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MG Midget and Sprite Technical - Sound deadening in a Midget

I'm at the point in my build where I'm thinking about where to put sound deadening materials inside the car. I have the usual pads over the transmission tunnel and on the floors to stop drumming but where else would it be beneficial? In places that MG never bothered with.

I have thought of inside the transmission tunnel, behind the vinyl trim panels in the foot wells, under the dashboard, inside doors etc. But where else?

Are modern glues any good since the use of solvents was banned? What is the life expectancy of the glue bond? How do they react to the hot/cold cycling expected inside panels and from the engine bay?

The last thing I want to be unable to wind the windows down due to the glue on inner door pads not being up to much and allowing the pad to detach and curl up in the bottom of the door.

I also don't want anything visible that wasn't fitted to the original car so inside the engine bay is a no-go area.

Rob
MG Moneypit

A couple of years ago I put a 187 x 265mm sheet of 2mm Silent Coat in each door. I couldn't believe the difference it made when closing the doors - a nice thud instead of the clank I used to get.

I also put a couple of sheets in the middle under the bonnet. It stops it ringing when closing or if its tapped. I can't say I noticed a great deal of difference when driving though! No sign of any peeling yet.

Jim
J Smith

I used two packs of Dynamat super lite from moss on my1275, its not cheap at £46 a pack, but it does make a difference, more so with the hood up. It is self adhesive, and sticks well.
I used it on the floors, rear bench, footwell sides, doors and boot.
Its not the miracle that the adds would have you believe, but it does make a difference.

Dave
Dave Barrow

I probably wouldn't do the insides of the doors but maybe stick it on the inside of the door cards...nor inside the transmission tunnel

The rear shelf and and the kick panel areas inside the cockpit amd the B post area warping back, and under the seats

I used the 18 x18 inch Danamate knockoff stuff and is still working today

It's got it's own self adhesive stick

To work the stuff correctly you need a heat gun to make it flow and contour to the shape of the car

If you want to do something really cool, to fight rust, make it waterproof and add a lot of sound deadening... a have the inside of the car Rhinno linned ... it's a spray in truck bed coating ...it just has to be super clean for adhesion but it is the meow... I wish I had done it back in the day but I love my engine bay sprayed with it, my hard top, and various other pieces...its great stuff
1 Paper

I don't know about sound deadening pads, but regarding glue I've been impressed with Gorilla Glue lately. I've also used Gorilla Tape which is a double sided mounting tape. I stuck thermometers to the engine room bulkheads with it and - well - good luck getting them off!
Greybeard

Sound deadening in the doors is much better applied to the door skin than the inside of the door card as it cuts down drumming of the thin sheet steel.
But l guess you could do both.

Some sound deadening is essentially to stop drumming, usually the bitumastic and aluminium foil stick on stuff. Other deadening is to cut down on air borne noise and the thick felt does this best. A good place for this is the back of the front bulkhead, behind the dash.

Time consuming, but effective is to add silicon sealer around any gaps and grommets, especially between engine bay and cockpit.

And then, - there's always ear plugs ! Well worth using on longer journeys.
GuyW

By pure chance I was just talking to a mate who self-builds campervans because I'm doing up a Diahatsu microcamper. She reckons industrial carpet is as good as anything as long as it's not anywhere oily. I know exactly what she means as I have it in my office upstairs and I think it was about a tenner a metre, but 5 metres width. It's also fire-retarding. Just a thought...

Also what Prop said about Rhino Liner. My mate Don has a van lined with it because he transports fish in it. It turns out it is available in UK - there's a place near Stirling apparently that does it any colour you like. I've driven Stinky (the van) many times and it's noticeably quiet. Practically no panel booming. Just another thought...
Greybeard

Rob,
I've got sound deadening pads all over my car but the one place I'd like to get some more on is the front wings, the headlight apertures seem to act like reverse trumpets for sound bringing noise back to the cabin.

I've got pads on the underside of the bonnet they're self-adhesive purchased from an adhesive company they seem very firmly fitted and haven't moved since fixing. They can easily be cut for smaller pads or shapes (note the pads do add a bit of weight, I could weight one if you wanted).

