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Sound Generator Modification

Posted: Sat Nov 21, 2009 2:47 pm
by sk93
I wasn't able to find a difinitive how-to for this realatively straightforward mod, and as I wanted to try it, I thought I'd put one together.
Again, all the thanks should go to the other members of this forum, who's posts and tips enabled me to do and write this!

Requirements
1x BMW Z4 3L
1x Medium-sized flathead screwdriver
1x Plaster for inevitable cut finger.

Costs
Zero.


Step 1
Open the bonnet and look for the plastic tube that leads from the air intake tubing, into the cabin.
Standing at the front of the car, the tube is located at the back right side of the engine
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Step 2
Gently pull the tube out of the hole that leads to the cabin. Mine felt a little tight to begin with, but a gentle bit of twisting whilst pulling and the tube came straight out.
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Step 3
At the other end of the pipe, it is secured to the main air intake trunking with a jubilee clip.
Using the flathead screwdriver, loosen this clip. Once it's loose, attach the plaster to wherever the screwdriver slipped and entered your finger.
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Step 4
Under the middle section of the sound generator is a small clip that keeps the pipe attached to the side of the engine block.
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Unclip this clip, then lift the piping up until the plastic groove on the top edge of the generator clears the rim of the engine block top.

Step 5
With both clips now unclipped, the jubilee undone, and the far end removed from the cabin, you should be able to remove the entire sound generator from the car.
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Step 6
With the sound generator removed, you can now seperate the rear pipe from the big front section.
Using the flathead screwdriver, carefully prise the small pipe from the main unit.
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Step 7
With the pipe seperated, you should see a peice of dark coloured foam in each end:
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Remove both peices, so that the small tube is now empty:
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Step 8
Re-assemble everything in reverse order and you're done!





It's a pretty easy mod to do, and only took me about 20 minutes including taking the photos.
I recorded a soundclip (from inside with the roof and windows closed!) so you can hear what having no foam in sounds like.
http://blog.ianmellor.co.uk/images/car/ ... rding4.mp3

TBH, for me, I found it extremely loud under heavy acceleration (wouldn't hear stereo!) and when moving slowly, it sounds like you've got a hole in the exhaust.
I'm going to put the foam that sits closest to the engine block back in and retry to see what that's like... I'll probaby edit this with another sound clip once done.

However, here's the complete HowTo - and it's not hard, so go do it yerself :P

Re: Sound Generator Modification

Posted: Sat Nov 21, 2009 3:08 pm
by sk93
stuck the foam back in nearest the engine block, and it sounds much better.
the "roar" is still there, but it's not deafening anymore and it also removed the "broken exhaust" sound at low speeds.

Still recommend you try different combinations of the foam yourself, but this got my vote :)

Re: Sound Generator Modification

Posted: Sat Nov 21, 2009 3:24 pm
by cj10jeeper
Nice write up.

I think most people who have done this mod and lived with it, have gone for variants of trimming the foam or removing one piece. I'm sure both out is way too loud.

Re: Sound Generator Modification

Posted: Sat Nov 21, 2009 3:53 pm
by Wondermike
Yeah nice write-up, like the MP3 :thumbsup:

Re: Sound Generator Modification

Posted: Sat Nov 21, 2009 4:59 pm
by Spud
I'm running it with both out. Hooligantastic :rofl:

Re: Sound Generator Modification

Posted: Sun Nov 22, 2009 12:23 am
by daveg
Spud wrote:I'm running it with both out. Hooligantastic :rofl:
Same here - dangerous move though. Car's MPG has dropped so much since doing it :? :evil:

Re: Sound Generator Modification

Posted: Sun Nov 22, 2009 11:44 am
by Spooky
Great write up. :)

Re: Sound Generator Modification

Posted: Sun Nov 22, 2009 4:10 pm
by sk93
:D Thanks for the positive feedback all :thumbsup:

Re: Sound Generator Modification

Posted: Wed Nov 25, 2009 1:12 am
by peddy
daveg wrote:
Spud wrote:I'm running it with both out. Hooligantastic :rofl:
Same here - dangerous move though. Car's MPG has dropped so much since doing it :? :evil:
I don't see how it can effect the MPG??

Re: Sound Generator Modification

Posted: Wed Nov 25, 2009 1:16 am
by sk93
peddy wrote:
daveg wrote:
Spud wrote:I'm running it with both out. Hooligantastic :rofl:
Same here - dangerous move though. Car's MPG has dropped so much since doing it :? :evil:
I don't see how it can effect the MPG??
you'll be amazed how the noise increases the depression of the throttle.
it's a viscious circle. press pedal - hear noise - pedel gets pressed harder - hear MORE noise - rinse and repeat :P

Re: Sound Generator Modification

Posted: Wed Nov 25, 2009 1:23 am
by peddy
sk93 wrote:
peddy wrote:
daveg wrote:
Same here - dangerous move though. Car's MPG has dropped so much since doing it :? :evil:
I don't see how it can effect the MPG??
you'll be amazed how the noise increases the depression of the throttle.
it's a viscious circle. press pedal - hear noise - pedel gets pressed harder - hear MORE noise - rinse and repeat :P
'doh' i feel stupid!! :oops:

Re: Sound Generator Modification

Posted: Wed Nov 25, 2009 1:28 am
by sk93
peddy wrote: 'doh' i feel stupid!! :oops:
It's late - I'm sure we can let you off :P

Re: Sound Generator Modification

Posted: Wed Nov 25, 2009 10:27 am
by easty027
Good write up. i did mine about a year ago and still have a single piece removed (the foam closest to the cabin) and its great under hard excelleration towards the higher rev range. People always comment on how good it sounds. At the slowr speeds you cant hear it which in my opinion is a good thing.

I tried both pieces out, and it just didnt sounds right to me. Its a brilliant idea by BMW though for fitting it in the first place.

Re: Sound Generator Modification

Posted: Wed Nov 25, 2009 10:36 am
by sk93
easty027 wrote:Good write up. i did mine about a year ago and still have a single piece removed (the foam closest to the cabin) and its great under hard excelleration towards the higher rev range. People always comment on how good it sounds. At the slowr speeds you cant hear it which in my opinion is a good thing.

I tried both pieces out, and it just didnt sounds right to me. Its a brilliant idea by BMW though for fitting it in the first place.
+1
That's exactly my oppinion :D

Re: Sound Generator Modification

Posted: Sat Dec 12, 2009 5:10 pm
by Johnnybwaiting
Wow Guys,
Thanks for the fascinating how to. Now I have a weekend project. Very informative and great recipe style directions I may be able to do it without screwing anything up. But that remains to be seen
great presentation