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-   -   Discovery on STi JDM axleback and perhaps others (https://www.ft86club.com/forums/showthread.php?t=143514)

gpvecchi 12-10-2020 05:34 PM

Discovery on STi JDM axleback and perhaps others
 
Some times ago I fitted the STi JDM axleback, instructions said to replace nuts, gasket, and hangers, but I didn't do it as my car was new.
I was happy with the sound, except an annoying resonance at 3000 rpm.
I asked here, and I was said it was drone, nothing to do, characteristic of the exhaust; it was not drone to me, but a resonance inside the cabin.
Recently I discovered a japanese article: I was right, and I made a great mistake.
I didn't check the part numbers of the additional parts, as I took for granted that they were the stock ones; but the hangers weren't, they were a different part number!
The article said that the cabin resonance frequency of the 86/BRZ is 125 Hz, and the STi steel exhaust (the titanium one don't) needs that specific hangers to avoid the noise. AND THIS WORKS!
If you have resonance, and you want to try risking just few bucks, you have to replace just the 2 rear hangers (the ones toward rear bumper) with 44066AJ010 part number. The front ones has to remain stock.

NLSP 12-10-2020 09:16 PM

Thank you, I might have to give this a try. I experience pretty much the same thing around the same RPM with my Blitz Nur-Spec R, because it's pretty tame and drone-free at any other speed.

Amazing how even the exhaust hangers have some sound engineering behind it.

HaXx 12-10-2020 10:35 PM

before and after video clips would be awesome. my system is loud, but im not sure if i should call it drone or resonance, or just loud.

gpvecchi 12-11-2020 03:27 AM

I tried taking videos, but it's completely useless, like all videos on exhaust noise, you have to hear it in person to understand dB, pitch etc..

nikitopo 12-11-2020 12:07 PM

Yes. I am using these 2 STI rear hangers.

botbs 12-11-2020 12:26 PM

Quote:

Originally Posted by nikitopo (Post 3392339)
Yes. I am using these 2 STI rear hangers.

What exhaust do you have? Thanks!

nikitopo 12-12-2020 04:11 AM

Quote:

Originally Posted by botbs (Post 3392345)
What exhaust do you have? Thanks!

The same like gpvecchi. The STi JDM axleback.

Cephas 12-14-2020 01:18 PM

Where did you find the Axle-back?

gpvecchi 12-15-2020 03:31 AM

Imported from Japan

norcalpb 12-15-2020 10:55 AM

Thank you sir! Another small mod to keep my mind busy.

mav1178 12-15-2020 09:57 PM

a good explanation of why OEMs spend so much time and money on R&D.

gpvecchi 01-12-2021 03:47 PM

Confirmed working with the replace of all 4 hangers on HKS Spec-L.

norcalpb 01-12-2021 08:11 PM

I ordered mine on the 15th and they're still not here...

gpvecchi 01-13-2021 04:02 AM

I ordered the remaining 3 (one for midpipe too, it's the same as the others), I'll update with the results.


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