Soundproofing the cabine of a Fulvia Coupe

When I first hear the incredible sound of a Fulvia’s engine it was like music to my ears , because the sound was so offensive that I could understand immediately the character of the car. When the engine has high rpms the sound is so strong and powerful that gives you the feeling that you are driving a much bigger car and even when the engine is at the lowest rpms the sound is so unique that you can understand clearly the condition of the engine. After that introduction it’s sounds strange that I am going to write what I did to make my Fulvia soundproof so it is important to mention that when I took for the first time my wife for a drive with my Fulvia and when sometime she tried to avoid me of passing another car but she didn’t succeed it because the engine sound was so strong that I couldn’t hear her (What a pleasure!) , she declare to me that if I didn’t do something for that "terrible noise" she will never been in the car again. So I have two possibilities ,first to leave the car the way was it and making lonely walks and second to someway decrease the sound of the engine in the driver’s cabin . I decide to make the second so I did the following actions.

The bonnet .
The boot.
Soundproofing of the bonnet.jpg (12458 bytes) Soundproofing of the boot.jpg (19766 bytes)
The gearbox area under the car
I used three types of soundproofing materials .
  1. A hard but not so thick one, that usually used on floors
  2. A very soft and thick material whitch its opposite to the sound generator surface is cellular so gives the best results ,
  3. A thin soft material that its form is like a sandwich with its external surfaces made from aluminum and its inside part that is made from a cellular plastic material.
So I did the following actions

  1. I repair very carefully the exhaust system of he car to avoid big noises from there. For someone that don’t know the Fulvia’s exhaust system it composed from three parts , the front the middle and the back part .The middle and the back part have little barrels who soundproofs the engine so the good condition of these is very important for a low engine noise.

  2. I spread on the floor under the rubber carpets the material of the first type to eliminate the sound from the floor .That job is not so easy because I had to be careful to cut that material in the correct shape not only for soundproofing reasons but for sensitive reasons too. Everything I was doing had to look professional so I was working exactly like a tailor. I put the two seats away and I imprint the whole floor in paper and after that I cut the paper and the soundproofing material in the same shape . I glued the pieces of the material on the clear floor with strong glue and I put the rubber carpets on top of it.

  3. I replace the two inner surfaces of the doors with others witch are much thicker because are composed from soundproofing material and they look more luxury too and I put inside the doors thin leaves of material of the third type I mention below .(that is not so easy because of the door and the window mechanism)

  4. I glued on the inner surface of both the bonnet and the boot a thick leaf of the cellular material of the second type. This is the most important part of the whole job because the distance between the inner surface of the bonnet and the primitive cause of the noise is very small so that sound hindrance could bee very effective . The only thing that have to mention is the lamp in the middle of the bonnet that has not to be covered from the soundproofing material and the using of a special glue because of the high temperature not only from the engine but from the sunshine too. That material makes the sound of the bonnet and boot shutting very dull and reminds me more younger cars. The reason that cover not only the bonnet but the boot too with that material is first the noise that comes from the back part of the exhaust , and second the covering of the inner surface of it that didn’t like it too much. That material is thick enough that when the bonnet is closed ,touches in some places the engine but I didn’t care about a probability of fire because that material is not only soundproofing but fireproofing too.

  5. I glued the same type of material with the cellular surface on the inner part of the gearbox tunnel to eliminate the noise from that. That job was too difficult not only because the car was standing on an elevator but because there is not a lot of space between the gearbox and the car body so it took time to do that but the result was too effective.

  6. I glued to the back surface of the back seat a thin leaf of the material of the third type to avoid noises from the back part of the car .There are two points of that seat that the seat connected with the car body so the leaf had to be thin otherwise that connection is very difficult.

  7. I put out the little baskets that exists beside the driver’s and passenger’s feet with the plastic surface that this is screwed on too , so I had access to the area under the wing where I put a lot of soundproofing material .With the same way I removed the plastic surface that covers the inner back wing (where the seat belt is screwed on) and put soundproofing material in inner area of the back wing .The last place I put that material is under the surface in front of the back windscreen ( where are usually two sound speakers of the tape ) .

  8. The last place that I wanted to put soundproofing material was the roof of the car but as you understand it was too difficult to remove the plastic material of the roof without help from a professional so I ask from an upholsterer to put out that plastic material , to put a thin leaf of the soundproofing material and to replace the roof surface with a new one. But after that I think that the result was not so effective for the cost of that job.

The finally result of all these actions is good enough. When the engine is at the lowest rpms and the windows are closed I cannot hear anything from the engine , only the vibrations of the engine reminds me that the engine is on. But the best result of that soundproofing is at high rpms of the engine because after 3500 rpms the engine noise became smoother and at last you can hear the radio sound at the same time you are passing another car. Of course when the windows are open the sound from the engine coming again but not so strong as before .