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Bulkhead exterior soundproofing

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I'm after people's experience/tips on what to use for the exterior bulkhead for soundproofing.

The interior's been done to death: typically camping mats, or WOR stuff, but exterior seems to have very little on it.

The lead sandwich (http://www.cbsonline.co.uk/product/Lead_Foam_Sandwich_1M_x_1200mm_LFS4) is meant to be the best, but christ it's expensive.

Then there's stuff like this which is a lot cheaper, but is it still effective to use?

http://www.woolies-trim.co.uk/c-129-sound-damping.aspx

Or any other suggestions?

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I used fatmat which came from ebay, I can not tell you how good it is as I have not finished my rebuild yet.

Easy to cut and fit and it realy sticks.

IMAG0045.jpg

Regards

Frax ;)

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I used fatmat which came from ebay, I can not tell you how good it is as I have not finished my rebuild yet.

Easy to cut and fit and it realy sticks.

Regards

Frax ;)

I've seen a couple of people on here using Fatmat, but I don't think anyone's actually finished their truck yet! :D

The thing that annoys me is that in the UK it appears to be double the dollar price compared to the US. Was hoping work would send me to Texas this year and I could use up my luggage allowance on a roll...Ahh well there's always the tightwad's option...

Hi-Tack-Flashing-Strip_medium.jpg

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I used 10sq ft at £33 and that did the bulkhead just.

Regards

Frax ;)

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I used fatmat which came from ebay, I can not tell you how good it is as I have not finished my rebuild yet.

Easy to cut and fit and it realy sticks.

IMAG0045.jpg

Regards

Frax ;)

Hi Frax,

PITA question I'm sure but I'm rebuilding too and have pretty much the same setup. Terrafirma shocks etc. Could you by any chance tell me the size of the nuts on the shocks. The parts cat says they should be 1/2 UNF as standard but they are not so I assume terrafirm used something else. I've lost 2 of mine.

Cheers

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I think they are m12 but not 100% sure as I have nothing to check them with.

Regards

Frax ;)

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I used 1 square metre (roughly 10 sq ft) of Noise Killer's material on the bulkhead (even more coverage than Cat_J has managed) as well as their Defender bonnet and Series inner wings kits at great expense and it made no discernible difference to the noise level. The WOR kit that was already fitted seems much more effective. The NK bonnet pads also tend to come unstuck, despite being thoroughly reattached with impact adhesive and the foil tears and peels away.

However, fitting some of NK's interior matt to the hard top sides made a very big difference to the thrumming from the back of the vehicle.

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Interesting. I've heard similar things about the NK bonnet kit, but I'd have thought that the lead sandwich would have had a noticeable effect.

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Interesting. I've heard similar things about the NK bonnet kit, but I'd have thought that the lead sandwich would have had a noticeable effect.

I had the WOR kit fitted both before and after my big rebuild. The NK full engine bay lining was added during that rebuild, and it didn't make a jot of difference. What it will do is impede airflow around tight cavities and trap water (they use open-cell foam), so will encourage corrosion. I don't have to worry about that too much with a galvanised chassis and bulkhead, but it is an issue for most. The glue failures on the bonnet lining could be due to engine heat. Mine is held in place by a combination of the standard LR black fibre bonnet liner and the bolts securing the Quickfist for my bonnet mounted pioneer tools, so I don't have to worry about the large pad falling off and jamming the steering linkages (SIII).

Fitting the NK kit to the door skins, tub and hard top does make a considerable difference, though, and shouldn't have any negative effects as it should all remain dry and cooling airflow is not a consideration in there.

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I did about as extreme a soundproofing as possible and it helps but the #1 most important thing to do is seal everything every pinhole lets in more noise than you think.

Weight added will help a lot but my next thing is dealing with the oil pan, a heavier alloy pan with ridges to stiffen it should reduce alot of noise as so much goes through the thin pan now.

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Have since found this site and read it: http://www.sounddeadenershowdown.com/

Sees that the way you should do vehicle soundproofing is:

vibration damper

then

closed cell foam(more to separate the MLV from the panel than anything)

then MAss Loaded Vinyl (or similar) to act as a barrier.

So, if I did a reasonable job on the inside with this system and WOR, should I bother with the outside at all?

Or do I say sod it, get something cheapish, like fatmat, as it all adds up?

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Putting my 90 back together at the moment and haven't put sound proofing on the outside of the bulkhead yet. Its probably got a bit to far to put much on now. But just wondering how people are getting on with it now after a few years. Has it remained tidy, is it easy to clean etc? has it still stuck. My bulkhead is galved and painted so rot shouldn't be an issue.

I was in a rush putting my bulkhead back on so didn't get chance to cover it but not sure whether I want to or not. I have now brought some silent coat so am going to do a lot of the interior bulkhead before the rest of the dash goes in. 

I only have the lower dash in so far, I am not sure whether to unscrew this and put silent coat behind it.

I will do the battery box, trans tunnel and floor plates.

Thanks 

 

Jon 

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My experience and a chunk of research shows that this works well...

 

Layer 1 - Damper sheets (dynamat or whatever). Strong note here, it is completely pointless covering everything with this, you literally need a small amount on unstiffened panels only to remove the resonant vibration.

Layer 2 - foil backed closed cell foam. glued down, seal each piece together with aluminium foil tape and cover the area. Does many things, adds noise and heat insulation, acts as a vapour barrier to stop warm interior air holding moisture hitting the cold exterior panel and it stops the passage of air which carries loads of sound.

Layer 3 - As mentioned Mass Loaded Vinyl. This works by moving, you must not glue it down. Idea is it is so heavy it can absorb lots of energy, as sound waves hit it it moves slightly and eliminates it through dampening. Because you can't glue it it's a pain to handle on anything that isn't horizontal, you can bolt or pin it etc. Some have a felt like backing to help stop it sliding, but it's so heavy you normally don't have a problem anyway.

 

Adam

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