Coating Backside of Fenders & Quarters

[Ferrino]

What combination of coatings is typically used for the backside of front fenders and rear quarters? I'm going to be welding on turbo flares (therefore introducing a welded seam) and am wondering what the best way to protect the insides is. Something like epoxy primer and UPOL Gravitex?

[962porsche]

after we dress the welds on the under sides we then use epoxy primer mixed as a surface spray one or two medium coats .
then let it dry and sand the epoxy with a red pad and with a two part seam sealer like SEM's 40377 we will spread or brush it over the seams getting in any nooks .

then let it dry and chip guard the undersides of the panels . we use the U-pol for the chip guard .

you don't have to seam seal over the epoxy primer but we do as it's the under sides of the QTR's so we want all the protection we can get on the bare metal .

[Ferrino]

Awesome, thanks! Presumably the 3M 08308 2-part seam-sealer would be appropriate too? Reason is I just purchased the 3M 2-part applicator gun for their panel adhesive.

3M Heavy-Bodied Seam-Sealer

[962porsche]

my guess is it would be just fine . I thing the 3M is a non sagging and that's what you would want to use so it does not end up dripping on the floor .

[47silver]

which u-pol product and what color do you use for the undercoating?
the bedliner U-Pol Products 0825 RAPTOR Black
or
U-Pol 722 Gravitex Stone Chip Protector, 1 Liter Bottle, White?
or?
thanks

[962porsche]

we now use the U-pol gravitex white tinted to match the old OE color .
bed liner products do not work very well for chip guard material .
you would think it does but it will not hold up as well as chip guard does .

[47silver]

not sure what my under color was is it yellow or is it to match the color of the car?

[962porsche]

it should be a very light beige color .
by now it will look like yellow as the color faded over time .

[47silver]

any pictures of the color that we can use to tint the white too?

[JohnJL]

How about on the underside of glass or CF fenders? What works to eliminate or minimize crazing later on should rocks get kicked up inside?

[jpnovak]

What is the difference between the UPOL Gravitex 0721 and 0722? Is this just a replacement line product? 0722 is more expensive.

[962porsche]

the difference in the numbers is what color it is .
they have white , black and gray .
they are all the same price no matter what color you buy .

[962porsche]

Originally Posted by JohnJL

How about on the underside of glass or CF fenders? What works to eliminate or minimize crazing later on should rocks get kicked up inside?

it will help a little but nothing is foolproof !

[Ferrino]

962, do you have any tips on how to mimic the texture of the factory chip-guard, using the Gravitex and their "schutz gun"? e.g. psi and distance from surface? Thanks!

[962porsche]

sadly no I do not !
I don't like there gun and the guns like it .
the gun I own for doing chip guarding is totally adjustable having adjustments more like a paint gun does.
being adjustable you can change the way the product will lay down and it's texture .

[Cook&Dunning]

Like 962, this guy Darryl is a guru. I think Darryl is a sometime poster at Pelican, his website is amazing, and his attention to detail is impressive. In his rust repair here he shows how he gets the texture.


DarrylD's Porsche 912 Project Page - Phase 8: Right Longitudinal Channel Repair