Looking for a replacement solution to the original fuel tank pads that retain moisture and rust the tank from the outside in.

Was thinking about some type of rubber padding that may be used similar to the below. Would also like to line the top of the battery tray with it as well.

Any thoughts?

Waxman 2-Pack 4-in Black Rubber Pads (w/ adhesive backing)

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I’m using self adhesive rubber. So much better than the pieces of carpet that was used originally.

There's no way water should be getting on those pads. I just finished a big restoration and just put new felt pads in there.

Got some leftover felt if you need some.....

mouse pads?

It may be that water should never get on those--but it does.

I used some neoprene rubber that I bought at the hardware store. Glued it into place like the stock felt pads. Had to use two layers to get a decent thickness.

--DD

mouse pads (cheap neoprine cut into nicely proportioned squares)

You guys aren't worried about the neoprene wicking moisture through capillary action between the tank and neoprene and trapping it? I think the ideal pad would be non-absorbent, but ventilated like a spun nylon or something like that.

The original felt pads got wet and the tank had pin holes in it. Don't use felt.

I used old wetsuit material (neoprene) when my tank went back in.....

https://www.youtube.com/watch?v=RdNEEzlR4pk

I think I might go for something more like this https://www.mcmaster.com/#polyester-felt/=1e2olep. Or find some spun polyester filter material that will provide the cushion while letting the space breath. While neoprene is non absorbent, I think it would still trap moisture against the tank surface.

https://www.grainger.com/product/E-JAMES-EP...;searchBar=true

lots to choose from

Please don't use the felt again. Over the winter, we started smelling gas in Betty's car. I chased it for over a month, replacing all the fuel lines, new Tangerine fuel line kit, etc. While pulling the tank for the umpteenth time to check the lines and pump underneath, Betty noticed the felt pad was dripping. I was going to blow it off because it was raining outside at the time. She touched the felt pad stuck to the bottom of the tank, and found out it was gas. That explains why we couldn't smell gas until we filled the tank. When we put in under 5 gallons, it didn't leak, and didn't smell.



I had to replace the fuel tank to fix it. I used rubber sheet to pad the tank when reinstalling.

This is why Larmo is so well loved within the 914 community!

So what is the consensus as to which material is more suitable, neoprene or polyester felt and what would be the recommended thickness?

It's pretty clear that felt is out and neoprene wins. Old wet suits are perfect if you can find them. Free often. Mouse pads are dirt cheap, and some may need the fabric ripped away if it could trap moisture or at least put back to back so only the neoprene touches anything. Thickness isn't super critical, think similar to original but with better material.

I know i'm speaking alone here but I have serious doubts that a neoprene pad is solving the problem of moisture being trapped against the tank surface. It is just trapping the moisture it in a different way. If the surface of neoprene or rubber is textured to minimize the contact area with the tank, I think that would be ideal. Another option might be to smear the pads with a sealant just before dropping the tank in to prevent water wicking between the surfaces. It would be easy enough to test a neoprene pad by placing a piece of glass with a little weight on top and then spraying water on the edge so you could see how much wicks under the glass and how long it takes to dry.

I agree completely.

If your felt pad, or whatever pad, is getting wet....you've got bigger issues.
As long as your trunk seals are in good shape, why would you be getting water in and around where the felt pads lie?
That part of your front trunk should be "bone" dry.
If not....

A) My trunk doesn't leak
B) My car is garaged
C) I don't drive my car in the rain
D) It doesn't rain in California anymore, anyway
E) I have plenty on old wetsuits, we live at the beach
F) I don't ever wash my car with water
G) My car is a driver
H) I don't really care

Me three. I’ve never had one of those pads get wet either. Even when driving in the rain at hiway speeds. This is in an air cooled and water cooled with large front cutout. If anything I’d use a Scotchbrite Pad for a replacement. Maybe even cardboard. Any material that will breath.

I guess I'm going with the assumption that it will get wet, but does seem like the pads on a car with good seals should stay dry. It occurred to me though that condensation on a metal tank full of liquid could be an issue and where neoprene would be a big improvement over standard felt since the neoprene would insulate the tank at those spots whereas the felt would just soak it up and hold it. Regardless, I still think the best pad would be a non absorbent cushion that is well ventilated.

