Shake or Vibration Issues

[Wrench589]

£

Edited December 20, 2015 by Wrench589

[pm26]

Using torque extensions with an impact wrench should not be a problem, unless the guy picks the wrong extension rated for much lower torque than these lug nuts call for, or his air impact wrench is incapable of achieving 140 ft-lbs, either because the shop air pressure is regulated too low or the air impact wrench it is set to a minimum torque setting, much lower than 140 ft-lbs.

 

If the bolt circle is not machined properly and is not concentric around the flange center, this would cause the lug nut not to seat properly and they could conceivably come loose, even if torqued properly to 140 ft-lbs.

Edited December 18, 2015 by pm26

[pm26]

I have a question about brake rotors:

 

I have been looking for replacement aftermarket rotors for one of my cars, and many new rotors I look at (even premium rotors sold by NAPA) do not show any signs of ever having been balanced. Typically, brake rotors are balanced by removing some metal from the heaviest spot on the outside of the rotor, from the inside portion of the two rotor flanges. Some new rotors have these typical "slots" showing where the metal was removed during balancing, but most do not, even the most expensive rotors. Are you aware of some other balancing technique for the rotors that would eliminate cutting the slot when removing metal in the heavy portion of the rotor? Brake drums are typically balanced by welding a weight in the light spot.

 

Are OEM rotors on these trucks balanced properly? If not, this could definitely contribute to vibration problems, as wheels are almost always balanced off the vehicle and if the brake rotor is out of balance, then all bets are off. The only way to correct such a problem is to balance the wheel on the vehicle together with the brake rotor and the hub. However, even if you find a place that will balance the wheels on the vehicle (special balancer is required and they are quite rare these days), you cannot rotate the tires without rebalancing everything all over again.

 

With larger wheel diameters, brake rotors are getting bigger and bigger, and consequently much heavier too. The market is literally flooded with cheap aftermarket rotors and I suspect that balancing those would add significant cost to the part, so they elect to skip balancing and just sell them as is. I hope GM is not doing this with OEM rotors, but it is a good idea to find out and eliminate the brake rotor as one possible source of vibration.

 

If there is some other rotor balancing technique other than removing the metal from the outer portion, I would like to know. And how can I tell at a glance if a rotor has been balanced this way? Perhaps they drill extra holes in the rotor hub?

Edited December 19, 2015 by pm26

[Snoringbear]

Has anyone seen data stating what percent of GM trucks are exhibiting this problem? Just curious...

[FogDucker]

Has anyone seen data stating what percent of GM trucks are exhibiting this problem? Just curious...

I think that only GM can answer that and they're maintaining radio silence.

[pm26]

Has anyone seen data stating what percent of GM trucks are exhibiting this problem? Just curious...

According to the service manager of my local Chevy dealer, about 10% of all the 2014 trucks they sold came back for service for vibration problems. This is data just from one fairly large Chevy dealership.

Edited December 19, 2015 by pm26

[Hardin083]

So my truck is back at the dealer for the final repair attempt. GM engineers acknowledge the vibration and also picked it up on the pico scope. Once again they are hung up on the tires and wheels. They did check the shocks and verified them as good. So for now they found 3 of 4 wheels without tires were calling for over 7 ounces of weight just to balance and I was told the limit is 4. They ordered 3 new wheels and all 3 came scratched so they ordered 3 more. They were able to balance one wheel tire combo and after they balanced it they did a bead massage...... Really? A bead massage? Anyone else had this done I've never heard of this and laughed when he told me. Also after the bead massage the tire was again back out of balance. Wtf? The dealer seems to be really trying which is nice but this truck just flat out sucks. The service director also had his hunter rep come out and calibrate their balancer which was good and required no calibration but one was done anyways. I have the factory 22" black wheels with Bridgestone dueler a/t tires and this is also already my second set of wheel and tires. The new wheels they ordered will be my third set. Anyone ever had the dealer check the wheels before they put a tire on to balance? Service director said all tires/ wheels balanced good and had low road force numbers but the wheel itself should not be over 4 ounces out of balance. I'm just passing info along and hope it helps someone but I'm sure mine won't be fixed but who knows. He saga continues! Service director also confirmed the wheels are hub centric and also verified the right cone was bein used per the hunter rep.

