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I’m cutting and installing the new interior insulation/sound deadener on the firewall.
The reproduction oem upper firewall insulation pieces are no longer available from any vendors so I’m making my own using Thermo Tech Cool It Mat.
When I disassembled my 73 there wasn’t any oem insulation on the large flat area directly under the wiper tray, but there is evidence of some type factory glue was applied in the area.
My questions are:
Was there insulation/sound deadener installed in this area from the factory?
If not, are you guys applying sound deadener or insulation up under the wiper tray?
The AIM for my 73 shows there was upper insulation pieces applied but it isn’t specific as to what areas were covered.
Thanks,
Greg
Hello Greg,
I believe the rough 'jute mat' was typically applied to the flat faces of the inside of the firewall with the typical interior adhesive.
It was 'die cut' but still often looks like it was torn into pieces when being stuck into place.
Regards....
Just saw a thread further down the page for a birdcage...shows just how much glue was used. c3 roadster birdcage?
Thanks and I’ll probably do the same!
My only real concern was if there would be any clearance issues between the top of the a/c unit and the under side of the wiper tray.
Hello Greg,
I believe the rough 'jute mat' was typically applied to the flat faces of the inside of the firewall with the typical interior adhesive.
It was 'die cut' but still often looks like it was torn into pieces when being stuck into place.
Regards....
Just saw a thread further down the page for a birdcage...shows just how much glue was used. c3 roadster birdcage?
Thanks Alan,
I know the faces get the Jute was attached, but I’m wondering about the area facing downward under the wiper tray.
Nowhere near original but it insulates and sound deadens very well,,,1/4" thick...two layer would turn the cabin into an Igloo. I insulated EVERYTHING....
iNCLUDING the underside of the deck lid...then cover that with headliner material to hide the foil.
Last edited by doorgunner; Jan 26, 2026 at 02:14 PM.
Hello Greg,
Here's a picture of the jute insulation that was on the top of the transmission tunnel.
Die cut but still somewhat torn and ragged.
Regards....
Thanks Alan!
Those shapes look familiar.
For the past three days I’ve been up under the dash with pen paper and a measuring tape making stencils for the firewall insulation.
I should be finished attaching all the pieces today.
Then I can start taping all the seams and edges with aluminum tape.
Sometimes I’ve felt like a pretzel so it’s a good thing I’ve kept in shape.
I’ll post a couple pictures when I’m all done.
Thanks again for all your help.
It may seem strange coming from an originality guy like me, but the material you have chosen for your insulation is superior in that regard to the jute material that Alan and I use for our restorations. In addition, I doubt that the original jute material adds much if any benefit in sound deadening over the foil backed insulation.
If I was doing a non-stock car, I’d just continue to use the product you have already chosen… Seems that would be the better choice.
Greg,
I looked at some photos when I was doing my VA and I have a 1/4" carpet looking padding under the wiper bar area right where the VA main unit sits and I didn't have any issues with the install. You should be fine with the stuff you're using. Hopes this helps.
It may seem strange coming from an originality guy like me, but the material you have chosen for your insulation is superior in that regard to the jute material that Alan and I use for our restorations. In addition, I doubt that the original jute material adds much if any benefit in sound deadening over the foil backed insulation.
If I was doing a non-stock car, I’d just continue to use the product you have already chosen… Seems that would be the better choice.
Regards,
Stan Falenski
Thanks a lot Stan!
I’ve been hoping it would be at the least as good.
I bought all original replacement Jute from Al Knoch and their carpet as separate pieces.
I plan to lay down the Cool It mat, then the Jute with the carpet over the top.
If it becomes too thick, I might just put the carpet directly over the Cool It mat
I’ll let everyone know which way I end up going but I could have a bunch of Jute to give away!
I also purchased this piece of reproduction firewall insulation from Corvette Central.
It came with the separate piece for under the brake/clutch pedals which got cut apart trying to get it fit.
I won't be using this piece and can’t see throwing it away.
If anyone wants or needs it for a 73, just claim it and it’s yours.
It works for non ac cars and has the areas marked for the cut outs for ac cars as well.
Last edited by OldCarBum; Jan 26, 2026 at 03:13 PM.
Greg,
I looked at some photos when I was doing my VA and I have a 1/4" carpet looking padding under the wiper bar area right where the VA main unit sits and I didn't have any issues with the install. You should be fine with the stuff you're using. Hopes this helps.
Thanks for taking the time to do that.
It does help so I won’t worry about getting things to fit properly.
Upper Firewall Insulation Installation Question?
