I put Dynaliner and Dynamat on my floors and firewall. It definitely helps keep the interior cooler. It is hard to say whether any sound deadening is appreciable, particularly because I run 37” mud grappler tires, which are very loud.

 

I also used something like dynaliner (2-3 layers) and then added a layer of sound deadening mat under the carpet in the whole Jeep. Put the headliner in my hardtop and now you can easily talk going down the highway. Made a BIG difference, but was a lot of work gutting everything and fitting it in but well worth the effort.

 

I used the amazon brand "kilmat" and that stuff worked wonders when I lined the floor and sides of my Jeep with it. Much cooler in the summer and considerably less vibration too. I personally wouldn't worry about the firewall mainly because how hard it would be to apply deadening to it. Most vibration and sound comes in from the floor direct from the frame.

 

I used SoundSkins as it is a 3:1 material. You get the foil & rubber butyl like you do with most product but you also get a layer of acoustic foam. The rubber butyl layer reduces vibrations, the foil layer acts as a sound and heat blocker and the acoustic foam layer absorbs sound. It is waterproof and temp resistant. I have been very pleased with the product but considering I have a soft top you can only do so much.

 

thanks for the replies, really going after the FW - its really hard to find a picture of it totally exposed from the inside (lots on just taking the top dash cover off). Might just try and work around where I can with that off and hope that getting >50% will help a bit. Its a little obsessive but addicted to dynaliner!

 

thanks for the replies, really going after the FW - its really hard to find a picture of it totally exposed from the inside (lots on just taking the top dash cover off). Might just try and work around where I can with that off and hope that getting >50% will help a bit. It's a little obsessive but addicted to dynaliner!

If you want something that will really control the heat look into ThermaGuard. It is a applied with a brush/roller/spray gun and a 1/8 thick application, 2 coats, yields an insulation factor of R12. And because you can apply with a brush you can get coverage in those hard to reach places where putting down a peel and stick product won't work.

TG-1 keeps your vehicle cool and comfortable!

 

I did the entire interior and doors with a single layer of deadening and then insulation on top of it. The results were nothing short of astounding. The stereo sounds better, talking on the OEM hands free at any speed is imperceptible to whoever I’m speaking with, the HVAC does a way better job (hot and cold), it feels more solid as a whole. Basically worth every penny and the amount of time it took to remove the entire interior.

As for the firewall, I got up as high as I could without removing the dash. I still get engine noise, but it is infinitely better as a whole. One thing to keep in mind- and I‘d read about this being an issue in years past once you start down the path of sound deadening a vehicle- is that when you quiet down one location, you find another than needs done, and another, and another, and so on until you’ve basically done the entire machine (what I did).

But like I’ve said, it’s as quiet as my wife’s Range Rover at freeway speeds and is WAY more comfortable. This is the first time I’ve undertaken an exercise like this in a car, but I’m a bit mad at myself for not doing it years ago.

I also did a layer of deadening and a layer of insulation in the entire hard top, many of the dash pieces, and even the A Pilar trim when put gauges in there. I did a layer of insulation on the inside of the door cards and the deadening on the doors themselves.

I couldn’t recommend doing it more. I probably have 60+ lbs of deadening in the vehicle now (the insulation weighs nothing), but for the comfort, it is unquestionably worth it.

 

The long version, but there is a point to this...We purchased our YJ about six months ago knowing it would need some TLC. It had a new battery, but the old battery had apparently broken and spilled the acid across the back of the firewall. Fortunately the PO must have caught it and rinsed it down pretty quick. It left a wide patch where the paint was all gone and just some surface rust. I cleaned this up and soaked some towels with canning Vinegar (10%) to remove the rust and then primed.

The battery box and firewall cleaned up like new. I then primed with rust inhibiting paint and got the idea of coating everything with "Flex Seal" (hate to sound like a commercial), including about a third of the firewall. This really made a difference in the sound level inside the Jeep. Unfortunately my wife has requested that I complete the job. I know they don't advertise this as a sound deadener, but it really made a difference.