How to soundproof?

[Fatmobile]

Here's a pic of my, '84, 4 door project.

The '84 has a foam cover on the firewall.
I also read on the vortex, that rubber acylic roof coating can be used to reduce noise. It sticks to the surface, handles heat well, and goes on thick to add sound absorbing weight. It's the white stuff on the firewall.
I have the headliner off now and it is very noisy. I plan a couple coats for the inside of the roof with Kool-seal, from Ace hardware.... and some closed cell foam, maybe the stuff used for sleds.
I also plan to use these sleds for under the carpet.

[ahistand]

When re-doing my Caddy I bit the bullet and bought about $100 worth of FatMAt brand sound deadening material....I know, not the most economical way, but whatever. I had the whole interior pulled out anyway to replace the dash, put new carpet in, clean everything, etc. My truck had been sitting for about 12 years out in the weather, so it was funky.

Anyway, I basically put the FatMat on every surface possible, right up the b-pillars and including the roof. Inside the doors is really important, because they are like big resonators for sound. They were also a pain in the A.. to do. Also, when you pull the old carpet and insulation out, there is some ungodly nasty glue that the factory uses that is unbelieveably difficult to remove. But you need to try to get rid of most of it so the sound dampening material will stick properly to the floorpan.

After I did all that, I found some insulation with a sticky side to it at a yardsale....a whole roll for like $5 and I put that stuff all over the floors, and several layers glued to the roof. Then, new carpet, new headliner, etc, etc.

It is now maybe about as quiet as a stock A2 gas car, for comparison. Its certainly not luxury quiet, but much much better than stock. As for rattles, just try to isolate them one by one and you get rid of most of them. Insulation in glove box is a great idea, like someone else said, its amazing how much loose crap can rattle and make noise in there.

Right now, with the windows closed, at highway speeds my two biggest noise factors are exhaust resonation and very poor window sealing. I want to get new window seals, but my God those are expensive. I am gonna try to cure the exhaust problem when I install my Turbo motor and build a proper exhaust system that focuses on noise abatement rather than diesel growl. With the windows down, well its just loud.

[Caddyman]

VanagonMark...

One thing I forgot to add, the G60 Valve cover/rubber gasket
set up requires the use of shoulderless valve cover studs.

FYI, I just got my valve cover gasket kit in yesterday via UPS. Looks like a really nice one piece gasket. The studs come in the valve cover gasket kit usually (mine did at least). P/N is 15-31692-01 by Victor Reinz. It also has VDD-SATZ at the bottom.

[Caddyman]

I have drastically reduced interior sounds and I dont even have carpet or a headliner yet.
First I replaced the roof sound deadening with a layer of thin foam/foil stickybacked insulation from home depot, then glued new foil backed jute padding to that. That cut down a lot of sound
Then I covered the underside of the hood with the double foil backed jute, and the firewall. That helped some.
Another effective noise killer was adding a layer of sticky backed asphalt roofing to the inside of the doors to cut resonance. I replaced the door plastic seal with hardwood floor foam underlay/water barrior stuff. I used home acrylic dap caulking to stick it to the door and applied a lot of it because the rubber also dampens vibrations.
The real sound killer was what I did today. I picked up the under carpet deadener which is a dense jute with a thick rubber mat attached to it, from a 99 oldsmobile cutlass. I suppose nearly any type of semi luxury car would work, cadillac lincoln whatever. I put this under my rubber floor mats, remember no carpet yet. Its now reasonably quiet inside the car especially considering I have a 2 1/4" downpipe, motorcycle muffler, ported head, ported intake, and the air intake draws air through a 3" tube which goes to the rain tray/cowl. This thing was painfully loud before...literally. Now its nice to drive. Once the headliner is back in, the carpet is done and the exhaust has an effective muffler It will be luxury quiet. I also have stuffed all open dead space in the back of the car in the hatch and by the wheelwells with foam chunks.

Lexus is one if not the quietest cars on the road today (interior wise). They use a sheet of lead sandwiched between two pieces of neoprene (IIRC).

[ajt3nc]

We pulled the carpet out of the house to do wood floors and I used the padding to cut down the noise in the 86. I was happy with the results.

[Ziptar]

A few suggestions...

I swapped a 1.6L Eco engine into an 89 Carat. I did a bit of sound proofing along the way. Full details here.

Supposedly, additional sound deadening (tar mats stuck to body panels) was part of the Carat package. Based on what I saw in the Ecodiesel Donor and in the Carat I'd say it was true. Not a huge difference but, it's there.

First, if you are on the highway allot a transaxle with a higher gear ratio will help allot. I used the ASF code transaxle when I swapped, it's great. On the interstate RPMs are just under 2750 @ 70MPH, exactly 2500 @ 65MPH. Much less noise than the AVX trans requiring 3250+ RPMs for those speeds.

