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25 year old body work


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I'm at a crossroads and I am seeking advice.


I have some light filler under the paint on my rear quarters and it is starting to flake off. There are several pieces about the size of a post it note that there are visible rusty cracks. This is a paint job and body work that was done in 1985. I haven't done any major body work before.


Strip, sand, prime and eventually paint or just let nature take its course? I'll eventually repaint the whole car. Ive been doing a lot of research and just want some input from those who've done it before.



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I would strip it and refinish as needed but don't leave it in primer as primer is not waterproof and will allow it to rust. If you leave it alone it will cause rust. So it's kinda a catch 22. Your call but if it is starting to rust now I would take care of it.

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I would strip it and refinish as needed but don't leave it in primer as primer is not waterproof and will allow it to rust. If you leave it alone it will cause rust. So it's kinda a catch 22. Your call but if it is starting to rust now I would take care of it.


There are primers available that are waterproof......epoxy......got some

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There's only one way to deal with heavy rust/rot/holes........cut it out & weld in new metal. Any other method (screws, rivets, bondo, fiberglass etc etc) simply will not last the tests of time & additional rust issues. If you only want to make it look better at this point, then go ahead and break out the cracked pcs, bondo it again, and primer it, but don't spend the money & lay a new paint job over that kind of bodywork, cuz it WILL bite you in the ass later! Just my 2c...........

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3M makes some purple colored disks called "clean & strip disks"  they start out about 4" in diameter, and do a really goos job of removing paint, old filler, and even light rust, leaving bare metal.

I can get a picture of them at a more normal time of day.


There is a debate that has been going on about applying plastic body fillers on bare metal, on primering the metal first.  no doubt you are seeing what happens when you put body filler on bare metal.  The metal rusts underneath.


Almost all plastic body fillers are polyester resin based.   Same resin used in fiber glass work.  Polyester resins absorb water from the air.  this water they absorb makes the metal rust.  Use an epoxy primer on the metal first, and let the primer cure, according to the directions. 


My suggestion use PPG DPLF.  You can also use other epoxy primers.

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This is a picture of 3M clean and strip disks.


This version needs the mandril with the washers to hold the disks.  The mandril and nut have a left hand thread, so using it witha normal rotation drill will tend to tighten the nut.

I have heard there is also a version that is a flat disk, with a 7/8 hole in it that can be put on a small angle grinder.

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Yeah Ive got the 3M one for a drill.

Spoke with Barry at SPI and came up with a good plan. Sand to primer with 180 grit except in areas that need metal repair. Prime with epoxy, filler, 2k primer, sand, primer, sand, ProSpray base coat and SPI Universal clear.

I like this rather than stripping to bare metal since most of the paint is solid. Best customer service Ive ever seen, and he likes Datsuns too!

Gonna use the 3M disc on the filler and rust, then an orbital sander with 180 discs to hit the rest of the car.

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I have read a lot of people swear by SPI products over on the Hotrodders.Com forum.  I would like to get your impression of SPI products.

A common comment I see over there is complaints about PPG DPLF, because you can wipe it off with lacquer thinner.   In the data sheet, it says you can recoat DPLF for a week without having to resand.   My thoughts, DPLF is designed to not fully cure immediately, so the next layer of primer, surfacer, or top coat gets a good bond to the DPLF.  Besides, where I live, it does not rain lacquer thinner.

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Ended up getting some epoxy primer from Summit for a Christmas present from my parents.

Still flip-flopping over paint color and still need to get a quote for a sprayble gallon of ProSpray base.

Found some sort of repair over the rear fender lip, maybe fiberglass resin with plastic filler over top? Its weird.

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