pontifex4

Thanks! I agree -- a well-damped car will really lower your irritation level if you're a big daily driver. If you're not too concerned about the weight (for instance, if you could stomach adding about 50lbs, mostly low down, and between the axles) you could probably get it to Toyota Camry-quiet in two weekends, for around $400.

That would involve doing what CurtP did, above (gutting the interior, scraping out the old, now-hardened-and-ineffective insulation and laying down the sorts of products above, then attacking the backs of interior trim panels with some kind of damping material and coating anything which moves with super-heavy grease, then, finally, shooting a sound deadening undercoating underneath, in your wheel wells).

It's hard work, and you'll cut yourself in surprising new ways, but it really does change the car's character.

In terms of my costs, so far, they're more or less $0, since I've been using stuff I had lying around from other jobs. However, here's a rough breakdown:

1. half a 50 square foot roll of B-Quiet Ultimate (would be about $130 USD for a full roll, and you'll definitely find uses for this kind of material, even if it's not all in the car)
2. 1 sheet of B-Quiet V-Comp ($65)
3. 1 can of Duplicolor Grease and Wax Remover (this is a terrible product to use for what I'm doing -- I far prefer Varsol and a scouring pad, but have run out of both - $8)

_________________________________
Total would be about $200, plus shipping.

As for the sound reading, no, I didn't take any. I used to measure, but it's kind of demoralizing to spend an afternoon breaking your back for what only reads as a single decibel improvement! It also distracts you from what you're really doing, which is chasing down specific areas which resonate in quite a narrow range of frequencies. The sound of the exhaust at highway cruising speed, for instance, or the noise your rear tires make on rough pavement. I'm still better at finding those with my ears, though I recognize that some are really handy with a meter.

guardsred944s

Charlie, you seem to really know what your doing here thanks! Question though, are you are just sticking the dynamat directly behind the trim panel of the doors or actually inside of it?

And another, do you think there is any value in doing your vinyl/foam mat idea in the boot (watching too much top gear) without actually putting down dynamat on the steel?

I completely soundprroofed my miata a cpl of years ago, and I always think of myself (someone else) years down the road wanting to strip it down to a track toy... and subsequently hating my past self.

BTW, the SP helped... but there are much better ways to spend your time haha!

pontifex4

This time, I'm relying on a single (complete) skin of adhesive mat over the whole inner skin of the door (between, as you say, the trim panel and the door), with aluminum blanks to fill the gaps in the inner skin. That's new territory for me, though, since I normally do the back of the outer panel, as well. More on that coming shortly.

I'd love to have a definitive answer on that, but I didn't test the mat without the vinyl, or vice versa. My suspicion is that it wouldn't be especially effective alone, since the areas I used the adhesive mat on were especially resonant at around 400Hz. It's probably better to think of the vinyl barrier as an attenuator for all frequencies, and the adhesive mat material as a way to modify peaks in the imagined trace of your car's resonance response graph.

For instance, if you're cruising along at a fixed 50 MPH, you might be hearing a transport truck engine at 125Hz, your tires at 300Hz, and a whole host of wind, other cars, echoes and gremlins at 1KHz (a very busy place for ambient noise in an automotive environment, and the place where most factory-tuned OEM stereos tend to have a big frequency bump).

WARNING: GRAPH!

Each of these would appear as a peak on a graph, like this one (excuse the weird graph, I don't have any real ones handy):


You just need to imagine where these peaks are, figure out what's causing them, and dampen the offending surface(s). It's very much like "EQing" your car, rather than the stereo, and it's actually a fairly rewarding activity.

pontifex4

Installment 2: The Doors

I was reminded for the first time in a long time of what a joy it is to work on the interior of a car from the '80s. In the 1980s, If car interior designers wanted to attach something to something else, they'd use a screw, not Amorphous Poly Alpha Olefin, or some kind of crazy hot-melt thing.

Speaking of amorphous, pictured below is the better of my two original front door speakers. Amazingly, the other one (with less than 50% of its foam surround remaining) sounded better than this one!

