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Discussion Starter · #1 ·
I just fixed my 1/4 panel rust and i couldnt find any kind of write up on the repair before i started mine. It was sort of a shot in the dark. So im making a rust repair how to for all your preludepower members to follow. I didnt have apicture of every step because i did the job alone, and it was pretty hard to get a picture of every single step, but i did as best i could. Hopefully i help somebody out with this.

FIRST: I cant guarantee that this will apply directly to your car, because everyones rust spots are a little different.

SECOND: I am not liable for any damage you do to your car while you do this repair, this is simply a guide to give you an idea of the repair, that way your not completely in the dark.

THIRD: I cannot guarantee that this method will prevent rust forever, more thanlikely it will return if you dont section and weld a new 1/4 panel, but who can do that in their garage? This is a writeup for a manageable doable method that will last for a few years if done properly.

With that out of the way lets get started. Before you start this repair, you will want to make sure that you have the proper materials and tools for the job, so here is a list of the things i used. Everything is available at your local pep boys/autozone/sears/lowes/home depot/ace hardware.

An adequate air compressor. This is not a complete necessity, but its gonna make life much easier.

Air Nozzle to blow off excess dust/rust etc etc.

A D/A sander. Again, not a must, but its nice to have.

Cordless drill. An absolute must. Make sure you fully charge it the night before

Metal files/picks: a must

Sanding block. A must.

Grinding discs for your cordless drill.

Sandpaper: 80, 120, 180, 320 grit

Body filler mixing board, spreaders, and a knife to churn the filler

3M/Bondo Fiberglass Jelly filler: a must for rust holes.

3M/Bondo premium body filler

Bondo brand repair backing patch

Your preferred rust preventing spray

3M green automotive masking tape


Dupli-Color filler primer

- Ok Lets get started. Lets assess the rust on the 1/4. Here is mine.

- If you have rust on the 1/4 where the bumper starts, you need to take your bumper off to assess the rust.

- Heres how you remove the bumper

- Pop your trunk and remove the 5 screw clips by the weather stripping that hold he bumper on.

- Remove your tail lights, and remover the 2 screw clips that are hidden under the tail lights.

- Remove the 10mm bolts that hole the bumper to the 1/4 panel by the wheel well.

- Remove your rear bumper marker lights

- Remove the few screw clips on the underside of the bumper.

- At this point the bumper should slide off easily.

- Here was the damage underneath my bumper on the underside of the quarter panel on the second rust spot.

- Now its time to gather some nerve and break open the rust. Open up your grinding discs and put the 36 grit disc into your drill and start giving the 1/4 rusted spot of the panel hell. Dont be shy, all the rust needs to come off. So just grind the hell out of it.

- Here is my first rust hole after a little grinding

- Eventually, youll start hitting bare metal. If there is a hole, you need to file the edges down. If the edges are weak, file them until you get all the rust off, keep filing until you hit strong metal. you will know when its healthy metal because it will become hard to file down. Keep picking at any rust and just keep grinding till you get bare metal. After you have as much rust gone as possible, stick your air nozzle into the hole and blow it out. make sure the hole is relatively clean inside.

- After the rust is gone, and your down to bare metal, you need to prepare for body filler. My first rust hole was about the size of a dime, so i didnt bother using a backing patch. The fiberglass filler is plenty strong enough to fill a hole up to the size of a quarter without any kind of backing patch.

- The first step is to take your 80 grit sandpaper on your d/a or sanding block, and sand down past the damage a few inches. anywhere you want to have filler, needs to be sanded down with no smoother than 80 grit paper.

- Next, hammer in around the hole slightly. Maybe a 1/16th of an inch. This will recess the area slightly, so you can fill your build your body filler up for a little added strength and "bite"

- Next, blow the area dust free with your air nozzle

- Spray on your rust preventing spray once the area is dry and clean. Allow this to soak in for 15 minutes to a half hour. whenever its dry. After you feel its soaked in enough, blow off the residue with your air nozzle.

- Now mix your fiberglass filler. For ever gold ball sized clump of filler add an inch line of hardener. Note: make sure you churn the filler before putting it onto your board, and knead the tube of hardener before squeezing it out.

- Mix the filler and harener together until you get a uniform color with no streaks. Then begin your fill.

- Now, its time to fill your hole. dont be scared to cake it in the hole. Try to spread lightly towards the edges of the filler, it will make it easier to sand down. But make it nice and thick towards the center of the fill area.

- Right after the spread, still wet.

- Allow the filler time to dry. It should take 15-25 minutes depending how think you spread it. After fifteen or twenty minutes attempt to sand it down. If the residue is white and powdery, its ready to sand. If its still tacky, allow the filler more time to dry. While your filler is drying, clean off your filler board and spreader with acetone.

- Here is my first coat of filler after it dried. you can tell it has a slightly different look

- Now its time to sand down the filler. If you have rough edges or rough high spots in the fill, go ahead and use 80 grit on your D/A. If you have a pretty clean fill then just use your sanding block. Its easier to keep the shape of your body line and keep from removing too much filler if you do it by hand. You will be surprised how quickly you can knock the filler down if you san it with your block. Take off as much filler as needed until you fill the hole and have smooth transition into the metal with no noticable high spots.

