Techical Discussions => Tech- -BODY => Topic started by: firedome on October 25, 2008, 07:54:17 AM

Title: foiling the Rust
Post by: firedome on October 25, 2008, 07:54:17 AM
So I'm cleaning up the underside of my '70 Nova 6 cyl sedan(topic is
generic and useful for our Mopes too) and after scraping off loose
undercoating - now there's a fun job - and any of the removable scale,
the metal that lies beneath is solid, so it won't need replacing, but I
need to keep the rust in abeyance so I won't have to weld in metal
later on.  Now, this may have been addressed before, and if so,
sorry,  but what have your results and experiences been:  Por
15?  Clean it off with chemicals and brush on heavy primer and
paint? Re-undercoat afterwards, or no?  Some of the nooks are hard
to get to. Also it's upside down, the underside of the car. I tried
Extend once, it didn't really stop the rust...Sandblasting is not
really an option. I gotta use hand tools and brushes, but want to
preserve a old one-owner family car bought in February of 1970. The NY
climate sucks for old cars....!

Title: foiling the Rust
Post by: Stan Paralikis on October 25, 2008, 08:04:22 AM
Eastwood now has a rust encapsulator in a rattle can...
Title: foiling the Rust
Post by: Stitcherbob on October 25, 2008, 08:06:26 AM

At the resto shop we would heat the undercoating with a propane torch and scrape it all off. Then we cleaned the metal with lacquer thinner soaked rags until the metal was bare. We used rotary wire brushes of different shapes to get the heavy rust off, and then primed the  underside with epoxy primer and painted the floors black DuPont IMRON.
Now they have POR15 black and that can take the place of the primer and IMRON, as long as sunlight doesn't get to it (it isn't UV protected and turns chalky when exposed to direct sunlight). I would then undercoat back over the POR15 with 3M Body Shutz black (much nicer than those spray bomb undercoats that stay gooey).
stitcherbob2008-10-25 13:09:33
Title: foiling the Rust
Post by: Steve on October 25, 2008, 08:16:01 AM
You could also do what Bob said, or prime is and shoot it with Shaker Bed Liner.  Comes in shakers, and found in WalMart-Automotive.  You'll need at least 6 or 7 cans.  It's tough as nails, Sticks to everything and has some great sound deadening qualities.  I sprayed a noisey rear with it and it cut the noise in half.
It will give you a nice semi gloss finish, and look like undercoating.  It's easy to clean too.  Just make sure you cover everything evenly so nothing can pop through.  It looks like it sticks to undercoating too, but I wouldn't trust that too much.
As far as it getting wet, it dries water quickly.  Because of the tighter finish, it doesn't absorb moisture.
I'm using it on Polaraco.  I went under there to finish some spots I hadn't done and was pleasantly surprised.
It's a Chevy.  It needs all the help it can get (
Title: foiling the Rust
Post by: Leaburn Patey on October 25, 2008, 01:00:51 PM
What I had done with the BoaB is after scraping the undercoating,I clean the metal the best I can.If there is any flash rusting,I  use a rust convertor and paint over it.
Or depending how tight a spot you are working on,after getting the metal bare and shiny shoot it with a couple coats of epoxy primer,wait 24 hours  then paint.Rock solid and no more rust. 
Title: foiling the Rust
Post by: firedome on October 26, 2008, 04:16:57 AM
Thanks for the advice - my uncle who's the Nova's original owner
restores Model A Fords, he also advised using 3M Body Shutz... I just
wonder if it would trap moisture the way the original dealer
undercoating did.    Any advice on what kind of epoxy
primer to use?

Yeah, be cool if it was a Dart Swinger, but it'a a family car with
memories... I was suprised to find when I looked up production numbers
that the 4 door is much rarer than the 2 door, unlike with Darts... the
OCPG prices for the 2 and 4 dr are virtually identical. Can't remember
last time I saw a 3rd gen Nova  4 dr sedan. She still runs like
new with the big 6 and PowerGlide and 104 k original miles. After
sitting the last 5 yrs we poured gas in the carb, jumped the battery,
and she started right up.

Title: foiling the Rust
Post by: Jay Holder on November 08, 2008, 11:48:21 AM
if you can get your hands on it, U-tech makes a really good epoxy primer. it'll be sold at any auto paint store that sells Sikkens paint. you do need to use a etching primer first though. it promotes adhesion to bare metal and helps prevent rust