Sound Generator Modification
- Thread starter sk93
- Start date
Just did sound generator improvement but on a 2.5. I have found out on google that you need 8 parts together to do it on a 2.5. So I have ordered it in Bmw Croatia, and here it cost me 100£ for all 8 new parts+17£ for the mechanic to put it in. Took both sponges out and it sounds awesome, not loud at all, just perfect. Tried with one but was not so raw as without any. When I had Mazda Rx-8 I had a k&n typhoon system and that sounded like jet fighter landing.
Bad_Pritt said:
Worth saying this is for a pre-facelift - the facelift N52 engine is different, as is the sound generator. This has just reminded me I promised photos... I can't do a how-to to fit one, but will try and at least take some that show where all the bits are over the weekend.
Promised some photos, so here they are... Sorry it has taken me so long 
Note that this is for the N52 engine - so facelift, and mine is a 3.0 which already has the sound generator installed. The M54 sound generator is different ; I do not know if a facelift sound gen will fit into a pre-facelift car. ///Ms do not have a sound generator - arguably the engine itself and the two extra exhausts do that job
All this will do is show you how to find the right bits in the engine to remove the foam. It is NOT necessary to take the whole sound generator assembly out as the initial how-to on this thread indicates, only the ends of the pipe that contains the foam.
This is the sound generator. The large rectangle shows the main body of the part, the second smaller rectangle shows the bit we are interested in, which connects to the firewall bulkhead :
Close up pic from the same angle :
Close up pic from a different angle looking from the front of the car, bulkhead connection circled :
First stage of this mod is to simply pull the bulkhead end away from the firewall. Takes some force but just pulls out. Then twist the tube up towards you and you see this :
The foam will be clearly visible in the hole that is circled. Mine is, of course, not present :evil:
The circled bit is important - it is rigid plastic and must be "clipped" back into the metal hole in the firewall. I use quotation marks because there is no set position, just line it up feeling with your fingers and push till you hear it click in. This is the hole in the firewall :
If you want more noise, you need to take the foam out the other end near the engine - this is stage two of this mod. You need to undo the jubilee clip to the right of my finger below (circled in pic 2 above) - quite a long way - and work the tube off. This takes some effort and can result in skinned knuckles.
Your choice whether you remove it completely, cut it down, or not at all. I have cut about 1/3 of it off and then stuck it back in and that's just fine for me. All foam out made my ears bleed and (to my brain) soundedlike I was murdering the engine at 6-7,000 RPM.
Getting this tube back on can be a bit of a PITA - there is a notch in the end of the tube you need to line up with a corresponding 'bump' on the fitting that is attached to the rest of the sound generator. Takes some wiggling and some force too - more skinned knuckles potentially, but worth it. Sorry, no pics of that as I was short on time - but you'll figure it out :wink:
I thought about re-posting the OP's text and my pics, but I wouldn't do it that way, and I didn't have time to take the whole assembly off. Hopefully that helps anyone else looking at this thread now the original photos are gone.
Note that this is for the N52 engine - so facelift, and mine is a 3.0 which already has the sound generator installed. The M54 sound generator is different ; I do not know if a facelift sound gen will fit into a pre-facelift car. ///Ms do not have a sound generator - arguably the engine itself and the two extra exhausts do that job
All this will do is show you how to find the right bits in the engine to remove the foam. It is NOT necessary to take the whole sound generator assembly out as the initial how-to on this thread indicates, only the ends of the pipe that contains the foam.
This is the sound generator. The large rectangle shows the main body of the part, the second smaller rectangle shows the bit we are interested in, which connects to the firewall bulkhead :
Close up pic from the same angle :
Close up pic from a different angle looking from the front of the car, bulkhead connection circled :
First stage of this mod is to simply pull the bulkhead end away from the firewall. Takes some force but just pulls out. Then twist the tube up towards you and you see this :
The foam will be clearly visible in the hole that is circled. Mine is, of course, not present :evil:
The circled bit is important - it is rigid plastic and must be "clipped" back into the metal hole in the firewall. I use quotation marks because there is no set position, just line it up feeling with your fingers and push till you hear it click in. This is the hole in the firewall :
If you want more noise, you need to take the foam out the other end near the engine - this is stage two of this mod. You need to undo the jubilee clip to the right of my finger below (circled in pic 2 above) - quite a long way - and work the tube off. This takes some effort and can result in skinned knuckles.
Your choice whether you remove it completely, cut it down, or not at all. I have cut about 1/3 of it off and then stuck it back in and that's just fine for me. All foam out made my ears bleed and (to my brain) soundedlike I was murdering the engine at 6-7,000 RPM.
Getting this tube back on can be a bit of a PITA - there is a notch in the end of the tube you need to line up with a corresponding 'bump' on the fitting that is attached to the rest of the sound generator. Takes some wiggling and some force too - more skinned knuckles potentially, but worth it. Sorry, no pics of that as I was short on time - but you'll figure it out :wink:
I thought about re-posting the OP's text and my pics, but I wouldn't do it that way, and I didn't have time to take the whole assembly off. Hopefully that helps anyone else looking at this thread now the original photos are gone.
Good set of pictures Bing - did mine this afternoon in a couple of mins.
The filter was grey foam, not black like some.
The filter was grey foam, not black like some.
Having read previous posts when I took it out of my first Z4, I only took out the bulkhead foam 
NeilP, somewhere between 1.5 and 3.5k RPM is the real sonorous sweet spot I find. I took both bits out, hated it. Stuck the bulkhead side back in, not enough noise. Removed bulkhead, cut 1/3 off the engine side. Now pretty perfect. Makes my ears shudder with pleasure every time I boot it
this will defo be my first mod
EdButler said:
Hi, I hope not to tread on anyones toes here with the mods.
As the gentleman describes above, I too encountered a rattle at low speeds or just brishing the throttle with my little toe which totally ruined the whole fun of driving with both bungs out. I did find a solution to this by taking the whole assembly down to parts and attatching a cable tie right next to where it hooks into the lower part of the spring housing inside the unit itself. This straightens the spring and stops it from rattling on itself. This seemed to do the trick. I hope it is of help to othere members that found this little issue.
