Floor tar repair/ restoration Options

[TonyA]

What does everyone use to repair floor tar sound deadening material. I have some popping up very little rust the cause of course. I am removing a small amount to good sound completely rust free areas and want to restore that to like new appearance. Any suggestions?

[mepstein]

I don’t know how to repair it. If you want to go all new, AA sells a pre cut kit. If you are getting the car painted, I would remove it all, paint and then apply new and then paint the tar. The tar was known to crack and trap moisture so if you are laying it down again, I would want a full coating of modern paint under the tar or at least a good epoxy primer.

If it doesn’t have to be original, a modern product would be my choice, instead of the tar.

[rjames]

A modern replacement would be a lot lighter, too. (IMG:style_emoticons/default/smile.gif)

[Superhawk996]

A modern replacement would be a lot lighter, too. (IMG:style_emoticons/default/smile.gif)

Modern constrained layer damping (i.e. Dynamat) is lighter and way more effective than OEM tar.

[930cabman]

A few pics would help

[JeffBowlsby]

School me on this please. Anyone have any actaul technical data indicating comparative acoustical performance of the original to new membranes? Not anecdotal diatribes.

I really dislike the look of the newer sticky membranes (with all the logos!) and they are so thin, its hard to beleive they do much. The original asphalt based mat at least has some thickness and mass to it. The original mat can be removed easily enough (with dry ice and scraping), I cannot imagine how the sticky membranes could be removed without a torch creating serious fumes and possible metal warpage

[rjames]

School me on this please. Anyone have any actaul technical data indicating comparative acoustical performance of the original to new membranes? Not anecdotal diatribes.

I really dislike the look of the newer sticky membranes (with all the logoso!) and they are so thin, its hard to beleive they do much. The original asphalt based mat at least has some thickness and mass to it. The original mat can be removed easily enough (with dry ice and scraping), I cannot imagine how the sticky membranes could be removed without a torch creating serious fumes and possible metal warpage

I don’t have technical data to offer, but you only need to heat up the tar enough to allow it to be scraped off. Burning it isn’t necessary, so fumes aren’t really an issue (st least that I recall when I removed the tar in my car). Definitely didn’t get things hot enough to warp the panels.

[Superhawk996]

School me on this please. Anyone have any actaul technical data indicating comparative acoustical performance of the original to new membranes? Not anecdotal diatribes.

I really dislike the look of the newer sticky membranes (with all the logoso!) and they are so thin, its hard to beleive they do much. The original asphalt based mat at least has some thickness and mass to it. The original mat can be removed easily enough (with dry ice and scraping), I cannot imagine how the sticky membranes could be removed without a torch creating serious fumes and possible metal warpage

I’ve posted on this in the past so not going to do the whole thing here. Many books have been written on the subject of automotive NVH. Can’t do it justice in a short post.


What I can share is my experience having worked in that world for many years.

The OEM asphalt is the oldest and least effective solution. Liquid Applied Sound Damping (LASD) has largely replaced Bitumen sheeting. It is lighter, and more effective.


Constrained layer damping (CLD) like Dynamat is generally more effective than LASD but is costly. In OEM use it is more selectively targeted due to cost. Dynamat has sound reduction data on their website (unlike others). Unfortunately I’m not quickly finding a chart comparison of LASD VS CLD.

If you don’t believe CLD damping is very effective you are mistaken.

Here is a quick video. Notice how little butyl was applied and how big the difference is.

https://www.youtube.com/watch?v=fK2GAce4vCw


Data on Dynamat - hard to find comparable data for the Amazon competitors


All OEMs have entire departments that are focused on NVH and reducing noise. The field has progressed immensely since 914s were in production. Better NVH can be obtained with modern materials vs the heavy mass damping that was used in 1969.

[rjames]

I still haven't replace the tar I removed with anything and I don't recall noticing a big difference. One day I'll probably get around to putting something down, but 914s are pretty noisy no matter what.

[dr914@autoatlanta.com]

we sell an exact cut factory duplicate floor pan tar kit designed from original factory pieces we had for years. six pieces, just heat and beat to install


b914556110kt

What does everyone use to repair floor tar sound deadening material. I have some popping up very little rust the cause of course. I am removing a small amount to good sound completely rust free areas and want to restore that to like new appearance. Any suggestions?

[jettonjoshua]

An exact cut factory kit, but manufactured out of modern materials, would be ideal!

[nathanxnathan]

It's not necessary to have total coverage with modern sound dampening material. I've read Dynomat, it's recommended to cover 25–30%. It's about dampening a resonant panel.

