Sound proof on the cheap.

[Kalstar]

An affordable alternative to Lizardskinz and such. I have some on the way....@ $50.00 per gallon it is by far the least expensive I have found. Its called Liqui-damp. I will report back after I install. Has anyone else thought about just liquid and no mat? I figure no matter what, the engine will be screaming behind you, I just want to get rid of the tin/aluminum sounds.

Thoughts?

[riptide motorsport]

I'll be intersted in the feedback

[kabacj]

Hey Jim, I am using just lizard skin and no mat. The lizard skin is fire rated and definitely damps all the ring out of the aluminum panels. Its also reasonably light weight. it even gives a nice thud to the doors when applied to the fiberglass. After a coat of paint its reasonably sturdy too. All my panels save the exterior of the bottom of the car are covered with the stuff.

John

[timmy318]

Hey Jim, I am using just lizard skin and no mat. The lizard skin is fire rated and definitely damps all the ring out of the aluminum panels. Its also reasonably light weight. it even gives a nice thud to the doors when applied to the fiberglass. After a coat of paint its reasonably sturdy too. All my panels save the exterior of the bottom of the car are covered with the stuff.

John

My dad and I just finished our '33 but had it plastered with Dynamat..... Hadn't heard of this stuff yet until we had the car all finished. Looked at it and the way it sounds is that the people who use it are very pleased with the result. I want to use it on my 818 that I'm going to build(sorry, not meaning to hijack your thread or anything). John, what is the process ect.... for applying this and do you need any special tools?

[edwardb]

Lizard Skin is normally sprayed. That's what I have in my Mk3 Roadster. I'm very happy with it, and was planning to do the same with my Mk4 build. But interested to see the Liqui-Damp product can be brushed. Plus appears to be about half the price. Interesting.

[VD2021]

An affordable alternative to Lizardskinz and such. I have some on the way....@ $50.00 per gallon it is by far the least expensive I have found. Its called Liqui-damp. I will report back after I install. Has anyone else thought about just liquid and no mat? I figure no matter what, the engine will be screaming behind you, I just want to get rid of the tin/aluminum sounds.

Thoughts?

J,
The mats and the liquid versions (unless the liquid has additional additives) serve the same purpose. This is to dampen (control/lower resonance) in the panel it is applied to. Any lowing of the noise floor gained is a result of the panel not resonating and amplifying or passing the noise. This is why you don't have to completely cover a panel to dampen it. Normally a 50% coverage is as effective as covering the entire panel. They are not designed to block or absorb noise. You would have to apply an inch+ to accomplish that.

Mat and liquid dampeners both have their pros and cons and are best used in combination dependant on the installation and preference. Most of the liquid dampeners say their product can be used as an undercoating. This would make it a great candidate for the wheel wells and undercarriage where mat is not.

To really lower the noise floor (as much as is practically possible with an engine/exhaust inches away) the best route is to use a three part approach. First dampen the panel (as you will be doing) with mat/liquid dampener. Second, add a sound absorbing/decoupling layer (closed cell foam or auto insulation mat). Third, add a blocking layer (heavy massed vinyl). This combination is used in luxury and high-end autos to lower the noise floor and quiet the cabin.

My approach is the combo.

[VD2021]

Lizard Skin is normally sprayed. That's what I have in my Mk3 Roadster. I'm very happy with it, and was planning to do the same with my Mk4 build. But interested to see the Liqui-Damp product can be brushed. Plus appears to be about half the price. Interesting.

Most liquid dampeners say their product can be applied with a brush/roller and you should be fine as long as you're working on a horizontal surface. The only draw back is; it's difficult to get the coverage thickness when brushing/rolling onto a vertical surface.

[tirod]

Every pound of sound deadening is still a pound of dead weight, but a die stamped floor panel - even in steel - is deliberately designed to lack resonance. The problem solving method's first step is to define the problem - flat aluminum panels resonate.

The answer is, don't use flat aluminum panels.

What can we do to fix that? Rib them with hand tools. Plenty of tutorials on that exist in the old car street rod forums. The point is, with a grooved routed into a block of good dense wood, you can hand hammer a rib into the sheet. It might distort the overall shape slightly, further hammering will actually stretch the aluminum back to shape. Aluminum is actually a bit too malleable anyway, go slow.

Take a stroll at the pick and pull yard, look long and hard at floorboards in cars with no carpeting. After a while you will see the way the engineers worked creases and ribs into the panel shapes, giving them a lot of 3D shape. Nothing out of the factory is dead flat, ever. It always has curvature to resist oil drumming.

Whether you make the tools your self, buy them from HF, or invest in a Pullmax, you can get the flatness out of the panels, and that is the #1 thing to do first. Then add sound deadening as needed - also conveniently available from the same salvage yard, or your donor.

