Bad Vibrations

P. A. Schilke

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Hi Chris,

I think you may have a couple things going on at the same time depending on vehicle speed.

First would would be to zero in on tire balance. Then I would recommend that the dealer do a powertrain neutralization including loosening the exhaust at the manifold. Lets see what that produces. What I am also suspect is a driveline 2nd order but it is not all that bad compared to the wheel tire. Do you have aftermarket wheels and if so are they hub centric? These kind of problems are what we faced most times in NVH...it is not just one thing where you find the magic bullet.... Patience and determination are your ally here...

Good Luck!

Best,
Phil
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MIBuckeye

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Hi Chris,

I think you may have a couple things going on at the same time depending on vehicle speed.

First would would be to zero in on tire balance. Then I would recommend that the dealer do a powertrain neutralization including loosening the exhaust at the manifold. Lets see what that produces. What I am also suspect is a driveline 2nd order but it is not all that bad compared to the wheel tire. Do you have aftermarket wheels and if so are they hub centric? These kind of problems are what we faced most times in NVH...it is not just one thing where you find the magic bullet.... Patience and determination are your ally here...

Good Luck!

Best,
Phil
Wow Phil, you're ON it again!! Thank you. This is all stock tire/wheel but do have 1" wheel spacers and a 1" front level. I'll tackle the wheel balance issue then see what happens. Interestingly, this thing just kinda "reappeared" shortly after adding rack, tonneau cover and replacing my bed drawers with a bed slide, and of course the 1" lift too! Never had a truck so finicky about such little things....I'll push forward on the balance and let you know any progress. Thx again!!
 

P. A. Schilke

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Wow Phil, you're ON it again!! Thank you. This is all stock tire/wheel but do have 1" wheel spacers and a 1" front level. I'll tackle the wheel balance issue then see what happens. Interestingly, this thing just kinda "reappeared" shortly after adding rack, tonneau cover and replacing my bed drawers with a bed slide, and of course the 1" lift too! Never had a truck so finicky about such little things....I'll push forward on the balance and let you know any progress. Thx again!!
Hi Chris,

In the world of NVH, tracking orders is helpful. Example. If engine rpm is 1st order, then firing frequency is 2nd order and is inherent 2nd order shaking forced of an inline 4 cylinder engine. Then if you see something that is 3.73 less than first order...you are looking at driveline and maybe half of that for U joints. This is why the dealer NVH equipment tracks orders....I do not know if you cell phone has the capability, but if it does, this can be useful too... NVH is to a degree still a "black art" and one of the tough arenas in which to make your living. I chose that path to begin with to meet the challenge and became a Technical Expert before moving up the "Executive" ladder... These Forums give me a rare opportunity to actually delve back into real Engineering, but it is with trying to tread water while wearing handcuffs...so to speak...

Best,
Phil
 

MIBuckeye

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Hi Chris,

In the world of NVH, tracking orders is helpful. Example. If engine rpm is 1st order, then firing frequency is 2nd order and is inherent 2nd order shaking forced of an inline 4 cylinder engine. Then if you see something that is 3.73 less than first order...you are looking at driveline and maybe half of that for U joints. This is why the dealer NVH equipment tracks orders....I do not know if you cell phone has the capability, but if it does, this can be useful too... NVH is to a degree still a "black art" and one of the tough arenas in which to make your living. I chose that path to begin with to meet the challenge and became a Technical Expert before moving up the "Executive" ladder... These Forums give me a rare opportunity to actually delve back into real Engineering, but it is with trying to tread water while wearing handcuffs...so to speak...

Best,
Phil
Well we all certainly appreciate you "giving back to the cause", if you will!

This tool does provide "ordering" at each vibration it recognizes...see below...
Screenshot_20220410-002434_NVH For Android.jpg

It calls out the most "egregious" issue first and expects you to solve that first then move on to the next. It also parses out each vibration into speed ranges like below...
Screenshot_20220410-003007_NVH For Android.jpg

Screenshot_20220410-003014_NVH For Android.jpg

Screenshot_20220410-003023_NVH For Android.jpg

Screenshot_20220410-003029_NVH For Android.jpg

Screenshot_20220410-003038_NVH For Android.jpg

Screenshot_20220410-003046_NVH For Android.jpg


Then finally breaks down each count by order and amplitude ...

Screenshot_20220410-003109_NVH For Android.jpg
Screenshot_20220410-003114_NVH For Android.jpg


It also allows playback of the entire recording.
 

canyonslicker

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Being an RF engineer this intrigues me. I’m well versed in the frequency domain but doesn’t really apply here.

That said I’ve had on 2 occasions where I could balance tires and a week later they went out of balance again… Dick Cepeks are the worst… it seems they haven’t been “cured” completely or designed for very short term use like racing..

The only way I could almost eliminate the balance issue was to remove all balance weights use “RideOn” that’s a goo type substance you put into the tires via the valve stem. It’s uses the same principle as balance beads but also has puncture protection.

Not ideal but a hell of a lot cheaper than new tires with pretty good results.. Not at all detrimental to tires and safe for tire shops to service, just messy when changing out..

First few miles it feels like square tires but after that then good to go for a daily driver, if it sits longer than week then back to square tire syndrome for the first few miles again…
 

P. A. Schilke

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Well we all certainly appreciate you "giving back to the cause", if you will!

This tool does provide "ordering" at each vibration it recognizes...see below...
Screenshot_20220410-002434_NVH For Android.jpg

It calls out the most "egregious" issue first and expects you to solve that first then move on to the next. It also parses out each vibration into speed ranges like below...
Screenshot_20220410-003007_NVH For Android.jpg

Screenshot_20220410-003014_NVH For Android.jpg

Screenshot_20220410-003023_NVH For Android.jpg

Screenshot_20220410-003029_NVH For Android.jpg

Screenshot_20220410-003038_NVH For Android.jpg

Screenshot_20220410-003046_NVH For Android.jpg


Then finally breaks down each count by order and amplitude ...

Screenshot_20220410-003109_NVH For Android.jpg
Screenshot_20220410-003114_NVH For Android.jpg


It also allows playback of the entire recording.
Hi Chris,

Certainly a lot of data, now the important part is extracting the information contained in the data. I think you might be seeing the affect of the 1 inch wheel spacers you added that are producing the 2nd order tire....JMO.... Still indicated tire vibration is front and center, and hopefully your tire shop can help with the diagnostics...

Best,
Phil
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