Cleaning up under the trunk and rear wheel wells

JR_Charger · May 4, 2022

I've made good progress getting the undercoating off, but now I've got this mix of good paint and surface rust -

How should I prep this surface and prime over it?

BTW, I intend to leave the undercoating forward of the crossmember that the shocks mount to. It's in good shape and appears to be doing its job just fine. Removing undercoating is too time consuming to fix what isn't broken.

zyzzyx · May 4, 2022

Wow you did a great job cleaning that area! Looks great. Scotchbrite and Vapo Rust. Keep it wet and
let it do the work. Scotchbrite the whole area and prime with epoxy primer.

JR_Charger · May 5, 2022

Thanks! I've spent the last few months going over it with various scraping tools, wire brushes, Goo Gone, and I've torched it a couple times. I don't think the torch is pulling any oil out of the metal though. It looks more like it's burning off condensation, which is eye opening.

Going down to bare metal is one approach. I've used Rustzilla on some of my other rusted parts though and I'm impressed with it - but it isn't good over paint. I've been thinking about some of the Rust-Oleum Stop Rust products, but I don't know how they do over paint.

Hemi2Much · May 5, 2022

I have the same issue with my car (1966 Coronet). It sat in a barn with dirt floors for many years and the car never had undercoating. There is very little rot but there is surface rust on everything and the paint has a lot of bubbled-up areas. Tiny little bubbles of light rust under the paint. I have been scraping it and scotchbrighting it
but I haven't used any chemicals yet. My problem is I don't have a lift and I'm working off a creeper under the car and wearing a full face mask. I hope more people chime in on this because I'd also like some ideas about how to tackle the underside of the car. I'm thinking about sandblasting the entire underside of the car and engine compartment and repainting. I've already dropped the K Member and all suspension,
gas tank, fuel and brake lines. All that's left is the rear end and leaf springs.

zyzzyx · May 5, 2022

You are not burning off condensation, the byproduct of the torch flame is moisture
which is condensing on the colder sheet metal! It's like when you install a new hot
water heater in your house and water drips down on the burner the first time you
fire it up. The tank is not leaking, it's the condensation of the flame gasses on the
cold flue of the water heater. You may want to do some localized blasting for stubborn
spots, but it looks great! Make sure you degrease the whole area with Acetone or
lacquer thinner before you prime it. It'll look like new when you're done!

JR_Charger · May 5, 2022

Hemi2Much said:
I have the same issue with my car (1966 Coronet). It sat in a barn with dirt floors for many years and the car never had undercoating. There is very little rot but there is surface rust on everything and the paint has a lot of bubbled-up areas. Tiny little bubbles of light rust under the paint. I have been scraping it and scotchbrighting it
but I haven't used any chemicals yet. My problem is I don't have a lift and I'm working off a creeper under the car and wearing a full face mask. I hope more people chime in on this because I'd also like some ideas about how to tackle the underside of the car. I'm thinking about sandblasting the entire underside of the car and engine compartment and repainting. I've already dropped the K Member and all suspension,
gas tank, fuel and brake lines. All that's left is the rear end and leaf springs.

I'll share my special tool for moving that rear end around if you don't have help -

It sure helps to have the rear end, leaf springs, and driveshaft out of the way.

If you've got a sandblaster and want a smooth factory finish in an area no one will see, that will work. If you don't mind a little texture, Rustzilla is an awesome rust convertor. It's not toxic and hard to work with like POR-15, and doubles as a primer. The only reason I'm not using it is because I've got so much paint left. I used it on other parts that were totally surface-rusted.

zyzzyx said:
You are not burning off condensation, the byproduct of the torch flame is moisture
which is condensing on the colder sheet metal! It's like when you install a new hot
water heater in your house and water drips down on the burner the first time you
fire it up. The tank is not leaking, it's the condensation of the flame gasses on the
cold flue of the water heater. You may want to do some localized blasting for stubborn
spots, but it looks great! Make sure you degrease the whole area with Acetone or
lacquer thinner before you prime it. It'll look like new when you're done!

Yeah, I'll hit it with acetone. Got to figure out what to prime with - Picklex20 looks very interesting as a pre-primer surface prep. I feel better about taking the paint off if I can follow with Picklex20 and take the flash rust off.

matthon · May 6, 2022

JR_Charger said:
Goo Gone

Make sure it's the automotive Goo Gone.