[pm26]

They were able to balance one wheel tire combo and after they balanced it they did a bead massage.

Did they use a certified masseur or masseuse for this very important step?

 

And they needed to call a Hunter rep to calibrate their balancer?

Edited December 19, 2015 by pm26

[FogDucker]

 

 

Did they use a certified masseur or masseuse for this very important step?

Yes, but there was no happy ending.

 

lol

[C6Bill]

They should have at least bought us a nice dinner before they sold us these trucks, didn't even talk dirty to me to get me in the mood.

[Wrench589]

Has anyone had their wheel/tires Lateral Force measured on the Hunter when they did the Roadforce balance? So far, I don't recall anyone talking about that. It's an optional feature in the Hunter GSP 9700. No idea if GM's version of the Hunter (GM buts their own branded version of the GSP9700) has that feature, or if GM is using if. I highly doubt it because the GM specs and Bulletins don't say anything about it at all.

 

I am thinking about taking mind to an independent shop and having the Radial Force Variation and Lateral Force measured and if they are high, go back to the dealer.

[pm26]

Has anyone had their wheel/tires Lateral Force measured on the Hunter when they did the Roadforce balance? So far, I don't recall anyone talking about that. It's an optional feature in the Hunter GSP 9700. No idea if GM's version of the Hunter (GM buts their own branded version of the GSP9700) has that feature, or if GM is using if. I highly doubt it because the GM specs and Bulletins don't say anything about it at all.

 

I am thinking about taking mind to an independent shop and having the Radial Force Variation and Lateral Force measured and if they are high, go back to the dealer.

That would be a very mindless thing to do. lol

 

I have seen lateral runout on the rims measured but no force variation associated with the same.

Edited December 20, 2015 by pm26

[Wrench589]

That would be a very mindless thing to do. lol

 

I have seen lateral runout on the rims measured but no force variation associated with the same.

 

That's my point. The normal road force variation measured and reported by the Hunter machine is only a Radial Force Variation measurement. Any lateral forces would not be included in that measurement. And so a wheel tire could look fine but put it on the vehicle, and the lateral runout and/or lateral force variation would cause LATERAL shaking of the suspension. And, on a vehicle with shear type body mounts, that could be a significant problem.

 

Taking the Lateral Force measurement is an extra step, in an extra menu option on the Hunter machine. I doubt most operators do it. One guy I had balancing some tires for a car one time didn't even know the machine had that option, when it asked him about it!

 

But hey, if it's mindless, then never mind! I'll keep my mindless suggestions to myself.

[pm26]

Just had a thought. Has anyone considered lubrication of the u-joints as a possible issue? I'm sure they are not greaseable, so not sure what one would do to inspect or do something about. I've actually never had apart a driveshaft with the new style "sealed for life" u-joints, but wouldn't it be a kicker if the supplier screwed up?

You know, after reading all these posts, you cannot honestly eliminate anything anymore. It seems like there is a certain percentage of defective parts that find their way into certain trucks which are then nothing but frustration for the owners. while I do not think that improperly greased U joints could be a major vibration contributor, improperly installed U joints could be , improperly balanced shaft could be, as well as improperly welded shaft with excessive runout.

Edited December 20, 2015 by pm26

[Wrench589]

Using torque extensions with an impact wrench should not be a problem, unless the guy picks the wrong extension rated for much lower torque than these lug nuts call for, or his air impact wrench is incapable of achieving 140 ft-lbs, either because the shop air pressure is regulated too low or the air impact wrench it is set to a minimum torque setting, much lower than 140 ft-lbs.

 

If the bolt circle is not machined properly and is not concentric around the flange center, this would cause the lug nut not to seat properly and they could conceivably come loose, even if torqued properly to 140 ft-lbs.

That's a lot of ifs to go right. I'll take a proper torque wrench over those lazy-man extensions any day, thank- you.