To undercoat or paint?

[Kim57]

Curious as to what you guys are doing to the bottom of your cabs.
Are you just painting them or are you using some kind of undercoating?
I've read where the undercoating can actually make corrosion a bigger problem than just painting.
I'm going to use a sound deadening mat on the inside so that's not a concern.
I've already put epoxy primer on it.
Thanks for any reply's.
Kim

[mgchevyparts]

I would not undercoat. I have found cars with undercoating have more rust then those without. When the undercoating seperates from the metal it's a place to trap dirt and water. If you can guaranty the undercoating will never separate then it would be good. Paint looks better also. Amatuer applied undercoating is usually done by those trying to hide problems.

[crossfire84]

I am having mine rhino coated.

[1958Warrior]

I found very very little rust under the under coating I removed from the bottom of my cab. Most of the Stuff was hard as concrete. The rust was actually where their was no under coating, not under the undercoating.

After removing it all, I used rustoleum rusty metal primer and rustoleum gloss black paint. Applied both with brush, and let it dry for a week between primer and paint. (used the same on the frame)
Then used I think it was 8 cans of spray undercoating.

I think it'll be good for another 57 years.

[NEWFISHER]

I always paint mine and then undercoat them.

[LEEVON]

"Undercoating" like the popular dealer add-on in the 70's and 80's is totally different than modern polyurethane/polyurea coatings. I just had all my rust replaced and bedliner sprayed top and bottom of the floor and inside the firewall. Very impressed with how it turned out and I can't see rust being a problem for a long time now.

[_Ogre]

i too did rhino liner under the cab and behind the stock fuel tank
also sprayed it under all my fenders and inner fenders
this was more for rock protection popping up but it also firms up the sheet metal

you can see the line of the bed liner up on the firewall

[oldman3]

Kim, I didn't use any undercoating on mine. I did paint it with POR15, then immediately mist on some primer and let in dry. This makes it possible to paint over POR15. Then I painted the same as rest of cab. 10 yrs and 22,000 miles later still looks good...Jim

[Kabwe]

Epoxy primer for rust protection and then I sprayed raptor liner. I don't see how liner could cause rust used as just a top coat. Also remember with the way we are tearing these trucks apart and redoing them most of us will not be around by them time they rust again. And for us weekend cruiser guys who will baby are trucks I do see how the could rust. These trucks were driven and treated harshly way before we got them and I believe we really over think a lot of this stuff. They did not have the paint technology we have today nor did they baby them back then.

[Kim57]

Thanks for the info guys.
This gives me some things to think about.
I've been looking at the Raptor liner as the kits without the gun seem to be pretty inexpensive and I have access to a gun.
Thanks again.
Kim

[xRAY76]

my truck i just bought about a month ago (60 c-10) has what im guessing is old undercoating under the cab and on the inside of the cab floor... it feels like a solid truck, but im afraid to find out what is between the layers.

i think if i had my cab off, and was at the paint stage. i would probably rhino line the underneath and behind the tank...but thats about it

[Highsider]

I am very happy how the steps are protected on my daily driver.

I had the undersides of the fenders done to protect them from whatever the tires fling up at them.

[BOXER957]

I blast,clean,por-15 and then use the Raptor on anything underneath also inside any parts like inner/outer rockers that get welded together. The Raptor should be enough by itself and the por gets stronger with moisture so between the two I don't forsee my grandchildren having to fix anything. Plus I figure if any water does get into a closed cavity it will be like it's sitting in the bed of a pickup.

[Kim57]

Thanks guys.
I do like the way the Raptor looks on Bam's truck so I'll more than likely go that route.
Kim

[roger55]

Just black SPI epoxy primer on mine.



Same for the underside of the hood and the inner fenders.





I did undercoat the fenders and the wheel side of the inner fenders though. Put on the epoxy primer first then did it.

[_Ogre]

fyi... i did epoxy primer before sending out for rhino liner
i think that is an important step

[OrrieG]

Originally Posted by 1958Warrior

I found very very little rust under the under coating I removed from the bottom of my cab. Most of the Stuff was hard as concrete. The rust was actually where their was no under coating, not under the undercoating.

After removing it all, I used rustoleum rusty metal primer and rustoleum gloss black paint. Applied both with brush, and let it dry for a week between primer and paint. (used the same on the frame)
Then used I think it was 8 cans of spray undercoating.

I think it'll be good for another 57 years.

Me too! Except I use white rustoleum brushed on. Contrast helps to show coverage for the undercoating. White really helps under the dash area during installation and fabbing. I did not undercoat the frame, just under cab, firewall up to the change from diagonal to vertical and inside of fenders. Just make sure any drain holes are not plugged.

[Kim57]

I have it all sprayed with SPI grey epoxy right now.
I know I'm definitely going to under coat the inner fenders for protection from rocks but not sure about the cab bottom yet.
Kim

[Highsider]

A wise man speaketh:

Originally Posted by Kabwe

I don't see how liner could cause rust used as just a top coat. Also remember with the way we are tearing these trucks apart and redoing them most of us will not be around by them time they rust again. And for us weekend cruiser guys who will baby are trucks I do see how the could rust. These trucks were driven and treated harshly way before we got them and I believe we really over think a lot of this stuff. They did not have the paint technology we have today nor did they baby them back then.

[Lokin4AReason]

i would under coat, but that is me ....

[butchp]

Originally Posted by Highsider

I am very happy how the steps are protected on my daily driver.

I had the undersides of the fenders done to protect them from whatever the tires fling up at them.

What is on the step?

[Highsider]

Originally Posted by butchp

What is on the step?

Just bed liner goop.
Probably 1500 short-run miles of wear and tear and it is working super good.