JR_Charger · May 6, 2022

matthon said:
Make sure it's the automotive Goo Gone.

Why, will the wrong thing eat the metal? I've been using the Pro Power but I can't recall if it's automotive or not. It works well on the undercoating but isn't budging the paint.

matthon · May 7, 2022

Imo, only the automotive version works, and works extremely well. I don't know anything about it eating metal, I don't believe it's that harsh.

Spray on liberally, walk away, come back next day.
It may look dried out after, it just soaked in, spray a little more if you want, but don't forget to walk away and leave it alone.

Scrapes right off leaving nothing but a little goo mess. I couldn't believe how well it worked, and how little effort to remove.

I just used it again recently.

JR_Charger · May 7, 2022

Is there supposed to be something that goes between the front leaf spring mount and this brace? Like the isolators between the leafs of the leaf spring? On both sides I've got this scale looking raised area, but it doesn't appear to be coming from the brace or the back of the leaf spring mount. Not sure what's going on. It sure looks like something is stuck to the brace.

matthon said:
Imo, only the automotive version works, and works extremely well. I don't know anything about it eating metal, I don't believe it's that harsh.
View attachment 1281399

Strangely enough, the automotive version is the one that didn't appear to do anything for me - but the Pro Power is doing a great job. I've let both soak for hours, or overnight.

matthon · May 8, 2022

I just used it yesterday. Sharpened a scraper, in thinner areas it stayed wet, in thicker areas it looks dry.
Dry areas scrape off like a lumpy flour, for lack of a better description.
Scrubbing with a hard plastic brush and some more goo liquefied what remained.

That scale looks like the part of the metal that didn't rust and hasn't pulled away yet, at least that's similar to what I've found here in rust country.
Can it be chipped off?

JR_Charger · May 8, 2022

matthon said:
I just used it yesterday. Sharpened a scraper, in thinner areas it stayed wet, in thicker areas it looks dry.
Dry areas scrape off like a lumpy flour, for lack of a better description.
Scrubbing with a hard plastic brush and some more goo liquefied what remained.

That scale looks like the part of the metal that didn't rust and hasn't pulled away yet, at least that's similar to what I've found here in rust country.
Can it be chipped off?

I chipped it off. It looks like it was a thin sheet of metal between the shackle and the brace. The brace was undamaged underneath and the shackle wasn't rusted enough for the scale to come from it.

JR_Charger · May 13, 2022

Getting close to having everything cleaned up - what epoxy primer is good? I've also got Rust-Oleum's Stop Rust for bare metal, which I'll be putting on the lower control arms.

T2R9 · May 13, 2022

Looks good! SPI epoxy is good stuff.

JR_Charger · May 13, 2022

Looks like I'm going to have to get set up to spray paint. I've got a compressor that should be adequate, but not a good or other accessories. I'm a little worried about spraying in tight quarters.

JR_Charger · May 15, 2022

Let's talk about welding skinny metal. I've got a few rust spots to fix - this looks like a good place to start -

I can cut this thin stuff out with my Dremel, but where do I get new metal to replace it with? Any recommendations on a 110 volt TIG welder? I've watched a few videos on welding thin metal, but any tips and tricks are welcome.

JR_Charger · Jun 26, 2022

Here's the finished result, sorry for the lens flares. I decided to finish this with Rust-Oleum Rust Reformer and pro grade undercoating. I'll let a body shop handle the rusted out parts, so I've left the wheel wells and the inner quarter panels unfinished. I've got the feeling that this will last a long time, perhaps longer than I do. Or it could prove me wrong and peel off in a year, but I doubt it. I think it's going to be fine for a couple decades and if we're both still around maybe I'll send it to a professional restoration place and have everything done right.

JR_Charger · Jun 26, 2022

Well hey I think I just found out what that mysterious metal scale between the leaf spring hanger and the body brace was - a thrust alignment shim. If rear end alignment needs to be adjusted in 1/32" increments, I'm going to have to clean the face of that brace up and get it smoothed down for the shims to slide in.

1Tlew0 · Jun 26, 2022

Nice work! I recently cleaned the underside of mine, and what a pain in the *** it was.

JR_Charger · Jun 26, 2022

Yes it is. I hope not to do that again but I just watched a video that said to sand with 240 before primer. I did 320.

Cleaning up under the trunk and rear wheel wells

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