Undercoating Opinion

[Tangerine]

I have a 71 Super with original floorpans and most body panels (only 1 fender has been replaced). I've removed some of the undercoating and the paint/metal under that has been (so far) 99% rust free. Since the undercoating is 46 years old and pretty much dry and cracked. I'm planning on removing all of it (eventually), as I've heard that loose undercoating can collect and hold water, causing rust issues. Should I put new undercoating on or leave it bare? If replace, any suggestions on brands would be appreciated also. Thanks.
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68 Variant FI
71 SB Sedan
73 SB Cabriolet

[Buggeee]

Chris Vallone of buggin youtube fame has a video explaining that he likes to put a light coat of rubberized undercoat just under the fenders. When the fenders were just paint under there he had some rocks occasionally ding the metal from underneath, causing a star patterned cracking of the paint on the top side of the fender. He said the rubber coating stopped that from occurring. He seemed to think the undercoating all over the place, however, would trap water if I remember. So he just does the fenders.
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1966 Sportsmobile Camper https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0
72 Super Duper http://www.thesamba.com/vw/forum/viewtopic.php?t=672387
(adopted out) 61 Turkis Pile https://www.thesamba.com/vw/forum/viewtopic.php?t=728764

[TDCTDI]

The undercoating has preserved your car to this point, I’d say clean the old off & reapply.
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Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[vamram]

Agreed, clean it off well, clean the surface, and re-apply. Well-worth the trouble in my experience.

But yes, water getting in where it's dried out and cracking will become rust at some point.
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Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!!

[volksworld]

i prefer a rocker schutz or bedliner style product thats paintable....the foamy spray can stuff is crap...its primary function is to conceal really bad welding and attempts at rust repair on a vehicle you're trying to sell

[vamram]

I've not had any issues w/the sprayable stuff. Although it's not nearly as durable as the stuff the dealerships slathered on.

I will try the paintable stuff when I go over the pans this summer...
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!!

[MI-Bug]

I like the painted look so am going to try clear "chip guard" under the fenders and wheel wells... once I have all the old undercoating cleaned off.

[Tangerine]

Thanks for your suggestions/thoughts. I was wondering if the spray can stuff was any good. Some better than others?
Also, on same car but different issue, I'm rebuilding the front end with the TopLine kit and have a question about that. I got their Caster-Fix option, but I'm not sure if I should install it. The car is original height/stance. Should the Caster-Fix option be used if I'm not going to lower the car any or change the springs? If I did install it, what would be the result of increased caster? I'm not a suspension person, but I'm assuming a stronger 'centering' function?
Thanks.
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68 Variant FI
71 SB Sedan
73 SB Cabriolet

[vamram]

The caster adjust kit is only for cars that are lowered.
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!!

[bluebus86]

the worse thing is appling new under coat over old failing under coat
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[HippyTom]

I painted the inside of my fenders and wells. No undercoat or bedliner.

[theKbStockpiler]

[modok]

I used Morton epoxy bedliner. It's holding up very well about nine years later.

[73SlowBug]

I used flex seal. Yes, the stuff the crazy guy on the tv sells. It takes about 7 cans to do the whole floor pan and all the fenders. One can doesn't go very far. Its expensive. But it works, and it looks great. My whole interior is done with the stuff too. Its holding up much better than I expected. But my car is by no means anywhere near a show car.

[AlmostHeavenWV_VW]

Why not have an undercoating that actually works to prevent rust?

https://www.eastwood.com/eastwood-rubberized-rust-encapsulator-undercoating-black.html
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1973 Standard Beetle
1600DP AK case
Solex 34PICT3 Carb
Bosch DVDA 205AJ Distributor

[BIGMIKEY]

Anybody figure out how to coat the inside of the heater channel or Napoleon hat? Actually done it? I have used the Internal frame coat inside the tunnel and frame head. Also inside the frame horns. Fluid film would work well too but since it's oil based it could cause grief if you ever needed to do any welding or bodywork/paint in those areas.



Mike T
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BIGMIKEY

Deserter Series 1 project.
https://www.thesamba.com/vw/forum/viewtopic.php?t=787047&highlight=

1973 Beetle Driver, Marina Blue.

[Zundfolge1432]

I wonder what particularly harsh environmental areas would call for, say North Sea oil rigs with constant exposure to salt spray or military and commercial aircraft which see heavy duty cycles 7 days a week. Going from 90 degrees plus temp on the ground to 50 below at altitude in less than half an hour. I bet they ain’t using the shit available at auto zone Walmart or harbor freight.... or some rubberized crap that traps and hides moisture or the stuff Uncle Bob spayed in his truck bed. As Glenda the good witch of the north observed “ “You had the secret dear all along it’s the ruby slippers” now click them together three times and say there’s no place like home...

[dualbay]

Undercoating sprays are not sealers - you would first have to apply your usual sealing coats of paint then from that point adding undercoating is up to you, but in general I don't see the point.

[dualbay]

[Frodge]

I had floor pans installed a couple years ago. There is no undercoating on my pans. I had this discussion with the installer, who had done 100s of pan installations. He said the undercoating traps moisture once it gets a loose spot. He went in to say to check the paint a couple times a year.