Cost:
Firewall Insulator Pad £80
Dynamat is anywhere from £75 for three sheets, up to £420 for Extreme bulk pack. Shop around to get what you need in the quantity you need. There is standard, light weight or Extreme versions etc. There other makes on the market that are almost identical, I have used a mixture of all sorts.
Background:
The only way to sound proof a car is with sound absorbing matting made out of a mixture of fibres which is stuck in place, or use a sticky mat of some sort. As the car was a complete nut & bolt restore the decision was made to sound proof the car inside as I wanted a noisy exhaust. The under dash area is particularly noisy as the engine right up against the fire wall and the gearbox with prop shaft are close to the floor pans. The standard interior fitting for the dash is a rubber mat with a fibre backing which held in place by plastic rivets into pre drilled holes on the fire wall.
The holes are a generic set of pre-cut holes that are pressed out to fit the options of the car such as air con etc. The large plastic studs are pressed through the mat into the fire wall which is gripped by a serrated splines on the plastic to stop it coming away. They will break if you try to remove them.
What’s in the Box:
Depending on what you bought you will get a sheet(s) that are either flat or rolled in various sizes.
Fitting the Dynamat:
The basic principle here is fit it like carpet, make strategic cuts to allow it fall into the corners and match up. It’s not essential to use a heat gun of some sort like a hot air gun or hair dryer. You only need to warm it up to make the backing more sticky and malleable, no need to over heat it.
The matting is essentially a two-part piece consisting of a heat reflecting silver surface and a black sticky backing. The matting has a peel-able waxy sheet backing that is pulled away to expose the sticky the part of the mat.
Lay the matting onto the area to be fitted and cut away the excess. make allowances for any curves that will take up more matting. The mat is easy to cut with a sharp knife. If you cut it wrong it doesn’t matter as it can be patched in very easily.
The mat is easier to lay when it is warmer that will allow for bends and curves. Start at one end and peel back enough backing to expose enough sticky to grip where you are laying.
Press the sticky section down and continue to roll the backing away under the matting and press it into place as you go. With the mat in place get a hot air gun or similar to warm the mat up. Use a roller to press the matting down into the areas you have just covered while it’s warm. With the corner areas or tighter spaces use something similar to a broom handle with the rounded end that will press the mat into curved areas. This will ensure good adhesion to the surface being covered.
If you need to use small areas, just peel the complete backing away and position into place and press home to ensure good adhesion. Here is a section completed on one side of the transmission tunnel and the other side being matched up to the previous sheet and pressed into place.
With the areas all pressed down and smoothed into place it should look something like this.
This just becomes one giant patchwork quilt.
It doesn’t matter where you start from, front to back, or back to front, side to side etc. I fitted mine in sections; the front and firewall, rear foot wells, seat plates then under the rear seats.
All the smaller off cuts can be reused into the small tricky areas that don’t quite meet up. The principle is to lay this stuff like you would a carpet. Once it grabs a hold it’s very difficult to remove again without tearing it.
To fit it to vertical places the principle is exactly the same, press on, warm up and smooth into place. For the tighter places such as inside the doors I used the same principle, cut smaller as required and patched it together. The last thing you want is for this expensive material to stick to itself.
How Long to fit?
This depends on how well you want to smooth the mat down and make it look good. technically you will not see it as it’s under the carpet. Me being a little OCD over it so I made a nice job of it and it took me a complete day. It can be done quicker, but there’s no rush in case.
Results:
The car weighs more as this is not a light material, especially if you go mad with it all. The car will be certainly be quieter and any resonance from car door skins or rear quarter panels will disappear. The other bonus is this layered coating will make a superb barrier for rust as no moisture will get past this layer.
Conclusion:
This is a seriously recommended addition to any restoration especially if it’s a nut and bolt before the carpet and interior is fitted. The money for the mat is worth while for the long-term benefits and comfort of driving an old car, especially if you want a loud exhaust and not have a brain pain after a few miles down the road. This is part of a restoration that is skipped for cost savings as it’s never really seen. Lift the carpets on a restoration to see just how much time and effort has gone into the car. This matting is a big clue!