66 Coronet 440 undercoat removal

bob32268 · Jul 17, 2026

I took the Coronet 440 to it's first judged car show this past sunday. I had the car looking sharp (see pics) and I got a 3rd place trophy in my class (all 1960 to 1979 cars). I think it would have done much better except for the
underneath which was HEAVILY undercoated. When I was working on the brakes etc. I cleaned it all off the suspension parts, oil pan, tranny and repainted the correct color. But there is still a lot of undercoat on the frame,
floor pans, gas tank etc. Does anyone know of a better (easier) to get this stuff off? I used a heat-gun and scraper, on other previous cars I used aircraft paint stripper (damn fumes will kill you). I was wondering if their is some type
of safe chemical that will break down the old hard dried up coating and make it softer and easier to remove. Also, where can I get a full-size trunk mat for my 66 Coronet, most of the repros seem to be too short to reach all the way
to the back of the back-seat ?
Thanks
Bob32268

ct71rr · Jul 17, 2026

I soak it with Automotive GooGone in a spray bottle and then cover in plastic over night. It scrapes off with a plastic scraper. It may need 2 treatments depending on the thickness.

YY1 · Jul 17, 2026

"Automotive" GooGone?

ct71rr · Jul 17, 2026

The Rebel · Jul 17, 2026

They judged your car by looking underneath it, never heard of that.

Personally I'd leave it as is as removing it sounds like a huge chore.

bob32268 · Jul 17, 2026

ct71rr said:
I soak it with Automotive GooGone in a spray bottle and then cover in plastic over night. It scrapes off with a plastic scraper. It may need 2 treatments depending on the thickness.

Thanks, sounds like a good idea, Il'l give it a try.
Bob32268

bob32268 · Jul 17, 2026

The Rebel said:
They judged your car by looking underneath it, never heard of that.

Personally I'd leave it as is as removing it sounds like a huge chore.

Oh yes, 10 points for the outside (paint, chrome) , same for interior, 10 for the engine comp., 10 for trunk area, and 10 for bottom (underside) of the car, the judges get down on their hands and knees to see the underneath. Yes, it's a big chore, I did it on a 66 GTO once, took 3 months, I started after the Holidays and just about every night after work I'd go down to the garage heat and scrape a section, then clean up
the residue with steel wool soaked in lacquer thinner, then primer and paint it semi-gloss black. The GTO (Montero Red) was a consistent trophy winner, usually 1st place, sometimes Best of Show.
Tks,
Bob32268

The Rebel · Jul 17, 2026

That's very interesting never been to a show where they looked underneath and assigned points.

Good luck with the project.

RemCharger · Jul 17, 2026

Forget the shows and take up drag racing lol. Much easier on the head

Sam69sat · Jul 17, 2026

There's dry ice blasting but i imagine it's expensive.

matthon · Jul 17, 2026

GooGone Automotive is the bomb for removing undercoat.
Make sure it's exactly as posted in the pic above.

Cover in plastic wrap to keep it from drying out and let it seep into the undercoat.

You can pull the plastic wrap and scrape it off, it's usually still a bit gooey.

Could also pull the plastic wrap and let it dry out. Later it should scrape off, well, like dried out undercoat.

Either way, once you're down to the last bits of undercoat using the spray straight out of the bottle and a rag should clean it up nice.

As mentioned above, plastic scraper, if you care about leaving the paint underneath.

65PlymSatellite · Jul 17, 2026

I like Using Siphon CO2.

Score yourself a 20Lb tank off Craigslist or Marketplace for cheap. Then go swap it at your local Weld Supply. Call them first to make sure they carry SIPHON CO2 tanks.

Then I break it off with a scraper.

bob32268 · Jul 17, 2026

RemCharger said:
Forget the shows and take up drag racing lol. Much easier on the head

I did a lot of drag racing at the local drag strip with my 70 GTO back in the late 90's, at my current age (81) I doubt if they'd let me on a track ! GTO had a beefed up 400 cu engine and turbo-hydramatic tranny.
It would run a very consistent 14.2 secs. I did very well in bracket racing. Since I'm done racing I put the 4-speed Muncy tranny back in and I just take it to shows and Cruise-Ins now
Tks,
Bob32268

JonR · Jul 18, 2026

A couple years ago I got mine from Classic Industries, part number MB583 in plaid. It looks right, covered the entire area all the way to the back seat, and fit about 90% correctly. It was too wide up on the hump by the back seat and was a little off on a couple of the cutouts. I did a little simple trimming and am very satisfied with it. I had the original mat but it just started tearing everywhere so had to replace it.

Love your 66! Looks perfect!

bob32268 · Jul 18, 2026

JonR said:
A couple years ago I got mine from Classic Industries, part number MB583 in plaid. It looks right, covered the entire area all the way to the back seat, and fit about 90% correctly. It was too wide up on the hump by the back seat and was a little off on a couple of the cutouts. I did a little simple trimming and am very satisfied with it. I had the original mat but it just started tearing everywhere so had to replace it.

Love your 66! Looks perfect!

Thanks so much, I'll check out Classic Industries then. I bought one at Carlisle for my Charger a few yrs ago. It was all wrapped and sealed in plastic, and when I got it out of the packing it was short.
Tks,
Bob32268

Davefinan · Jul 18, 2026

The Rebel said:
That's very interesting never been to a show where they looked underneath and assigned points.

Good luck with the project.

I would say more than half of the judged shows I ve been to,the undercarriage was judged.

The Rebel · Jul 18, 2026

Oh wow, I had no idea some shows did that. Thanks for the info!
On a side note, we are talking about a car show and not a strip joint

Davefinan said:
I would say more than half of the judged shows I ve been to,the undercarriage was judged.

66 Coronet 440 undercoat removal

bob32268

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