The "Noise" in NVH

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Re: The "Noise" in NVH

Postby Steve Smith » Mon Sep 07, 2015 10:45 am

Hello Mark, NICE WORK, and thank you very much for your post, sharing the information, and taking the time out to produce the attachment. (I know how time consuming this can be)

Could you post a psdata file of your captures if possible?

Did you find the squeak as a result of your application using the scope?

Thank you again, take care.......Steve
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Re: The "Noise" in NVH

Postby Mark Dalton » Tue Sep 08, 2015 1:42 am

Hi Steve,
We did and we didn't find the noise. We determined the noise was in the rear axle/suspension support frame, although we were never able to identify the root cause. But we did find out that after the frame was returned to GM Holden Engineering they found a broken spot weld. The replacement of the support was a fairly big repair and was not a cheap warranty repair. Using the set up I did gave us the information that, although we couldn't pinpoint the source of the noise, we knew it had to be in the support frame. And we could provide the data to GM Warranty to back up our diagnosis.
I haven't got the psdata. just now, it could be on any one of the 6 workshop laptops, I'll have to go hunting for it.
I will attach a sound file of the noise and a pdf. of some information I passed on to GM Tech Assist on what I found.
Hopefully from that you'll see the differences in the amplitude from the different locations.
Regards,
Mark.
Attachments
1EN3CLa.pdf
(2.13 MiB) Downloaded 101 times
1EN3CL.m4a
(535.49 KiB) Downloaded 96 times
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Re: The "Noise" in NVH

Postby Steve Smith » Tue Sep 08, 2015 7:33 am

Hi Mark and thank you again.

I sincerely hope GM technical assist are singing your praises as it does make life easier when we can present evidence of audible noise.

Noises must be one of the most difficult phenomena to describe as there are no industry standard descriptions of what a knock, creak, squeak, thump, flutter, buzz or thud actually sound like.

Taking a recording and presenting a visual representation of what you could actually hear is undeniable evidence there is a real problem.

Whilst this was a failed spot weld resulting in a creak, it does not bear thinking about what fault/failure we could have seen had this been ignored, 5 years from now!

The knowledge of what components were not responsible for the noise proves invaluable and allowed for an informed diagnosis of the support frame based on the test results.

I said it before and will say it again, nice work and thank you for posting the results.

No need to search for the psdata files

Take care......Steve
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