My car is without any soundproof matting and only the thinnest cheapest carpeting know to the usual suppliers.

https://www.ebay.co.uk/itm/CAR-VAN-VEHICLE-SOUND-DEADENING-PROOFING-PADS-SHEETS-10/220649059457?hash=item335fb57481:g:kpQAAOSwbsBXpEoe

ETA: yes apply them to the metal, even tiny pieces on the boot inner support arms?/bracket? help reduce drumming.
Nigel Atkins

What is drumming ?
1 Paper

Cherry was very very quiet, and when I took her to pieces I found underlay pretty much everywhere in the cockpit - the ordinary straw-coloured hairy stuff, spray-glued in place where necessary. But also, every hole between cockpit and engine bay was seriously grommeted, with flexible sealant added around the cables or whatever. The rear axle hump and wheel arches were very well underlayed - cut to fit, with the loose mats lapping onto the glued.

Nothing at all on the bonnet or doors.


Nick and Cherry Scoop

Prop,
drumming is the vibration you can get on a panel from the use of car's mechanical bits and it moving over the road surface.

The deadening pads are used to reduce this drumming whereas the old style fibre matting soundproofing more muffles the sound.
Nigel Atkins

For inside the doors (on a VW camper so a lot more room!) I've used self adhesive lead flashing tape.
It's a lot cheaper than the sound deadening proprietary brands and has IMO, the same effect i.e. it dampens any resonating. It also gives the desired 'thunk' rather than 'clank' when the doors are closed. You don't need very much either - only small pieces are needed to eliminate the drumming.
Putting sound absorbing material in the doors is likely to have a minimal effect and there's a chance of water being absorbed or retained.
Jeremy MkIII

Thanks Nigel

Tbh... I'm not sure we even have an actual name for (drumming) on this side of the pond

Here we call it road noise or vibration sounds aka (some kind of vibration Sounds in the transmission tunnel)

What an interesting oddity that we have no real term for the issue


I'm going to have to use (drumming) next time I'm in getting new tires just to see there reflection...

""boys my tires are worn I'm looking for a set that will signiagantsignificantly reduce the drumming effect"".... haha that will set them back on there heels

Prop
1 Paper

Jeremy,
a cheap and effective solution is to allow panels to get well coated inside (and out if you want) with muck, crud and mud - this will give a more solid sound to the panels. :)
Nigel Atkins

LOL Nigel :)
Jeremy MkIII

Prop,
I should have also put that the soundproofing (fibre matting) helps to insulate from external sounds and temperature and helps to hold the internal temperature whilst reducing/absorbing internal sounds so is useful stuff.
Nigel Atkins

Prop,
A flat, or nearly flat, sheet of steel like the bonnet, the front and rear wings or the door skins, will vibrate back and forth and this works just like the skin of a drum - hence the word drumming. This not only transmits noise from outside the car but like the skin of a drum it actually generates extra noise as it moves the air. Its not just existing noise transmitted, its added bonus noise!

The way to stop this is to either stiffen the steel sheet so it doesnt move, or to coat it to dampen out the movement. This is often best done with pads of dense rubbery material stuck directly to the steel. Your Rhino Liner material is probably very good at doing just that, particularly if applied quite thickly, or maybe built up in layers on the larger flat areas of steel.

You may not have heard of drumming, but even so you have probably dealt with it pretty effectively!
GuyW

Thanks for all the feedback, some good ideas there. Particularly like the self stick lead flashing idea, although I suspect it isn't really lead anymore.

I would like to put some on the insides of the transmission tunnel which has a good coat of brushed on 2 pack. This seems particularly smooth and should be ideal for self stick.

I also intend to put some on the inside bulkhead once I get around to putting a coat of paint there. Inside the car foot well sides before I put the trim on, as well as under the carpets and on the back shelf over the rear axle.

Bonnet and boot underneath, inside doors and inside rear wings.

I might need to pep the engine up a bit to carry all this extra weight.

Rob
MG Moneypit

This thread was discussed between 24/11/2017 and 27/11/2017

MG Midget and Sprite Technical index

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