It seems to me that leaving the low spots uncovered and selectively placing strips on the high spots would offer good sound protection, not trap moisture, and afford the ability to dry any spills etc that would gather in low spots.

[mepstein]

My pick - https://lizardskin.com/

[Superhawk996]

My pick - https://lizardskin.com/

Very ineffective vs LASD or CLD

Suspicious that they don’t have any published noise reduction data on their spec sheet.

In reality there is no singular NVH solution. Look at OEM and you’ll see a variety of solutions tailored to the specific problem area

LASD largely used on body structure because it’s effective, cheap, and easily applied with robotics.

Door panels and trunk panels are more likely to get small patches of CLD targeting resonant panels and to improve door closing sound quality.

Then you’ll see a lot of textile sound deadner under carpets, up under the instrument panels etc targeting higher frequency acoustic noise. Same up in the headliner.

914 had a acoustic material on engine side of the rear bulkhead for acoustic absorption and blockage. Then on the inside, there was that heavy asphalt mass damper for the low frequency structural noise. Asphalt mat was then covered by the back pad which then provides another layer of acoustic absorption and blockage. No one product is going to handle the whole frequency spectrum from 10hz structural on up through 1000 hz+ acoustic noise.

[JeffBowlsby]

This is an interesting topic! I found some LASD online, reasonably priced. Spectum by Second Skin and other products. Applied by spray, roller or brush to 40 mils in two coats. Can be laid down at the interior or as undercoating. Thinking to use it as undercoating on the pan and apply the AA mats inside for additional protection and an original look.

Input?

[nivekdodge]

I would imagine the determining factor here is the open engine cover being 12" behind our heads.And the fact that not many have A/C and the ability to close the windows in summer. The high end cars were using two layers of steel with nvh material in between. I put some dynamat on the floor because I had it but I don't expect it to be quiet. for you guys that get together, Is anyone's car quieter than other?

[Superhawk996]

This is an interesting topic! I found some LASD online, reasonably priced. Spectum by Second Skin and other products. Applied by spray, roller or brush to 40 mils in two coats. Can be laid down at the interior or as undercoating. Thinking to use it as undercoating on the pan and apply the AA mats inside for additional protection and an original look.

Input?

Like the Lizzard skin above it won’t be as effective as modern OEM LASD that is usually 2-4mm thick and then it is baked in the paint ovens where it hardens. OEM LASD usually also has some “structure” like ribs or garden rows that add stiffness vs a flat uniform coating. Even the orientation of the ribs has an effect on noise reduction.

Complicated subject where testing with data acquisition and software is used to determine the problem, what’s causing it, and developing a cost efffective solution.

Look for sound reduction data on the products your considering. If there is no data - then consider it skillful marketing.

[Superhawk996]

I would imagine the determining factor here is the open engine cover being 12" behind our heads.And the fact that not many have A/C and the ability to close the windows in summer. The high end cars were using two layers of steel with nvh material in between.

(IMG:style_emoticons/default/agree.gif)

Modern cars also using laminated (and thicker) glass on things like the side windows (usually just tempered glass) to reduce outside noise intrusion.

914 rear glass is thin by modern standard.

There is a ton of NVH treatment in a modern car that most have no appreciation for other than to appreciate that new cars are far quieter than they were back in the 70s.

Modern cars often have the entire suspension mounted to an isolated sub-frame. It’s great for noise reduction but adds transient delay to steering. 914 is much more directly connected to the road precisely because it lacks that sort of isolated subframe. The down side is much more noise transmitted into the cabin.

[bbrock]

I really dislike the look of the newer sticky membranes (with all the logoso!) and they are so thin, its hard to beleive they do much.

Me too. So I painted mine. Honestly, I question how much lighter or thinner constrained butyl mats are than tar, but I don't question their improved performance.

Noico mat before paint. At least it isn't slathered with logos but I still dislike the Mercury spaceman look.

(IMG:http://www.914world.com/bbs2/uploads/post-20845-1540326236_thumb.jpg)

After primer:

(IMG:http://www.914world.com/bbs2/uploads/post-20845-1540326945_thumb.jpg)

After top coat. Sorry for the color distortion. It is silver metallic.

(IMG:http://www.914world.com/bbs2/uploads/post-20845-1542334603_thumb.jpg)

[rick 918-S]

Wished i had known you sell a kit George. I ended up with a nice result but needed to cut and fit the stuff I used. Same as the factory material. If I had to do it again I would just purchase the kit. Infact I think I will purchase one anyway just to have it in stock here. (IMG:style_emoticons/default/idea.gif) The original was lightly oversprayed from the factory in this car. I am doing the same when it comes time for paint. I also dislike the foil advertisement stuff.