Tech Articles

Sound proofing

In a stock BJ60, the roar of the engine and drivetrain is quite impressive. Particularly with a 4 speed transmission. And on a long haul at 2500-3000 rpm, it is rather deafening.

I've installed Reflectix under my carpeting and as a hoodliner to help dampen the sound. The result: for the first few days I was over-revving the engine a little, and had to watch the tach more closely for shifting (I usually shift around 2500 rpm, but was hitting 3000 before it sounded ready). It still sounds like a big old diesel though.

Reflectix is basically bubble-wrap with silver foil on both sides. Available from home building stores, it's intended as an insulator. It does a good job as a sound insulator as well, used on the firewall and under the carpets.

The procedure is straight-forward, but it took the better part of a day. It was simply a matter of removing the front carpeting, and cutting the Reflectix to fit, using duct tape to piece it together. I used two layers from the firewall (as high under the dash as I could get), right back to under the back seat, and retained the original carpet and padding.

In corners where it bunches, or where two pieces meet, I recommend trimming the overlap. Otherwise the extra bulge may make the carpet too bulky.

For the hoodliner, I removed the stock liner, and made a Reflectix piece the same size. I also cut smaller pieces to fit within the hollow spaces of the hood (between the supports). Then I replaced the stock liner, with the new layer between it and the hood. In removing the liner, I had broken some of the tabs, but I got screw in replacements from my local auto parts shop, which were much easer to deal with.