Discovery on STi JDM axleback and perhaps others - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

gpvecchi · 12-10-2020, 05:34 PM

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

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

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.

12-10-2020, 05:34 PM	#1
gpvecchi Senior Member Join Date: Mar 2018 Drives: Toyota 86 GT Limited PP (Model G) Location: Italy Posts: 1,018 Thanks: 406 Thanked 335 Times in 187 Posts Mentioned: 14 Post(s) Tagged: 0 Thread(s)	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.

12-10-2020, 10:35 PM	#3
HaXx Member Join Date: Dec 2017 Drives: jrsc_brz Location: boston Posts: 966 Thanks: 726 Thanked 675 Times in 336 Posts Mentioned: 4 Post(s) Tagged: 0 Thread(s)	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. __________________ JACKSON RACING l RALLYBACKER l FORGESTAR l FORTUNE AUTO l INVIDIA

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12-10-2020, 09:16 PM	#2
NLSP Senior Member Join Date: Dec 2013 Drives: 2014 Ultramarine FR-S Location: Vancouver, BC Posts: 517 Thanks: 414 Thanked 543 Times in 244 Posts Mentioned: 2 Post(s) Tagged: 0 Thread(s)	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.

12-11-2020, 03:27 AM	#4
gpvecchi Senior Member Join Date: Mar 2018 Drives: Toyota 86 GT Limited PP (Model G) Location: Italy Posts: 1,018 Thanks: 406 Thanked 335 Times in 187 Posts Mentioned: 14 Post(s) Tagged: 0 Thread(s)	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..

12-11-2020, 12:07 PM	#5
nikitopo Senior Member Join Date: Mar 2014 Drives: '15 BRZ RA Location: Greece Posts: 3,787 Thanks: 2,416 Thanked 1,944 Times in 1,261 Posts Mentioned: 29 Post(s) Tagged: 0 Thread(s)	Yes. I am using these 2 STI rear hangers.

12-14-2020, 01:18 PM	#8
Cephas Senior Member Join Date: Aug 2018 Drives: 2017 Toyota 86 (860 SE) Location: Dayton, OH Posts: 328 Thanks: 537 Thanked 434 Times in 167 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Where did you find the Axle-back?

12-15-2020, 03:31 AM	#9
gpvecchi Senior Member Join Date: Mar 2018 Drives: Toyota 86 GT Limited PP (Model G) Location: Italy Posts: 1,018 Thanks: 406 Thanked 335 Times in 187 Posts Mentioned: 14 Post(s) Tagged: 0 Thread(s)	Imported from Japan

12-15-2020, 10:55 AM	#10
norcalpb Senior Member Join Date: Oct 2013 Drives: 2013 BRZ, 2023 Model 3 Location: SF Bay Area Posts: 2,296 Thanks: 1,212 Thanked 861 Times in 570 Posts Mentioned: 15 Post(s) Tagged: 0 Thread(s)	Thank you sir! Another small mod to keep my mind busy.

12-15-2020, 09:57 PM	#11
mav1178 Senior Member Join Date: Apr 2013 Drives: 2005 Toyota Camry Location: 91745 Posts: 6,562 Thanks: 493 Thanked 6,093 Times in 3,029 Posts Mentioned: 95 Post(s) Tagged: 3 Thread(s)	a good explanation of why OEMs spend so much time and money on R&D.

01-12-2021, 03:47 PM	#12
gpvecchi Senior Member Join Date: Mar 2018 Drives: Toyota 86 GT Limited PP (Model G) Location: Italy Posts: 1,018 Thanks: 406 Thanked 335 Times in 187 Posts Mentioned: 14 Post(s) Tagged: 0 Thread(s)	Confirmed working with the replace of all 4 hangers on HKS Spec-L.

01-12-2021, 08:11 PM	#13
norcalpb Senior Member Join Date: Oct 2013 Drives: 2013 BRZ, 2023 Model 3 Location: SF Bay Area Posts: 2,296 Thanks: 1,212 Thanked 861 Times in 570 Posts Mentioned: 15 Post(s) Tagged: 0 Thread(s)	I ordered mine on the 15th and they're still not here...

01-13-2021, 04:02 AM	#14
gpvecchi Senior Member Join Date: Mar 2018 Drives: Toyota 86 GT Limited PP (Model G) Location: Italy Posts: 1,018 Thanks: 406 Thanked 335 Times in 187 Posts Mentioned: 14 Post(s) Tagged: 0 Thread(s)	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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