Wheel-arch - Sound-Deadening internally or externally?

[VanDamMan]

Hi,
Do people add sound deadening material to both the inside and external arch area? The inside of my van is going to be coated with insulation and sound deadening wherever possible but if it's also better to do externally then I might do that as well. Thanks!

Hi. @vwski ...Did mine 18mths ago..Thought about it and decided easier to do just inside..lots more work to do out side safely ( unless you have jacks and stands) so when I ordered the silent coat I brought some thicker sheets just for wheel arches (the science behind it is the thicker the insulation better sound proofing)
Just make sure you work into the contours...so when you add the carpet it will look neat

 

[The Bear78]

The only problem with deadening the inside is that the finish may affect how nice the carpet looks if that is the eventual plan. Like anything, take the time to do it neatly and with no overlapping joints then it shouldn't be a problem.
If you have a jack and axle stands then the outside is easy and probably quicker including the wheel removal as there is no need for neat joins. The outside will need a decent clean and de-grease as VW splat some inhibitor wax around the area (not particularly carefully...). I have also seen the outer arch liner soundproofed with foam as there is a gap between it and the metalwork.
Having deadened the outer arches I chose to use 6mm Dodo liner foam on the inside. This is much easier to form around the double curves and was thin enough to keep the shape of the pressings in the metal which looks nicer once carpetted. I figured a bit of both would fit the bill.
Essentially, you can do as much or as little as you want.

 

[Lucio]

The only problem with deadening the inside is that the finish may affect how nice the carpet looks if that is the eventual plan. Like anything, take the time to do it neatly and with no overlapping joints then it shouldn't be a problem.
If you have a jack and axle stands then the outside is easy and probably quicker including the wheel removal as there is no need for neat joins. The outside will need a decent clean and de-grease as VW splat some inhibitor wax around the area (not particularly carefully...). I have also seen the outer arch liner soundproofed with foam as there is a gap between it and the metalwork.
Having deadened the outer arches I chose to use 6mm Dodo liner foam on the inside. This is much easier to form around the double curves and was thin enough to keep the shape of the pressings in the metal which looks nicer once carpetted. I figured a bit of both would fit the bill.
Essentially, you can do as much or as little as you want.

Was told by the guys at silent coat to only use 2 or 3mm max thickness for exterior arches
what are you using?

 

[The Bear78]

I used 2mm everywhere as I bought a bundle. I don't see why there would be a maximum thickness on the outer arch as there is plenty of room. Considering the shape of the arch with all the pressed in stiffening it's likely that anymore than 3mm would see little improvement.

 

[Lucio]

I used 2mm everywhere as I bought a bundle. I don't see why there would be a maximum thickness on the outer arch as there is plenty of room. Considering the shape of the arch with all the pressed in stiffening it's likely that anymore than 3mm would see little improvement.

Email from Silent coat company


Hi,

Silent Coat deadening can be applied externally providing the panel is clean and grease free prior to application. If this will be suspended upside down when applied to the arch I recommend using the 2 or 3mm versions instead of 4mm plus.

Kind regards,
Matt

 

[The Bear78]

That doesn't explain why but I silent coated the inside of the arch behind the panelling so only the very inside of the outer arch needed covering. There is no suspended area as such. Sure, some is on the top and therefore upside down but these pieces were all linked to the vertical wall and unlikely to fall off regardless of thickness or weight which I am sure is the their primary concern.

@vwski I hadn't realised which thread this was. If you read the first two pages then everything has already been answered.

 

[Lucio]

That doesn't explain why but I silent coated the inside of the arch behind the panelling so only the very inside of the outer arch needed covering. There is no suspended area as such. Sure, some is on the top and therefore upside down but these pieces were all linked to the vertical wall and unlikely to fall off regardless of thickness or weight which I am sure is the their primary concern.

@vwski I hadn't realised which thread this was. If you read the first two pages then everything has already been answered.

Im just saying what they said at SCoat
4mm Is likely come off apparently

 

[The Bear78]

I would assume so. I imagine 4mm is quite a weight.

 

[bootsam]

I did mine externally last weekend or so. I have jacks and stands courtesy of my ex old T2 pile of rust. It was a doddle to do. Just remove wheel and plastic shroud. Plus wash wax coating off. I had some trepidation removing this but as I was covering it all with SC, i relented. I did both in a matter of a few hours. Plus has the benefit of putting SC on the extension of the arch between that accessible from the inside and that on the external skin, that ordinarily would be tricky to get to. My bus had already been carpeted on the inside and they carpeted over the OEM panels and the arch, so I wanted to retain as much carpeting as has been done without adding a full recarpet to my budget. Hence externally made more sense.
Are the OEM trim panels cardboard or plastic? Also are they easily carpeted? I ask because my next job is to trim the carpet around the edge of the panels, leaving an inch for trimming, to allow me to gain access to these panels to remove them. Then trim the excess and carpet the panels and pop back on. Any description of the oem panels would be handy, thanks.

 

[VanDamMan]

I did mine externally last weekend or so. I have jacks and stands courtesy of my ex old T2 pile of rust. It was a doddle to do. Just remove wheel and plastic shroud. Plus wash wax coating off. I had some trepidation removing this but as I was covering it all with SC, i relented. I did both in a matter of a few hours. Plus has the benefit of putting SC on the extension of the arch between that accessible from the inside and that on the external skin, that ordinarily would be tricky to get to. My bus had already been carpeted on the inside and they carpeted over the OEM panels and the arch, so I wanted to retain as much carpeting as has been done without adding a full recarpet to my budget. Hence externally made more sense.
Are the OEM trim panels cardboard or plastic? Also are they easily carpeted? I ask because my next job is to trim the carpet around the edge of the panels, leaving an inch for trimming, to allow me to gain access to these panels to remove them. Then trim the excess and carpet the panels and pop back on. Any description of the oem panels would be handy, thanks.

Hi @bootsam Oem panels are made from composite pressed fibre.....never did my own carpeting but some companies use a thicker board to cut down on noise and mounting of speakers

I assume this what you mean ..

 

[bootsam]

Thanks VDM. I was afraid of that. I'll have to look at a set of better panels than that to re-apply.

 

[DXX]

I added 10mm self adhesive acoustic foam to the front arch liners today, from the top down to the rear, the front half left bare. It made a noticeable difference for very little cost and time. There was no requirement to use longer screws as cut out for the body flange and two pads on the liner.
All arches are now externally fitted with Dynamat Xtreme, rear liners completely covered with 10mm foam and front liners covered 50%.
Both doors are done with Dynamat Xtreme and 10mm foam on the cards.
Both front wings are done with Dynamat, they ring like a cymbal when bare, not sure how much was entering the cab so did them anyway.
Rest of the van was done professionally with Silent Coat and foam except the cab floor which I’ll be leaving for now.
Next I’m doing the front steps and scuttle.
I highly recommend foam coating the arch liners.

 

[M0RGZ]

I’m just starting on a few upgrades and want to add a bit of carpet to my Kombi. Initially I want to do the wheel arches and I’ll slowly work my way around the rest of the van. Guess now is the time to insulate the arches (before I carpet). I’m a complete novice and a bit confused by all the different material options, help, what do I need?
Can the job be done without removing anything else or do I need to pull some of the rubber flooring out to do a proper job?
Also on the exposed metalwork around the tailgate (rear pillars etc) is there insulation to use on those bits or just carpet?
Any advice would be massively appreciated.
Cheers

 

[Lucio]

I added 10mm self adhesive acoustic foam to the front arch liners today, from the top down to the rear, the front half left bare. It made a noticeable just difference for very little cost and time. There was no requirement to use longer screws as cut out for the body flange and two pads on the liner.
All arches are now externally fitted with Dynamat Xtreme, rear liners completely covered with 10mm foam and front liners covered 50%.
Both doors are done with Dynamat Xtreme and 10mm foam on the cards.
Both front wings are done with Dynamat, they ring like a cymbal when bare, not sure how much was entering the cab so did them anyway.
Rest of the van was done professionally with Silent Coat and foam except the cab floor which I’ll be leaving for now.
Next I’m doing the front steps and scuttle.
I highly recommend foam coating the arch liners.

Just asking why did you only cover half on front arches? Also is the acoustic foam and dynomatt 10mm the same thing or two different sound deadening?

 

[DXX]

Just asking why did you only cover half on front arches? Also is the acoustic foam and dynomatt 10mm the same thing or two different sound deadening?

Only did the rear half of the front arches as that is the area facing the cab, the front of the arch is unlikely to affect the noise level in the cab. Dynomat Xtreme was applied to the steel arch externally. Self adhesive 10mm foam was applied to the plastic liner so that It is sandwiched between the Dynomat and the plastic liner.
They are two separate products.

 

[Lucio]

Only did the rear half of the front arches as that is the area facing the cab, the front of the arch is unlikely to affect the noise level in the cab. Dynomat Xtreme was applied to the steel arch externally. Self adhesive 10mm foam was applied to the plastic liner so that It is sandwiched between the Dynomat and the plastic liner.
They are two separate products.

Oh ok
Take it the foam is waterproof?
Thinking of doing similar as it’s easier to do it externally than taking seats out and carpet?
or have you done inside the cab as well?

 

[DXX]

It’s closed cell foam so I guess you can call it waterproof, the adhesive is so strong that the foam rips before the adhesive lets go.
Yaheetech Sound Proofing Deadening Vehicle Insulation Closed Cell Foam Sheet with Adhesive Backing 50cm X 30cm,12 Sheets Yaheetech Sound Proofing Deadening Vehicle Insulation Closed Cell Foam Sheet with Adhesive Backing 50cm X 30cm,12 Sheets: Amazon.co.uk: Car & Motorbike

The only inner sound deadening on the cab is both doors and roof.
The rear is fully converted as a camper and as such fully sound deadened and insulated.

 

[Lucio]

Thanks. Will see if I can find anyone with a volume pack of 3mm silent coat in stock.

I've got a pack of dodo dead mat which is 1.8mm, if I've got enough could I double up on the arches externally
Or won't it make any difference?

 

[DXX]

I did the Dynamat on the arches way before doing the foam on the arch liners. IMO the foam made the biggest improvement by far.
Two layers of 1.8mm will make a difference.

 

[DXX]

I've got a pack of dodo dead mat which is 1.8mm, if I've got enough could I double up on the arches externally
Or won't it make any difference?

Just to point out that I've never used dodo dead mat so I can’t be sure if the adhesive is good for external application.
Dynamat is.