Under bonnet insulation, worth doing?

[mab01uk]

Interesting that in 1980 the factory said "under bonnet insulation made little difference to noise levels inside the cabin" of a Mini....

[richardACS]

Interesting that in 1980 the factory said "under bonnet insulation made little difference to noise levels inside the cabin" of a Mini....

Very interesting article, in a way it is understandable why the bonnet would not help in reducing cabin noise but will certainly feel more weighty and less 'tinny' sounding. I wonder why they didn't fit soundproofing on the rear bulkhead (behind the upright seat back) or to the rear quarters and doors, I'm sure the door closing would benefit from the additional weight - maybe not the performance though!

[Andrew1967]

Doors and rear quarters have that jute type soundproofing, well on early cars anyway. I’ve seen that black perforated sticky pads stuck to them on later cars .. those strange wind up window varieties .

Even the headlining had soundproof strips laid in between the metal frames and also another stuck to the roof.

I’ve never bothered with the bonnet insulation, Minis are inherently noisy no matter what we do to them. All part of the appeal

[mab01uk]

Interesting that in 1980 the factory said "under bonnet insulation made little difference to noise levels inside the cabin" of a Mini....

Very interesting article, in a way it is understandable why the bonnet would not help in reducing cabin noise but will certainly feel more weighty and less 'tinny' sounding. I wonder why they didn't fit soundproofing on the rear bulkhead (behind the upright seat back) or to the rear quarters and doors, I'm sure the door closing would benefit from the additional weight - maybe not the performance though!

I am guessing they never fitted soundproofing on the rear bulkhead (behind the upright seat back) as the rear seat back padding was effectively a layer of soundproofing for the rear bulkhead? As can be seen in the Ad for the 1980's "Quiet Minis" they did start fitting a thick padded rear parcel shelf trim. I seem to remember the insulated rear parcel shelf was "quietly" dropped a few years later probably during the usual cost reductions.
As most Minis leak into the front floorpans at some point.....the black rubber backed/thick foam insulation under the carpets and behind the carpet on the front wheel arches did a very good job of acting like a wet sponge and accelerating the rusting process!

[snoopy64]

So… re sticking the black vinyl has only been partially successful, now stuck (no pun) with the felt firmly fixed to the bonnet and the vinyl peeling. I wonder if rolling it up to ship it didn’t help? Maybe the original glue wasn’t good in sheer?

[gs.davies]

I’ve just fitted some to LFF. Along with a bulkhead blanket it’s made a significant improvement to noise. And the bonnet now has a lovely solid feel to it. I will also use some felt on the doors, rear quarters and inside the roof.

[Pandora]

Personally, after I had the under bonnet insulation in a Ferrari 330 GT catch fire when it backfired, I'd take a bit of drumming over scorch marks any day. I imagine a Mini one would fairly soon become oily and 'petroly' and ready to catch, especially if it droops over time (as was part of the problem on the 330).

Luckily there is a starting procedure for then that meant damage was limited and I got the fire out quickly. Always keep an extinguisher handy fellas!

So back to the original question - is it worth it? I'd say 'no'

Al