Auto Body knowledge needed

[brew hoperator]

My wife's car was hit by some object on the freeway and it caused a softball sized dent in the car door. The paint over the dent was also removed by the object and we are noticing very small spots of rust where the paint use to be.

I am trying to get some advice on a cheap and easy way to cover the exposed door and inhibit any further rust development. I have seen a product called Bondo before at Home Depot, but I don't know if it is easy to work with and right for this application.

Any help is appreciated.

Thanks!

 

[mattmcl]

Before you do anything, you have to sand the rust down to bare metal. The smoother you make the metal, the better. If you don't care about looks, just put some spray automotive primer over the sanded metal and call it good. You'll have to hit it again in six months or so, but it will stop the rust from progressing.

 

[sitandwait]

for surface rust there are a couple different products that chemically react with the rust to produce a paintable surface and they also inhibit further rust, the best one is called naval jelly, or like matt said sand all the way down, either way cover with a solvent based spray primer preferably a sandable one and make sure to hit it again every few months. Do not, absolutely do not use bondo unless you intent to prime and topcoat within a day, bondo will soak in moisture from rain and snow which will actually increase the rate of rusting

 

[nvr2low]

Before you do anything, you have to sand the rust down to bare metal. The smoother you make the metal, the better. If you don't care about looks, just put some spray automotive primer over the sanded metal and call it good. You'll have to hit it again in six months or so, but it will stop the rust from progressing.

the problem with normal spray can primer is the same as bondo, it will absorb moisture. just make sure you get the right kind!

 

[Domminigan]

Around my area, you can find cans of either Krylon or Dupli-color in automotive car and truck colors in automotive stores like Advance Auto, Autozone, PepBoys, and the like. The cans run from five to seven a piece, and are a decent replica of proper auto paint for consumers. They usually have primer in multiple colors, and a top coat similar in color to what your wife's car has. If you can't find one of these, go with a brand name enamel spray paint as close as possible to the right color. If you can't get one of those, use Nail Polish.

Like everyone else said, make sure you get all the rust off first. Wipe the freshly de-rusted area down with a clean rag with Acetone (Most nail polish removers contain acetone, so it will work in a real pinch, just make sure that you don't get some with oils in it for strengthening nails) and let it dry. It usually takes a few seconds to dry.
If you can use the primer, spray it on first according to the directions, and let it dry. Give it a light sanding with higher number grit sandpaper (250-1000 Grit)
Lightly and quickly wipe the area just sanded with another clean rag and more acetone to clean off the sanding dust and let dry.
Spray the paint on according to the instructions as best as you are able, and let dry.

Watch the area to make sure that rust doesn't start bubbling up below the paint patch.

 

[hopdog]

If the dent doesn't bother you, like others have said, just give it a bit of a sand and touch-up paint it. Bondo is kind of tricky if you have never done it. A bad bondo job can look worse than the dent itself.

 

[XXguy]

Honestly - if you've never even heard of Bondo before, you're better off farming this job out. Look for your local Vo-tech school & consider giving the kids a shot at fixing the car for nothing more than the cost of materials. You might just get a nicer job than you could do yourself, and the kids will get a nice simple repair on something other than a junker or rust-bucket.

 

[HBHoss]

Bondo is like spackle for metal. If it's too thick, it will crack and if the metal isn't prepped right it will come loose.
If you can get the door panel off and pop the dent out that would be good. Then, like others have suggested, use some fine grit wet/dry sandpaper and get rid of existing rust. Find a good primer and use tape to mask off the area so you don't get over spray on the rest of the door.

 

[Domminigan]

Bondo is only good for smoothing custom fiberglass and patching broken boats. Okay, and fiberglass parts on cars too. I have had so much trouble with people using bondo to smooth parts on cars. One decent impact, and all the bondo cracks while half of it pops off.
The biggest problem is that Tommy Teen decides that he's going to fix the bent fender that he got from the fender bender with bondo before Daddy buttspanker gets home. The next thing you know, Tommy Teen sells the car and the next person has problems with the car's paint and then the sh** cracks off, there's rust underneath it and you've got a whole fender to replace.
Grrr... I hate great globs of bondo on cars!

 

[Domminigan]

What ever happened to lead filling the sheet metal? Is this a lost art?

 

[XXguy]

What ever happened to lead filling the sheet metal? Is this a lost art?

Pretty much a lost art, but also not time-effective, and thinner sheet metal on modern cars doesn't take well to using heat to smear the lead around and get it shaped. Also, when it comes to environmental concerns - acid wash & lead/tin solder isn't high on the list of "green" substances.

 

[onejdn]

when it comes time to fix it properly there are some really nice, lightweight fillers on the market now. I would highly recommend having someone else do the job. They should be able to get the dent out most of the way. the filler is to smooth the minor imperfections after the metal work is done. I used to hate it when customers brought me a car that they tried to fix, I would always charge them more to undo their "repair" and fix it right.

