Shake or Vibration Issues

[hotrodz37]

Going to focus on the drivers rear first and see what the results are. I did clamp the rear springs last night like buster12 had posted and it made a significant improvement. Cheap thing for anyone else to try and takes about 10 minutes to install. Most autoparts places have them in stock for about 15 bucks.

 

Awesome to hear! Did it stiffen the ride up at all? Also, would you be able to post a pic of where you put them so we can replicate? Thanks in advance!

[abominable z71]

 

When they Road Force Balance the tires/wheels, they should be checking this.

The arm on the balancer checks the runout on the tire and wheel assembly but not the hub on the truck itself. Runout shows up in the tire as roadforce variation and they typically rotate the tire on the rim itself to minimize the affect, this is what they refer to as match mounting or vectoring the assembly. As long as the number is below spec which is 25 or 30 lbs on a LT tire they will still deem the tire as within spec even with a little runout. I know one of mine has some runout but the roadforce on it was 9.

The wheels are made in China. My Yukon Denali wheels are and my Sierra AT wheels are, at least. I believe the country of origin is stamped (or cast) on the inside of the wheel.

 

Can't comment about quality.

My factory wheels are chinese as well.

[14silverado4.3]

If the studs are not concentric (off center) to the centerline of the axle, this explains why GM is requiring RF numbers 1/2 of what may be the industry standards. This also would explain the success of those few that have had their tires balanced directly on the vehicle.

 

Basically, a road force balance of 10 or less works fine until you have to rotate your tires. That explains a lot.

[14silverado4.3]

Hold the press... Are we running hub centric or lug centric stock wheels?

[hotrodz37]

Hold the press... Are we running hub centric or lug centric stock wheels?

 

Mine shook with the stock wheels (hub centric I believe) and still shakes with aftermarket wheels that are lug centric if that helps any. No change at all whatsoever.

[14silverado4.3]

Are all stock wheels for the Silverado hub centric, I am running 18"s

[abominable z71]

 

Awesome to hear! Did it stiffen the ride up at all? Also, would you be able to post a pic of where you put them so we can replicate? Thanks in advance!

Rides much better IMHO. It tightened things up a bit and improved the handling. As I mentioned before the truck would vibrate pretty bad when really getting on the gas 4300 RPM plus. This helped in this area significantly, I'm thinking about getting another set and clamping in front of the axle as well to see if it helps. I'm also looking at fabricating my own body lift blocks out of polyurethane to replace the hard plastic pucks that came with the body lift to gain a little damping.

 

Attached are the pics. I mounted them 7" from the edge of the lift block to the center of the clamp I don't think this measurement is crucial. I am curious to see if moving them further away from the block would be better. That's more of a weekend testing thing though maybe this weekend ill try and find the best distance and if front and rear clamps are better or not. I'll try and dial in the best setup and let everyone know.

 

[abominable z71]

Are all stock wheels for the Silverado hub centric, I am running 18"s

I believe all factory wheels are hub centric, well sort of, they still use acorn style lugs which inevitably center the wheels on the bolt circle.

 

Mine shook with the stock wheels (hub centric I believe) and still shakes with aftermarket wheels that are lug centric if that helps any. No change at all whatsoever.

Have you tried hub centric rings on your aftermarket wheels?

[14silverado4.3]

Hub Centric - if the rib is not press fit (which it is not), there is obviously going to be some slop between the rim and centering hub, if the bolt circle is out, could the tightening of lug nuts literally move the rim a few thousandths off center.. I guess how far can you go before you feel it?

 

I really did not pay attention to this even though I have had the tires balanced or RF checked at least 10 times!

[Mcarlo24]

So the flange holes need to run true to the center of the axle shaft? How far off can they be before you feel it?

 

When you mount the tire to the hub the nuts center to rim on the stud bolts?

 

Are we thinking that the bolt circle is shifted off center to the axle center? Someone can lay this out in CAD program? Cut out the bolt holes and place it over the flange? It should at least give an idea how far off center?

I have several CAD programs here at work and can lay out what you want, PDF it and e-mail wherever...

 

Let me know if I can help..

 

Dan

[14silverado4.3]

I have several CAD programs here at work and can lay out what you want, PDF it and e-mail wherever...

 

Let me know if I can help..

 

Dan

Thanks, now in discussion because these are hub centric.

[pm26]

I believe the axles are machined by automatic milling machines, so what is the probability that the lug nut stud hole circle could be machined off center? I suppose it is possible if there was a glitch in the machine programming or some problem with the machine hardware itself. And even if, what is the maximum permissible tolerance on such machining? Is quality control sufficient to catch such issues before they produce thousands of parts with this defect and sell them to GM? Would GM knowingly install defective parts on new trucks?

Edited December 17, 2015 by pm26

[rpoffen]

Hub Centric - if the rib is not press fit (which it is not), there is obviously going to be some slop between the rim and centering hub, if the bolt circle is out, could the tightening of lug nuts literally move the rim a few thousandths off center.. I guess how far can you go before you feel it?

 

I really did not pay attention to this even though I have had the tires balanced or RF checked at least 10 times!

 

If the lug circle is not perfectly centered with the hub, then tightening the lug nuts certainly is changing something, if there is slop in the hub fit, then the wheel/tire is going to move off center. If the fit is tight on the hub, then tightening the lug nuts will put stress on the wheel.

[abominable z71]

Thanks, now in discussion because these are hub centric.

Simple answer. Is one half the difference between the center hole in the wheel and the outer diameter of the pilot flange.

[pm26]

Typically all OEM wheels are hub centric because the inner hole of the wheel will fit tightly over the protruding round portion of the axle flange. Aftermarket wheels are often lug centric, as the center wheel hole is made bigger than the axle protruding flange to fit a lot of different vehicles. With lug centric wheels you should use lug centric adapters to provide a tight fit. It is not a good idea to center the wheels only by lugnuts, even if they are the self centering tapered type lug nuts because lug nuts are not designed to properly resist up and down shear forces that are properly resisted by a tight wheel to axle flange connection (i.e. hub centric connection).

Edited December 17, 2015 by pm26