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Soundproofing success on the 997.1

Luke997

Member
Joined
20 Sep 2017
Messages
17
Hi all, I managed to get a good result in tackling the excessive road noise on my 997.1, but had a few learning points to pass on if someone should google Porsche 997 sound proofing. You could make a difference to a 997 just by doing under the driver and passenger footwell and the outer rear arches through the speaker openings, which wouldn't take too long, but I went full monty and did as much as I could, adding about 5kg of soundproofing dynamat extreme. There wasn't much reduction in engine noise, if you have a sports exhaust you'll still hear it just fine.

Ultimately, I managed to get my cabin interior noise on the motorway down from approx 91db to about 87 using the decibel X app on my phone, which doesn't sound like a lot, but due to the exponential of how Db is measured, I've cut my interior cabin noise by half (noise doubles every 3 db) I still have new tyres to put on which will ultimately help a lot too. Ultimately, auwful sections of poor road will still transmit a lot of noise through any soundproofing, but I'm now much happier as it's now easier to hear the nicer aspects of the ehaust as it isn't all drowned out by tyre roar.

I ordered this pack of dynamat which was more than enough. If you want even better results than me, also consider some Dynaliner too. https://www.amazon.co.uk/Dynamat-10455-Xtreme-Bulk-Pack/dp/B00020CB2S

You will also benefit from a interior trim removal tool and a narrow rubber roller to press the film down.

This book is also very useful. 101 Projects for Your Porsche 911 996 and 997 1998-2008 (Motorbooks Workshop) https://www.amazon.co.uk/dp/0760344035/ref=cm_sw_r_cp_tai_PtXEAbG4HKKZT

I did the doors and driver passenger footwell first, followed by the rear arches. I decided that the doors were an important step as I measured the db in different locations within the car and it was also fairly high near the large speakers within the doorcards.

Doors-
Some of the clips in the door cards are very difficult and will almost certainly break off. It would be useful ordering five clips in advance. My end result was similar to what was achieved in this link, but Also made sure I left the side impact airbag eruption point in the door card clear of dynamat. http://www.audiofile-incar.co.uk/audio-upgrades/porsche-997

It is also important to remove the large speaker to give you access to the metallic skin of the door on the naked inside 'wet side' of the door, and you can apply a generous amount of dynamat where it will be most effective.

After the doors it is the drivers and passenger footwell, dynamating whatever I could underneath the carpet. The metal of the floor was very tinny here and my highest decibel measurement on the motorway was from the footwell and near the rear speakers on the rear arches. The footwells were relatively straight forward to do and didn't really need the front seats removing, I just peeled back the carpet and applied what I could. The only difficulty was unplugging the accelerator pedal which took about ten minutes of perseverance to press the pale coloured clip into the connector enough to release the plug. Once you've pressed the clip enough, it clicks and stays pressed into the connector. Some of the carpet is retained via contact adhesive so having some to hand for putting the carpet back is a good idea. Also be careful not to block your water drainage holes with dynamat.

Next came the removal of the rear trim and carpet. I left the drivers and passenger seat in to do this but it made the job very aukward. I would advise taking them out. Once the rear seats were removed and the trim was all peeled back I dynamatted whatever I could get to, paying particular attention to the rear arches. Contact adhesive again here was useful. Of note is that there is a significant amount of naked metal wheel arch just the other side of the rear speakers - if you move a bit of trim out the way you can dynamat a substantial amount of extra wheel arch through the rear speaker access hole. This is an important area which a lot of people will miss. I then used dynamat to cover over the hole in the chassis behind the speaker to seal it all off.

I eventually got all the trim back, the total job for the whole car took about 15 hours. After reconnecting the battery, both my windows wouldn't work, and failed slightly retracted, this was due to not quite connecting one of the purple electrical connnections in the drivers door. You also get a PSM failure caption illuminate on the dashboard after reconnecting the battery, which will clear fairly shortly after you start driving down the road.

If you are tight on time and don't have many tools / competence then you can definitely apply dynamat under the footwell carpet, and also onto a significant amount of the rear arches merely by removing the rear speakers.

Sorry for the massive amount of info but I hope it helps someone else if they are considering doing the job properly. I can still hear my exhaust just fine but now have a lot less road noise from the tyres.
 

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Great work. This is something I am looking at doing although not as a DIY job. Does anyone have any good recommendations for someone in South/West London or Surrey?
 
You will have to drive around with the windows closed :dont know:
 
Nicely done Luke997

do you have any pic of the work whilst it was in progress
 
I don't think the doors will achieve much, it's the rear arches that are the killer. It would help to apply something on the outside of them too.

M
 
Well played Luke997! This was a constant bugbear in my previous car (also a 997); the road noise almost killed off anything that was coming from the Bose sound system when travelling at motorway speeds. Quite possibly the biggest gripe I had in my car. If you have pictures, these would be welcome on the forum.

~ Maxie :thumb:
 
Dynamat is incredible stuff, but there are plenty of off-brand options if you're not keen to spend that much.

I'd personally stick to using Dynamat on these cars, but I used some cheaper alternative for my Mx5 track car
 
Sound deadening? In a 911 ? :what:

I must be in the minority who actually like the road noise :)

All that dynamat must weigh a fair bit too.
 
Thats a good Post , I know it was discussed doing the rear arches in another recent thread think it was a Boba thread. I was led to understand the soundproofing in the gen2 is much better but it would be interesting to know what could be improved and were on a gen2 if anyones done it.
personally I found fitting a cargraphic sports exhaust has got rid of almost all my road noise :grin: :grin: but joking aside if the footwells were not well deadened on a gen2 I would be up for doing that. :thumb:
 
Dynamat in conjunction with Dynaliner gives great results I did my Defender 130 with it a few years back the difference it made was amazing..
 

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I did this some of this on mine, when I stripped out the seat belts. Most of the noise from a 997 comes from the rear tyre roar amplified through the rear arches.

The rear quarters and arch's have a 2 inch piece of foam, that does nothing, putting Dynamat or better down as well makes a big difference.
 
Great post Luke. Dynamat extreme is seriously good stuff. had a vw T5 lined with it and the difference was startling. The big van doors and tailgate clunk rather than rattle when shut.
 
Alfaian said:
Sound deadening? In a 911 ? :what:

I must be in the minority who actually like the road noise :)

All that dynamat must weigh a fair bit too.

I though this would be a thread about removing sound proofing around the rear seats to get more induction noise into the cabin



I hear Nissan Leafs are really quiet




Its it leafs or leaves?
 
Thanks for the feedback everyone, I've added only a few pictures which I managed to get, sorry I should have taken some more. Just to add to the original post, there is a lot of talk about rear arches, but I took the car out on the motorway after doing the left hand passenger door and footwell, and logged a decibel drop of about 1.5 - 2 compared to the in un soundproofed right hand side, especially within the footwell. There is just as much noise coming into the car from the footwell, so it is worth doing, and it is among the easiest of all the areas to do, especially if you have left over dynamat after doing the rear arches!
 

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