Bad Vibrations

[P. A. Schilke]

I bit the bullet and spent the $99 for the NVH App for Android. I'd been feeling vibration at 70MPH recently and attributed it to needing new tires. After new rubber, alignment, balance and then road force balance I was still feeling the vibration. The NVH App indicated drive shaft issues. My experience with service techs diagnosing subjective issue like vibration was going to turn into a debate so $99 seemed like a good investment to have some additional evidence to support my case. At first dealer's tech reported could not duplicate issues (seat of pants) diagnostics and I had to remind them it was at 70mph that symptoms appeared. So they redid the test drive and tech detected vibration. Next step was to do another test drive with NVH sensors. Dealer says results indicate all tire related vibrations! Uugh , here comes the they said/they said conundrum between Ford dealer and tire dealer.
I was able to convince Svc writer and manager to do a wheel swap test drive with wheels from a new ranger to completely rule out vehicle drive line issues. Waiting for them to get around to that in the next day or so.

Will let you all know how my saga plays out.

Hi Larry,

What frequency do you show on your NVH software? There will be a huge difference in driveline frequency at 70mph than tires and should guide you. Tire balance is 1st order, Tire out of round (ovality) is 2nd order and driveline will be a magnitude above this by about 3.73 or what the rear gear is. Going by the engine as 1st order imbalance, 2nd order is shaking forces of a 4 banger and if driveline it will also be 2nd order as it is the frequency of a u joint at 8th gear which is one to one...then tires will be some 3.73 lower frequency that that for tire imbalance and half that for ovality... Hopefully between you and the dealer you can radar in on this.... Tire swap is a good idea in the meantime...

Want to play around a bit....use your NVH software and get a capture of the vibration. Then slap a hose clamp or two with the heads together side by side...now see what your NVH software reads as you have grossly imbalanced your driveshaft... This will start to give you a feeling for sensitivity of the software and to some extent calibrate your assometer too...

best,
Phil

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[Chris M]

I bit the bullet and spent the $99 for the NVH App for Android. I'd been feeling vibration at 70MPH recently and attributed it to needing new tires. After new rubber, alignment, balance and then road force balance I was still feeling the vibration. The NVH App indicated drive shaft issues. My experience with service techs diagnosing subjective issue like vibration was going to turn into a debate so $99 seemed like a good investment to have some additional evidence to support my case. At first dealer's tech reported could not duplicate issues (seat of pants) diagnostics and I had to remind them it was at 70mph that symptoms appeared. So they redid the test drive and tech detected vibration. Next step was to do another test drive with NVH sensors. Dealer says results indicate all tire related vibrations! Uugh , here comes the they said/they said conundrum between Ford dealer and tire dealer.
I was able to convince Svc writer and manager to do a wheel swap test drive with wheels from a new ranger to completely rule out vehicle drive line issues. Waiting for them to get around to that in the next day or so.

Will let you all know how my saga plays out.

Dang!
Tire dealer has ordered me a new tire for left rear (this is the wheel/tire that gave so much trouble during road force balance). When it comes in I will have the tire changed out, all the wheels balanced again. I have also since purchased another stock sport wheel and we will all be paying special attention to the seemingly offending wheel to see if it's at all out of round. If so, I'll have them swap the wheels out and we will try that.

If this doesn't fix it, I WILL be buying the app and we'll start all over with whichever the app shows to be the culprit. I watched video of one of the android apps and am kind of impressed with how it works (supposedly).

I don't think my chances of trading out this truck are very good at present, so I have to do all I can to make this go away.

 

[Chris M]

Hi Larry,

What frequency do you show on your NVH software? There will be a huge difference in driveline frequency at 70mph than tires and should guide you. Tire balance is 1st order, Tire out of round (ovality) is 2nd order and driveline will be a magnitude above this by about 3.73 or what the rear gear is. Going by the engine as 1st order imbalance, 2nd order is shaking forces of a 4 banger and if driveline it will also be 2nd order as it is the frequency of a u joint at 8th gear which is one to one...then tires will be some 3.73 lower frequency that that for tire imbalance and half that for ovality... Hopefully between you and the dealer you can radar in on this.... Tire swap is a good idea in the meantime...

