Shake or Vibration Issues

[abominable z71]

 

 

I was about to ask the exact same question. I'm almost willing to bet its the material.

 

 

abominable z71, did you happen to take a pic of the mounts side by side, or compare the materials at all?

 

If GM won't do it, any aftermarket supplier that comes up with a better stock height body mount kit will make a fortune.

 

Old vehicles vibrate. They just do. 50's, 60's, 70s, but the vibrations were kept down with rubber motor, trans, cab/body and suspension mounts. Modern suppliers offer the same parts in polyurethane or some other much stiffer material, but that usually ends up making the old car/truck vibrate or feel the road more.

The mounts are just a very hard plastic puck. My guess is they are either a glass filled delrin or glass filled nylon they are very light. 1-1/2" thick and about 3" in diameter. They function as a spacer between the body and the factory body mounts, They don't actually replace the body mount. My guess is the added space between the body and frame is what did it, it just interrupted the transmission path. The other option to look at is replacing these hard plastic spacers with a dense rubber compound of the appropriate density and shore hardness to support the body and gain a damping effect. Some sort of SBR would be the best candidate the rubber would deform do to the vibration input essential converting the mechanical vibration into heat which is how most passive damping systems work. I have job walk about 40 miles away later this morning all freeway 75 mph plus. I set the cold air pressure in my tires to 42 PSI last night (10 ply toyo LT tires max PSI is 80) 42 PSI keeps the factory load rating at 2400 lbs per tire to match the SRA's that were on it. We shall see what it does.

[pm26]

So in summary, you did not eliminate the source of vibration, but isolated the cab from the source enough to mitigate the problem to the acceptable level.

[14silverado4.3]

The mounts are just a very hard plastic puck. My guess is they are either a glass filled delrin or glass filled nylon they are very light. 1-1/2" thick and about 3" in diameter. They function as a spacer between the body and the factory body mounts, They don't actually replace the body mount. My guess is the added space between the body and frame is what did it, it just interrupted the transmission path. The other option to look at is replacing these hard plastic spacers with a dense rubber compound of the appropriate density and shore hardness to support the body and gain a damping effect. Some sort of SBR would be the best candidate the rubber would deform do to the vibration input essential converting the mechanical vibration into heat which is how most passive damping systems work. I have job walk about 40 miles away later this morning all freeway 75 mph plus. I set the cold air pressure in my tires to 42 PSI last night (10 ply toyo LT tires max PSI is 80) 42 PSI keeps the factory load rating at 2400 lbs per tire to match the SRA's that were on it. We shall see what it does.

Keep us posted

[WLC]

So in summary, you did not eliminate the source of vibration, but isolated the cab from the source enough to mitigate the problem to the acceptable level.

If it spins it vibrates. Just depended on the tolerance factor. We worked with electric motors than had speed increasers than took hours to align and get the vibs to acceptable levels! Jet engines are at a tight tolerance.We are dealing with poor made parts by many manufactures and put together into one truck.No testing for the most part!

[southern_sierra]

HI,

 

I've been playing with my new car for the last few days so the Tundra still has under 300 miles on it, but It is sticking right at 15 MPG around town.

 

I am taking it on a nice highway round trip to New Hampshire tomorrow. I'll clear the data and let you know how it does.

Thanks

[abominable z71]

So in summary, you did not eliminate the source of vibration, but isolated the cab from the source enough to mitigate the problem to the acceptable level.

That is correct. At least I hope they don't find a new path back into the cab. There is no doubt they are still there though.

[hotrodz37]

That is correct. At least I hope they don't find a new path back into the cab. There is no doubt they are still there though.

 

So for the second day in a row, it's still quite a bit improved?

[jmckeone]

To those who have received a vehicle repurchase what can I expect as an offer? Did you get your full sale price plus tax/tags/title fees? What if you had a trade in at the time or purchase, how would they work that into the offer? Im sure I will lose mileage and the interest I paid on the load already. Im just trying to prep myself for arbitration shortly. I will NOT accept an upgrade, Im moving on to another brand.

[pm26]

To those who have received a vehicle repurchase what can I expect as an offer? Did you get your full sale price plus tax/tags/title fees? What if you had a trade in at the time or purchase, how would they work that into the offer? Im sure I will lose mileage and the interest I paid on the load already. Im just trying to prep myself for arbitration shortly. I will NOT accept an upgrade, Im moving on to another brand.

I think they will refund you the amount they gave you for your trade, and then depending on your case settlement details, will subtract so much for mileage on your truck and then take the amount you financed plus any other downpayment and refund the adjusted amount to you. They should also refund the tax paid. I do not know about other fees.

[14silverado4.3]

I do remember something about mileage goes back to when the problem was first detected.

[Buster12]

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.

[dave07]

You should be made whole like the purchase never happened minus a usage fee based on the amount of miles when the issue first occurred. Anywhere from .10 to .40 cents a mile.

 

 

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Edited December 15, 2015 by dave07

[audreez]

Anyone with a truck shell have issues? I have it on and don't have vibs almost 2k miles I put it on early on so not sure if I ever had them

I'm thinking added weight and probably more aero downforce might be helping

 

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[abominable z71]

Well I'm sorry to report the vibes came back just the same. It was a glorious 2 days though. Back to the drawing board, hopefully no one ran out and bought a body lift hoping for a fix. Not sure what made the vibe go away for a few days before coming back.

[abominable z71]

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.

I've tried a shit ton of things, but none of what you mentioned. I've been contemplating new rear springs from atlas or alcan for that last few months but its a little over a grand for custom packs. I work literally next door to betts springs but I'm not sure if they do one off custom packs. Going to clamp the springs first thing and see if it has any effect. What type of truck? crew cab 4x4?