Shake or Vibration Issues

[ekimsinnigcm]

Truck is back from its second dealer visit. Vibration is 90% gone and at what I feel is an acceptable level. They replaced the left rear wheel and tire due to "excessive runout" at least that's what the repair order states.

 

I've got a 2wd RCSB w/ 5.3 and tow package for reference.

Edited December 16, 2015 by ekimsinnigcm

[pm26]

Many have stated that tires are not the problem here. However, I am convinced that in some cases they are. These vibration problems do not seem to have a common cause. They are caused by random installation of defective or poorly balanced rotating parts on any particular truck and/or poor assembly practices coupled with insufficient quality control at all levels. Let's say each lot of 100 parts like wheels , driveshafts, or transmissions contains 5% of defective parts, or defective components within assemblies such as transmissions. Some trucks will get one of more defective parts or components within assemblies installed, some will not have a single bad one. This is why some trucks have no issues, and some are horrible. Evidently the degree of vibration is dependent largely on the magnitude of the defect of any given part. Some tires a lot worse than others, some brake rotors may not be properly balanced, driveshafts may not be straight and be balanced wrong, transmission torque converters can be defective, wheel hubs can be out balance, axle shafts can be badly machined, differential housing machining can be off, differentials may be assembled improperly, body mounts may be defective, engine flywheels balanced wrong. And evidently the worst case trucks have several defective components that seem to make the overall vibration even worse.

When the overall quality control slips at all levels and cost cutting is the primary goal, it is difficult to find the root cause of problems, as everything is suspect.

Edited December 16, 2015 by pm26

[hotrodz37]

I just finished an experiment related to vibe and shake. Installed leaf spring clamps about 4-5" behind the rear axle. Huge reduction in both.. Not perfect but 80% better... My tires are road force balanced perfect (I had a severe shake due to RF balance but that's fixed).. I think the rear axle is moving around causing the shake/vibe to transmitting up the drive shaft, through the transmission to the engine. Engine shake is shaking and grounding out the motor mounts but the source is the rear end. I suspect one of three problems.. 1- crap leaf springs, 2- ring/pinion, and motor mount ground out (needs 3mm shims)

 

My idea came from the fact that my truck rode better after I had it parked facing downhill or it changed based upon weight in the bed. Noticed the leaf spring spacing looked different every other day.. Floppy leaf springs are causing the rear axle to float around and then the drive shaft oscillates.

 

Next steps - traction bars from calvert racing or replacement leaf springs... Check ring and pinion backlash..... Either new motor mounts or 3mm shims... Most likely all three of these items need to be done for a comprehensive solution.

 

It's been a year and I'm done with GM.. fixing it myself.

 

Buster, thanks for the input! Can you post a link to where you got your clamps, and possibly a pic of them installed on the leaf springs? Thanks in advance!

[Big_D]

 

Buster, thanks for the input! Can you post a link to where you got your clamps, and possibly a pic of them installed on the leaf springs? Thanks in advance!

 

Size/shape? I want to pick some up before headed home from work. THX

[abominable z71]

 

Buster, thanks for the input! Can you post a link to where you got your clamps, and possibly a pic of them installed on the leaf springs? Thanks in advance!

I picked up some clamps at autozone for 16 dollars, 2-1/2" leaf spring clamp they had 5 pairs sitting on the shelf. Going to install them tonight.

[abominable z71]

Many have stated that tires are not the problem here. However, I am convinced that in some cases they are. These vibration problems do not seem to have a common cause. They are caused by random installation of defective or poorly balanced rotating parts on any particular truck and/or poor assembly practices coupled with insufficient quality control at all levels. Let's say each lot of 100 parts like wheels , driveshafts, or transmissions contains 5% of defective parts, or defective components within assemblies such as transmissions. Some trucks will get one of more defective parts or components within assemblies installed, some will not have a single bad one. This is why some trucks have no issues, and some are horrible. Evidently the degree of vibration is dependent largely on the magnitude of the defect of any given part. Some tires a lot worse than others, some brake rotors may not be properly balanced, driveshafts may not be straight and be balanced wrong, transmission torque converters can be defective, wheel hubs can be out balance, axle shafts can be badly machined, differential housing machining can be off, differentials may be assembled improperly, body mounts may be defective, engine flywheels balanced wrong. And evidently the worst case trucks have several defective components that seem to make the overall vibration even worse.

When the overall quality control slips at all levels and cost cutting is the primary goal, it is difficult to find the root cause of problems, as everything is suspect.

I think runout in the hubs is an issue and why countless tire balances don't solve the problem. The tire that is perfectly balanced about it's axis is no longer turning on it's axis this creates two problems, one being a balance issue and the other is the tire now travels up and down as it rotates, both problems causing a vibration together that is likely a second or third order vibration not just a typical first order tire balance vibration.

