teach me the ways of rust repair :)

[05Nissan350z]

Hey guys i have no experience in body repair at all. Luckily it's just surface rust that I'm looking to repair. I don't know what all I'll need and would like to get a good list. Here's some pictures of the cancer. If anyone who has experience and can give me steps on when to do what would also be very greatful! I don't want it to look like ass .

 

[91-GS]

Hopefully it is just surface rust, and not that stuff that eats up the panel from inside. Poke it with a screwdriver to be sure.

If it is just surface rust, use a grinder to remove it. Any grinder will work for a small area like that. Might even be able to do it with a steel brush instead of a grinding disk. Sand, primer, and paint after that.

 

[eric4g63]

Same as 91 said sand it down with some rough grit sandpaper then fine grit get all imperfections out then prime it and sand again if needed then paint.

 

[Breezio69]

That doesnt look like "surface rust" from my couch.

Pic 2&3 look like they are significantly rusted. Any vehicle I've ever owned that has rusted up and bubbled/cracked like that, it has rusted through and required cutting it out and tacking in filler pieces of metal... also, pic 3 looks like someone has already previously tried to hide or fix a dent/rust spot and the bondo let loose.

Quickest way to find out is a paint blending disk on an angle grinder and make sure you clear an area a little larger than the spot itself... like 4-6" around it.

Edit, to add to what all three of us have said, you'd need to get a rust neutralizer and make sure it is all taken care of, then bondo, sand for days, prime, paint.

And I also recommend a "paint blending" disk over a "sanding disk/flap wheel" when dealing with rust. Its a lot less abrasive and you have less of a chance of grinding through the metal.... if you don't know what it is, go to the grinding wheel section and look for the wheel that's 3/8" or so thick and looks like dried blue ramen noodles .. hahahaha

 

[05Nissan350z]

Alright thanks alot guys. Any idea what grit sandpaper I should use?

 

[92AWDHX40]

Start with some 80 grit depending on how bad it it is, and work your way up I just guessed on my sanding takes time and experimenting.

 

[91-GS]

If you don't have a grinder, grab a scraper or a large flat screwdriver and pick/scrape off as much rust as you can. That way you won't have to sand as much.

Have your car always been a notherner? Road salt can destroy a car pretty quick. You might have other spots that have not shown yet.

 

[Breezio69]

If you don't have a grinder, grab a scraper or a large flat screwdriver and pick/scrape off as much rust as you can. That way you won't have to sand as much.

Have your car always been a notherner? Road salt can destroy a car pretty quick. You might have other spots that have not shown yet.

Not to naysay or argue. But even at home depot you can pick up an angle grinder and one of the stripper wheels for around $40. The angle grinder in the conversation even comes with some cut off wheels and a few random tools to protect your fingers and get the job done....

think of it this way.... you either have a new tool you didn't need today, but may need a month from now... or you spend $30 on different packs of sand paper, realize the rust has gone through the panel, and have to spend $40 on the grinder with cut off wheels and paint stripper attachment anyways... haha.

Either way, its a tool you will use as your experience in working on cars advances. May as well invest now... 2 hours in sanding clearcoat, paint and primer down to bare metal at your jobs hourly wage =$????-or- 40 seconds with the right tool you can use multiple times and knowing what you're into.

Hell, even down the road after you fix the body up good, you buy the $10 buffer attachment and buff the hell out of your amazing body work... any way you cut it, a new tool is a time saver and a win.

 

[lewishamilton]

Not to naysay or argue. But even at home depot you can pick up an angle grinder and one of the stripper wheels for around $40. The angle grinder in the conversation even comes with some cut off wheels and a few random tools to protect your fingers and get the job done....

think of it this way.... you either have a new tool you didn't need today, but may need a month from now... or you spend $30 on different packs of sand paper, realize the rust has gone through the panel, and have to spend $40 on the grinder with cut off wheels and paint stripper attachment anyways... haha.

Either way, its a tool you will use as your experience in working on cars advances. May as well invest now... 2 hours in sanding clearcoat, paint and primer down to bare metal at your jobs hourly wage =$????-or- 40 seconds with the right tool you can use multiple times and knowing what you're into.

Hell, even down the road after you fix the body up good, you buy the $10 buffer attachment and buff the hell out of your amazing body work... any way you cut it, a new tool is a time saver and a win.

You sure you don't work for Home Depot?
You sold me on one, it's being added to my list of tools to get for the car.

One question, how much restraint needs to be used when buffing and sanding on the car? I don't want to do too much damage with one of these things.

 

[91-GS]

Sanding's pretty easy. Basically work until (1) You remove what needs to be removed (2) Grinder/sander overheats (3) You say F-it and go have a beer. If you are talking about sanding the clear coat, sand it until it's almost smooth. If you go too far, you will go through the clear and get into the paint. With more experience you will learn to judge how deep the clear is and decide if it's safe to sand more. If you sand it until it's "almost smooth", yet has a pit here and there, don't worry much. Buffing will hide small imperfections.