Anyway, it was an enjoyable task to pop the door panels off my car, peel off the vapour barrier, then, finally, scrub off the grease, glue and wax so I could get started applying mat.

This did bring me to a logical fork, though: On every car I've done this to, I've treated the inner side of the outer (body panel) part of the door with either blown-in liquid damping material, or snaked-in strips of adhesive mat before sealing it off on the inner skin.

Admittedly, this was partly so that if anyone asked about it, you could rap your knuckle on the door and everyone would nod appreciatively at the sound it made, compared to the door of the cargo van parked beside you, etc. It was also because, by approximation anyway, the axis of road noise is perpendicular to that of the rotation of the wheel, so deadening road noise properly should require treatment of anything along that axis (rear quarter panels and outer door skin, in this case).

This ran hard up against my unwillingness to pull out the window regulators in each door. Since the space is so small, and the ways to reach in so convoluted, doing it properly would either involve stripping the entire door or pulling it off the car, laying it outside-down and flooding it with liquid damper.

This seemed like a terrible idea on a sunny weekend afternoon, so I greased anything which had to move to kill vibrations (lock pusher, door release cable end, window regulator gears) and set to work with the tin snips on some aluminum sheet to make blanks to fill the openings of the door. Unfortunately, I didn't take any pictures of that part. Just imagine cutting out shapes in aluminum to fill openings in the inner skin of the door, then "taping" them in place with little pieces of adhesive mat, before matting over everything.

One note about the door-release cable: it has a hard outer sleeve, and is routed past a few annoyingly-resonant things. I highly recommend taping it in place with adhesive mat, since it's likely what you hear rattling in your door right now. Be sure to put some tension on the cable by pulling the interior lever, to make sure that you haven't stuck it down at an odd angle which will make pulling the lever difficult.

Keen students of car stereos will no doubt note that I haven't left any openings for speakers in the door. This is a temporary measure, as I have some immaculate 10-speaker panels which I will be substituting for my current panels, once I finally have the head unit rewired the way I want it.

Total weight added so far: approximately 20 lbs, half of which is the rear vinyl barrier, which is removable.

JohnKoaWood

With the exception of the silver backing, they look almost identical to my Dynamated 951 doors...

Previous owner went ape all over the car with Dyna mat... but at least I get to hear every single hatch squeak and can narrow down loose trim screws in .5 seconds on the highway...

Do yourself a favor, and poke a hole in the mat, make sure when putting the panel back on you hook the door panel hook into the door or your handle will move when pulled on... there is a felt covered hook on the inside of the door panel.. go look.. it is there... on the screw that holds the handle to the door panel...

pontifex4

Good catch, John -- this was an in-progress photo, and I hadn't cut the hole for the hook, yet. I actually found that I could cut it as a flap, then fold it over into the middle area of the door, so that the hook (which had lost its felt on mine) wasn't metal-to-metal with the door skin.

Does your dash rattle? Mine does. I know it's going to start bothering me, now.

JohnKoaWood

After all is said and done, make sure your windows go up and down as well... the clearances are TIGHT on these cars, if the wires from the switches push in too far tehy will catch the bottom edge of the window, and if the mat pushes in too far it will wipe itself down the inside of the window..no talk about irritating..

No dash squeaks, but plenty of others... Hatch, sun roof, trim panels I keep pulling off and half way putting back on....

Looks good, nice to know not everyone here is concerned with ripping out everything to turn their car into a track car... keep up the good work, and keep those pics coming...

CurtP

I need to correct myself - I didn't add any dampener to the outer door skin, but I added a little to the inner door. It's around the speaker and in a couple of key areas, but I didn't add much. I'd bang my fist on the inner door and listen for anything that rattled - there really wasn't much that did. Like I said, my goal was to add as little weight as possible, but not have a car that buzzed and rattled like crazy. I also used some deadener around the rear speakers, but not behind them.

