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Looking for some advice, although I’m 90% sure which way I plan to go.
I’d like to find something heat-resistant to cover the interior trans tunnel before reassembly, so I’m looking for suggestions.
The interior trans tunnel has its jute (spelling?) padding removed. I took it out this week to vacuum loose debris from under the consoles*, and the possible critter/bugs that may have been in there. [*center gauges, shifter housing, and park-brake housing: all removed from car.] The firewall jute is still there - no plans to pull the heater box … yet.
A few prerequisites of this undertaking…
1) Alternative to brand name heat/sound pads
2) Don’t want to roll the dice on some of the online vendors - based on reviews from CorvForum
3) Non-adhesive, because I’d prefer not to deal with removal if/when necessary
4) No more interior removal [carpet and seats still installed, but will replace/recondition some time from now … if I can]
So I’m looking at the DynaMat DynaPad 21100
I can deal with the price, I know they’re a good name, and the Pad is non-adhesive, cut-to-fit, and “replaces carpet padding”.
If you were in my shoes, would you use the 21100?
Or is there another recommendation / product that I haven’t found / considered?
Thanks!
John
[BTW… I've read up on the importance of the underside trans tunnel insulation & seal, along with the lower shifter boot being a source of ‘heat-leakage’. I’ll tackle those as soon as the interior is an insulated a lil more.]
Another thing to consider is some type of of insulation between the exhaust and floor pan.
On my 71 I used a DEI insulation that kind of has a waffle looking metal inner and outside with fiberglass in between. I used high temp spray adhesive to attach.
Yeah, it’s in the works to do the underside, buuuuut…
I'm working on the floor, and hesitant to pull the shifter just yet.
71 Vert, it sounds like you’re talking about the DEI 10517 or 10516 [literally just different sqft. coverage between the two part numbers] …
Foil ‘waffle’ texture one side
Heat blanket on the other side
In their promo material, they wrapped manifolds & turbo pipes with it, so I’m sure it’s designed to do a great job as underside shielding. S’posed to be good to 1400°F, so it sounds like a better option than the DynaPad at 225°F.
I'll appreciate the suggestion and the fact that you’re reinforcing the idea that the DEI insulation is what to use. Buy once; cry once.
Great! Thank you!
Another good review of the DEI insulation.
You’ve both made a strong case for it, so I think that’s the direction I’ll go.
Now, would either of you have considered putting it inside?
I know the underbody trans tunnel shielding is there to reflect the heat before it warms the floor and becomes radiant interior heat, so would it be worth it to install the DEI shielding under the center console?
Last edited by The_JC_L46; Oct 6, 2025 at 02:21 PM.
Just to be clear the DEI under floor insulation that I used had the waffled foil on both sides. With the fiberglass in between.
Just make sure to clean the bottom of the floor plans really well so the glue works.
What ever you use, be sure the product is not thicker than the oem juke or you could have problems re installing the interior panels and consoles.
Keep in mind that the glue or adhesive is there to hold the materials in place so they won’t move around or ball up under the carpet.
As for heat materials for under and over the transmission tunnel, some of the vendors offer precut insulation pieces that work much better than trying to make your own.
When you do replace the underside transmission tunnel insulation, it is the perfect time to replace the positive battery cable as it runs between the underside body and the tunnel insulation.
Do you have results / comments / critiques?
How well does it perform?
I don't have any performance results to report as yet because I'm now in the process of installing new carpet.
As for comments:
Since the DEI material is stiff, I needed to create individual pieces to fit into the different contours of the floor and rear wheel wells. That process required cutting templates out of brown wrapping paper and then transferring the pattern to the DEI material. I also made sure to not cover any of the locations for the seat track bolts and seat belt bolts.
The DEI material that I used has an adhesive backing so I first had to scrap/clean out the old rubbery tar material that had been applied by a PO.
I have a 1968 C3 that came with it's 427 and few options. It is now running a L88 Clone engine with it's high compression and makes a lot of heat out of the radiator, off the engine block as well as the exhaust manifolds.
By going to a set of Ceramic Coated headers the heat in the engine compartment was reduced considerably. Inside my C3 I have never had any issues with HOT feet or a uncomfortably warm interior. Even with the Chambered exhaust system running under the floor. I have never had to insulate the floor because it has not been an issue. Even in the middle of the summer the floor is not hot so I have never insulated it. I have had this Corvette for 34 plus years and never got cooked inside the car yet....
Had heat been an issue then I would have likely bought a roll of the silver bubble insulation material at Home Depot and installed it myself. The material in a roll is not that expensive at Home Depot and it looks and feels the same as other floor insulation material. By using a can of spray Contact Cement it would take a while but the cost of insulating the car would be far less than using the pre-cut square or rectangular pieces.
D.E.I. makes great products and I use several of them on my C3. I use their tube insulation covering to protect the fuel lines on the way to the front of the car and a fire proof sleeve over the fuel lines for the front 10' going back to the fuel tank. D.E.I. products frequently work better than you would expect them to and the quality is never an issue as they are good manufacturers.
If heat were a problem for me in my C3 then I would have likely tried to stop it before getting into the cabin. Reflective Heat shieldsover the mufflers, exhaust pipes and even catalytic converters under the body would potentially reduce the temperatures pretty dramatically. This would make the car cooler to cruise in.
I have no A/C so I depend on the goodness of Mother Nature when going on trips. Having a Convertible with functioning Astro-Ventilation system is a great way to stay cool while cruising around. Without AC my C3 is only driven on nice days where the weather is cooperating and no rain is forecast. I don't like driving convertibles with the top up. I have the hard top for those days and even with a hard top I don't drive it in wet weather or when rain is in the forecast.
Using an electric Heat Gun when installing some of the insulation as it makes it easier to handle when warmed up. Heat also can be useful at removing the old glue they used previously.
The Horse-Shoe collar that goes under the center of the dashboard really keeps the air from flowing back into the car. The insulation blanket is good at keeping the center console from getting too hot. Personally I would not drive my C3 without both protective insulation pieces under the center console.
The DEI material that I used has an adhesive backing so I first had to scrap/clean out the old rubbery tar material that had been applied by a PO.
FYI.
The factory sound deadening material that was sprayed in was nasty stuff.
It took me a long time to remove it all from the interior of my 73.
In some areas it was hard and 1/16” thick.
In other places it was 3/16” thick, tar like and came off in large chunks.
Another great review for DEI products! Thank you.
I already renewed the Astro-Ventilation, so if it works as well as you say [and illustrated by sales literature], I think I’ll be good once the trans tunnel is covered.
…too bad most vendors have the horseshoe on backorder right now.
OldCarBum,
Yeah, cleaning the interior insulation is nasty business. Shop vac, respirator, rolling/peeling the adhesive … not fun, but worth it.
Last edited by The_JC_L46; Oct 8, 2025 at 04:45 PM.
Interior Insulation
