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Posted by: jmargush Sep 26 2022, 05:24 AM

I built my car as an autoxer years ago and never installed carpet or sound deadener after the restoration.

Now as I age and have an opportunity to take a longer trip in the car I am looking for a little more "comfort" in the car.

Question is how much will carpet and/or sound deadening improve the road noise?

The back pad has been removed and there is sound deadener and felt covering the firewall currently.

Curious as to what you all might have experienced or recommend.


I am also thinking about dialing back the suspension setup for the long trip.

Posted by: Cairo94507 Sep 26 2022, 07:10 AM

I believe the sound deadener makes a dramatic difference in our cars. My floor, firewall and doors are all done. Anything you can do to keep heat and sound out is a good thing.

Posted by: Superhawk996 Sep 26 2022, 07:38 AM

Duplicate

Posted by: Superhawk996 Sep 26 2022, 07:46 AM

I have been involved in data analysis and modeling to correlate ride quality with 3rd party quality metrics like Consumer Reports, JD Power, OEM customer satisfaction surveys.

Sound is a highly correlated variable even though it has no direct effect on ride quality. That is to say that most people if they perceive that bumps are “loud” they are also perceive the bump to be more severe than it really is as measured by seat track accelerometers.

So - a quieter car is perceived to ride better than an equivalent car that is noisy.

Addition of constrained layer damping like Dynamat will get you a huge improvement over what you have (nothing). This treatment will reduce the structurally transmitted noise low frequency noise <100 Hz.

Addition of carpet and a back pad over Dynamat will reduce the higher frequency airborne noise above 100 Hz.

You really want both types of noise reduction treatments since they each affect different noise frequency ranges.

Don’t forget the felt liner on the targa top - that big fiberglass panel is a noise reflector.

Dialing back your suspension from an AX setup would also be a significant improvement for long trips.

Posted by: mlindner Sep 26 2022, 08:29 AM

jmargush, I did the same thing last year, interior tar mat, then 1/2 foam and then thin layer of perlon carpet. I do not have anything on the engine compartment wall. It nocked noise down by more then half. I do have Ben's sport muffler so that end is pretty loud. Mark

Posted by: emerygt350 Sep 26 2022, 08:43 AM

What do you suggest for the roof? Mine has nothing at the moment, didn't really consider the added sound deadening it would provide. Mine is pretty quiet but I could always use more..

Posted by: Superhawk996 Sep 26 2022, 09:22 AM

Something like this. I don’t recall my OE headliner having edge binding but this should be close. On my 2nd car it is missing and yet to be replaced but I’ll use this or just cut some Perlon.

https://www.pelicanparts.com/More_Info/APBZHL914PFB.htm?pn=APBZ-HL914PF-B& amp;gclid=CjwKCAjwm8WZBhBUEiwA178UnM8e_sivCpAf4g45wsYVSI9t8rohzvqG2EURB9VNzgfiGG
430N3deBoCu4MQAvD_BwE

Posted by: jmargush Sep 26 2022, 09:32 AM

Thanks guys great info!

Posted by: Retroracer Sep 26 2022, 01:08 PM

My car (faux GT) has almost zero sound insulation, but I did rework my roof panel a while back to try and reduce heat transfer inside. I used a product called Dynaliner:

https://www.dynamat.com/products/dynaliner/

on the bare fiberglass, then purchased a precut headliner piece from 914Rubber:

https://914rubber.com/oem914563321113-1-700-charcoal-1-2975

to finish it out. Can't really comment on whether the heat insulation reduced the sound as the rest of the car is so loud at speed anyway; but the thermal reduction worked a treat ;-)

- Tony

Posted by: jmargush Sep 26 2022, 04:42 PM

Another question is there an opinion on whether loop carpet is more effective than perlon at reducing sound?

Posted by: mlindner Sep 27 2022, 04:19 AM

Loop all the way. Perlon is very thin and light.

Posted by: emerygt350 Sep 27 2022, 06:49 AM

Any opinion on just applying a sound deadening mat to the targa without carpet? Was thinking maybe a sheet of this stuff and calling it a day.

https://www.amazon.com/Siless-Sound-Deadening-Black-Deadener/dp/B07CG2YPRJ/

but that price I could just get carpet (if it were in stock).

Posted by: Superhawk996 Sep 27 2022, 08:24 AM

@http://www.914world.com/bbs2/index.php?showuser=25740

I’d avoid that product. It is just butyl as a mass damper. A constrained layer product like Dynamat is going to be more effective than just butyl.

I guess I’m wrong - looked again and it says it does have the aluminum constraint layer like Dynamat.

Posted by: bbrock Sep 27 2022, 08:52 AM

I'd do a search on other recent threads on sound deadening. As @http://www.914world.com/bbs2/index.php?showuser=22428 said earlier, different materials reduce different frequencies of sound. The firewall also has the engine noise to contend with which is why sound deadening in that area was designed as a sandwich of different materials to reduce sound levels.

Posted by: rfinegan Sep 27 2022, 09:41 AM

Coming back from Octeeener fest, MY 75 914 did not have the fire wall blanket, on on return I purchased and installed a Synthetic blanket from Rix914 at the show..EZ install and made a noticeable difference in the reduction of engine noise in the cabin. Wish I had done this upgrade earlier . Rick is a great guy to work with too

Posted by: jim_hoyland Sep 28 2022, 07:10 AM

Does that mount inside the cabin ? Are they available on-line ?
@http://www.914world.com/bbs2/index.php?showuser=15499

Posted by: bbrock Sep 28 2022, 08:13 AM

It replaces the heavy tar/fiber mat inside the engine bay and is https://www.rix914parts.com/store/p29/914_Firewall_Heat%2FSound_Reduction_Mat.html.