[pm26]

Can't you eliminate the suspected hub runout issue by measuring the lateral and radial runout with a good dial indicator gauge?

[abominable z71]

Can't you eliminate the suspected hub runout issue by measuring the lateral and radial runout with a good dial indicator gauge?

I have .015" rear driver. I have no idea what the tolerance is nor would the dealer tell me. Unfortunately axle shafts are 235 dollars and no guaranty the hub circle will be any tighter on the tolerances plus it requires tearing the rear end apart to change. I just have no idea at present what else it could be. Checked the ring and pinion back lash, pitch line pinion nut torque and pinion flange runout and everything was good there with a really good pattern. general rule of thumb has been less than .030" radial at the hub and less than .005 lateral, but with these newer designs being lighter and stiffer the natural frequencies are getting lower. They are pushing the tolerance limits and frame and body design to increase fuel economy but not tightening the tolerances on the rotating parts to go along with it and now they're running into resonance issues, there is just very little forgiveness in the design when it comes to NVH.

Edited December 16, 2015 by abominable z71

[Front Runner]

Since most trucks experience vibs at 70+ mph, could it be possibly connected to AFM? Is anyone with an aftermarket exhaust w/o a valve experiencing major vibs or shakes?

[EastCoast HD]

Cats out of the bag. Wonder how much attention it will grab?

 

http://www.autoguide.com/auto-news/2015/12/there-s-a-big-issue-with-gm-s-suvs-and-no-one-seems-to-have-a-solution.html

 

 

 

 

The NHTSA database also shows a host of similar complaints on brand new GM pickup trucks. “The contact owns a 2015 Chevrolet Silverado equipped with Goodyear Wrangler SRA tires,” reads a NHTSA complaint (NHTSA ID Number: 10807437). “While driving between 65-75 mph, the vehicle started to vibrate. The tires were replaced, but the failure recurred. The approximate vehicle and tire failure mileage was 3,400.” There are also massive forum threads covering the issue with the pickup trucks.

 

[pm26]

Have you checked the rear axle bearings to make sure they are not oversized, allowing the axle shaft to move slightly up and down as it rotates? if you remove the axle shafts and take them to a machine shop, they should be able to tell you if they run true or not. On half ton trucks the axle shafts are machined in one piece and they can be mounted on the lathe and runout checked. doing this sort of check takes the possibility of improperly dimensioned rear axle bearings out of equation.

 

Yes, I know it is a not pleasant to have to open the rear differential cover (assuming no drain plug), drain the oil, loosen the pin locking bolt, remove the pin take off the wheels, push the axle shafts in, pull out the C locks, then remove the axle shafts, but at least you could eliminate these parts that way. Removing rear axles is really not that difficult. After all, you are not working on a 10 ton Army truck with six 400 lb wheels.

Edited December 17, 2015 by pm26

[rpoffen]

Since most trucks experience vibs at 70+ mph, could it be possibly connected to AFM? Is anyone with an aftermarket exhaust w/o a valve experiencing major vibs or shakes?

 

People in this thread have repeated the experiment in M5 mode which disables AFM and it changes nothing.

[abominable z71]

Have you checked the rear axle bearings to make sure they are not oversized, allowing the axle shaft to move slightly up and down as it rotates? if you remove the axle shaft and take them to a machine shop, they should be able to tell you if they run true or not. On half ton trucks the axle shafts are machined in one piece and they can be mounted on the lathe and runout checked. doing this sort of check takes the possibly improperly dimensioned axle bearings out of equation.

Hub flange turns true. Bolt circle for the studs is completely off center shouldn't be an issue for hub centric wheels except the wheels are drilled for cone seat nuts which inevitably tries to center the studs in the holes, and since the center portion of the wheel is oversized by about .040" to allow a free fit on the hub pilot flange the wheel is allowed to be mounted with it's axis off center from the hub center and aligns itself with the bolt circle. I have one tire with a little bit of runout in the tire itself I'm going to try and mount the high spot of the tire 180 degrees out from the high spot on the stud bolt circle and see if that offers any improvement might alleviate the up and down during rotation but the center that the balance was used for will still be off by .015".

[BO TIE 1]

Since most trucks experience vibs at 70+ mph, could it be possibly connected to AFM? Is anyone with an aftermarket exhaust w/o a valve experiencing major vibs or shakes?

I have aftermarket exhaust and afm disabled and it still vibrates.

Tech at the dealer said my exhaust was probably causing the vibration [emoji34] .....It vibrated with the stock exhaust also.

 

 

Sent from my VS990 using Tapatalk

[Front Runner]

 

 

Okay.

Edited December 17, 2015 by Front Runner