Want to play around a bit....use your NVH software and get a capture of the vibration. Then slap a hose clamp or two with the heads together side by side...now see what your NVH software reads as you have grossly imbalanced your driveshaft... This will start to give you a feeling for sensitivity of the software and to some extent calibrate your assometer too...

best,
Phil

That all makes my head hurt...

 

[MIBuckeye]

I bit the bullet and spent the $99 for the NVH App for Android. I'd been feeling vibration at 70MPH recently and attributed it to needing new tires. After new rubber, alignment, balance and then road force balance I was still feeling the vibration. The NVH App indicated drive shaft issues. My experience with service techs diagnosing subjective issue like vibration was going to turn into a debate so $99 seemed like a good investment to have some additional evidence to support my case. At first dealer's tech reported could not duplicate issues (seat of pants) diagnostics and I had to remind them it was at 70mph that symptoms appeared. So they redid the test drive and tech detected vibration. Next step was to do another test drive with NVH sensors. Dealer says results indicate all tire related vibrations! Uugh , here comes the they said/they said conundrum between Ford dealer and tire dealer.
I was able to convince Svc writer and manager to do a wheel swap test drive with wheels from a new ranger to completely rule out vehicle drive line issues. Waiting for them to get around to that in the next day or so.

Will let you all know how my saga plays out.

Mine continues to vibrate with NVH indicating wheel vibration. First order tire vibration almost consistently. Im headed in for the first oil change next week and headed down the same path. Keep us posted on the wheel swap.

 

[P. A. Schilke]

That all makes my head hurt...

Hi Chris,

Not intending to make anyone's head hurt but to show how useful the Frequency portion of the NVH software is when understood...Otherwise it is a much less capable tool. You cannot just do NVH and get an answer much less a correct answer.... I was an NVH Technical Expert for much of my career at Ford....it took years of training to get there and it is very hard to impart that in a couple paragraphs, but if it clicks for just one other person to a degree it can be very helpful.

In your case....Take three Ibuprofen might help, eh?

best,
Phil

 

[MIBuckeye]

Hi Chris,

Not intending to make anyone's head hurt but to show how useful the Frequency portion of the NVH software is when understood...Otherwise it is a much less capable tool. You cannot just do NVH and get an answer much less a correct answer.... I was an NVH Technical Expert for much of my career at Ford....it took years of training to get there and it is very hard to impart that in a couple paragraphs, but if it clicks for just one other person to a degree it can be very helpful.

In your case....Take three Ibuprofen might help, eh?

best,
Phil

Hey Phil, wondering if you can answer a question. Is there a way to home into the location of a vibration with a tool like NVH? My assometer tells me the vibration is stronger on the drivers side front. When i monitor with NVH sitting in the passenger seat, i get a 1st order vibration with a higher amplitude. When placing the NVH on center console, i get 2nd order vibration with lower amplitude. Then when in drivers seat, 1st order and higher amplitude. Is it possible to use this to locate a specific wheel? I have loads of data but like you said, it's just data at this point.

I have swapped tires, had them rebalanced, road forced and inflated/deflated, rotated in the spare. It always is there. Just feels different each time.

I swear this feels like a darn wheel bearing grinding but then resonates around 40-50 and again at 70 and beyond. Can't drive out of it that i can tell either ...ive been fooled before with bad tires thinking it was a bearing, so.....

Could it be a unbalanced font drive shaft i wonder?

 

[P. A. Schilke]

Hey Phil, wondering if you can answer a question. Is there a way to home into the location of a vibration with a tool like NVH? My assometer tells me the vibration is stronger on the drivers side front. When i monitor with NVH sitting in the passenger seat, i get a 1st order vibration with a higher amplitude. When placing the NVH on center console, i get 2nd order vibration with lower amplitude. Then when in drivers seat, 1st order and higher amplitude. Is it possible to use this to locate a specific wheel? I have loads of data but like you said, it's just data at this point.

I have swapped tires, had them rebalanced, road forced and inflated/deflated, rotated in the spare. It always is there. Just feels different each time.

I swear this feels like a darn wheel bearing grinding but then resonates around 40-50 and again at 70 and beyond. Can't drive out of it that i can tell either ...ive been fooled before with bad tires thinking it was a bearing, so.....

Could it be a unbalanced font drive shaft i wonder?