 

[nvr2low]

Bondo is only good for smoothing custom fiberglass and patching broken boats. Okay, and fiberglass parts on cars too. I have had so much trouble with people using bondo to smooth parts on cars. One decent impact, and all the bondo cracks while half of it pops off.
The biggest problem is that Tommy Teen decides that he's going to fix the bent fender that he got from the fender bender with bondo before Daddy buttspanker gets home. The next thing you know, Tommy Teen sells the car and the next person has problems with the car's paint and then the sh** cracks off, there's rust underneath it and you've got a whole fender to replace.
Grrr... I hate great globs of bondo on cars!

great globs and properly used are two entirely different things. there is not a car on the road with out some filler on it someplace, and if it is used correctly you will never know it. its when people use it incorrectly that it gets a bad rap.

watch the tv shows like overhaulin, they are always using bondo or ice to do the fine finishing work on the cars. you are not going to get metal that perfect on every edge and corner, and when used correctly filler can be a great tool. now when its used to build a panel instead of smooth one you are going to have some issues.

 

[pen25]

What ever happened to lead filling the sheet metal? Is this a lost art?

very very few body men will lead. most of its cause of osha regulations. and you never want your filler more then a 1/4" thick. bondo is a leveler. and no bondo is not just for boats. you use fiberglass for boats bondo is a 2 part filler and you can add fiberglass to help make it tougher. as others have said try your local votech. or save the hundred or so and take it to macco and have them sand and shoot it. you can use primer ment to go over rust that has built in rust converter and then spray color on it. as long as the rust isnt flaky it can be converted. spray it and save a couple hundred and pay a body shop to fix it and fix all the little dings and dents then take it to macco and have them prep and paint it. the prep will cost you more then the advertised price. they wil actually do a decent job.

 

[Homercidal]

My father-in-law has threatened to lead the roof seam on his 67 Cougar, but fortunately it ended up not needing it. Plus, he would have only did it to be accurate in the restoration. He decided also to not do a strict restore, and has often mentioned how the modern fillers are so much better than they used to be.

Anyway, if you want to knock the dent out, I recommend getting a fairly heavy piece of metal on the outside, and tap carefully with a hammer (body hammer if you got one) on the inside. This would require removing the inner door panel and etc.

Then again, if you just want to fill and paint it, first use sandpaper to sand the rust completely. Then use a product like Eastwoods rust converter, which is basically an acid that converts the rust to a protective layer. THEN apply the body filler, in several light coats if necessary.

Use a modern body filler, heavyweight to start if the dent is deep. Once it has been filled you need to sand it down well, until it's just below the level of the metal (barely feel the difference with your hand). Then switch to a lightweight filler like "Icing". This will sand easier and give you a better feel for when the spot is getting close.

Then paint with an automotive primer. Once the primer has cured, lightly spray a "guide coat" on it. Just a dusting of a contrasting color which will wear off as you sand. This will help you see where there are any high or low spots.

Repeat the primer until the guide coats sand evenly. Then finish with a color close to the original, and then top with a clearcoat. When that is fully cured you can rub with compound and polish to match the orange peel from the factory.

For quick and dirty, just sand with sandpaper, spray with a sealer paint, then automotive primer and then a color close to the original. I'd paint the whole panel to help make it less noticeable.

 

[jgln]

Softball sized dent huh?

 

[jgln]

My father-in-law has threatened to lead the roof seam on his 67 Cougar, but fortunately it ended up not needing it. Plus, he would have only did it to be accurate in the restoration. He decided also to not do a strict restore, and has often mentioned how the modern fillers are so much better than they used to be.

Anyway, if you want to knock the dent out, I recommend getting a fairly heavy piece of metal on the outside, and tap carefully with a hammer (body hammer if you got one) on the inside. This would require removing the inner door panel and etc.

Then again, if you just want to fill and paint it, first use sandpaper to sand the rust completely. Then use a product like Eastwoods rust converter, which is basically an acid that converts the rust to a protective layer. THEN apply the body filler, in several light coats if necessary.

Use a modern body filler, heavyweight to start if the dent is deep. Once it has been filled you need to sand it down well, until it's just below the level of the metal (barely feel the difference with your hand). Then switch to a lightweight filler like "Icing". This will sand easier and give you a better feel for when the spot is getting close.

Then paint with an automotive primer. Once the primer has cured, lightly spray a "guide coat" on it. Just a dusting of a contrasting color which will wear off as you sand. This will help you see where there are any high or low spots.

Repeat the primer until the guide coats sand evenly. Then finish with a color close to the original, and then top with a clearcoat. When that is fully cured you can rub with compound and polish to match the orange peel from the factory.

For quick and dirty, just sand with sandpaper, spray with a sealer paint, then automotive primer and then a color close to the original. I'd paint the whole panel to help make it less noticeable.

67 Cougar...nice car. I had a 73 Cougar, wish I didn't junk but had no place to keep it and was rusting out.

 

[Homercidal]

His ex did some body work to it with a hammer the day he was going to take it to the body shop for it's new coat of paint. He ended up trading his bass boat to have them fix all the dents. It looked good, but I hear he sold it. Who's got time for an old car AND a new woman?