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I have searched the archives but couldn’t find an answer to my question. I am in the process of restoring the interior of my 68 convertible and I am at the point where I will be installing Dynamat. I have seen pictures of previous Dynamat/sound and heat insulation installations by Forum members but had a question regarding the installation of the seats and the seatbelt bracket underneath the seats.
Are the seat rails installed over the Dynamat or do people cut the Dynamat out and then mount the seat rails to the floor? Same question for the seatbelt bracket underneath the seat. Do people mount the seatbelt bracket on top of the Dynamat or do they cut out the Dynamat and mount the bracket directly to the floor without the Dynamat in between?
I know the rear of the seat rails are mounted over the carpet but I also have a concern that mounting the seats on top of the Dynamat will raise the seat height a little bit. And with new seat foam, etc., I don’t want the seats to be too high.
I didn't trim mine. I believe the Dyna Mat is only about 3/16" thick some it doesn't add much. I did the whole interior floor pan and behind the seats with Dyna Mat.
I didn't trim mine. I believe the Dyna Mat is only about 3/16" thick some it doesn't add much. I did the whole interior floor pan and behind the seats with Dyna Mat.
You don't need to trim it, just get a couple of those thin pointy probe thingies from harbor freight, you'll need them. I used a rubber mallet to insure a good contact of the adhesive side to the fiberglass. Oh, and don't ware clothes that you don't want to throw away. If you haven't already bought the material, check out Amazon second chance, I needed a third box and got it for half the regular price.
You don't need to trim it, just get a couple of those thin pointy probe thingies from harbor freight, you'll need them. I used a rubber mallet to insure a good contact of the adhesive side to the fiberglass. Oh, and don't ware clothes that you don't want to throw away. If you haven't already bought the material, check out Amazon second chance, I needed a third box and got it for half the regular price.
My car was painted that exact same color when I bought it... (where the paint hadnt bubbled and peeled off anyway) I like it... British racing green I think.
So dprinter1, you’re saying to use an awl or some other pointy tool to open up the holes in the floor pan where things bolt onto the floor and just mount everything over the Dynamat?
When I did mine, I thought about the same thing. I am 6'5" and can't loose ANY room. I did not trim it in the end, The Dynamat compresses with the tightening of the bolts as mentioned, not worth trimming. BTW, it made a HUGE difference in the hot house torture chamber that was the passenger foot well according to my wife.
Dynamat is a great sound deadener, but has a very low r-value. Dynaliner or reflectix are much better at keeping the heat out. Dynamat carries a weight penalty as well. It deadens sound by inhibiting the vibration of flat panels, so you don’t need to use it in a continuous layer over everything. Heat insulation is best achieved by a material with lots of internal deadened air space; think down blanket or fiber matting. Dynaliner is made to go over Dynamat for the best of both sound and heat insulation. The better heat insulators need to go around the seat attachments to not weaken them.
So dprinter1, you’re saying to use an awl or some other pointy tool to open up the holes in the floor pan where things bolt onto the floor and just mount everything over the Dynamat?
Yeah....it came handy, especially when I forgot that I had covered over stuff. As I went along, I did my best to use a utility knife and cut an X across the holes, then cut the remaining pieces off, but I did forget to cut some of them out.
Instead of hunting around for the bolt holes with a awl to find bolt holes just screw in the bolts as needed and then find the lumps once you lay down the Dyna Mat. Also on my C3 I added DEI insulation to the under side of the floor pan above the headers.
Thanks everyone. Excellent suggestions. I planned on using Dynaliner over the Dynamat on the floorboards, so that should help with the heat. I’ll begin the installation this weekend. Hopefully it doesn’t take too long. We’ll see. Doing it right is more important than speed at this point. No need to rush it.
Dynamat is a great sound deadener, but has a very low r-value. Dynaliner or reflectix are much better at keeping the heat out. Dynamat carries a weight penalty as well. It deadens sound by inhibiting the vibration of flat panels, so you don’t need to use it in a continuous layer over everything. Heat insulation is best achieved by a material with lots of internal deadened air space; think down blanket or fiber matting. Dynaliner is made to go over Dynamat for the best of both sound and heat insulation. The better heat insulators need to go around the seat attachments to not weaken them.
Exactly. I see people using a ton of Dynamat to keep heat out and that is not what it's meant for. Dynaliner for thermal insulation / blocking. Dynamat is for sound/vibration and adds weight.
Dynamat is a great sound deadener, but has a very low r-value. Dynaliner or reflectix are much better at keeping the heat out. Dynamat carries a weight penalty as well. It deadens sound by inhibiting the vibration of flat panels, so you don’t need to use it in a continuous layer over everything. Heat insulation is best achieved by a material with lots of internal deadened air space; think down blanket or fiber matting. Dynaliner is made to go over Dynamat for the best of both sound and heat insulation. The better heat insulators need to go around the seat attachments to not weaken them.
Sorry, I use Dynamat interchangeably like every soda is a Coke and every tissue a Kleenex. I need to be more careful with that. THANKS!
I trimmed mine. I've read (on this Forum) that even Dynamat doesn't expect you to do 100% coverage. The butyl rubber stuff (Dynamat, Hushmat, and others), dampen vibrations, and don't need to cover every inch with heavy goop. Certainly not where you are bolting down a seat.
I have about 80% Hushmat coverage in my 79, and 40% in my 80, and then 90% Reflectrix on top of both. In my 80 in particular, I can't hear any road noise over the sidepipes.
I used the generic stuff from ebay myself and did the whole interior minus the where the compartments are in the back... still have a bunch left over too. mine is foil faced too not sprayed black... not sure how much effect that realistically has on heat rejection but..
It's amazing how much difference a few 16ths makes when you're trying to get holes to line up. Cut around the holes. It'll be fine. Even Dynamat says so. They say "minimum 30% coverage".
06-06-2022, 03:18 PM
Installing seats and seatbelts with Dynamat
