1973 Convertible Project: Undercoating Decision Time

[Steve McMahan]

It’s like POR 15, but it includes a variation in language when your hand slips and the wire wheel catches your leg.

 

[midlife]

POR 15 is a "Paint Over Rust" converter which is a bitch to remove once applied. Lots of folks like it; I do not because it can hide a lot of rust and is extremely difficult to remove to see the actual damage.

 

[Steve McMahan]

I’m into denial

 

[Steve McMahan]

Ok, so I’m at that point where I have to decide what treatment I'm going to give the undercarriage. Last week I was 100% certain I wanted to do a bed-liner treatment over the POR-15. Today, I’m hedging my bet. Mostly because of the stories I’ve been reading on-line what other cars guys will interpret I did, or didn’t do, to the restoration of the body pan. I read those before and kinda shrugged them off, but now I’m reconsidering.

Let me make clear how I intend to use this car, and maybe beyond the stupid self-inflicted opinion of my work, will help others give me an informed opinion on what would be the logical treatment to do. This will be my fun to drive car. It will be garaged in Fort Mohave, Az, a very dry climate with very little rain. I don’t see myself driving it in the rain, but it could happen. I also won’t likely wash it a lot; I believe like @Hemikiller that washing is generally unnecessary (I hope I quoted him correctly). I like the look of the bed-liner more than I care for the additional toughness it gives the pan from road objects.

What is your advice?

 

[Sheriff41]

Check out Lizardskin coatings. They apply easily and don't have the rough finish of bed liner and traditional undercoating.

 

[cv_72mustang]

Maybe do nothing. If it's original metal and really no rust

 

[midlife]

In your AZ environment, undercoating is not needed, even if you drive in the rain on occasion. You're unlikely to encounter salted roads, which is where undercoating can pay dividends (in the Northeast/Midwest).

 

[Hemikiller]

I wire wheeled the under side of my 71, just like you, then applied POR15 from the torque boxes back and that was it. I did apply some spray on undercoating in the rear wheel wells. The front clip was painted with primer and then catalyzed satin black enamel. This was in 2003-ish.

FWIW, the POR15 paint that everyone uses is not a rust converter, it's a moisture cured urethane paint. They recommend their MetalReady beforehand, which is a phosphoric acid based rust remover / converter. I've found the MR to be very handy to keep around for lots of general rust removal and prep tasks.

 

[351c1971]

I was more worried about the inside of the frame rails than the floor pans. I wire brushed the floor pans inside and outside and painted them with black enamel. The wheel wells were coated with rubberized undercoating. Finally, the inside of the frame rails and doors was sprayed with Eastwood Rust converter.

 

[Steve McMahan]

Yea, I’m ordering the Eastwood inside frame spay can, with the hose. I used a rod of silver solder with Emory cloth on one end to make a sanding drum to try and clean where it couldn’t reach, using my drill motor with it for extra cleaning. That was an adventure.

 

[351c1971]

IMHO the Eastwood inside frame spay can with the hose is also an adventure. The hose works well...until it clogs. I advise shaking the can well before each use.

 

[351c1971]

Also keep in mind that undercoating is needed to protect the area under the front fender where there is no wheel house from road stone dings.

 

[Steve McMahan]

I’ve got the fenders off to do a thorough job on them. I only want to do this once.

 

[AcesArneson]

Sounds like Por15 would be overkill for your car just like it is for mine. I embarked on my project with less than half the knowledge I needed. Por15 is for projects that have rust involved in the metal already. If you are going down to bare metal I wouldn’t waste the time or energy. If you are worried about rusting inside any frame rails perhaps you might want the Por15 inside them but not on anything you take down to bare metal.

 

[Steve McMahan]

Too late. I’ve got 1/2 of it already in POR-15. I’m sure it’s overkill. It’s like HP. Is there ever enough?

After the inputs, and thinking it over, what I would like to do, over the POR-15, is to finish it with a nice treatment. Not quite a bed liner toughness, but with a textured to the finish, and a satin black color. What does that sound like to you guys?

 

[tony-muscle]

IMHO the Eastwood inside frame spay can with the hose is also an adventure. The hose works well...until it clogs. I advise shaking the can well before each use.

The hose is pretty much a one time use item. I have tried cleaning them to use afterwards but it is hit-or-miss. Just be aware that if the line clogs and the nozzle comes out, it can shoot paint back towards you or other surfaces. It is very liquid so it will drip from every little hole in the frame so make sure you are ready to collect the drip.

 

[AcesArneson]

Too late. I’ve got 1/2 of it already in POR-15. I’m sure it’s overkill. It’s like HP. Is there ever enough?

After the inputs, and thinking it over, what I would like to do, over the POR-15, is to finish it with a nice treatment. Not quite a bed liner toughness, but with a textured to the finish, and a satin black color. What does that sound like to you guys?

If you have the Por15 on already you will need to scratch it up because nothing adheres to it. I made the same mistake when I was priming the bottom of my car. I let the first coat dry 24 hours before putting on a second coat (which is totally unnecessary by the way). I should have read the instructions a bit closer to see that a second coat should go on when the first is tacky. If memory serves the instructions are to sand it with 200 grit if you let the top coat dry. Incidentally, if you like the look of the Por15 primer, they sell a Top Coat Clear that will retain that wet black look. Once I finish wire-wheeling the welds to my shock towers I am going to scuff up the engine bay on mine and touch up the grinding marks with Por15 and spray on the Top Coat Clear. In any event you will need to finish it with something because the black will fade when exposed to sunlight if you don't Top Coat it.

 

[Steve McMahan]

Yea, I knew I had to sand it with 300 beforehand. I just didn’t have the schedule to do it all together. So, the clear coat does the same finish like clear on paint? Anyone apply a texture kind of paint?