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Discussion Starter #1 (Edited)
great day all
anyone know of a sound deadening foam or otherwise
or is there not much vibration/use in trying to quiet this area. though there is quite a bit of space, and the sound must resonate.
 

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If you google sound deadening lotus elise lotustalk you'll find tons of threads. Here's a long one for you Quieter Elise
 

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Are you referring to part #1 in this diagram (this is some of the optional insulation that comes with the Touring Pack):

1267709
 

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Discussion Starter #4 (Edited)
Nothing spoken about the rear, outer. As far as I can tell. Have been reading for a few years. Might have missed a post.
Not the touring pack, as there is nothing fitting to the outer skirt/sill between roll bar/bulk head.
Have Dynamat, and Second Skin products. As well as other closed cell foam for places. I hadn't thought about the skirt/sill till now.
 

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Discussion Starter #5
the question would be, from the Quieter Elise post. Is, if the largest factors are the exhaust 1, and wind 2.
1 like a harley davidson, sound travels backwards. So at speed, I would suspect 2
To quiet 1 at low speed, ample protection from 1. So, the more around where the bulk head is would be better. As far as I can tell.
2, there is probably lots of flex in the glass fibre panels including doors, clams. I had planned on under coating and dyna mat under where panels meet body. As the under aero must create vibrations, probably creating sound.
 

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Discussion Starter #7
probably I will have some seat, headrest speakers.
already have 4 x 1" for sun visor and rear mirror. Claimed 200watts per, we will see.
don't need to go more deaf
do want to cut the sound as much as possible
 

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The last link showed some sound dampening in sills and bulkhead I think. I can't find the recent read where someone did db readings with different sound deadening materials.
 

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Discussion Starter #9
i bet, a better heat/sound sink/shield at exhaust manifold. With a bunch of sound absorbing material would be a great trick.
 

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Most of us live for that sound... That being said this is about bulkhead deadening. My Dynamat experiment
 

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2005 Lotus Elise Nightfall Blue
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Are you talking about the door sills /armrest area?

I considered doing that location. So far I have decided not to do it.

There are some big blocks of foam in there already, I think mostly to keep the oil and A/C lines from banging around plus some sound absorbption. But there's also a pretty sizable open air volume. If I do end up doing it, I'm going to probably stuff some open cell foam in there just to fill up the volume and absorb more sound. It would be very difficult to do an MLV and decoupler in there, though. Tight space to work. You could maybe get a damper sheet in there, though, only aluminum frame and it might help. Hard to say. I'm not sure how much of a difference it will make due to other factors:
  1. The doors cover half this area anyways, so you might be better off just doing the work in the doors as best as possible
  2. You can't get on the inside of the aluminum frame - just the outside. The aluminum chassis itself transmits a lot of noise, so it may not have a big effect.
Nearby though, I did some areas under the dash:
  1. I did the "coin tray" areas in front of the door sills. There are big open air channels that go more or less directly to the front wheel wells. I put Luxury Liner in these locations, however I didn't notice a difference, but I also haven't done the doors yet. I think the doors must be done to really have a big impact. At least on my car, it sounds like the majority of the noise is coming from the doors and little holes letting in wind noise around the seals, particularly in the upper corner where the roof, side window, and windshield come together.
  2. I also put some luxury liner behind the tubes for the HVAC system underneath the dash. I think the car comes with some open cell foam here from the factory, but at least on my car it looks like the passenger's side was ripped out, presumably when the oil line recall was done (Pretty sure the oil lines go up through an area here, or maybe it was an A/C service, since I know the A/C lines go through this area). So I just ended up putting in luxury liner where the stock foam had been ripped out on the passenger's side. I didn't do anything on the driver's side under the dash.
 

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Discussion Starter #12
"some big blocks of foam in there already"
above that, beside the roll bar. the large area in the pictures.
I filled (out side of enough room to turn a wrench for the clam bolt) with closed cell. After rear clam is affixed, I will add dyna liner to cover the bar to outer skin of sills.
I believe the sound bounces around in there. but, what do i know
 

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Ohhhh, I wasn't talking about those locations. I was talking about the lower area by/below the doors.

In any case, yeah people did this spot, it's documented somewhere towards the early/middle part of the "Quieter Elise" thread. psoup did this mod : Quieter Elise

He spend a bunch of time shaping foam to put in that hole and then covered it with luxury liner. I haven't done this mod/area yet, but one thought that might be easier: You can use expanding foam in a bag to create self-formed foam blocks. Spray foam needs air to cure, so it can be hard to get it to cure properly in-place if you spray it into a bag, but you could buy a product called Instapak Quick RT on ebay for like $10 each and stuff in that hole, activate it, and it should expand to fill the volume. I suggest using Instapak over spray foam since this is the job it's designed to do - much less probablity of failing to cure or get foamy adhesive goop all over the place.

Instapak probably isn't fire rated if that's important to you for this application,and may not be a good sound absorber / blocker on it's own.
 

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Discussion Starter #16
exactly, well. we will see. I went about it from an audioholics perspective. block any corners and sound resonating.
don't have before #'s
 
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