support bearing and the Z71 crew cab with short box, which has a single section steel material drive shaft.

All the drive line tubes are welded to the yoke.

 

F150 uses a two section steel material drive shaft on all configurations with intermediate support bearing, except the regular cab regular box, which has a single section aluminum material drive shaft.

The tubes are press fit and heat shrunk to the yoke with pressed fit compression ring over the tube for steel and aluminum drive shafts. There are NO welds.

 

The drive shaft must have have maximum .005" runout tolerance on the ends and a maximum .010" run out tolerance in the middle of the tube.

 

The drive shaft must also be dynamically balanced.

Note that the drive shaft maybe balanced, but still have excessive run out.

Excessive run out will cause excessive forces can create vibration in adjacent structures.

 

Run out can be reduced by straightening the drive tube by applying torch heat on the high side then quenching with water to shrink the metal. It is much easier to straighten a steel tube compared to an aluminum tube because the two metals behave much differently when heated and cooled. Drive line shops are more experienced with steel drive shafts than aluminum drive shafts.

Posted

Go hang out at some F150 forums and you can have some good reads on out of balance drive shafts on 2012-2015 models.

  • Like 1
Posted (edited)

Raven3 - you are so wrong....

I have a 2015 double-cab, short box 4x4 (not Z71) with steel prop shafts both front and rear.

Edited by Robbo6615
  • Like 1
Posted

Just purchased my 2015 and put 4,000mi on it. Took it in to get serviced, the usual tire rotation and oil change. Then the vibrations began.. currently in the shop hoping the rotation was the reason behind it.

 

Anyone else experience the vibes after rotation. Mine were rather violent at times from 70-75. I had never noticed them at slower speeds.

Posted

If you didn't have vibes before but did after the tire rotation then it sounds like a tire out of balance. One of the rear tires was probably the one out of balance and when they moved it to the front you noticed it. I would rotate them back to the way they were and see if it changes anything.

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