This raises a question. Why should that area get wet??? Do you have leaks? Maybe it's more about what absorbs moisture. If you have water getting in there, that's another problem. Seriously, it's about what TRAPS moisture. Which felt does and neoprene does not.

Actually, my car sat outside for over 20 years with rotten trunk seals and when I pulled the tank out, the pads were dry as a bone and no sign of damage on the tank. Curious because everything else on the car had rusted. But as I said before, the one thing might be condensation. A metal tank full of cool liquid sitting in cool humid air would likely condense on the surface and get absorbed by the felt. Other than that, I agree, the pads shouldn't get wet if seals are in good shape.



This is what I am challenging. Yes, felt will absorb water and trap it against the metal. No question. Neoprene will not absorb water inside the material, but if you have a piece of rubber pressed tightly against a smooth metal wall, you likely create a micro-space where water will be drawn in through capillary action. Capillary action is powerful enough to pull water from the ground to the top of a 300 ft. redwood. Once the water is in there, the properties of the neoprene work against you because there is no air present to evaporate the water. It is trapped against the tank to do its damage. The physics say it is at least a good possibility. I think the Scotch Brite pad idea is a really good one. Best of both worlds. Nothing to absorb moisture and plenty of air to evaporate any air that does find its way in before it causes damage.

Wow Brent....that's a lot of science. I think my head just exploded. Nice one.

Here's another perspective. We know the felt just holds moisture. So cleaning things up and using a fresh less-absorbent material will get you through at least the next 30 years or so.

Roger that and agree that neoprene is probably better than the original felt.

Just glue the neoprene to the tank. That way it won't trap moisture between the tank and the neoprene.

I agree with Clay! My tank and well were rusted in way of the felt pads due to condensation, not rain. The ends where the curved rubber spacers were located were perfect suggesting impervious rubber might have an advantage. But solid rubber might squeak unless lubricated or neoprene has less tendency to do this. I used Neoprene wetsuit material as it does not absorb or internally wick moisture. As for the interface micro-wicking minutia, if you glue the neoprene to either face so it is sealed and POR-15 the steel on the tank or the support areas where the felt had been, it should be better than new and good for another 50 years. Good enough for me anyway.

Sorry, no pictures, I'm impatient and usually working too fast to pick up the camera while I'm in the middle of a task. Seems I don't get pictures during, but after when everything is closed up and not visible. Maybe that's why my car is not on jack stands even though it is still a work-in-progress.

Larmo-

NICE tutorial ...Is that your old VW bug in the background?


You're a bad boy

Oscar

I used Scotch pad, which I guess will not wick.

Most of these apply to me as well. I care though. I’d have to guess that between the 25 years the original owner had it on jack stands in a garage and the time I’ve owned it, my car has only occasionally been really wet during its first five years. The original felt pads were fine when I restored the tank so back they went.

My car spent most of its life in the PNW specifically Portland/Seattle and was for the most part rust free.

When the tank was pulled it had enough corrosion to open up some pin holes upon media blasting prior to powder coating.

This is what I was dealing with. Whatever caused it, I have no idea.

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Here is what it looks like after paint.

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Wanted to update this thread with the chosen solution:

Black Foam Padding, Rubber Sheet
Self Adhesive Weather Strip Rubber Cutting Mat Insulation
Closed Cell Foam
12" X 8" X 1/4"
by MAGZO available on Amazon



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I used an old inner tube cut to size, doubled up and glued with Permatex adhesive. no problems with moisture or rubbing.

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what about 3M Nomad mat material

This Stuff:

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10% Ethanol gasoline is hygroscopic (will absorb water) and can absorb 50 times more water than conventional non-alcohol gasoline.

With that being said if you are not using a nitrile lined hose in your fuel system under the tank the the fuel/ethanol weeping through the natural rubber will attract moisture in the fuel tank compartment which will condense at some point or another.

Another issue is condensation on the outer tank itself when the cooler fuel in the tank meets a humid day. I think may actually be the biggest culprit.

As for material to make the pads, I had a section of self adhesive rubber that I cut up and used.

My gas tank compartment has actually been a mouse pad....

I cut pipe insulation down into squares for where the tank rides.

https://www.lowes.com/pd/Frost-King-1-2-in-...ulation/1060001