When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Has anyone successfully installed the underbody transmission tunnel insulation (see pic) in a 4sp manual without removing the transmission? How about the collar piece? A lot of mixed opinions on this with one theory that manuals are possible autos are not. Would be awesome to hear from someone who has actually done it!
Alternately, can you achieve similar heat reduction by applying a layer of insulation internally?
Hello,
This question is asked frequently.
I don't think it can be done without cutting the shield into pieces.
Yes it can be insulated on the interior side of the tunnel.
Regards.....
Even if you insulate from the inside remember to still put the foam collar in place atop the bell housing right behind the engine
I agree with Alan71. The factory-style insulation is pretty rigid; trying to slide it into place won't work because of the shifter, the positive battery cable with its attachments, and the insulation clips riveted to the tunnel. Even cutting it in pieces, you're going to run into these same issues.
If you don't mind going to a more flexible material I'd think you'd have an easier time working it over the transmission and attaching it by some other way than the factory clips.
Hello,
Here's a photo from St.Louis.
I think it's telling that the transmission shield is in place in the tunnel and the foam collar is in place on the bell-housing.
This may indicate there was no ability to move the shield once the body in place on the chassis.
Regards....
Hello,
This question is asked frequently.
I don't think it can be done without cutting the shield into pieces.
Yes it can be insulated on the interior side of the tunnel.
Regards.....
Even if you insulate from the inside remember to still put the foam collar in place atop the bell housing right behind the engine
Thanks Alan, I appreciate the info. Wanted to check before ordering this. I did see a lot of posts on this topic on this and other forums but opinions seemed mixed, so hence my hope for clarification. I think I'll try using a flexible material on the inside first.
I agree with Alan71. The factory-style insulation is pretty rigid; trying to slide it into place won't work because of the shifter, the positive battery cable with its attachments, and the insulation clips riveted to the tunnel. Even cutting it in pieces, you're going to run into these same issues.
If you don't mind going to a more flexible material I'd think you'd have an easier time working it over the transmission and attaching it by some other way than the factory clips.
The collar that goes on the bell housing is easy. The silver insulation I replaced when the engine/trans was out so I couldn't tell you if it possible to do with them in place. I have a 4 speed.
I purchased the oem style tunnel insulation for my 73.
I have swapped from an automatic to a TKO600 manual transmission.
I was able to easily remove the original insulation piece without too much hassle with the TKO600 installed.
There is a lot of room between the transmission and the tunnel so I hope it will install easily or without too many four letter words.
I’m getting close to installing my new battery cable and then installing the new reproduction insulation piece.
I’m just waiting for the battery cable lugs to arrive.
If you aren’t in a big hurry to get it installed, you can wait to see if I get mine in without having to cut it up or not.
I’ll probably remark in my build thread or the what did you do to your C3 today thread.
I purchased the oem style tunnel insulation for my 73.
I have swapped from an automatic to a TKO600 manual transmission.
I was able to easily remove the original insulation piece without too much hassle with the TKO600 installed.
There is a lot of room between the transmission and the tunnel so I hope it will install easily or without too many four letter words.
I’m getting close to installing my new battery cable and then installing the new reproduction insulation piece.
I’m just waiting for the battery cable lugs to arrive.
If you aren’t in a big hurry to get it installed, you can wait to see if I get mine in without having to cut it up or not.
I’ll probably remark in my build thread or the what did you do to your C3 today thread.
Yes, I'll definitely wait and see you yours turns out! I'm not familiar with the size comparison between your Tremec and my original Muncie M20 but if they are similar in size perhaps my experience will be the same as yours. A few years back I put in four post hoist which does make underside work so much easier. Thank you for the response.
Maybe not for you but on my 71 C3 with a LS/4L60E swap I used on the under side of the tunnel over the trans a product from DEI. It's two side waffle type SS/Alum? material that has fiberglass insulation in between. Had to cut pieces to fit the tunnel.
I cleaned the bottom of the of the tunnel really well and used high temp spray adhesive. Worked well.
Inside the car I started with Dyna Mat like generic sticky material from the firewall to the rear bulk head. Then over that again from DEI two sided foil insulation with fiberglass insulation. Then new carpet. Zero heat in the cabin.
Maybe not for you but on my 71 C3 with a LS/4L60E swap I used on the under side of the tunnel over the trans a product from DEI. It's two side waffle type SS/Alum? material that has fiberglass insulation in between. Had to cut pieces to fit the tunnel.
I cleaned the bottom of the of the tunnel really well and used high temp spray adhesive. Worked well.
Inside the car I started with Dyna Mat like generic sticky material from the firewall to the rear bulk head. Then over that again from DEI two sided foil insulation with fiberglass insulation. Then new carpet. Zero heat in the cabin.
I'm in the process of applying Dynamat now. The kits I have (Front Floor, Trunk, Door) cover the sides of the tunnel but don't include pieces for the top of the tunnel, so looking for something to install under the consoles. As you mention, DEI looks good, I'm also looking at Flatline Barriers as I can buy it in sheets and cut as needed.
A little off subject, but what type and brand spray adhesive are you guys using on the Dyna Mat to keep it in place?
Will you use the same thing to adhere the carpet to the Dyna Mat?
I haven't used Dyna Mat but I use Dyna Mat "like" insulation. I buy it in bulk from Summit and cut it to fit.
The mat has a peel off sheet on one side that exposes a really sticky material. Make sure you have it in place as stick it against the floor. You can buy a roller to smooth it out.
For adhesive to stick the carpet to the mat I use 3M high strength spray bomb.
A little off subject, but what type and brand spray adhesive are you guys using on the Dyna Mat to keep it in place?
Will you use the same thing to adhere the carpet to the Dyna Mat?
The Dynamat branded product is self adhesive. Its very sticky but you do need to prep the floor which means removing most of the old adhesives. Took me several days with a wire brush on my grinder to get back to a good surface. For sticking the carpet pad to the Dynamat I use 3M Headliner & Fabric Adhesive 38808 ($18) or 3M General Trim Adhesive 08088 ($34). Same again for sticking the carpet to the pad.
I personally believe that the most important piece of insulation is the U-shaped piece that keeps the air from flowing back over the bell housing. That one can stop the flow of hot air pretty effectively.
Fortunately you can replace this one without removing the transmission.
Transmission tunnel insulation