- After you snd it down, you may still have some low spots or even a couple small holes or craters. Go ahead and fill these with regular body filler. Its easier to work with and will fill the smaller holes better. Follow the same mixing instructions as the fiberglass filler.

- Then make your 2nd spread, and allow the same drying process.

- Sand down with 120 grit, then get it nice and smooth with 180 grit. you are done your first rust hole!

My Second rust hole is an example of a bigger hole. If this is what yours is like.

- After doing the first hole, i felt that the second hole would be much easier because it looked smaller. My assumtion was quicky shot down, because after grinding, i almost instantly surfaced a hole much larger than the first. Underneath this hole was a bunch of body iller from a previous repair. The underside of the 1/4 was rusted too. As well as part of the wheel well.

- I got my file and pick and began picking out as much of the old body filler and rust as possible. I alternated in my grinder on the cordless drill as well.

- After a half hour of grinding the outside, underside, and inner "wheel well" quarter, most of the old filler and rust was gone. starting to get bare metal.

- After another 20 minutes of filing, i fianlly hit STRONG uncontaminated bare metal. and had the old filler out. Remember to pick out as much rust as you can. If you cant get the drill into a spot, use 80 grit, or use one of the grinding discs by hand. get everything to bare metal. Just rid as much rust as possible.

- All of this came out of the quarter panel.

- At this point, i had the next hole ready for filler. Re do your steps for filler prep. sanding around the area, as well as recessing it with your hammer for a little added bite for the filler. Remember to blow off the dust.

- Since this hole is larger, we will need to use a backing patch. Cut the patches slightly larger than their respective holes. I used one on the outside, the underside, and in the wheel well. For the outside and wheel well, i was able to put the backing patches in from the inside. The underside one i superglued in place.

- Next spray on your rust preventing spray. And let it penetrate. After you let it sit, blow off the area again.

- Mix your fiberglass filler and make your fill. I opted to do one spread on just the outside hole of the 1/4 first that way the patch wouldnt fall or move. I wanted to only focus on one at a time. Let the filler dry like previously.

- Here it is dry.

- Now go ahead and sand it with 80 grit just like you did before. Be concious of the shape of the panel. try to keep the original contour. Heres my first spread sanded down. Still some low spots, so i decided to fill it again.

- Decided to do the 2nd spread on the outside at the same time i did the underside and inner wheel well. Note: I didnt picture this, but the inner wheel well hole was impossible to get a spreader into, and it will never be seen. so i caked it on with my finger. just ensure you cover the hole ENTIRELY. I didnt sand it down either. Just let it harden. It will never be seen. as long as it blocks water from entering, thats all i care about.

- Here is my 2nd fill of the outside, and the 1st and only fill on the underside. I opted to only do one coat underneath because it covered it adequately and would never be seen. plus it looked good with just 1 coat.

- I then sanded this fill with 80 grit on a block, then 120, then 180, and I was then finished with my repair :D

Now comes the easy part, primer. Make sure you use filler primer. Its better for body filler and flling any remaining small scratches/scars/craters

- First mask off the areas you dont want painted with your newspaper and masking tape.

- Make sure you leave any scratches or open metal or body filler unmasked so it can be primed and proteced.

- Sand down your repairs and any glossy paint with 320 grit by hand. Dont miss any spots.

- Blow off the area with your air nozzle to rid the paint surface of dust.

- Shake your can of filler primer for 1 mnute and begin priming. Keep 8-10 inches away from the paint surface and move quickly to avoid runs. You want to achieve a dry-medium first coat.

- Wait ten minutes and apply a second medium-wet coat, then wait another 10 and apply our 3rd medium coat.

-After 3 coats

-Thanks for robbing my whole day!

And voila, there you have it. A repaired 1/4 panel, and you just saved about 1000 bucks :) brag that you did it yourself :)


739 Posts
I applaud the effort.. but body filler, especially CHEAP body filler to fill rust holes? Hope it lasts for you!

If you don't have access to a welder and sheet metal and want another way to fix, I'd personally recommend fiberglass... That bondo is just going to crack, if not soon, then certainly later!
You also need to get a sealer primer on there, or it's just going to rust under the primer again. The filler primer isn't going to seal out moisture

1,030 Posts
I applaud the effort.. but body filler, especially CHEAP body filler to fill rust holes? Hope it lasts for you!

If you don't have access to a welder and sheet metal and want another way to fix, I'd personally recommend fiberglass... That bondo is just going to crack, if not soon, then certainly later!
You also need to get a sealer primer on there, or it's just going to rust under the primer again. The filler primer isn't going to seal out moisture
i second this. the finally molding and product of yours looks great but moisture will soon be in there cracking the bondo and causing little bubbles. same general concept with the fiberglass though..

1,011 Posts
I did this with a spot that wasn't even really rusted, but holy crap the paint does not match very well, that will be the biggest issue with fixing it yourself.
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