Interior decibel (DB) levels in your super

[creative native]

I installed today a decibel meter app and this was the reading while sitting in the driver's seat and the engine was warming up.

When restoring the interior, I gutted it and it was LOUD in there. After sanding the pans and treating them with Rust Bullet, I applied Fat Mat floor liner to replace the tar boards and fat mat in the luggage compartment, in the doors & behind door panels, as well as the roof. I also switched the transmission gear oil and engine oil to fully synthetic, which caused it to be much more quiet, especially the transmission. Also, I have stock exhaust and engine (1600 dp).

[Slow 1200]

Tar boards would make a difference (it resonates more without and gets back in the car from the outside even if you have the interior lined), something else that makes a huge difference are the pillows inside the quarter panels, not sure how those are on later cars.

[54bug]

That's an amazing question, with a lot of content

Here's my experience.

I have a 1969 Sedan, that was a body off restoration. In the process I added a 1961 rag sunroof, added a Kafer bar and sway bars, Installed Dynamat and foil faced closed cell foam as well as reinstalling the tar boards. The engine is a dual carb 1776 with an A-1 Header.

In the process I built an amazing audio system 400 watts X 8 of amp with 4 sets of speakers (Coaxial sets in the Kick panel & door, a triaxial set in the back quarters, Diecast cabinet monitors on the rear wall facing up through a cover, and a powered subwoofer under the drivers seat) I'm an engineer, musician, and VW fan, so I couldn't help it

The stock beetle was always loud, and the factory radio was hard to hear at highway speed. I hoped to manage the noise and listen to music at highway speed.

My results are: the car has less noise that it did in stock trim. but the suspension noise and engine noise is significant. While I can't help hear the radio, the car is still too loud. Noise is a relative and subjective thing. The beetle was a very simple car, and road noise wasn't a design consideration. My newer water cooled Golf is very quiet, and was designed with that intent, the Beetle is still a Beetle, and I love if for what it is.

The lesson: You can anything, but it's not always practical. Noise is a relative and subjective thing. I love the stereo in the car, but it's too loud at highway speed. The money spent on insulation wasn't wasted, but the effort didn't work as expected. What's perfect on a Golf, doesn't always work the same way on a beetle.

Good luck with the project

[baldessariclan]

One trick I've found that seems to work well for reducing engine noise a bit further is to find or make one of those parcel shelves that sits between top of the back seat and the rear window (think these became standard starting in 1974 or so - ?).

I made one for myself a while back, using some thin plywood, carpet padding, and felt. I've also heard of other people filling up that back luggage area with blankets or sleeping bags, to help deaden the noise from back there.
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1971 Standard Beetle — fairly stock / driver

baldessariclan -- often in error, never in doubt...

[vamram]

[1968BUGMAN]

I dont have a super but a 68. I have the whole thing done with kilmat deadener, at some point I will put down dynaliner and then new carpets. I dont have a headliner becuase I am lazy. I also have a fairly loud exhaust which makes it be fairly loud inside of the car. Here would be my tips to get it quiet. Use a deadener and something like dynaliner or just carpet padding. Make sure to deaden doors and literally everything. Try to get a hood that seals well, or just try to seal off the dash with a cover in the hood area or something. Use expanding foam in the corners of the engine cover where the wiring harness comes through. Put in a headliner, maybe even use a deadener on the roof before the headliner. No heaters and sealing up them will help with noise. Quiet carbs, or even a single carb will be the quietest. I had 44 idfs for a while and they are freaking loud, although sealing up the holes that lead inside the car where the harness comes through will help. You are going to want a quiet exhaust like stock, vintage speed, quiet pack. And the most important thing I would say is tall tires or even better a freeway flyer. I dont run small tires but they are smaller than stock. 195 55 on the back so the engine is up there in the rpms. A freeway flyer 4th gear would make cruising at 60-70 mph much much quieter. Even a slightly bigger engine might be quieter, becuase you wont have to use as much throttle. A 1776-1915 is probably the sweet spot. Honestly, if I have my windows up and I put in in neutral I have very little road noise even at 70+ mph. There is some whistling because my hood/vent windows dont close right. I would say you absolutely need a quiet exhaust. And as for a stereo look at my build thread. If I turn that up all of the way you hear none of the car sound. Literally no exhaust at all, its that loud.
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1968 Beetle Project | https://www.thesamba.com/vw/forum/viewtopic.php?t=...ae8942450a
Installing a Stereo Into a Classic VW | https://www.thesamba.com/vw/forum/viewtopic.php?p=9502179#9502179

[Busstom]

[baldessariclan]

[CWAVE]

Granted, I did lose the tar board, but it's not like I haven't anything. Sorry if I've lead you to believe that I removed all the sound deadening on the car but that's not the case. This is what I've done in leu of the stock tar boards as you can see in the following photos.

Then on top of the Dynamat Extreme on the floor I put Dynaliner. All the Dynaliner I put in is 1/2" thick.

Dynaliner was applied in various places as shown, before the carpeting was installed in the usual places. The Dynaliner is on top of the Dynamat Extreme.

And for what it's worth, when I ditched the smelly mouse latrine padding on the heat ducts, I did this to them:

So, ya... I am missing the tar board out back, but I do have what you see above in the photos.

And I do find it pretty quiet in the car. Wonder if adding a tar board would make any difference at this point. Probably wouldn't hurt. So, I guess the original pondering still stands which is... I'm wondering if this is better than stock?

Thomas

P.S. Also have a padded parcel shelf in the back.

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My 1973 Sports Bug Body off Restoration:
https://www.thesamba.com/vw/forum/viewtopic.php?t=666556

[Fiddlestyx]

57db at idle. I only have sound deadening on the rear firewall, luggage tray and rear inner fenders. My floor pans only have carpet, no tarboards.
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1983 Vanagon Westfalia Air-cooled
1973 Super Beetle

[CWAVE]

I had not checked my idle db level in the car since adjusting the idle speed. The car currently is idling at 900 rpm, and I'm getting a 55db reading.

Fiddlestyx, what was your idle speed at your measurement of 57db?

Thomas
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My 1973 Sports Bug Body off Restoration:
https://www.thesamba.com/vw/forum/viewtopic.php?t=666556

[vamram]

That's an amazing amount of sound deadening! I think your main issue is likey the open C-pillars all the way back to the engine compartment.
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Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!!

[Fiddlestyx]

[CWAVE]

Thanks.

I've reached out to the guy that makes those C-Pillar pillows, and think I'll pick those up to plug up those pillars.

Thomas

[Volks Wagen]

[vamram]

Creative Native - that is one quite Bug! Granted, I recently replaced the pea-shooters w/the Zoom Tube so it's a bit louder than it was a coupe of weeks back. At idle:

And at 65 MPH on the DC Betlway: