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Giving Up on the Source
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wmarlexingtonsc
- OneWave
- Posts: 23
- Joined: Wed Oct 26, 2022 2:19 pm
Giving Up on the Source
Hello everyone,
Reading through the posts on the NVH forum here at PICO, I notice that almost all the posts are focused on finding the SOURCE of an offending vibration or noise and eliminating the source itself, insofar as possible. This is of course the proper way to try to confront these NVH situations initially. However, I wondered if any of you, particularly those of you who work at dealerships, could share any stories about the materials and methods used when the vibration/sound source cannot be outright eliminated for some reason. Also, at what point does one make the decision to stop chasing the SOURCE of the vibration and start trying to mitigate its effects? Are there particular materials (e.g., sound deadening mats, perhaps) that are commonly used in interiors to quiet down the cabin? Are there universal dampers that can be applied to exhaust pipes to cut down on resonation?
The genesis of the idea for this thread came from a car in our shop. We were working on a newer AUDI. The customer wanted us to remove the rear mufflers and install custom tips. We did as he asked, but he brought the vehicle back to us a couple times after the work was done with complaints of a rattling/resonating sort of noise, which seemed to be emanating from the new, custom exhaust system at certain, random times. We inspected the vehicle multiple times on the lift for any signs of exhaust rubbing anywhere that could be causing the body vibration/booming noise at certain RPMS. This is normally the fix for exhaust complaints like this: minor adjustment somewhere where something is rubbing under certain conditions. Yet we could find nothing. I wanted to go further and see if we could diminish the effects of the vibration by installing some sort of damper device off the side of the exhaust pipe, as you see often on BMW products, for example. Unfortunately, the customer said that the noise did not bother him so much and did not bring the vehicle back to me to play with. Nevertheless, this got me thinking about the reasons why one might give up on finding and/or eliminating the source of vibrations or noises, and the methods and the materials that are used after one makes this decision to move on.
Please share with us your success stories in this area, if you have any!
Thanks for reading,
Josh
Reading through the posts on the NVH forum here at PICO, I notice that almost all the posts are focused on finding the SOURCE of an offending vibration or noise and eliminating the source itself, insofar as possible. This is of course the proper way to try to confront these NVH situations initially. However, I wondered if any of you, particularly those of you who work at dealerships, could share any stories about the materials and methods used when the vibration/sound source cannot be outright eliminated for some reason. Also, at what point does one make the decision to stop chasing the SOURCE of the vibration and start trying to mitigate its effects? Are there particular materials (e.g., sound deadening mats, perhaps) that are commonly used in interiors to quiet down the cabin? Are there universal dampers that can be applied to exhaust pipes to cut down on resonation?
The genesis of the idea for this thread came from a car in our shop. We were working on a newer AUDI. The customer wanted us to remove the rear mufflers and install custom tips. We did as he asked, but he brought the vehicle back to us a couple times after the work was done with complaints of a rattling/resonating sort of noise, which seemed to be emanating from the new, custom exhaust system at certain, random times. We inspected the vehicle multiple times on the lift for any signs of exhaust rubbing anywhere that could be causing the body vibration/booming noise at certain RPMS. This is normally the fix for exhaust complaints like this: minor adjustment somewhere where something is rubbing under certain conditions. Yet we could find nothing. I wanted to go further and see if we could diminish the effects of the vibration by installing some sort of damper device off the side of the exhaust pipe, as you see often on BMW products, for example. Unfortunately, the customer said that the noise did not bother him so much and did not bring the vehicle back to me to play with. Nevertheless, this got me thinking about the reasons why one might give up on finding and/or eliminating the source of vibrations or noises, and the methods and the materials that are used after one makes this decision to move on.
Please share with us your success stories in this area, if you have any!
Thanks for reading,
Josh
Re: Giving Up on the Source
Hi Josh,
I have personal experience from Bentley dealerships where noise is extremely important to customers as the expectation is far higher than at premium brands as Mercedes or Audi.
The NVH plays major role in decision and demonstration to customer (printed report) where customer feels the "noise should not be there" and expecting the vehicle be absolutely quiet.
As you in dealership dealing with the same cars and models all the time (in contrast with non-franchise workshops where the same model hardly comes again), the NVH kit will absolutely save your day when you have own database of noises from good known cars and use it as comparison to customer complaints.
This means you must use always the same model and measure it at the same condition, the same location for sensors and same road, gear, RPM etc.
For example, engine noise at idle, whatever fantastic noise insulation there is, if you really listen you can hear and feel the engine anyway. The question is where it is normal as designed or from what level it is different? Is there really higher noise level and some action should be taken?