It's the same mat I went with and I really like it. I measured 1 dB sound reduction inside the cab compared with a less expensive sound/heat reduction mat. Unfortunately, I got too excited about installing the new mat and forgot to measure sound with no mat at all. It is significant though.

Posted by: rfinegan Sep 28 2022, 02:00 PM

https://www.rix914parts.com/store/p29/914_Firewall_Heat%2FSound_Reduction_Mat.html

attaches with factor metal tabs and 3/ 4 push in fasteners from the engine compartment

Posted by: FL000 Sep 28 2022, 08:23 PM

Food for thought but don’t forget to focus on any window gaps as they contribute significantly to road noise and overall comfort.

Case in point I spent some time recently readjusting my door windows and seals. Couldn’t believe how much more relaxed I was driving the 1500 odd miles to Utah and back. My car is loud as hell so not implying it is quiet by todays standards, but my wife and I were never so relaxed after 5 hours in the car.

Posted by: Van914 Sep 29 2022, 04:40 AM

Years ago Stoodards used padding on the top above the roll bar to reduce sound.

Posted by: rfinegan Sep 29 2022, 06:11 AM

It was ez to install. I did mine right cat the car show. 10-15 mins. May be faster to remove the engine grill/lid but either way it is not difficult to install with the engine in and all accessories place. Its a little snug by the ECU mount on my 75, but slides right in place none the less.

Posted by: 930cabman Sep 29 2022, 07:06 AM

Road noise, how do tires factor into the mix?

Posted by: rjames Sep 29 2022, 08:30 AM

Are those push fasteners available for purchase anywhere? Can't seen to find them.

Posted by: rfinegan Sep 29 2022, 09:15 AM

included with purchase from Rix914

Posted by: rjames Sep 29 2022, 11:11 AM

Have the pad, just need the plugs. @http://www.914world.com/bbs2/index.php?showuser=3348 Do you make these?

Posted by: bbrock Sep 29 2022, 11:41 AM

You can pick them up at your local NAPA. Can't remember the part number, but they are easy to find.

Posted by: Mikey914 Sep 29 2022, 05:02 PM

Pretty sure I have them, I'll check and let you know tomorrow.
Mark

Posted by: FlacaProductions Sep 30 2022, 09:17 AM

https://914rubber.com/plastic-engine-padding-fastener-for-914
ITEM # 914-559-377-10
Plastic Engine Padding Fastener for 914

Posted by: bbrock Sep 30 2022, 01:09 PM

Found the NAPA part too: https://www.napaonline.com/en/p/BK_6653116?impressionRank=1

Posted by: Literati914 Sep 30 2022, 01:19 PM

Neither of my '72 cars have holding tabs or any holes for the plastic clips.. is that correct and what's the solution - I was thinking rare earth magnets, but...


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Posted by: Root_Werks Oct 19 2022, 09:45 AM

Just ordered this for my 914-6 conversion. I like how light it is, hopefully it helps to cut down on the noise.

Posted by: tpines Oct 19 2022, 07:04 PM

Hi Mark,
Love your interior! Looks awesome. Just a little concerned not having head rests for safety. Take care!

Clark

Posted by: Cairo94507 Oct 20 2022, 07:39 AM

@http://www.914world.com/bbs2/index.php?showuser=2105 I would love to hear your opinion after the install. Pics of the install would be nice too.

Posted by: Root_Werks Oct 20 2022, 09:10 AM

@http://www.914world.com/bbs2/index.php?showuser=9712

Will do. I've only had one 914-6 with the engine bay pad installed. It's a tight fit around the edges of the fan. Very curious how this will fit and stay in place.

Posted by: Cairo94507 Oct 20 2022, 09:26 AM

Terrific- fingers crossed it all goes to plan.

Posted by: Root_Werks Oct 24 2022, 08:28 PM

Arrived today, very nice quality. Came with 3 push pins.



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Posted by: Root_Werks Oct 24 2022, 08:31 PM

Installation was easy, holes all in the correct spot. Hopefully drive tomorrow and listen for reduced noise.




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Posted by: Cairo94507 Oct 25 2022, 06:25 AM

Looks clean.

Posted by: Root_Werks Oct 25 2022, 03:12 PM

Drove today, it certainly makes a difference and worth the money. I wish I had a before/after DB meter reading for folks. My ear says the cabin is quieter.

Posted by: Cairo94507 Oct 25 2022, 04:35 PM

Something else to think about. The problem is 6's never came with the sound deadening pad on the engine side of the firewall and they look so nice without it. I am going to have my back-pad off soon to replace the rear glass, I will look and see if anything more can be done on the interior side to provide a bit more sound deadening.

Posted by: Root_Werks Oct 25 2022, 04:43 PM

My 914-6 started as a 914-4 so the inner pad was still there.

Some place here I read real 914-6's had the longs covered in similar/same tar as floor boards? I could see that, there is a bit of noise transferred through those.

My 914-6 is a driver, everything is hooked up and works like heat, fresh air etc. Wager I'm getting noise through the heater tubes.

Either way, that engine bay pad helped!