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Discussion Starter #1
I am not expert on body work. I took an auto body class at the local CC a few years ago, and a welding class, so I thought I would try and tackle this projecy my self. This is kind of a continuation of this thread: http://www.mr2oc.com/showthread.php?t=287118&highlight=rust

I did get a little over my head, and the project was a little more involved than I wanted but you can see what I did if you need to do something similar your self.

I thought all I had to do was cut off the piece of the body, fabricate a replacement, weld it on, and then bondo and paint. There was a little more rust than anticipated so I did a little more than that.

Step 1: Cut off body panel.

Tools List -

4?" Grinder (~$35 at Lowes)
Cutting Wheel for grinder (~$5)

SAFETY!! This is important to know when using a grinder...

Get the full safety goggles or a face shield, not the regular sunglasses style. Sparks will be flying and they can get around the regular safety glasses. Ear protection is a HIGHLY recommended, a grinder is not quiet at all. Since I was in a garage in cold weather (20-30?F) I used a face mask for the fumes since I wasn't getting much ventilation.

I knew exactly where I was going to cut and would have marked the cut lines if I didn't have the body lines of the car to follow.




Step 2: Remove Rust

Given the amount of rust, I cut the inner rocker panel thing, and bent it upward to get at the rust better. I also noticed that there was a hole in the wheel well and that was the source of the rust. Water and salt had gotten into the car from that hole. It can be seen in the picture below (maybe not clearly, but I will post a bigger pic later)



I used a sand blaster to help clean p the rust. I rented a compressor from Hone Depot for $30/day, and borrowed a sand blaster from a friend. I had a problem because of the low air temperature - condensation would build up in the compressor tank, and clog the sand blaster. If I were to do it again, I would get a water seperator. However, I ran out of time and needed to take the compressor back.
 

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Discussion Starter #2
STEP 3: Fabricate metal Patches

Tools - Metal shears, leather gloves (protect the hands from sharp edges of the cut sheet metal), cordless drill, wood block, nails

I rented a welder and made 3 metal patches for the car. One to patch the hole into the wheel well, one to attach the inner rocker panel back to the car, and the one I showed in the previous thread to cover everything up.

This is the one to patch the hole into the wheel well:



It fits like this:



This is the one I used on the inner rocker panel:



This one I drilled holes that I used to spot weld to another inner panel that hard to see in the pictures. Since I don't have a drill press, I used a wood block and nails to hold the metal piece in place while I drilled holes in it. You cannot hold the sheet metal with your hands when drilling - BAD IDEA! Luckily I learned from someone elses mistake years ago. This is how I drilled the holes:

 

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Discussion Starter #3 (Edited)
STEP 4: Weld

I rented a wire feed welder with mixed gas (75% CO2 25% Argon I think, or vice versa - the welding guys will hook you up). Bought some welding goggles (the type used for acetalyene torch) and upgraded the filter to a 10. It comes with a 5, but thats not dark enough when welding. An 8 might work for the car stuff.

All uncovered skin will get sun burned unless you wear long sleeve shirt and/or sun block. The welder emitts a lot of UV radiation.

This is the patch for the rear wheel well welded in place. Just a couple of tack welds to hold it and then I sealed it from the wheel well side with under car rubberized coating.



This is the second patch welded in. I highlighted it in blue to better see it. Also you can see how the inner rocker panel was cut and welded back again (not very well, but good enough). The problem is that welding on metal that is rusty is difficult to impossible depending on the severity of the rust.

 

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Discussion Starter #4
Here is a picture of the last piece welded in place. I had also taken the grinder to it, to rough the surface in preparation for bondo, and also to smooth out the welds.



I used a grinder wheel that is made up of overlapping sand paper sheets. I think it works better than the ceramic wheels for scuffing the surface and cleaning up the welds since it is not as harsh but still pretty powerful (see img below).



Next I had to deal with two gaps between the patch and the car body. I anticipated this when I was fitting the metal piece, and I knew I wouldn't be able to weld it very well since the car body at that section was very thin due to rust, and the patch was much thicker.

 

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Discussion Starter #5 (Edited)
STEP 5: Fiber glass (FG) and bondo

Bondo and fiber glass are very similar. The bondo is like the fiber glass resin except instead of having sheets of glass, the resin has a filler material already in it that makes it easier to sand and shape.

Tools - cardboard, wax paper, mixing device (tongue depressor works well), bondo spreader things (sell them at auto parts stores), scissors, sand paper of different grits (80, 160, 320 is good), GLOVES! (very handy!)

So I cleaned the area with soap and water to remove dust, dirt and any oils that will make it more difficult for the bondo and FG to stick. Keep in mind that bondo is not great at bridging gaps, that is why I used the fiber glass.

I bought a "fiberglass repair kit" that had the resin, hardener, a sheet of glass and a stick (for mixing with). The difficult part about mixing the resin and hardener was that the directions didn't give a very good ratio (? bottle of resin to ? tube of hardener). Well I was going to use a lot less than ? a bottle. So I poured out a puddle of resin about the diameter of a golf ball and added 15-20 drops of hardener. Too much and the resin will set to quickly and to little and the resin will never get hard. Also, I heard, that if you add to much hardener, it can create bubbles in the resin as it hardens.

I mixed the resin on the wax paper thoroughly after cutting out the size and shape of glass I wanted and another piece of wax paper a bit larger than the glass. Then I dropped the glass on, and made sure it was saturated before putting it over the hole. Then I put the wax paper over the glass and then pressed the glass onto the car and into the voids.

The pic below is me mixing the resin and then of the glass on the car with the wax paper piece on top of the glass.





It took about 20 minutes to get decently hard. It was a little jelly like even then. I had a halogen lamp to help the process along. I probably could have added more hardener since I think it should have gotten harder faster.

BONDO - (the technical term is "body filler")

When mixing bondo, its like a mass about the size of a golf ball + 1" of hardener squeezed out next to it. Then use a spreader and fold the hardener into the the resin. If you use Bondo brand bondo, then the color should be light pink color when you are done mixing. There is about 10 minutes of working time or less so get cracking. If you don't make enough you can always apply more bondo over what you already spackled on.

Mine looked like this when I was done. There is a tool called a cheese grader that makes it a little easier, since you can start shaving off the bondo when its thick, but not yet hard. Now I just have t sand and I am done!



I haven't finished yet since I had to drive the car the next day and it was getting late. I sprayed it with primer and I will sand it down and re-primer and paint in a couple of days.
 

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cool stuff. This is now a sticky. Thanks for the write up...Great work.
 

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Thanks helps alot :D

i have some rust problems on my mr2 also, and the local place estimated 700-900$ on 3 spots (ripppp off)

one is on the rocker.





 

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I might have to learn how to do this- I was quoted $2000-2500 to repair a hole on each rocker, a dent in the driver's door, respray the rear bumper and hood, and repair minor lines of rust on the edges of the front fenders..
 

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I too have a rusty mr2 that needs to get some surgery and welding like how you're doing but I don't know jack about welding. What kind of welder is a wire feed welder (Mig/tig)? What type of sheet metal did you use?
 

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Discussion Starter #14
Well, the welder you need is a MIG with argon mixed gas. If you go to a weld shop, they can hook you up with the right gas. As for the sheet metal, I went to Home Depot. For the rocker panels I think I used 16 ga. I can't remember now, but it was thicker than what I would have used for cosmetic body work (fenders, doors or whatnot) since the rockers are also where the car sits on jack stands.

Unless you got some time and money to practice, welding is not a skill that most people can pick up and just do; especially body work. Its very easy to just melt holes through the metal than to actually weld 2 pieces together. Also, welders have a couple adjustments and if you don't know what you are adjusting then you can really screw things up.

However, if you rent a welder from a welding supply place, they can give you some pointers, give you a general range to set your welder at and sell you a couple of pcs of metal you can play with.

PS - you should disconnect your battery from the car when welding, but I have forgotten to do this and it didn't seem to hurt anything. Make sure the welder is ground close to your weld spot in a logical place

TIPS----
1. When welding a piece of metal onto a car, you don't make a continuous weld around the whole piece of metal all at one time. The heat created will start to warp the piece you are patching in and the body of the car. Tack the piece in with some spot welds around the perimeter then slowly weld around the patch piece. When I say slowly, I mean weld an inch or so, then weld an inch on another side - kind of like when you torque down your wheels, you tighten a little then go to another lug and tighten that. The same thing needs to happen when you are welding since the metal is going to be expanding and contracting and creating stress in the metal.

Take a lot of breaks to let the metal cool - a fan could help

2. tack welding - hit the "go" button on the welder for like 1.5 seconds for a good tack weld.

3. Rusty metal will not weld - it just disintegrates, so make sure to grind off all rust. This is true of the rust is bad and even if its on the opposite side of the weld

4. HAVE A FIRE EXTINGUISHER READY!!!! There is a lot of heat created when welding and paint, under body coatings and rubber close to the weld can catch fire.

5. Don't use the welding mask that you have to hold up in front of your face - your free hand can be used to steady the welding torch or for making sure you are in the right spot when you start instead.


Thats all I can think of right now. If you have any questions, feel free to PM me, I should get an email now whenever someone PM's me and I will respond as soon as I can.
 

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that's awesome! really good to see a write up like this as many of us are needing to do a little body work as our cars get older... thanks!

i found rust in my rocker today, panicked, and was considering a new shell from japan!
 

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a write up on the doors would be great, i have rust staring on both doors and was looking to fix it, great job on the rocker panel
 

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im an auto body tech and just want to say filling instead of welding is never the way to go its a temporary fix. its well worth the money to have it done right
 

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Good work. I plan on tackling my restoration this Spring since I finally got a welder. Another tip is to use an air hose spray and blow the welds to cool it.
 
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