Before I did all of this, I'd get a unacceptable amount of heat from the tunnel. Most of it was coming from around the shifter, and it persisted even after changing the foam block that goes between the tunnel and torque tube and replacing the inner rubber shift boot. It wasn't really that hot, but it really annoyed me. Since I've done it, there has been no radiant heat issues at all.

I don't really have any good pictures of my headliner. I had a really hard time getting any of the pictures to come out at all. I bought the fabric online from Stock Interiors and it took about 4 yards of 54" wide material - 3 yards for the roof, and another yard for the sunroof. If you don't have a sunroof, then 3 yards should be enough. What I did was instead of running the length of the material from front to back, I ran it side to side. That allowed me to cover the entire roof and the B and C pillars with a single piece of fabric instead of covering the pillars separately. I'm sure it created more waste, but at $15/yd, I didn't really care. I had used Stock Interiors adhesive in the past, but I didn't really like it that much. So for this project I used 3M 8090. If I can get some decent light today, I'll try to get some new pictures of my interior.

CurtP

Oh, and I forgot to mention my dash. When I first bought the car, I had all sorts of noises coming from the dash. As I took it apart, I found that there were a *LOT* of missing screws. The trim pieces that surround the steering column were missing a bunch causing it to make all sorts of noise. Most of the plastic trim was brittle and the screw holes were broken. When I put everything back together, replaced all of the plastic dash trim and made sure that all the screws and fasteners were in place. I have absolutely no noises coming from the dash. I only have two noise issues right now - a squeak coming from the hatch (I suspect that the glass is separating from the frame) and a rattle from a broken trim piece that covers the seat motors that I forgot to replace yesterday.

When chasing down squeaks and rattles, I use wiring harness tape to squelch them. The fuzzy harness tape available from VW works well. I've also been known to use the fuzzy side of Velcro. For wiring harness connectors, I usually wrap them with adhesive backed felt that I get from McMaster Carr. I've found it doesn't fall apart after a couple of years like foam does. In a pinch, the wiring harness tape or fuzzy Velcro works on the connectors too.

xsboost90

i just bought a louder exhaust- now i dont hear any squeeks..

pontifex4

Hey, John -- I actually made covers for the openings with sheet aluminum (cut with tin snips). They keep the mat from sagging into the window, and help you control noises a little better. I really should have showed this step, but my hands were a little too dirty to handle a camera!

The tightest clearance point I found was on the lower wide opening, where the window regulator arms sit when the window is down. There is next to no room there, so I ended up shimming the aluminum filler piece to add a bit of clearance behind it.

Next time, I'll take more pictures in the middle!

pontifex4

Dan, your car also makes more than twice the power mine does, which presumably means that you hear even more tire roar and wind noise than I do!

pontifex4

Okay, noted. I certainly do find that my hand gets pretty warm if I leave it near the shifter. About how big an opening did you leave in the barrier around the shift lever?

As for the headliner, I'm really interested in the material you used. That seems like a far better approach than simply putting adhesive mat on the inner skin of the roof, then putting the same hard plastic headliner back up there.

In previous installs, I've often regretted doing the roof with adhesive mat because a car roof (especially one in a sedan, or without a sunroof) tends not to be particularly well-braced. What you end up doing, then, is mass-loading a big diaphragm, substantially lowering its resonant frequency. Depending on the car, this can really make a mess of its overall resonance by dropping road noises down a few octaves, resulting in a really boomy, shuddering sensation over bumps and competing with your stereo's low-end.

Actually filling open areas with foam (where the foam comprises most of the volume of the opening, rather than a tiny skin on the walls) can be a good way of cutting a persistent echo. This is something I'll be exploring later in the inner wheel wells and pillars.

Thanks to everyone for the input! When I get a little farther along, I'll summarize my progress and draw up a parts list.

CurtP

I made the opening "snug". There's no metal exposed.

guardsred944s

http://soundmove.com/secretaudio.htm

Another way to make your car quiet, well aesthetically anyways.