Silence of the Bruce

Sound Proofing a Troopcarrier

Troopys aren’t exactly known for their interior comfort. Before doing this work, I actually likened it to driving a tin shed. In fact, the noise in the cabin was loud enough that after driving for an hour or so, a headache was more or less guaranteed! The noise comes from a combination of the engine, the wind and the fricton of the tyres in the road. The best way to bock it out is by soundproofing the thin metal panels that make up the doors and floor pan in the cab.

Under Floor Vinyl Matting

This stuff is a pliable, sticky, black rubbery substance called mass loaded vinyl. One side sticks to the metal surfaces of the car. The other is covered with foil, which has the added benefit of insulating against heat (The 75 series floor gets pretty warm on a long drive). It works by adding mass to the metal panelling to reduce sound vibrations.

Phase 1 – Prep

First things first, I removed the seats and the seatbelt sockets. This was very straight forward. Just four bolts for the seat rails and one for each seat belt.

The original vinyl matting was in fairly good condition but pretty grubby, so this was a good chance to clean it up a bit.

Ahh yes! 17 years of grime under the vinyl. This car has definitely been on red soil before! Out came the vacuum and then the degreaser.

Removing the flooring also showed up a couple of other small issues. There’s a small plastic blind plug missing – No biggie, genuine replacement part from Amayama was about $3. The other one was a bit more concerning, but it certainly would have contributed a lot to the noise in the cabin!

If you look at the cover over the transmission (sorry for poor image quality), you can see that there’s a gap. That goes straight through to the gearbox! The solution here was to create a gasket using Selleys 3 in 1 Adhesive, Sealant & Gap Filler. Much better!

Amazingly, there was hardly any rust under all that dirt. There were a few small areas with very minor surface rust.

Here’s Bron sanding it off with some glass paper. After that, we sprayed some white paint over it to keep it sealed.

The stuff in the foot wells is like a hard bitumen substance. I had a go at getting it off but it wouldn’t budge. It should help reducing the noise and heat anyway, so other than looking ugly, it doesn’t matter.

Nice and clean!

In case you’re wondering, the wires on the left are for the rear speakers and power for the fridge.

Phase 2 – Installation

Next I put the vinyl tiles out on the floor pan to get an approximate idea of how it was going to fit together. I bought about 4m² of the stuff, which was plenty for the cabin floor (not the back) and the front doors.

Once I had a rough idea of where it was all going I started peeling off the backing and sticking it down. The lino roller is used to smooth it out and mould it into the crevices and the scalple is used to cut it to shape. The edges on the foil are very sharp so paper cuts and swearing ensued.

I Made sure to go as far up the firewall as possible to help dampen the sound of the engine. Ideally I suppose you would take out the whole dash to do it, but that’s taking it a bit far!

All done! Just need to put the vinyl flooring and the seats back in.

Phase 3 – Doors

I also decided to do the inside of the doors, as that’s another large panel that takes a lot of road noise. Taking the door cards off was fairly simple; it has plastic clips behind it that pop out with some gentle prying. The door handle has a screw to undo in the middle and then it slides to the left a little (right on the driver’s side) and pulls out.

The window winder is a little more difficult. It’s held on by a hidden spring clip thats shaped sort of like Ω. You have to get a rag and slide it between the door card and the handle. Then pull the rag side to side in the opposite direction from where the handle is pointing.

I put the sound deadener in through the openings in the inner panel. It’s quite fiddly and the edges are sharp so I did get a few scratches. The moisture barrier was also damaged, so i replaced it with some plastic sheeting.

So was it worth it?

The noise level is now far more bearable! Bronwyn and I can actually have a conversation without shouting at each other!

The cost of the sound dampener was $120 on eBay. There are various brands, Dynamat being the most prestigious, but all of them seem to be pretty much the same stuff.

Time wise, it took about a weekend to complete. There is still some noise from the engine and the road. It’s louder than a modern saloon but I would definitely recommend it over doing nothing.

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