Buffing is trickier since if paint is not cured or you keep the buffing wheel on one spot for too long there is a chance that it will cause damage. Buffing by hand, obviously, does not give you those problems. If you do end up using an electric buffer, make sure to always keep moving while the tool is spinning. You will learn over time about how fast to move and how much pressure to apply. Might not hurt to practice on a separate piece of metal first.

Don't over-do it. You are probably the only one who would ever know that there are imperfections since you were the one fixing them.

 

[Breezio69]

You sure you don't work for Home Depot?
You sold me on one, it's being added to my list of tools to get for the car.

One question, how much restraint needs to be used when buffing and sanding on the car? I don't want to do too much damage with one of these things.

Haha, no, I do not work for home depot. I just own one myself, and I've had it for a few years, from cutting up steel tubing, making a bumper for my jeep, tubbing the rear end to fit 37's the right way, cutting off axle mounts and cleaning up the entire assembly, to sanding paint down and grinding welds smooth and seamless.

The sanding all depends, if you use a flap wheel you can do a lot of damage really quickly to any thickness of metal... let alone a body panel. If you use a blending wheel it actually removes the paint and takes some force to start digging into metal and causing damage.

When you are talking about buffing, cutting and buffing a car by hand can take hours.... block out a half a day (like 12 hours) to do it right. Using some power tool assistance really depends on the abrasive you use (any polish will have an abrasive to it, and they advertise it on the bottle). Generally anything that is motor assisted you will need to move fairly quickly, you need to keep the buffer in motion or you will burn through the paint... an example is as simple as rubbing your own finger over the same spot on your skin, gets hot don't it. You don't want to be running a buffer over the same spot too much.

 

[Hydecotsi]

If u use power tool keep speeds low to keep from causing warping. You can cause a bigger problem than you started with in a hurry. Bodies of car are like babies if u want them to be correct. Lots of time, money and patience. Body work is not easy it takes time and patience and then more time. A lot of people think its easy but it's a lot different than what most think.

 

[4wsaddict]

That doesnt look like "surface rust" from my couch.

Pic 2&3 look like they are significantly rusted. Any vehicle I've ever owned that has rusted up and bubbled/cracked like that, it has rusted through and required cutting it out and tacking in filler pieces of metal... also, pic 3 looks like someone has already previously tried to hide or fix a dent/rust spot and the bondo let loose.

Quickest way to find out is a paint blending disk on an angle grinder and make sure you clear an area a little larger than the spot itself... like 4-6" around it.

Edit, to add to what all three of us have said, you'd need to get a rust neutralizer and make sure it is all taken care of, then bondo, sand for days, prime, paint.

And I also recommend a "paint blending" disk over a "sanding disk/flap wheel" when dealing with rust. Its a lot less abrasive and you have less of a chance of grinding through the metal.... if you don't know what it is, go to the grinding wheel section and look for the wheel that's 3/8" or so thick and looks like dried blue ramen noodles .. hahahaha

I agree with this method, only thing I have to add is just from the way I learned and that is take off as much rust as you can with out removing metal so if once the paint comes off the rust is flaky or pitted just pick up a cheap spot blaster and some aluminum oxide media and just knock it off and then use the bondo to fill it in.

 

[lewishamilton]

Thanks guys, can these same techniques be applied to mild frame rust? Or is that a lost cause?

 

[05Nissan350z]

Hey guys sorry i forgot my password and didn't have time to reset it ! My friend and i Did a good sanding and re primering just for winter sake. I'll be having the bad rust holes fixed hopefully this weekend!

Pics are giving me a hard time to upload. The black trim is new

 

[Smilinjay]

Breezio69 nailed it on the head. 99% of the time, rust bubbles are actually rust holes, since the metal often rusts from the back side, allowing moisture to get under the paint and cause bubbles. In pic 3 it looks like someone tried to slap some bondo over the rust and call it good. The proper way to fix a rust hole is to grind until you reach good metal, cut out ALL of the rust, weld in a patch panel, and then use a small amount of body filler to make the repair level. Sand, then feather edge the old paint, and of course primer and repaint the repair area. Remember, rust is cancer, and it will always come back unless you get rid of it all.

 

[4wsaddict]

one trick if you weld the hole is set a peice of aluminum behind the hole, it still conducts to weld but you cannot weld to it. it will just fill in the hole and not let your spot go out the back side.

 

[Warpathdsm98]

I would cut that whole section off a few inches past the rusty section to get nice clean metal and weld in a patch. The main thing is to take your time and be patient. I generally sand bondo with 220 grit and try to stay 1/8" or less so it wont crack. I suggest the small rubber bondo scraper things to spread it, they are cheap don't use a piece of cardboard. Don't mix up a giant batch of filler either as it will start to harden before you can apply it all and if it starts to get kind of dry looking while applying toss it, that's just more sanding.Also for some reason and I've tried all different quantities of hardner, the sand paper seems to clog on the first few passes, change paper and continue. Remember patience.

 

[05Nissan350z]

Alright the passenger rear quarter panel is doneee. All that's left is the passenger side, swapping the drivers door, and fixing under the bottom trim pieces. Then it's time to paint!