Steve 88

Since my car is in dry dock for a few days (re: today's "dying shark" post), I thought I would do some sound reduction while I wait for a 14 pin connector replacement. I have read many past threads on this subject. I think my focus will be the rear wheel wells and the doors since most posts claim that's where you get the biggest improvement for the effort.

For the rear wheel wells I will try the rubberized undercoating method ala the advice on Greg Nichol's site. For the doors, I began looking at Brown Bread and Dynamat but found cheaper subsitutes like Fatmat and B-quiet where you can get the price close to $1 per square foot in quantities. I also saw material that you spray using a aerosol can or a larger spray gun.

It's the door challenge that brings me to my question: If you go the rubberized spray route for the doors you would be spraying the inside of the door to reduce the resonating road noise - probably sticking the nozzle in the openings that are usually covered by the door panel and spraying the metal surfaces within. But if you use a material like Brown Bread, the "how to" pics on the websites show the material applied on the exterior of the door facing the cabin (usually covered by the panel) with little cut-outs for speakers and door handles.

It seems like the spray approach is dampening the sound within the door while the material approach is blocking the sound from entering the cabin. Does that sound correct?

Would love to hear opinions or advice on any aspect of this project. Many of the threads I reviewed were a little old. Thanks very much.

Chuck Schreiber

Stevie,

Don't spray that shee-hot all over the car. Use the Brown Bread Brutha!

Here's the site http://www.b-quiet.com/
and here's the deal. Yes, there is some areas that you can spray, like inner fender wells hard to reach speaker areas in the rear quarter area (inboard) etc.
I'll tell you that on my 79 that has about 1/10th the sound deadening of a GTS it made a huggggeeeeee difference!!!!!!!!!!
It's got just slightly better performance than dynomatt-extreme but at about 2/3 the cost. What a world of difference it mad in the 79. I put it in from front to back and it took out all the rattles and most of the road noise. I've done the entire car except for the doors. According to Jim Mayzurk here at our club in DFW land, the doors make the biggest difference. So, In the next few weeks, my 79 (when the doors are done) should be cruising quiet as a Caddilac!!!

You can roll this on to the body panels under the doors, carpet, roof, rear quarters, etc. Not very expensive at all. It's what all the big time stereo guys do so you cant here the road, but hear all the music. If you have any questions, give me a shout. Your 88 is already quieter than my 79 so you are on your way to driving in a living room environment. Good Luck with it!!!!

docmirror

For years Dynamat was the industry standard. Problem was, it was so damn expensive, and sold through only a few dealers. Now, there are several companies that make similar products that are much less cost. You can't go wrong with Dynamat, and it's been around a long time, but I would probably look into the stuff Chuck mentions.

One thing, most of the sound you are trying to dampen is in the under 100Hz (cycles) range, so all the specs about huge reductions at 200-1500Hz is meaningless. BTW, the DB scale is logarithmic, so a 3Db reduction is half as audible. The specs with big Db numbers are kind of misleading.

Doc

Donald

Chuck-
What quantity and combination of product did you use?
P.S. Received "the package" today, thanks!

Jim M.

I've tried the spray on undercoating and IMO it did nothing for the sound reduction. On both my 89 and the GTS, I used dynamat on the doors and it made a huge difference. The brown stuff may be better, but the dynamat was available locally for me. On my 89 and I think your 88 the rear wheel wells only have a partial liner. The forward liner (over the "B" pillar) is just a plastic cover and the entire area is hollow, JUST LIKE AN ECHO CHAMBER. I filled that area with closed cell foam and injected the rest of the cavities with insulating foam from Home Depot. That also made a big difference, but not as much as the doors.

Do just those two areas and you'll be amazed at the difference.

Jim Mayzurk
93 GTS 5-spd

Steve 88

OK, guys I'm going to get some material and get to work. I'll only use the spray to get to small irregular areas. Jim, where exactly in the doors did you put the dynamat? I have seen it applied to the inside of the door against the outer wall or on the front of the door right behind the door panel (with holes for speakers, door handles).

Jim M.

I applied it on the inside door panel (with holes for speakers, handles and wires). If you use the spray stuff on the inside of the doors, make sure you don't seal up the drain holes. Quite a bit of water gets in the doors during rain and car washes from the seal between the glass and the outter door.

Jim mayzurk
93 GTS 5-spd

fabric

Jim-

Your talking about the outside still here, right? i.e between the fender liner and the frame. Not the inside of the car underneath the innside quarter panels? There's a similar "echo champer" in the front fender aft of the fender liner, probably not as big, I wonder if that would pay any dividends to eat up some space.

CMW

Jim,

So you did experience a big difference dynomating the doors even on the GTS?

touque

I've heard really good things about QuietCar... http://www.quietcoat.com/

It's a spray/roll-on material that you decide how much sound you want to reduce by applying more layers. People that have used it say it works very, very well and is more of a true sound-reducer than the dynamat or B-quiet deadener.

I have B-quiet extreme (not as good as brown bread but also from B-quiet) and still NEED to reduce the tire howl in the back. I'm seriously thinking about this option or in the interim, going to the expanding spray foam.

kshipp

Jim and Chuck - could you provide some pictures of what you did? or if any of you try it, please shoot a before & after to share with the rest of us. I'm very interested in this as well, but haven't found the DIY details that I've been looking for yet.

Chuck Schreiber

Don,

I I've used about one big roll and part of a small one. I think I paid like $120 or something like that including shipping and the roller to roll into tight areas. I've only used the Brown Bread so far. It's easy to use and there is virtually no waste. You can cut it up and use every last piece. I've done the entire car except for the doors and according to Jim, the doors make the biggest difference. Especially on the early models. Kelly, sorry I don't have any pics of the install. As Jim said, you basically remove the interior apply and then reinstall. You can do this in phases, a little at a time. First day the doors, next day the front section, etc. Really easy, just takes some time.

For those of you that have not done it, it's a pretty nice upgrade especially when you're at cruising speeds!!!

Steve 88

Without job/wife/kids/lawn this wouldn't have taken me so long, but at last I finished the sound dampening work on my shark. I am extremely pleased with the results.

I started with Mike Clemens' tip (on Gregg Nichols site) using a rubberized undercoating spray on the metal surfaces of the rear wheel wells. This step noticeably softened the sound coming from the rear.

Then I followed Jim Mayzurk's directions on stuffing foam and spray insulation into the chamber behind the plastic liner in the forward section of the rear wheel wells. This step sharply reduced what I was hearing from the rear. At that point most sound in the cockpit seemed to come from the sides.

Further following Jim's advice, I attacked the doors using B-Quiet (works well, not so pricey - thanks, Chuck). Wow! A huge difference in road noise. I applied the B-Quiet sheets to the inside of the door to dampen the reasonating sound. Then I applied B-Quiet to the surface of the door that is covered by the interior door panel. Covering the holes made a huge improvement in the noise that makes its way into the cabin.

My shark is now a very quiet car. Between 40-60 mph on a smooth road the noise from the top of windshield is the loudest sound in the cabin (future project maybe?).
Many thanks to Rennlisters for their advice.

hans14914

If you are looking for a great, low cost product, with excellent technical support, I highly recomend raamat. I am personal friends with rick, the owner, and have several rolls going into my 928 as we speak. The ensolite does wonders of decoupling the interior pannels from the car, and killing buzz. Check his product out:

http://raammat.com/

Chuck Schreiber

Steve,

Glad it worked out for you. You probably have the quietest shark around!