Keep it down: How to stop the noise in your 4WD
Sound deadening is a worthwhile upgrade to make the interior of your 4WD that little more comfortable.
It's a quick and easy modification anyone with a screwdriver can make, and boy, does it make a difference!
Before it was impossible to have a conversation over 80kmh, and after a couple of hours in the saddle the exhaust drone was enough to drive a man mental.
Now you can hear my passengers loud and clear. Although we're not convinced that's a good thing.
Start by removing any trim pieces and accessories bolted down in the way. In an older bus it's generally just Philips head screws holding trim in. Something newer can require trim removal tools, although if it's that new you probably don't need this mod.
To get down to the metal you'll need to carefully lift the existing carpet up and out of the way. In most cases it'll be joined somewhere awkward like under the seats, making removal near on impossible, so you'll need to position it in a way that won't rip it.
New carpet is a pain in the ring gear to install. Although it looks like something died in the back of this 60 so that might be happening soon enough.
Under the carpet you'll see a layer of the most disgusting material you'll ever find - the original underlay has probably been soaked in mud and Macca's chips more than its fair share. It's also useless as a sound deadener, although on the positive side of things it is very easy to remove, pulling up in large strips.
Under the underlay you'll find 20+ years of sand, dirt and grime. Crack out the vacuum cleaner and give it a good scrub in every nook and cranny. The cleaner you can get it the better the sound deadener will stick.
When you remove the underlay there will be a fine layer of material stuck to the sheet metal. You'll need to get as much of this off as possible to ensure a good finish, a wire brush will make short work of it. If you're feeling really adventurous you can remove the existing sound deadener, although we've never noticed a difference either way. It's a tough slog to get it off and normally requires dry ice to freeze it and then a hammer and chisel.
To give the sound deadener the best possible chance to stay stuck down you'll want to give the metal a once over with wax & grease remover. It'll clean the surface, allowing the matting to stick to sheet metal, not the fine layer of grime above it.
Remove your matting from the packaging, being careful to leave the protective cover over the sticky side, and lay it out over your area to see how it best works with minimal loss. It's a reasonably cheap modification but nobody likes throwing away $30 worth of offcuts.
When you've got your layout figured out, pinch the scissors from the kitchen and trim the pieces to suit. You'll normally need to angle them where they butt into the back corner, and around the wheel tubs and fuel filler neck if it extends into the cargo area.
Once you're happy with how it's all laid out, it's time to start applying the material. Pull 15cm of the protective layer off underneath and start sticking it down. You'll want to minimise the amount of air bubbles underneath so push it into every ridge and contour. Some stiffer materials can require the use of an applicator.
With the rest of the sheets laid down it's time to go through and do any final trimming. Tie down hooks will need to be cut out as will any mounts for accessories or child restraints.
Pay close attention to the factory access panels too. In the middle of the 60s cargo area is a small hatch to access the sender in the fuel tank. Two minutes with a stanley knife now can save a whole lot of headache later.
From here simply reassemble the carpet and interior trim and take it for a test drive. You'll be blown away by how much quieter your 4WD is.