As part of my swap I had the entire interior out so I could swap the Diesel CE2 Wiring in place of the gasser CE1 Digi harness. While I was at it I removed all of the old Jute Padding and did a $27.00 sound deadener / insulation experiment. I read a really lengthy thread about sound deadening vs. sound quality on a car audio forum. Basically the acoustic mat adds mass and improves sound quality but, the padding is what adds sound deadening. I also came across a couple of threads about a $6.47 closed cell camping mat that Walmart sells and, apparently it's made of the same stuff the audio places sell for allot more. I picked up 4 rolls. I used it under the dash and in front of the A/C box on the firewall as I put everything back together. It's decent stuff, cuts and forms easy. Seems to do the job and does make it quiet, every bit as good as the factory jute padding at least. I put it everywhere though so it made fitting the carpet a bit tight, but it works. The closed cell padding is better than jute because it won't soak up and hold moisture from spills and leaks grow mold and get smelly.


I found another handy Walmart item. In the craft section they sell sheets of "Fun Foam" for kids crafts projects.

They are closed cell foam sheets about the size of an 8"x11" piece of paper and a few millimeters thick. They are $0.42 a sheet and so far I have found them handy for wrapping wiring harness and dealing with odd squeaks and rattles. There was a bit of a rubbing sound between the center console and dash at idle. I trimmed a piece to fit and squeezed it between them, no more sound. Heck of allot cheaper than wiring loom and a good replacement for the original VW foam on the wiring harness that long ago turned to dust.

I also repaired / sealed holes in the vapor barriers in the doors.

I have to say it's pretty quiet, not nearly as quiet as my 03 TDI Wagon but, for a 17 year old diesel, it's not bad. I can hear the radio just fine without blasting it, I don't go nuts from the drone during my 1.5 hour commute. I can even here people on my cell phone, and they can hear me say "I am driving, I'll call you back."

It may be hard to tell but, this is a video I took on the interstate

I still have other issues to work out.

Tires: I have 14" steel wheels on it with 185/60 Continental tires that aren't so great and are really noisy. As soon as I track down a set of 4 factory 14" Castalette wheels I'll get a set of 195/60-14 Michelin Energy MXV4+ Tires on it and that should bring the noise down considerably.

Suspension: The Carat Came with a set of Eibach Lowering Springs, Boge Turbo Gas Struts and some poly bushings on it. It's not bad but, it does transfer allot of vibration. These will get replaced with either stock springs or H&R OE 8 Valve Sport Springs (supposedly only lower car by .5" and supply a factory ride that is a bit more responsive) and some Bilstein HD struts with OEM Rubber bushings and stops.

No Headliner: The Carat came minus headliner so I need to track one down, I am sure noise is ricocheting off it making it worse.

G60 Valve Cover: I have one, the rubber gasket kit should be here next week, I'll see if it makes a noticeable difference. I bought it mostly because I am tired of my stamped steel, 3 piece cork gasket valve cover leaking precious $5 a quart synthetic oil

[Fatmobile]

Great tip on the camping foam pads.
I want to stick something like that to the roof before I put the headliner back in the 4 door project/driver.
I've been using the fun foam sheets for heating and AC stuff.
Holds the vents in place etc.

[surfcam]

I'll certainly second that about the great tips. It's one of those projects that has bogged down with to much RD for me anyway. Anyway I noticed some Yoga Mat's 24"x86" at XS Cargo a notorious purveyor of refurbished items. I was wondering what of the suitability of something like that. At $10 a pop I thought the price was pretty good. The only thing is they will probably have bottom prints on them but as long as she was a cute Yoga instructor I can live with it. They will also match your purple car.

[Homer T. Coyote]

Alright, yoga is where I draw the line. Unless it's some kinda turbo diesel yoga, I'm outa here! Come to think of it, we probably do some kind of yoga trying to reach some things in the engine compartment.

[davidpa28140]

I used foil backed hot air duct insulation under my head liner. It is self adhesive and fairly think seemed to do the job.

[Fatmobile]

I should start looking for high temp adhesive.
The roof gets hot on a sunny, summer day.
To disconnect the speedo cable I sit on the ground next to the car, back against the rocker,... and perform the snakearm posture.

[Ziptar]

Valve cover gasket upgrade kit arrived Wendsday afternoon so I put the G60 valve cover on early yesterday morning before my commute to work.

It does reduce noise somewhat, I'd say ~25%. It seems to me that it eliminates noise the most at highway speeds. It was most noticeable to me at 65-70 (2500-2750 RPM) seems to have made things much quieter. Idle is quieter also but I didn't really say Wow until I hit the interstate.

Wiped off the Garage Floor before pulling in last night and checked just now. NO CRANKCASE OIL SPOTS!!!