Hi Chris,

This is an example were there is some experience to be learned. A seat is its own spring/mass with associated resonance responses. What you are looking for is the forcing function frequency, so usually there is a spectrum of frequencies but for the various locations there will be a common frequency. Not always but most times you can id the common frequency. Orders are relative, so relative to what? Tire, Engine etc. You get a feeling for this via experience. Welcome to the world of NVH...complicated and inexact.

In your case, drive with your NVH software on the floorpan...no spring mass like a seat. Then keep speed at 70mph and change transmisson gear. Does the frequency remain the same? If yes....You just eliminated the Engine. If it changes then the engine becomes the prime forcing function. So for your vibration, what are the frequencies you are seeing, not orders. For example, at 70mph you can measure engine rpm...use 8th gear as it is one to one...so you know the rpm...divide by 60 and you have rps which are also cycles per second or a frequency. So lets say you are in 8th and engine is at 3,000 rpm which divided by 60 seconds per minute gives you 50 rps or a frequency of 50 hz. So your engine/driveshaft is at 50 Hz and your tires are turning at 3.73 times less or 13.4Hz. A big difference....now lets introduce orders. A U joint is a second order device so at 3000 rpm the u joint excitation is 100 hz and if a tire is oval the excitation is 26.8Hz.

So from the above example you can tell pretty quickly if you are dealing with a powertrain or a wheel tire. Now the hard part....you determine it is a lower frequency indicating tires/wheels. This is where you need the amplitude of the frequency. Lets say it is greatest in the left footwell. Okay...it is left side tires. Now try the back seat if a SCREW or more difficult the rear floor of a SCAB. This will point to the suspect left side tire/wheel based on amplitude.

This does not always work as there are many variables but in most cases allows you to radar in based on data, not an assometer, but do not ignore the assometer. It gives you a "gut" feel.

Okay....long winded and maybe of little help but I hope it helps the wheels in your head to turn to help id the problem.

Best,
Phil

 

[Larry]

Hi Larry,

What frequency do you show on your NVH software? There will be a huge difference in driveline frequency at 70mph than tires and should guide you. Tire balance is 1st order, Tire out of round (ovality) is 2nd order and driveline will be a magnitude above this by about 3.73 or what the rear gear is. Going by the engine as 1st order imbalance, 2nd order is shaking forces of a 4 banger and if driveline it will also be 2nd order as it is the frequency of a u joint at 8th gear which is one to one...then tires will be some 3.73 lower frequency that that for tire imbalance and half that for ovality... Hopefully between you and the dealer you can radar in on this.... Tire swap is a good idea in the meantime...

Want to play around a bit....use your NVH software and get a capture of the vibration. Then slap a hose clamp or two with the heads together side by side...now see what your NVH software reads as you have grossly imbalanced your driveshaft... This will start to give you a feeling for sensitivity of the software and to some extent calibrate your assometer too...

best,
Phil

48-50Hz seemed to be where most of the higher amplitude vibrations were recorded in the drive shaft and the amplitude of these drive shaft vibrations were 2 to 3x of any other tire detected vibrations. So I'm a little puzzled as to why the dealer's NVH sensors didn't pick up similar?

 

[P. A. Schilke]

48-50Hz seemed to be where most of the higher amplitude vibrations were recorded in the drive shaft and the amplitude of these drive shaft vibrations were 2 to 3x of any other tire detected vibrations. So I'm a little puzzled as to why the dealer's NVH sensors didn't pick up similar?

Hi Larry,

Do not know...sensor placement, inexperience could be part of the problem.

best,
Phil

 

[Larry]

Hi Larry,

Do not know...sensor placement, inexperience could be part of the problem.

best,
Phil

Agreed. Hoping to be able to ride along on the Wheel swap test drive tomorrow.
Will share results when I have some. My TireDiscounters manager has already committed to doing what it takes to resolve any tire issues if that's the final verdict. I did inquire about when he last had his balancer calibrated and it may have been just after I got these tires, so another puzzle piece to consider.

 

[Larry]

Update. Dealer made a haphazard attempt to rule out tire wheel vibration buy putting on a set they had "around". I looked at tire date codes (04/20) and guess what? They were 10X worse than my tires at tripping vibration sensors. No benefit at all in trying to isolate any other vibration sources.