Here is the good known graphic report printed from NVH application presented side by side with the complaint vehicle.
As per my experience about 90% customers accept such presentation and feel happy with their vehicle, seeing solid evidence and explanation by professional staff.
I really believe if this works with such sensitive customers as Bentley owners, it definitely has to work with premium brands as Mercedes, BMW or Audi.
With regards to your aftermarket or sport exhaust case, here the report would show higher noises and the explanation would be the vehicle was designed and tested to be equipped with original exhaust system and as it is not original system anymore, vibration and resonances from aftermarket exhaust are not supported by vehicle noise insulation. The result is as increased noise visible on this NVH printed graph.
Then you would use the same record as good known sample for this one customer vehicle, for any future complaints where the customer could complain “the noise has increased”.
So, what I want to say is the NVH at dealership is maybe more important as tool to prove there is nothing wrong with the vehicle and as presentation tool where customer has clear visual evidence stating his vehicle is in good condition.
Hopefully this may help you to see how the NVH is used elsewhere, I did not mean anything else than provide alternative opinion and share experience where the NVH kit is very helpful.
Especially as the Mercedes and VAG world has the Picoscope and NVH kit in the list of approved special tools.
Regards,
Roman
I have personal experience from Bentley dealerships where noise is extremely important to customers as the expectation is far higher than at premium brands as Mercedes or Audi.
The NVH plays major role in decision and demonstration to customer (printed report) where customer feels the "noise should not be there" and expecting the vehicle be absolutely quiet.
As you in dealership dealing with the same cars and models all the time (in contrast with non-franchise workshops where the same model hardly comes again), the NVH kit will absolutely save your day when you have own database of noises from good known cars and use it as comparison to customer complaints.
This means you must use always the same model and measure it at the same condition, the same location for sensors and same road, gear, RPM etc.
For example, engine noise at idle, whatever fantastic noise insulation there is, if you really listen you can hear and feel the engine anyway. The question is where it is normal as designed or from what level it is different? Is there really higher noise level and some action should be taken?
Here is the good known graphic report printed from NVH application presented side by side with the complaint vehicle.
As per my experience about 90% customers accept such presentation and feel happy with their vehicle, seeing solid evidence and explanation by professional staff.
I really believe if this works with such sensitive customers as Bentley owners, it definitely has to work with premium brands as Mercedes, BMW or Audi.
With regards to your aftermarket or sport exhaust case, here the report would show higher noises and the explanation would be the vehicle was designed and tested to be equipped with original exhaust system and as it is not original system anymore, vibration and resonances from aftermarket exhaust are not supported by vehicle noise insulation. The result is as increased noise visible on this NVH printed graph.
Then you would use the same record as good known sample for this one customer vehicle, for any future complaints where the customer could complain “the noise has increased”.
So, what I want to say is the NVH at dealership is maybe more important as tool to prove there is nothing wrong with the vehicle and as presentation tool where customer has clear visual evidence stating his vehicle is in good condition.
Hopefully this may help you to see how the NVH is used elsewhere, I did not mean anything else than provide alternative opinion and share experience where the NVH kit is very helpful.
Especially as the Mercedes and VAG world has the Picoscope and NVH kit in the list of approved special tools.
Regards,
Roman
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wmarlexingtonsc
- OneWave
- Posts: 23
- Joined: Wed Oct 26, 2022 2:19 pm
Re: Giving Up on the Source
Roman,
Thank you so much for your write up about your experience working as a Bentley technician. As you said, that upper echelon of comfort/quiet ride in a Bentley means that expectations are sky high with regards to reduction of any NVH related issues. It was very helpful to hear about how you use the PICO NVH as a guide, in many cases, to show the customer that there is in fact no issue with their car, relatively speaking, when compared to other like models. Thank you for sharing.
Anyone else have any stories to share when you have not only given up on a vibration/noise source, since it can be considered normal for the vehicle, but gone a step further and tried to modify what exists from the factory in order to mitigate/lessen vibration and noise concerns?
Thank you so much for your write up about your experience working as a Bentley technician. As you said, that upper echelon of comfort/quiet ride in a Bentley means that expectations are sky high with regards to reduction of any NVH related issues. It was very helpful to hear about how you use the PICO NVH as a guide, in many cases, to show the customer that there is in fact no issue with their car, relatively speaking, when compared to other like models. Thank you for sharing.
Anyone else have any stories to share when you have not only given up on a vibration/noise source, since it can be considered normal for the vehicle, but gone a step further and tried to modify what exists from the factory in order to mitigate/lessen vibration and noise concerns?