Amazon: Sound Deadening

[P1800Ray]

To complete the circle ...
I bought Dodo Acoustic Engine and Bonnet Liner and Dodo Hex Mat. I chose the former for under the bonnet as it should be continuous and it looks identical to the pre-cut P1800 insulation that Brookhouse sells.

I'm going to record going up our (quiet) road before and after and will report back.

[amaz'in]

Hi Ray,

I suspect treating the underbonnet area will give very good bang for the Buck results, be sure to check over the entire bulkhead area from engine bay and cockpit for any tired or missing grommets, replacing them makes a big difference,

I bought a bulkhead grommet pack from Brookehouse but it was bereft of a number of grommets so I sourced a grommet multi-pack on line, on Amazon's there's often a fair sized void where the steering column passes through the bulkhead.

The bulkhead area will reap big rewards too, if you get more adventurous.

[Derek UK]

The Amazon should have it's own rectangular sponge seal for the Steering column. It is held in place a spring wire clip which attaches to the floor with a single screw. Sponge easily made from a couple of off cuts of sponge underlay/soundproofing or buy from Brookhouse when you next place another order or the postage will kill you. Make holes a fraction smaller than the shaft, cut slot to allow fitting and then add some glue to keep them together . Have the cuts opposite each other to make a full all round seal. If squeaky add a little grease. No clip? Can't help but someone likely to have a spare. Not hard to make though. This hole is the biggest source of noise from the engine bay, Also right behind that slightly leaking exhaust manifold gasket (RHD) that you have been going to fix for far too long. Sponge stops the smells too but best to fix that leak.

[amaz'in]

It is indeed the single biggest source of noise and it's prudent to fix any such bulkhead holes at its questionable if any form of sound proofing and/or deadening is worthwhile otherwise.

11 years ago I used self adhesive neoprene and it's still in place doing a perfect job, it's a very awkward shaped panel where the column passes through the bulkhead.

[grumpydad]

Hi
I think lining the bonnet is is the best
but my fear is it gets hot and drops off
then who knows just the smell of hot stuff or a fire
I think you will also be surprised how mush heaver it makes the bonnet

[c1800]

1/2 inch foam with foil facing under my bonnet for 4 years now. Hasn't fallen off and/or started a fire. While I do think its prudent to prevent possible fires, I don't think this is a location that will generate combustion, unless the engine overheats and fuel is leaking etc.
The kits for insulating under a bonnet have been around for years, haven't read any stories of fires etc., and I have read a lot, but maybe it has happened ?

Yes my bonnet may be heavier, but it opens and closes just fine.

[Derek UK]

The bonnet and boot lid on the 1800 are easy to soundproof as they have just small areas to cover. Very little weight of sound proofing to help gravity unstick them. The originals don't last forever but cheap and easy to replace. The Amazon is different. The shape helps a bit but it's clangy and resonant, as a quick slap on the top will show. This can largely be cured by 4/5 of the old fashioned sticky pads like the ones on the floors and elsewhere. They can be applied neatly. If repainting fit before the final coats and they look as if they are original. Actual sound deadening factor probably quite low but will stop it amplifying the engine noise of our not so quiet engines. This is the same as having a single one of these on the door interiors. The Estate roof also has a lot of these on the underside of the roof. 2 rows of 8? I did try and count them at some point.
My 1961 122S back in the 60's had a full house Paddy Hopkirk sound deadening kit. At the time I had a trip in the dealers 1967/8 131. My engine was in the boot on its way for recon. The interior noise was terrible by comparison. My bonnet had a one piece felt liner. It did have a couple places that was coming unstuck, but not bad enough for me to strip it off and redo it. I had the car over 3 years. The felt must have been 3/4" thick and similar to the interior bulkhead felt but a bit more dense. It didn't have a hessian backing. Comment: Don't try and stick the hairy side of the felt to the underside of anything. Modern heat resistant glues are good but can't perform miracles.

[P1800Ray]

Well, after sound deadening the bonnet and using the hex sheets in side panels, tailgate, top of petrol tank, spare wheel well, under dash (around squeaky radio mount) I can hear an improvement. I used left over bonnet insulation to do the steering column hole. My floor and doors had sound deadening in already so I left that.

It reduced the tappet noise and generally things sound quieter. The big upside is that the quality of sound from the stereo is greatly improved. The one thing that’s left to quieten is the flip down rear seat (Estate). I think I’ll have to cable tie the side lugs into the housing (I already tried a small offcut of under bonnet foam) as it rattles over bumps.

[amaz'in]

Hi Ray,

That's great, it's no quick fix but very much worth the effort eh?

When I did my Amazon I spent 1 Day on boot area and two inside the car, this included carpet, new card trim panels and pouring Dinitrol rustproofing into certain areas. I still have the doors to do so expect to hear some benefit from this, if only for a nice thud when closing them.

Just a shame I couldn't really apply to underside of bonnet, roof behind headlong has got to be one of the biggest panel vibration areas. It's niggling me but I just know what a pain headlining can be.

[P1800Ray]

Agreed, I took a photo of the bonnet that I managed to do in one piece but I can’t post here as it’s asking for a URL.