I've asked the dealer to check and/or re-balance my wheels to his own satisfaction to rule out poor balancing from tire dealer (Perhaps tire guy's balancer was out of calibration or shoddy work) Not likely because I had them already replace two tires and road force balance all 4 .

Dealer agreed to this and we'll test drive again IF they are able to balance to their own satisfaction. If not back to Tire guy for replacement of all tires and start over with Ford dealer if vibration still persists.

More soon. Make yourself some popcorn this is going to go on a while

 

[Larry]

Update ... *Larry waives to waiter "I'll have a slice of humble pie with my Occam's Razor. Lol
Finally seem to have resolved my vibration issues. Ford Dealer did a rebalance on all tires and found two out of balance, one of them 1.5 ounces out!. After rebalance road test showed vibrations minimal and much more acceptable. A quick call to my Tire Dealer, who apologized profusely and offered my next oil change free on the house, made me feel almost whole.

Dealer's tech who did NVH diagnostics in attempting to diagnose took some time to show me the details and explain why he was pretty adamant about tire issues being the cause.

Strongly encourage any one with vibration issues to think tires first, confirm balance and radial runout are not issues then consider NVH diagnostics. Trust the science.

 

[MIBuckeye]

Update ... *Larry waives to waiter "I'll have a slice of humble pie with my Occam's Razor. Lol
Finally seem to have resolved my vibration issues. Ford Dealer did a rebalance on all tires and found two out of balance, one of them 1.5 ounces out!. After rebalance road test showed vibrations minimal and much more acceptable. A quick call to my Tire Dealer, who apologized profusely and offered my next oil change free on the house, made me feel almost whole.

Dealer's tech who did NVH diagnostics in attempting to diagnose took some time to show me the details and explain why he was pretty adamant about tire issues being the cause.

Strongly encourage any one with vibration issues to think tires first, confirm balance and radial runout are not issues then consider NVH diagnostics. Trust the science.

That's great news! Not to be a downer, I've gone through the exact same thing "1.5 oz off, sir", only to have the damn vibration back again about a week later. It's like herpes... just keeps flairing up! I sincerely hope yours lasts because i know how freakin annoying this can be so please chime back in a few weeks from now and let us know how its going.

 

[P. A. Schilke]

Update ... *Larry waives to waiter "I'll have a slice of humble pie with my Occam's Razor. Lol
Finally seem to have resolved my vibration issues. Ford Dealer did a rebalance on all tires and found two out of balance, one of them 1.5 ounces out!. After rebalance road test showed vibrations minimal and much more acceptable. A quick call to my Tire Dealer, who apologized profusely and offered my next oil change free on the house, made me feel almost whole.

Dealer's tech who did NVH diagnostics in attempting to diagnose took some time to show me the details and explain why he was pretty adamant about tire issues being the cause.

Strongly encourage any one with vibration issues to think tires first, confirm balance and radial runout are not issues then consider NVH diagnostics. Trust the science.

Hi Larry,

I am glad to hear a positive outcome and that the Dealer Tec took time to show you why. Again, you were in much lower that driveline frequencies that told me it was wheel tire. Rough rule of thumb...15 Hz .... Wheel/tire.....40Hz range...drive line... Otherwise...you are just SWAGing it or more likely WAGing it...

best,
Phil

 

[MIBuckeye]

Hi Larry,

I am glad to hear a positive outcome and that the Dealer Tec took time to show you why. Again, you were in much lower that driveline frequencies that told me it was wheel tire. Rough rule of thumb...15 Hz .... Wheel/tire.....40Hz range...drive line... Otherwise...you are just SWAGing it or more likely WAGing it...

best,
Phil

Phil,

Thanks for all your help on this site regarding NVH. Well, my vibration was tolerable and now again it's back... wondering if you could advise a little here (again). Getting lots of vibrations at 40-50 and again at 70 and up. They feel different. The lower speed feels like a shutter and the higher speed feels like a wheel balance issue to my butt and then it feels like both at the same time after that.... it's annoying to say the least. Here are a few screen shots of the NVH tool, captured from solid mount in center console. Frequency at upper end seems to suggest driveline and frequency at lower speed suggests tire balance based on your rule of thumb. Any thing you see here? Headed back to dealer again next week... thx!

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