Land Rover Series III 109 RHD 5 door: Seat Box Sound Deadening

Well, for better or worse, the Seatbox is done--covered on top and underneath with sound deadening materials. The good news is, I've learned a lot on this one project. The bad news is, it didn't come out the way I wanted and I doubt I'll ever have the opportunity to do this again (maybe I should be happy about that part though!).

The material I used for the top (or interior side) was 3/8 inch "carpet matting" from Hamilton Jet (www.hamiltonjet.com). This is 1/4 inch closed cell foam backed on one side by 1/8 inch limp mass vinyl. This comes in 54" wide rolls, cut to whatever length you need.

I was concerned about the wear and tear on the top front corner and leading edge of the seatbox where it would be constantly kicked getting in and out of the 109 so I decided to reduce the number of seams to one by cutting the matting to wrap around the seatbox. Since the matting is only 54" wide, I used three peices to full cover the seatbox.

Using the top rear edge of the seatbox as the reference point, I measured and cut the matting to fit and then created a flap on door-side face that was riveted to the footwell-side face of the matting.

This is the peice for the left-hand/passenger side.

This is the peice for the middle section. I used a 1/2 inch thin metal length of tubing to cut the holes for the seat slider bolts. I also purchased new stainless steel hardware for the sliders from Tacoma Screw (www.tacomascrew.com).

Here is the box with both end caps fitted:

And with the blank, uncut middle section:

After getting each of the three sections cut and ready to mount, I brushed on a contact adhesive to both the seat box and the matting, let both sit for 20 minutes and then bonded them together. In hindsight, I would have used an assistant because once the two peices touch, it is nearly impossible to pull them apart without damaging the matting. I used a small nylon roller to roll out the bubbles and smooth out the matting.

Here is the finished product. Both access hatches will also have matting glued to them.

A close-up of the middle section:

Now for the underside. The material I used here is Powerfoam, a fire-resistant expanding foam also purchased at Tacoma Screw. The underside of the seatbox was first cleaned with mineral spirits to remove all the grease and oil, then thoroughly wire brushed to remove all the crust and scum and finally brushed and wiped down.

This foam--at least with the cans I used--came out FAST for about 20 seconds and then really slowed to a trickle until they ran dry. The foam expands a lot more than I expected it to and it seemed to expand unevenly--the foam that came out first (the fast part) seemed to expand more than the foam that came out later and very slowly.

As you can see, I overshot the edge of the seat box quite a bit. The same thing happened along the edge of the transmission access hatch. Now I'll have to cut back the foam with a hacksaw and then find a way to "re-seal" those edges.