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Posted by: Dion Jun 14 2022, 03:41 PM

What do you guys think about cavity wax in the area where the hardened foam/urethane was?


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Posted by: mepstein Jun 14 2022, 04:04 PM

What’s there now?

Posted by: Dion Jun 14 2022, 04:37 PM

Nothing. Well, primer and chassis black paint. I bought it, but now I’m wondering about the heat in that area, not sure if this stuffs melting point vs say regular undercoating. It actually seems like my six is cooler than the 4 banger as far as heat generation. I don’t know . Just a casual observation.
Anyway opinions? Just put it on and see what drips :-) All suggestions welcome!

Posted by: bkrantz Jun 14 2022, 08:06 PM

After I fought to remove all the stock foam, I did rust treatment, and then paint. To keep crud out I installed the 914 Rubber fender liners.

Posted by: Luke M Jun 15 2022, 03:45 PM

On my brothers 6 conv. we dug out the foam too. Had chassis blasted then epoxy primed the whole car. In the rear fender area where the foam was removed I sprayed extra epoxy. Then sprayed bedliner product, primer, then paint. We shall see how it holds up. It has to be better then the foam. Just wash that area out a few times a year and should be good.

Posted by: worn Jun 15 2022, 04:57 PM

I think it would be no more a heat affected product than the original foam. Thanks, because I just removed the foam from my project and sprayed epoxy as well as I could. You set me to thinking. Now I think I will pack those regions with cloth and the wax so that at intervals I can pull the cloth out. Maybe fiberglass for those worried about heat.

Posted by: Root_Werks Jun 17 2022, 11:21 AM

I thought about using this on a few areas:

https://www.amazon.com/3M-Cavity-Wax-Plus-Fluid_Ounces/dp/B0741FHDPF/ref=asc_df_B0741FHDPF/?tag=hyprod-20&linkCode=df0&hvadid=366281352360&hvpos=&hvnetw=g&hvrand=8432892028476750255&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9033375&hvtargid=pla-818885330321&psc=1&tag=&ref=&adgrpid=83058288424&hvpone=&hvptwo=&hvadid=366281352360&hvpos=&hvnetw=g&hvrand=8432892028476750255&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9033375&hvtargid=pla-818885330321

I like it can be sprayed into areas.

Posted by: friethmiller Jun 17 2022, 11:36 AM

Like what could go wrong with foam and sealant? I think anything other then what the factory did, would probably work out fine. This was one area where I felt like a plastic surgeon but with a welder.

Posted by: bbrock Jun 21 2022, 05:47 PM

I'm a huge fan of 3M Cavity Wax Plus and use it in all internal cavities on top of epoxy and Eastwood Internal Frame coating. I don't know how well it will work in those rear quarters but I see no harm in adding it after any other protection you apply. Mine are epoxy primered and topped with bed liner. I don't remember whether I shot cavity wax in there but pretty sure I did. What would be the down side?

I'm actually not as critical about the factory foam as most. Sure, it fails, traps moisture, and promotes rust after 30-50 years but how long would those areas last without the treatment? Without knowing that, I can't judge whether the factory treatment was good or bad.