[r-mm]

Hi all

Im restoring a 73 GTV, front to back. Just completed the front suspension and now have the rear fully disassembled. I'm working towards rolling shell status before giving the car to the body shop. While I have the rear fully disassembled, including dropping the gas tank, I've been cleaning the road grime off the undercarriage to see where there is rust. Luckily things look pretty good rear of the floors.

When I cleaned up the front wheel wells I POR15'd the rust spots and then Wurth Undersealed the entire wheel wells. The process was relatively clean. I'm can't speak to durability, but the Wurth product came widely recommended. One thing that is slightly curious is that about 2 months after spraying it, it still feels gooey and a bit wet. Normal?

Is there any reason to use a different process for the rear wheel wells and undercarriage around the diff/gas tank etc? I would consider having the underside professionally undercoated but it will be a lot more difficult with the rear suspension in place.

EDIT - If the pics aren't obvious, I found bare (primed) metal above and around the diff, and original body color (tan) + red overspray on some sort of rubbery undercoating in the wheelwells.

some pics of what I've found upon cleaning up...

 

[flivesay]

The complete POR process seems to be pretty good. things that come off (like the fuel pump mount in your pic) can be wire brushed, then same process or whatever you want.. Captain Morgans rust remover (cap'n lee's) works pretty well in the POR process sometimes. Soft undercoating--maybe the wurth coating didn't work with POR? maybe it has to chemically bond with something other than POR? i've followed POR with truck bed coating --seems to be holding up well--

 

[Wayne]

Cleaning Method?

I don't have an answer for your question, but I could not help but admire the work you've completed so far.

How did you go about cleaning the underside, if you don't mind a question instead of an answer?

Thanks in advance.

 

[Dickson]

I am a big fan of Eastwood's Rust Encapsulator paint.

You can spray or brush it, and it's very effective.

Unlike POR-15, it's not UV sensitive (no topcoat needed), and needs no tie coat primer to topcoat if desired.

I've used it for years. I use a twisted wire wheel on my grinder to remove scale rust. Wipe down with lacquer thinner to degrease. Allow LT to evaporate, and paint.

As a test I left a rusty wrench that I painted with Eastwood's Rust Encapsulator paint outside for an entire year in New Orleans - which gets lots of rain, is very humid, and hot - and not a speck of rust.

Good luck! Dickson

 

[r-mm]

I don't have an answer for your question, but I could not help but admire the work you've completed so far.

How did you go about cleaning the underside, if you don't mind a question instead of an answer?

Thanks in advance.

Thanks for the compliment. I'm using POR-15's "Marine Clean" which I have to say I really really like. I lay down a drop tarp, squirt some marine clean, brush it with a plastic brush (this is painful without a lift), then squirt it with a water bottle / wipe it down with paper towels.

To be clear, I'm only showing pictures of the parts of the car WITHOUT the factory undercoating. This is just primed metal with overspray. Getting the factory undercoating off is supposed to be a pain. However, I did manage to get it off the INSIDE of the floors pretty cleanly by using dry ice. I wonder if putting dry ice inside the (now bare metal) floors again wouldn't help with the underside.

 

[Dickson]

Dry ice on the topside might help loosen the undercoating underneath...Dunno.

I have no affiliation with Eastwood, but see their undercoating remover:

Eastwood's Under Gone Undercoat ing Remover - Undercar Coatings - Undercar & Drivetrain

I've heard of folks warming up undercoating with a torch, and then scraping off...but this seems like a dangerous proposition, even with a lift.

Unless you have strong suspicions that there is a lot of rust hiding under the undercoating, I'd recommend leaving it alone. Dickson

 

[r-mm]

Unless you have strong suspicions that there is a lot of rust hiding under the undercoating, I'd recommend leaving it alone. Dickson

After a lot of reading, the alfabb consensus seems to be that the factory undercoating, at this age (and even when it was new) is responsible for a lot of the floor rusting probs we all have. I'm going to need to do some patch cutting/welding of the floors, so to some degree removing the undercoating is on the menu regardless.

I'm also wondering: do floors typically rust because of water infiltration from the inside or salt/water from the outside?

 

[red69]

I used a hot air gun and a metal scraper. Messy but effective. Wear a good respirator as the fumes are nasty.

Found corrosion under the undercoating. I would definately remove it all as that is the only way to be sure.

Marc

 

[Dickson]

Good point. A heat gun is a good stripping tool.

Still, cover up. I'd expect hot undercoating will burn you!

 

[gigem75]

I also use the Eastwood rust encapsulator and have had great results with it. It also goes on sale everynow and then too They also make another thicker product more like POR, anti rust or something like that, comes in cans and a spray. I used the spray in the holes for the door jam and shot some up the drain holes to get to the back of the rocker panels after blowing them clean as compressed air would get them.

 

[Dickson]

I think that the anti-rust is a wax compound like Alfa used...Suitable for mostly enclosed spaces, but I think that the paint is probably better.

 

[r-mm]

I also use the Eastwood rust encapsulator and have had great results with it. It also goes on sale everynow and then too They also make another thicker product more like POR, anti rust or something like that, comes in cans and a spray. I used the spray in the holes for the door jam and shot some up the drain holes to get to the back of the rocker panels after blowing them clean as compressed air would get them.

Does the Eastwood rust encapsulator stick well to unrusted metal? From the description it sounds like it does, but I know POR-15 doesn't like smooth metal.

 

[Dickson]

POR is very slick, so it would make sense that it needs some "teeth" for proper adhesion.

The Eastwood paint, in my experience, adheres well to most anything.

 

[frogeye]

In the UK I use/used 2 products - Jenolite to remove the rust and Bondaprimer to prime the metal prior to painting. If you are patient enough you can completely remove the rust with Jenolie - requires quite a few applications. Otherwise it converts the rust to a phosphate (I Think) which stops it in its tracks. Bondaprimer seems to be similar to the Rust Encapsulator but gives me a better finish when brushed on. I then brush coat 2k paint on ver the whole underside area to make sure I get paint in every place I can. I like to put stonechip on the arches an then spray 2k paint over all of that! Matt