Sound deadening

[anaconda]

Just got back from Cornwall - 850 miles in five days and not a squeek. 65 all the way - AAZ engine. It was the first really long drive and now cant wait to get it through France in August. One thing though, its really noisy, too noisy, a bit of a nuisance. Can anyone recommend someone/a specialist who knows their way around a T25 to get some decent sound deafening material fitted? Does this make an appreciable difference? Not interested in doing it meself, but dont mind paying for a good job

Saw an Orange/cream coloured tin top with an 80/90 sticker at the beach car park at Treyarnon Bay. Nice van that!. Ours was the met red tin top on the grass opposite. Cracking beach

[chuckle-bus-tom]

Most noise comes up through the seat box. Buy some flashband from eBay, take you seats out and fill the grooved 'X' with the stuff. Also, remove the floor mat and put a couple of squares of it on the floor. Then, get some space foil (the silver bubble wrap) from B&Q or the like (about 3 rolls) and pad out the seat boxes, line the cab floor to right up under the dash and fill a good few layers behind the door cards all round, particularly the tailgate to cut out that engine noise. I've also got a cut of carpet over the engine with a layer of space foil stuck to the underside. A square of flashband on the inside of each panel will help too.

Check your door and window rubbers are in good condition too.

[luckopig]

http://www.infinitysystems.com/ Found that a few bits and bobs from here helped deaden any road noise

[jojorose]

Daft question but why is it so noisy. Good engines arent! If it wasnt for my fabulous exhaust I cant hear a thing in mine.

[anaconda]

Dunno why its so noisy, but the engines running fine.

[anaconda]

Most noise comes up through the seat box. Buy some flashband from eBay, take you seats out and fill the grooved 'X' with the stuff. Also, remove the floor mat and put a couple of squares of it on the floor. Then, get some space foil (the silver bubble wrap) from B&Q or the like (about 3 rolls) and pad out the seat boxes, line the cab floor to right up under the dash and fill a good few layers behind the door cards all round, particularly the tailgate to cut out that engine noise. I've also got a cut of carpet over the engine with a layer of space foil stuck to the underside. A square of flashband on the inside of each panel will help too.

Check your door and window rubbers are in good condition too.

Thanks. Im assuming the seat boxes should be padded on the inside rather than under the external carpet covering? Also is it the door cards or the inside of the van panels with the space foil?

Did you notice the difference on your van?

[Si_P]

The most effective way of attenuating sound is to 1st block up any direct air paths between the noise and the receiver (you). Once that is done it is simply a case of increasing the mass of the separating structure (adding board etc.) Fluffy sound deadening will work up to a point but get the densest stuff you can.

Bear in mind the noise your experiencing may be the result of chassis born vibration caused by insufficient vibration isolation.

[anaconda]

The most effective way of attenuating sound is to 1st block up any direct air paths between the noise and the receiver (you). Once that is done it is simply a case of increasing the mass of the separating structure (adding board etc.) Fluffy sound deadening will work up to a point but get the densest stuff you can.

Bear in mind the noise your experiencing may be the result of chassis born vibration caused by insufficient vibration isolation.

Thanks. The roof material seems to be pretty dense, but may be a bit smelly! Any ideas regarding a solution for the chassis?

[chuckle-bus-tom]

Always a safe bet to check the WIKI

https://club8090.co.uk/wiki/Bo ... Insulation

[Si_P]

The only way to prevent chassis born vib is to isolate the source. VW have already done this via engine mounts etc.. So possibly not too easy.

If i'm honest my diesel is v noisy and this just seems to be the nature of the engine. I have just learnt to drive at speeds where its not too bad (55mph)

Soft insulation is the icing on the cake in terms of airborne sound insulation I would not expect an amazing change. Good thermal performance tho.

[chuckle-bus-tom]

That's a good point, the engine conversion may have shifted the intended Volkswagen engine insulation points.

[anaconda]

The only way to prevent chassis born vib is to isolate the source. VW have already done this via engine mounts etc.. So possibly not too easy.

If i'm honest my diesel is v noisy and this just seems to be the nature of the engine. I have just learnt to drive at speeds where its not too bad (55mph)

Soft insulation is the icing on the cake in terms of airborne sound insulation I would not expect an amazing change. Good thermal performance tho.

I agree re the speeds. 50 odd mph isnt too bad for noise but for high miles i really dont want to be dwelling on the inside motorway lane with the artics and caravans. I reckon i'll give the sound deadening adhesions/pads a go accross all the innner surfaces and if it takes the edge off the noise then that'll be enough. Driving 350 miles home was dead straightforward but it felt like id had my head rattled by the end. Im used to noisy cars having driven classics for years but this was a bit too much. There'll be lots of visits to France, long miles, so worth spending a few quid on it.

[skysurfin09]

Literally just finished fitting some flash-banding as recommended on here as opposed to using Dynamat. I'm not sure as I should be covering as much inner surface as possible or just strategically placed. Reason for the doubt is there are several videos on youtube showing both techniques. Which would produce the best results? Rob

[HarryMann]

Cover as much as possible. Strategically placed is mostly about a weight & £££ compromise. Use as much as possible. The rear engine hump is a good area to deaden. Ideally, from outside with the mass (flash banding/bitumatic stickums), heavy underlay or carpet on the inside. Ditto the whole engine cover and rear floor.

Increase the mass and/or stiffness of a panel and you will lower the fundamental frequency it will resonante at. This is equiv to creating a low-pass filter that will heavily attenuate anything above that frequency. So the lower the better, therefore the more mass or stiffness the better. The sound deadening we tend to use mostly increase mass per unit area, but also stiffens panel slightly. There's also some damping effect as well depending on the materials within the laminate.

Good bonding helps, the laminate (e.g. flash banding)does need to be bonded well over its whole area ideally. Degrease first and can use a small hard roller to press onto surface easily.

The suggestion that the engine mounts might contribute was a good one... is it a std. diesel conversion using the VW bellhousing and mounting bars?

Is the noise predominantly the normal diesel 'rattle' (knock/mechanical noise) or exhaust or inlet suction noise ?

Does it feel mainly acoustically transmitted (air-borne) or mechanically transmitted (through the body) ?

Other than the Wiki here, there's been recent discussion on the Brickyard about soundproofing (somewhere amongst its many and varied forums)

[Si_P]

I'm with the above post.

Unfortunately localising a source of low frequency noise is very difficult as we are not anatomically designed to do this and it will be setting up standing waves in the van which can result in 'sweet spots'. To further complicate matters even if the LF is airborne it could feel like its structure-borne. Good luck

If mid to high frequencies are a problem this is more than likely direct air paths. I would not anticipate these frequencies easily transmitting across the bodywork.