I was just watching a video on YouTube of a low mileage 1984 Berlinetta. (People seem to be fascinated with third gen berlinettas now because if the digital dash) anyway,the seller opened the doors and I noticed these black plugs covering holes in the body at the front and rear lower areas above the rockers. What the hell are those for? I’ve had many trans ams and have a 90 camaro and it doesn’t have any holes like that. What’s the story behind this?

 

In the door jams? Ziebarting/rust proofing?

 

Front photo

 

I am talking about the round black holes in the white painted area in the door jamb. That isn’t “ziebarting” not unless they drill holes into the door jamb and put undercoating inside the car and then push plastic plugs into the body.

 

yep ,look like rust proofing plugs to me. If this car had been on the road it probably would have rusted clear away by now. They always seemed to rot before the ones that weren't "proofed"

Granted, somebody may know more on the subject than me.

 

Interesting. I live in California so people don’t undercoat cars out here much. I had a feeling that wasn’t done by GM because I have never seen those holes on any third gen I’ve ever owned and I’ve had a bunch of them.

I always assumed undercoating was just that UNDER coating. Why would they bore holes into the body and put it inside? The road salt is going to get on the outside of the car.

 

not a thirdgen and this one has yellow plugs but...

 

Wow! Thanks for the info. I learned something new today.
I never realized how “spoiled” we are to live where this isn’t done. That would bother me having holes bored into the body like that. I always assumed undercoating was what the word implied, coating applied underneath the car. I had no idea that they actually put holes in the body and filled it full of undercoating on the inside

 

They don’t drill holes and fill it with undercoating. They use a waxy rustproofing product that is sprayed inside the enclosed panels.

 

Correct. I used to work there back in the early 2000s and did rust proofing before graduating to window tinting/sunroofs. No, I did not install any sunroofs in a single thirdgen, so everyone pipe down.

We had cordless drills with unibits and drilled holes in specific areas of the jam, then using special guns with rods attached, sprayed the tanish colored substance inside, rotating the rod and pushing in and out (get your mind of out of the gutter). This effectively coated the inside of the rocker area. On trucks, we'd take the tailights out and run longer rods down the inside of the bedsides. We also drilled and coated the inside of the tailgates.

 

These holes in the door jambs are considered "structural damage" at the auctions for any newer cars. So many cars from the 80s got the Rusty Jones treatment, and these plugs are everywhere. So, you buy a brand new car and pay someone good money to cause structural damage and devalue a new car. This is how we see it today, but it's obvious it was thought of differently back then.

The door jamb is a major part of any car's structural integrity. Every hole drilled, creates a new crumple zone by weakening that area. Unfortunately, my car has them also.

 

Any mechanic who lives in the Rust Belt will tell you that road salt gets everywhere. The further North you go, the worse it gets. Not unusual to see a four-or five-year-old car or pickup with rust so bad there are actual holes in structural members. Working on these crusty vehicles is a problem unto itself what with rusted-out fasteners, brake and exhaust components, not to mention the electrical issues caused by corrosion that manages to find it's way into even the best-designed harness connectors.

 

All that undercoating does is plug up the natural places where water would drain out of the car's structure. Instead the water is trapped, and the car rusts from the inside out. Lets create a little semi-controlled controlled damage now, to prevent damage later. At least that's what they were thinking, but a bunch of slimy rust proofing on everything is no better than a little rust here or there. In any case if the car is driven, you're going to have rust anyway, so do you want your rust with or without tar and heavy wax served on the side?

 

Much like life, rust finds a way.

 

Nothing lasts forever.

 

I agree with you on this. Living in SoCal I have never seen a car with this done in person,that’s why it baffled me at first. Last night I was watching a video posted by a guy who found a 7,000 mile showroom condition 1982 trans am in black and gold and I was disappointed when he opened the door and it had these holes bored into it and a “rusty jones” sticker on the door jamb.

 

Too me is makes no sense either. The salt spray is going to be thrown up on the OUTSIDE of the car,not inside the rocker,and as you say preventing the drain holes from working isn’t going to help anything.

Are they still doing this today?

 

Some clowns, somewhere are probably still doing it.

 

Rust proofing was a really 70's and 80's thing. On thirdgens is really pretty stupid since GM went to great lengths to zinc coat the body panels. A thirdgen shouldn't rust under reasonable usage, assuming the paint isn't chipped, and the car is washed fairly regularly. In South Dakota, my 83 Camaro had to deal with the pink quartzite gravel they lay down on the city streets all winter. That stuff would get kicked up by tires and chip the paint, crack windshields, etc. All the undercoating in the world wouldn't matter. Hell, the underside of my dad's Explorer came from the factory with the frame and most of the suspension components powder coated. Even going thru the car wash once every week or two didn't save that car from the effects of gravel and road salt. What I'm getting at is the only way to prevent rust completely is to not drive on roads covered in gravel and salt. Additional undercoating just gives the salt and water more places to take up residence. All those holes are just more places were rust can get at the unpainted steel.