Trunk/General Rust Repair Documentation- Recommendations/Suggestions

Terrorist 5.0

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Hi everyone, so recently I did some work on the weekend (removing my inoperable A/C, engine bay is way more open now), and after putting on my short belt, I noticed some rust by the frame rails in the front. Upon further research, it is common for 79-04 Mustangs to rust and/or completely rot out there. Needless to say, I wasn't happy, but it is 30 years old after all.

I began really digging in to the rest of the car and while I would say mine is in pretty good condition compared to others, it could be better. I know rust only gets worse with time, and I don't wanna lose this car, that I have put so much effort into, to rust in the future. I mainly found somewhat concerning rust in the trunk floors, and the metal bracing behind the rear bumper. The trunk floor doesn't look too bad, and for the places I can't reach, I'm going to dump motor oil in the crevices to at least slow it down some, especially since it is on the inside and not directly exposed to the elements, such as the frame rail mentioned before. The bracing behind the rear bumper is getting bad though.

There are small plastic boxes behind the rear wheels that I removed. The bolt heads snapped and I was able to pull it right off. They appeared to have retained enough wet dirt and debris that it was almost rock hard to get out. It is bad enough to the point that it is starting to protrude into the trunk area, where I said I would dump some oil. I think a body shop will be taking care of that needless to say, and while I am there, I will ask them to look over the car and see if there are any other concerning areas.

Being in Vancouver, cars don't really rust that bad if at all here, and I don't use this car in the winter, so it is worth saving, especially since I caught it somewhat early. But I am here to ask for recommendations. I went out and bought a wire brush attachment for my drill, some sandpaper, and some primer. Are there any products and body shops in Burnaby that anyone here could recommend? I will post pictures of my progress.

I started by taking out all the carpeting in the trunk, and tried a small area to see how it would work out. I cut out a small section of the sound deadening on top of the fuel pump vicinity using a hammer, chisel and a screwdriver. I plan to take all the sound deadening out so I soaked the spare tire part with penetrating fluid and will let it sit for a day or two, although it is already working pretty good. I took my wire wheel out and cleaned up a small portion of metal. I then tried the more pitted areas. It was more difficult, although I may have got the wrong wire wheel for this application. I may try the 40 grit sand paper I got before going back to the store. Anyway, it seemed to work decently. I brushed the area with some oil (automatic transmission fluid, all I had at the time) to give it no chance of flash rusting, and will pick up tomorrow after school.

After the trunk, I feel it would be a good idea to wire wheel the frame rails and paint them too. I know all this will not preserve the frame rails forever, but I think they will last a lot longer before needing patch work. Anyone reading this should check their car out. Find and fix the cancer before its too late.
 

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95opal

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Trade your wire wheel for a flap wheel on a 4"grinder.
 

95opal

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Little tight on cash right now, but I will see what I can do about getting one. Thank you.

Harbor freight is probably the cheapest you'll get. May not be the best but it will save you hours compared to that wire wheel.
 
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Terrorist 5.0

Terrorist 5.0

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Today I began grinding down one side of the trunk floor. First, I removed the rest of the sound deadening around the noisy fuel pump. Then, using a drill with a metal brush attachment, I spent about 2 hours grinding until all visible rust was gone. I paid close attention to any holes, specifically the fuel pump wiring hole. Once it was all grinded down, I quickly went over it with some 180 grit. I cleaned it all off with brake clean and laid down two coats of primer, and a singular coat of paint. Looking around, I found some other small areas that could use a touch up, including the trunk edges, which I will take care of tomorrow, along with the other side of the trunk. This will not be perfect, but should prolong the life of the sheet metal for quite a while. On the underside, it all looks decent. I have decided against removing the sound deadening in the spare tire well, but I had already sprayed it down, so I am going to blow dry it at another time.
 

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cobrajeff96

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Most of what you have is just patina. It's good you're addressing it now, the sooner the better.

If you have any junk on the underside of the car or anywhere outside the cabin, use Fluid Film. Undercoating could be considered but it seems Fluid Film is the new king on the block and will work out better in the long run.
 
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Terrorist 5.0

Terrorist 5.0

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I would hit the bare metal with an etch primer. CTC has some good products like Dominion Sure Seal.
The primer I bought has some sort of rust prevention in it. I can’t tell you the details off the top of my head, but it turned out pretty nice so far.
 
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Terrorist 5.0

Terrorist 5.0

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I would hit the bare metal with an etch primer. CTC has some good products like Dominion Sure Seal.
The primer I bought has some sort of rust prevention in it. I can’t tell you the details off the top of my head, but it turned out pretty nice so far
Most of what you have is just patina. It's good you're addressing it now, the sooner the better.

If you have any junk on the underside of the car or anywhere outside the cabin, use Fluid Film. Undercoating could be considered but it seems Fluid Film is the new king on the block and will work out better in the long run.
it’s pretty clean, I do have some minor surface rust underneath, but it is above the axle and fuel tank. Next time it is up on a lift I may just do what I did here. By fluid film do you mean just spraying some oil underneath? I know it works pretty good for preserving raw metal, but I feel it will wash off fairly quickly no?
 

Wmac

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U should be good to go on the inside of the trunk with 2x primer plus topcoat. Basically restored it to oem condition. Not noticeable with the trunk mat and panels.

Underside may require further treatment if there is any rust perforation or metal delamination. Pay close attention to where the strut towers meet the subframe, same for any panels to the rear subframe.

I removed and replaced the seal sealer on the inside of the trunk lid this year. Used the same methods as you. Scraped off sealer, wire wheel to surface rust, 2 coats etch primer, seal sealer and then topcoat.
 

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Terrorist 5.0

Terrorist 5.0

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U should be good to go on the inside of the trunk with 2x primer plus topcoat. Basically restored it to oem condition. Not noticeable with the trunk mat and panels.

Underside may require further treatment if there is any rust perforation or metal delamination. Pay close attention to where the strut towers meet the subframe, same for any panels to the rear subframe.

I removed and replaced the seal sealer on the inside of the trunk lid this year. Used the same methods as you. Scraped off sealer, wire wheel to surface rust, 2 coats etch primer, seal sealer and then topcoat.
I am also doing the trunk in the exact same spot you did soon. There is a spot in the back wheel well where I can poke dirt out from the inside, so that is definitely a problem. A body shop will do that though.
 
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Terrorist 5.0

Terrorist 5.0

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Quickly cleaned up and painted the hell out of the other side. Also grinded down the area surrounding the sound insulation in the spare tire well and hit it with primer only. Completely done, we will see how it holds up.IMG_7915.jpeg
 

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