Ok, take another look look at the daily driver. If the headliner fell down, even better. That is very much an example of what "Detroit" did to kill sound waves bouncing around the interior - covered it up with napped material over open cell foam glued to a porous fiber shell. And the other side? Woven carpeting - which actually doesn't do that good a job, that's partly why the sound deadener is under it, not the roof. Picking the correct materials to absorb sound is once again easy enough - look at what the factories do. Large, hard glossy surfaces aren't the norm.

The Cherokee guys know this, especially the ones who strip their interiors and then rhino line them. Cabin noise increases exponentially once the headliner and floor treatment is removed. The seats and door facing don't do much, it's all about being trapped between two large sheet metal panels with sound bouncing back and forth. The rat rodders on the street who haven't finished their interiors use the aluminum bubble wrap glued into place, and that seems to be much better than nothing in a lot of ways.

All sorts of ways to work it, but the primary thing is deal with the cause - flat metal panels. It's part and parcel of a kit, but it's anathema in the factory designs. There's a reason for that.

[crash]

Absolutely agree tirod. I don't really understand the desire to put all this dead weight into a GTM, but then I also don't really understand spending multiple tens of thousands on bodywork and paint. That isn't what this kit is about IMHO. There is certainly nothing wrong with coating things, but is it really needed? It isn't for me, but maybe that's just me.

As you have pointed out, whenever I am trying to address a problem I benchmark it by looking at what OEMs do. In almost all cases, the OEMs have addressed the problems already, and by looking at various OEMs and how they solved the problems, you can get a feel for different ways of doing things. Great advice on your part. :)

[VD2021]

Exactly. The vehicle manufactures have addressed this. You will also see the exact three part method in place when you take a look at an OEM. The floor will not be flat, but you will find strips/ squares of dampening material applied. Next will be the carpets insulation followed by a mass loaded layer (normally between the carpet and the insulation). The methods vary when dealing with the roof.

No need to re-engineer here. There are proven methods for lowering the noise floor and quieting the cabin.

But it begins to get expensive J, and your title says "on the cheap".

[edwardb]

As you have pointed out, whenever I am trying to address a problem I benchmark it by looking at what OEMs do. In almost all cases, the OEMs have addressed the problems already, and by looking at various OEMs and how they solved the problems, you can get a feel for different ways of doing things. Great advice on your part. :)

True to a point. But don't forget, every single detail in an OEM is signed off by design, engineering, marketing, accounting and manufacturing (among others). Yea, they want it to be the sleekest, best, hottest thing in the marketplace so it sells. But it also has to meet cost and manufacturing objectives (volume, efficiency, labor, etc). Sometimes the trade-offs they make cause you to just shake your head... Fortunately, for us hobby types, we don't have to jump through the same hoops, and we have a little more freedom. So I wouldn't always assume that what an OEM does is benchmark. Like nearly everything in life, balance is the key.

[Kalstar]

I would be willing to trade off 13.71 lbs./gallon for not having the car sound like a "road noisy" amplifier. If the build is a track or light street use car adding the extra weight would be silly, but shy of bending the panels as suggested (which does nothing for heat) for me I would say this is a good use of 13lbs. Gald to know others have been satisfied with just using the liquid stuff.

V What do you think the 3 method approach would weigh?

K. How does it hold up. Is it like undercoat spray or more like bedliner?

T. How much did you use in the 33? Wondering if one gallon will do it?

There is a youtube video that shows it painted on a vertical surface. Seemed to hold fine. Hopefully this is a product is easy to use while give the desired results "on the cheap".

[VD2021]

I would be willing to trade off 13.71 lbs./gallon for not having the car sound like a "road noisy" amplifier. If the build is a track or light street use car adding the extra weight would be silly, but shy of bending the panels as suggested (which does nothing for heat) for me I would say this is a good use of 13lbs. Gald to know others have been satisfied with just using the liquid stuff.

V What do you think the 3 method approach would weigh?

K. How does it hold up. Is it like undercoat spray or more like bedliner?

T. How much did you use in the 33? Wondering if one gallon will do it?

There is a youtube video that shows it painted on a vertical surface. Seemed to hold fine. Hopefully this is a product is easy to use while give the desired results "on the cheap".

Depending on the thickness the mass loaded vinyl will be ~the weight of an equal thickness dampener (mat or liquid). The foam is oz.s and may add ~3-5 lbs to the vehicle where auto insulation (depending on the thickness and make-up) will be slightly heavier than the foam.

IMO it's a no-brainer for a street car. If you can get the cockpit SPL down to 70db it will be long drive/trip tolerable. If it's 85db+ you will need hearing protection for any extended periods, unless your hearing is already degraded or you don't care.