Por-15

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vwmoparguy

vwmoparguy

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I pulled the rear end and gas tank out of my car. I want to make the underside of the body look better. Not sure if I should use Por-15 or rubberized undercoating. Any suggestions?
 
POR 15, but you have to put a top coat on it.
Undercoating is just a band-aid that actully holds moisture in.
 
You only have to put a top coat on POR-15 if it's gonna be in direct sunlight, there is no UV protection to it. I'm really hoping the gas tank and rear axle won't be seeing sunlight.

Riddler
 
Thats a great article as I wire brushed my interior and waiting for the time and weather to cooperate and use POR.
 
why would you do that when he even stated POR was the winner?

"Though there are small breaches in the POR, there is not the substantial rust creep where the scribe line has been placed. All samples have been scraped with a finger nail, and here you see the results."
 
POR 15 is good stuff . Used it on a 37 Ply coupe frame. After it cured I took a hammer to it to see if it would chip or scratch ...nothing. It will not take direct sun light there is no uv protection. Use laytex gloves when applying ,you get it on ya you wear it for a long time.
 
Thanks guys. It's for the underside of the body ,not the rear end and gas tank. I just pulled those out for resto and thought I'd do something with the underside of the body.

My car has alot of undercoating on it and I called Por15 today. They said it needs to be applied on bare metal. So, I either need to figure out a way to remove the undercoating or just fresh undercoat over it and por15 from inside the car.
 
Well, when I brushed POR15 on my Signet's underbelly 25 years ago it wasn't bare metal yet it still looks good today. Maybe that rep wasn't there yet.
 
Chassis coat, is the new product design from the person who sold the rights to POR15. Put it over anything. no worries on UV light either. Keeps the finished look. And it sticks to bare and painted metal. spray it on right out of the can using a harborfreight Cheapo gun.
 
vwmoparguy, I've used POR-15 on two different cars and was very happy with results. I use it under the car, in the trunk, on the floor pans, inside the doors, and on suspension components and brackets. I've always brushed it on, it flows out well and it looks great.

Here's how I prep the underside of the car before brushing on POR-15:

1. Get the car up on jack stands as high as you safely can outside on driveway or in your garage.

2. Clean off all dirt, mud and grease. I apply a heavy duty cleaner, (Green or Purple cleaner). BE SAFE and protect your skin and eyes!

3. Hose off under side of car, use a pressure washer if you have one. Let the car air dry. Inspect your cleaning job and make sure you got all the dirt and grease. Repeat as necessary.

4. Remove lose undercoating with a scrapper. Hopefully, it only has original undercoat. It someone undercoated (spray can) over rust you need to remove that stuff because it doesn't stop rust! Don't forget to do inside the rear wheel wells. DO NOT remove factory undercoat unless there is rust under it.

5. Remove loose rust with wire brush or wire wheel on a grinder or drill. Again BE SAFE and protect your skin and eyes.

6. Use metal ready on smooth surfaces, follow directions. Let it dry good before moving on to next step.

7. Brush on POR-15, again follow directions on product. Protect your eyes and skin, if you get it on your skin it will not come off with soap and water.

8. In areas where you have good factory undercoat I topcoat with POR-15. In the wheel wells I only paint areas that I removed factory undercoat, then when POR-15 is "tacky" I spray a light coating of "undercoat in a can" inside wheel wells to give it the factory look.

Have fun...this is a very messy job. Do this over a weekend if you can. Pick a time when the weather is sunny and warm because you will get wet.
 
I wouldn't even mess with POR 15 for it, especially where you live. The only rust you have to worry about is from leaky windows.

Maybe just clean and paint the undercoating?
 
Because of the amount of labor, time and money involved, I would top coat it simply because I would not want to do it twice. I've used POR15 before myself with good results. Although I think Rust Encapsulator from Eastwood is a little easier to work with.
 
StrokerScamp said:
Because of the amount of labor, time and money involved, I would top coat it simply because I would not want to do it twice. I've used POR15 before myself with good results. Although I think Rust Encapsulator from Eastwood is a little easier to work with.
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I agree. I have used both and thought the Eastwood product was better. Less streaking and brush marks. Plan on doing the entire job because neither of them store well in the can. My car was rust free and I don't really like the idea of painting over rust, I just used mine on the underbody and then finished with chassis black.
 
I did the underbelly of my Cuda in 05 and didn't use a top coat and it still looks great everywhere except a few spots in the front wheel well openings that some sunlight got too. Should have top coated them but I didn't think sun would get in but it did. Nice thing about POR-15 is it's tough as nails. There are a couple of real nasty rock chips where the front tires threw rocks up into the bottom of the fenders. It chipped the exterior paint but the POR-15 isn't chipped. I used foam brushes and you can't see any brush streaks.
 
Thanks guys. Lots of options. I do live in So Cal and it is an original So Cal car. It has only one tiny rust out spot I've found so far. And that's in the lower 1/4 panel. My idea is to make the underside clean and somewhat detailed. I only want to do it once.

I won't be able to work on it for 2 weeks but will get the car as high as possible and take a real good look armed with the options you guys gave me.

I get my rear end back from powder coating today. I guess I should a new post in the resto section.
 
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