Crawls Backward (When Alarmed)

IconProjects, musings about guitar builds, guitar repairs, vintage tube amplifiers, old radios, travel, home renovation, and other stuff.

SAAB c900 Convertible Sound Deadening

I have been working on the SAABmarine over the last couple of weeks.  I actually have some vacation time coming up over the holidays and am hoping to make more progress.  Here's what I've been up to.

The idea is to put some sound deadening onto the floors and behind the door panels and even in the top (!) before I put the new stereo in.

You may recall I have the front seats out, as well as the dash pad.  Now I need to get the carpet up so I can put deadening material under it.

The sill plates are easy to remove - just 3 screws.

With the plates off, you can lift the carpet up.  It's just tucked under the sill plates.

The whole carpet is actually one molded piece.  I toyed with the idea of pulling the whole thing out of the car, but I think I can get under it enough to install the new sound deadening material.

The original owner had one of those old cell phone speaker things on the windshield.  I removed it.

There is also some wiring behind the driver's side kick panel behind the carpet which I am also taking out.  Part of the phone installation was this 9v outlet.  Get out of my car, please!

It took me a while to figure out how to get the rear seat bottom out.  The Bentley repair manual has a factory picture indicating there are four bolts on a trim strip holding the seat bottom in place.

Not on my car.  I finally figured it out...there are two tabs holding the bottom in place.  Just pry the seat up off them.  Maybe early convertibles have bolts?

I like this mounting a lot better.

With the seat bottom out of the car, you can access the two bolts holding the bottom of the seat back in place.  This is one of them.

I believe these are 13mm bolts, but they could have been'll figure it out!

After you take the two bottom bolts out, you can access and remove the two bolts at the top.

There's a slit sewn into the trim behind the seat back on either side - you can get to the two 10mm bolts holding the top of the seat back in place there.

Yes, that is water, coming from somewhere.  I put a towel there to catch it for now.  It really doesn't go anywhere - it just pools up in the top well in heavy rains.

Here's the seat back after it's unbolted.  That must be Baltic birch plywood?

Now the real fun starts.

I bought supplies from Don at Sound Deadener Showdown for this project.  I did a lot of research about sound deadening and decided his method is the best.

You can read a lot on Don's site.  For most of the sound deadening, we're going to use Mass Loaded Vinyl (MLV) as the main deadener.  MLV is a heavy, dense material that will help keep road noise out.

The MLV is decoupled from the vehicle with Closed Cell Foam (CCF).  The foam keeps the vinyl from making contact with the sheet metal of the car.  In the picture above, you can see the MLV (black) about to be glued to the CCF (grey).

We glue the CCF to the MLV with vinyl glue. 

As it turns out, we need a special glue that will adhere to vinyl.  This is the stuff that's recommended - HH-66 Vinyl Cement.

Wear gloves and a mask when you use it.  It's potent stuff.

You can read about the technique on Don's site.

The other part of the sound deadener equation are these CLD tiles.  They're a metal tile that absorb and deaden vibration.  They are similar to the commercial tiles you may have seen (e.g. Dynamat), but they are more effective.

The tiles have an adhesive on the back which attach to your sheet metal.  Smooth them down with a wooden roller as I am doing here.

If you tap on the sheet metal of your car, you'll hear it make a high-ish frequency "ping" or ringing noise.  The CLD tiles deaden the sheet metal.  No ring, no ping, just...thunk.  I'll be installing tiles on the sheet metal behind the door trim panels too.

I put tiles on the sheet metal behind the rear seat.  That big seat back panel was like a gong when I first tapped it.  With the tiles in place, it doesn't vibrate at all.

You only need to cover 25% of the metal, and only the metal that vibrates.  I put a couple tiles on the floor, but most of the floor is quite solid, so I didn't need to do much there.

Here's the passenger side of the car with the carpet pulled up.  Note the factory insulation there - it's pretty thin.

I'm going to put the vinyl sound deadener right over the factory vinyl.

I made a paper pattern of the floor and then made up a CLV-and-CCF piece to fit.  Here's my test fit before I put it under the carpet.

Then I lifted the carpet and fit the vinyl under it.

On the 900, there are HVAC vents, seat wiring, and the seat mounting holes you'll need to cut slots or holes for.

One of the neat things about the CLV is that it will turn white when it's stretched.  To locate the seat mounting holes, I put the seat bolts in, then pressed the vinyl down over them.

You can now see where you need to cut.

Cut a hole in the vinyl with a utility knife and there you have it.

The carpet fits right back down over the sound deadening material.  The foam can be compressed to a very thin depth, and the vinyl is only a couple of millimeters thick, so it's easy to fit under carpeting or trim.  And note how I cut slots so the HVAC outlets and seat wiring pass up through the carpet as they did originally.

You can see the sound deadener sandwich (mmmm...sandwich) sticking out by the door sill.  The sill plate will go right back over it.

Is that carpet dirty or what?  I'll shampoo it before I put the seats back in.

I also used the same approach for the back seat.  In this case, we use heavy-duty velcro to hold the vinyl in place on the vertical seat back panel.

I almost forgot - there is a horizontal panel behind the seat, under the convertible top well, that I did the same treatment on.  That will help keep trunk noise out of the passenger compartment.

The seat back and bottom will fit right over the deadener material.

Next, I need to do the door panels and back seat trim panels.


Post a Comment 0 comments:

Post a Comment