Sponsored

Sound Tube Modification for GT Convertibles

CVCashmere

Well-Known Member
Joined
Mar 28, 2017
Threads
99
Messages
1,311
Reaction score
681
Location
South Jersey
First Name
Carl
Vehicle(s)
15 GT Vert w/Steeda lower brace, PP sways & susp
Hello Fellow Verts

As you all know, convertibles with the top up are noisier than hardtops. The sound tube that is connected through the Helmholtz resonator “picks up specific sounds” from the air being fed through the air intake system tube to the MAF (mass airflow sensor) and emphasizes them. The sound tube adds an engine acceleration sound when the throttle is opened.

This physical fact was described by Professor Helmholtz in his 1862 book, “On the Sensations of Tone”.

Between the road noise and the sound tube, I was losing the sound of the exhaust…which I want to hear! BTW…before I describe my modification, note the picture of the 2 Helmholtz chambers; the larger one is from a 2015-17 GT, the smaller one from the 2018+ version. Perhaps Ford decided to scale back the sound and its ugly appearance?
Size difference.JPG

I obtained an extra hose that leads into the Helmholtz resonator, bought a #4 rubber plug from the Ace Hardware Store, cut off the fatter end to fit into the hose, and filed it as needed. Then I lock open the large clamp, slipped in the plug into where the hose narrows, and superglued it so it would not get sucked out and wind up in the MAF.
Before.JPG


Plug cutting.JPG


Hose plugged.JPG

Yes, I have lost much of the engine noise but now, the H-piped exhaust tone comes through clearer while the interior is quieter. BTW…this works equally well for GT coupes.
After.JPG

Thanks for looking.

CVCashmere
Sponsored

 

Johnnybee

Well-Known Member
Joined
Jun 16, 2018
Threads
5
Messages
888
Reaction score
619
Location
Canada
Vehicle(s)
2018 convertible
Nice that worked for you. A much more simple fix than the Ecoboost. I have not "muted" the speaker generated noise in my car, so don't really know what the difference would be for me. One day in retirement when I have time, have bothered to get the OBD cord I need and downloaded Forscan, I will probably start fiddling with things. I know I can get at the mics but I don't really want to break any clips on the cover under the mirror, which I have read in various posts can happen.
 

BimmerDriver

Well-Known Member
Joined
Aug 24, 2018
Threads
44
Messages
601
Reaction score
464
Location
RDU, NC
First Name
Michael
Vehicle(s)
GT convertible w/3 pedals, BMW M550i
I plugged mine in my former coupe with a wine bottle cork. I honestly didn't notice much difference, so I haven't bothered to do it yet in the convertible.

It's amusing that some poor engineer spent a month working on this thing (probably on a marketing directive) and then we all try to disable it.
 

Sound Wave

Well-Known Member
Joined
Aug 31, 2019
Threads
2
Messages
133
Reaction score
64
Location
Honolulu, Hawaii
First Name
Gary
Vehicle(s)
2015 GT 50th Anniversary Limited Edition MT
Vehicle Showcase
1
There was a thread a while back about adding an in-line water shut-off valve to the sound tube. That way, you can regulate how much sound you want to have coming in to the cabin. At the time I thought it was a cool idea. I messed around with the settings for a while, but now I just leave it wide open like stock.

I was thinking that if I preferred the sound turned off, I was going to remove the whole tube from the car. However, it was too quiet in the cabin when the windows were up for me; but mine is a coupe.
Sponsored

 
 




Top