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Decibel limit in an Esprit cabin, ways to improve?


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Hi, as my wife and have got older we are of the misfortune to suffer from tinnitus (to many night clubs and bands in our younger years), which doesn't help when owning a loud car like a Lotus Esprit. It's not so much the level of noise my car produces in the cabin area, but the length of time we are being subjected to it. I've measured my noise levels and generally I get around 70-80 decibels all the time, regardless of speed. Apparently this level is normal office chatter level.

I'm considering when my car comes off the road soon on improving the rear bulkhead sound deadening, which is the easy bit. I'm just wondering what to do about the rear window, I've considered creating a double glazed rear glass to hopefully reduce sound through the rear cabin screen. 

Has anyone else improved the cabin noise level and what did you do?

Edited by OwenGT3
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Owen, 

If you've removed the stock exhaust, put it back on - same goes for sports cats. Going to factory spec reduces the drone considerably.

I'm not sure you could reduce the noise through the bulkhead too much, at least not without making a construction with an air cavity - and then you're losing cabin space. The glass can be made double glazed, but at what cost? 

How is wind noise in your car? I've noticed that any damage to the window channel felt and seals can lead to much higher noise levels as well. 

Another thought I've had is this - how much of the noise is structure borne? Technically a lot of noise from the 'box and engine could be transmitted by tired mounts and rubber components. Pays dividends to change these.

Up at speed, wind noise becomes significant, and here it will do you good to look at the shut lines - I believe @CHANGES has investigated this. The door shells could perhaps also use some dynamat since, behind the door card, you're just looking at bare GRP. 

Vanya Stanisavljevic '91 Esprit SE | '97 XK8

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Seat belt slots in the bulk head are a direct acoustic path between eng compartment and the cabin. Due to the engine heat, the padding inside the seat belt spool covers usually disintegrates aggravating the sound transmissibility.

Lotus used non-acoustic foam to line them up [just couple measly pieces of headliner material], which is totally inadequate.

Buy 1" foam from soundcoat.com and replace the headliner pieces (if any left, by now).

 

 

Vanya,  Re: wind noise problem.

You're on the right path thinking about lining the door cavities. I have implemented this and many other elements.

Please PM me on [email protected] 

I will send you a bunch of pictures.

Edited by MrDangerUS

MrDangerUS

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I replaced all my door seals including the sunroof around a year ago, so know they are good. My exhaust is not stock and never likely to be as I have the V8 rear valance look twin centre outlet, so no GT3 system will fit. Also it's guaranteed for life so not going to spend anymore money on exhaust anytime soon.

My wife does use gel ear plus in the car, I tend not to. I was just wondering if anybody had tried to address the level of noise other than personal wearing equipment. When I have my fuel tanks out I will check the seat belt openings. I think when my car comes off the road I will address the sound deadening in doors and rear bulkhead. I might try 'double glazing' the rear window by cutting a shaped perspex and just sticking it to the existing plastic, I'm sure anything will help. I do have nylon bushes in the suspension, so noise is going to travel more than rubber bushes.

If i can reduce it by 5-10 decibels that would be fine. As said whether you are going fast or slow, the level is always he same.

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Owen, go after the high frequency noises first - these can generally be solved by foam, lining, extra layers mounted directly to a panel etc. Booming etc is very difficult to address as low frequency damping generally requires a bass cavity when it comes to airborne noise. When you have the tanks out, replace all mounts etc to eliminate structure borne noise. Also have a look around for any equipment that is directly bolted to the body or chassis and whether it can be mounted elastically when replacing things!

Best of luck!

Vanya Stanisavljevic '91 Esprit SE | '97 XK8

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Blimey you want to drive my defender!

I've read up loads on soundproofing due to the Land Rover. Silent Coat is a good product, available on ebay, similar to dynomat. you would need to strip the bulkhead and stick it on. Lizard skin is supposed to be good, they do two versions one sound, one heat. I have read it is little more than house paint mixed with micro ballons. the mix being 20% micro ballons for sound or the other product is 80% micro ballons for heat. Micro ballons are used for model aircraft and are hollow glass beads, you must wear a good mask when mixing. I guess in the sound one the elastic property of the paint absorbs the sound waves, and in the heat product the hollow ballons absorb the heat.

 

 

 

 

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  • Gold FFM

What's the db reduction spec on the different materials ?

i had a nova developments kit car years ago - and when I redid the carpets on that - I used cloud 9 foam underlay - meant for houses ! It was superb 

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Turn the engine off? :getmecoat: 

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All we know is that when they stop making this, we will be properly, properly sad.Jeremy Clarkson on the Esprit.

Opinions are like armpits. Everyone has them, some just stink more than others.

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My guess is it's the exhaust that's creating the noise.  A stock exhaust is quieter and will solve your problems. 

My Esprit is quiet in the cabin.  My  Ford has basically a straight through exhaust and the boom in the cabin is staggering.  The positive is I can't hear my wife talk.

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If you want it to sound unexciting and just like a ford mondeo - I've got a stock rear back box off my v8 in the scrap pile 

1 hour ago, Mark Blanchard said:

My guess is it's the exhaust that's creating the noise. 

Just drive it faster and leave all the noise behind you....

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