Sound Dampening

One thing most older 240’s have in common is being loud. If you have ever driven a 1981 240 and then hopped in a 1993 240, you’ll notice a huge difference. The 1993 will be a lot quieter. The reason for this is that Volvo added a lot more sound-dampening materials to more modern 240 cars. However, with a bit of work, you can make your older 240 rival a newer one. Just doing the job I did, I noticed a massive reduction in road noise. My 1981 242 is now as quiet as a 1993 245 or a 1997 VW Jetta. (But it still isn’t as quiet as a brand new Volvo. If you want this level of quietness, be prepared to spend some money on premium materials.)A lot of people thought I was crazy when I went to add sound dampening material. Many people remove it in order to shave weight from their cars. This is a good practice for drag and track cars, but not for daily drivers. I like to be able to actually hear the radio and have a conversation with my passengers when I drive. Since I drive my 242 regularly and on the freeway, I decided that sound dampening would be a really good idea.


Many nice sound dampening materials are available. A good site for choosing them is chose to go the cheap route. After consulting the owner of a classic auto-upholstery shop, I followed his recommendations. I bought (at Diamond Home Improvement center) this silver, 2-layer, bubble-wrap type of insulation. This was for limiting thermal gain/loss in the car. I had experienced hot floorboards from my exhaust pipes, and wanted something to combat this. I also bought a piece of this sound-dampening felt from the upholstery shop. It is about 1/2″ thick and grey. Overall, it cost me nearly $100 plus about 8 hours of my time. Here is a materials list and a picture of what I got.

Material Price (USD) Total (USD)
2 rolls of silver insulation 16.99 33.98
roll of felt (1 x 8 yds) 5.00 per yd 40.00
Aluminum foil tape 9.99 roll 9.99
Contact Cement 7.99 ea 7.99
Brush 1.99 ea 1.99
Total 93.95
WARNING: Whenever you work with contact cement, do so in a well ventilated area (preferably outside with a fan in the car and the doors and windows open.) ALWAYS USE A RESPIRATOR TO PROTECT YOUR LUNGS. Contact cement and its vapors are very toxic. Use a NIOSH certified (or equivalent) respirator of this type:


Well, now that you’ve got the materials, it’s time to decide how much you want to do. I decided I didn’t want to go to the trouble of pulling the dashboard out, but you could if you wanted to cut down on engine noise a bit. However, it’s a lot of work. I removed the seats, the center console around the e-brake, and then the floor carpet. After that I removed the original sound dampening. It is about 1/2″ thick with a hard rubber side and a soft foam side. Odds are, it’s in pretty bad shape. I just threw mine away. There is another type of sound dampening (vibration dampening actually) that is glued down in thin, brown squares. I left this in place.I then cleaned the entire floor with an orange cleaner/degreaser and lightly sanded both the metal areas and the vibration dampening material to help the contact cement stick. I then cut out foil pieces to fit the car, using some of the original sound dampening for templates. After I was satisfied with everything I had cut out, I glued it all down. It was a very stick process. At this point, I was pretty tired so I quit for the day.

The next day, I proceeded to cut out and then glue down felt pieces on top of the foil. I recommend not putting felt down underneath the front seats (at least not completely) otherwise you will have a hard time getting the seats back on. Even with full felt though, I didn’t have any trouble getting the back seat back on. The foil and felt on my car extends all the way back to the rear window, underneath the back dash.

The most important spots to add sound dampening is to the rear wheel wells (not shown in photos) and around the shifter boot. I cut a special piece of felt for the shifter boot that just had a “+” cut in it for the shifter to move around. I have not done this on an automatic-transmission, so I don’t know what kind of stuff you would have to deal with in that situation.

I also covered the under-dash felt (black panels by your knees as you sit in the car) with an extra layer of felt as shown below. I did this in order to duplicate the effect of the super-thick under-dash mats that are found on the Volvo diesel’s. I think it helps.

I didn’t, however, put any sound dampening in the doors. I was concerned that the felt might absorb water that runs down the inside of the doors during heavy rains. I think in the future, I might use a type of sound dampening material (Dynamat, etc) that can handle water and do the inside of the doors as well.


Unfortunately, my camera died about half-way through the job, so I only have a few pictures.
Interior removed and insulation glued down:

Under-dash mats covered in felt.