rusty trunk

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jackpotts

Active member
Joined
Mar 28, 2016
Messages
26
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Location
Los Angeles, CA
My Car
'73 Mustang Coupe, 302 4bbl
So I realized that the trunk pan is a lot rustier than I thought, with a hole straight through in one place. There is no rust anywhere else on the car, but the trunk is pitted in a few places.

How much of a problem is this? If I don't address it, will it spread?

 
Post up a picture of the rusted areas.

The rust should be addressed and if not it will continue to spread.

Often wire wheeling away all of the rust you can get to, will reveal the full extent of the damage.

There are numerous rust treatments available that all work in varying manners. I like Evaporust if you can keep the part wet for a few days it does a great job. It doesn't stink, it doesn't burn skin and it is biodegradeable.

As to the hole- it depends on where it is and how big it is. There were two access plugs over the frame rails. If it is one of these then it is easy enough to get a new plug. If it is a true rust hole, then if it is small you can fill it with seam sealer and spread it smooth. If it is up to about 2" you can cut a metal patch and just glue it down with seam sealer or body adhesive. If it is larger than that, I would start to consider replacing the trunk floor.

Welding up the old rusted sheet metal is difficult as it burns through quite easily, and in this case would require removal of the gas tank to get good access and be safe. If the metal is mostly solid, but you are concerned about the cosmetics you could buy a trunk floor, trim it to fit as a "cap" and glue it in with structural automotive adhesive for a very hard to spot repair. Not good enough for a show car, but for a hot rod this works just fine.

 
Pictures would help.. When I have a floor that's badly rusted, I cut out the rotted area and section in a replacement. If you're handy with a mig or tig welder, the sheet metal can be tack welded into place a spot at a time in opposing locations as to not warp the metal.. Then, fill in with tack welds.. Grind the surface smooth and prep for paint..

Another method, if not rusted too bad, is to de-rust all areas and seal the area with POR or equivalent rust converter, fill any minor holes with (in my opinion) mat fiberglass and prep for paint.

Pictures show rot holes in the trunk and the progress on sectioning in new sheetmetal. It's not for the light hearted..

Mach 1 6-2-13 005.JPGMach 1 6-2-13 006.JPGLt side trunk floor repaired.jpg

 
For the damage Piper shows, I'd have cut a panel to overlap the depression and put it in with auto body adhesive, then dressed the seam down around the edges with a flap wheel after curing, and seam sealed it neatly. Then again, I have access to a nice supply of sheet metal and a nibbler and could probably fab that part up in less than 10 minutes.

Fiberglass works fine too, I've just used enough of it on building a boat that I don't care to work with it.

Please don't take my comments as being critical cause I think your work looks great.

Again, the extent of the damage will determine which options are appropriate for your car.

 
I will reiterate what Jeff mentioned above. Burning through the panels with a welder is very easy to do, especially the floors and trunk pan. While my recent situation was not a rust issue but a Dumb PO who though it was a good idea to cut four holes in the drivers side floor to try to retrofit an incorrect seat frame. It was a PITA to weld in the patches without burning through. A lot of patience is required. Didn't help I was laying on my back under the car while welding either. But got them in, ground down and sealed with seam sealer and painted. Can't even tell they were patched. The guy who initially taught me how to weld taught me on very thin sheet metal, telling me the thick stuff is easy. If you can weld thin sheet metal without burning holes in it or warping it, you can weld up about anything.

 
I will reiterate what Jeff mentioned above. Burning through the panels with a welder is very easy to do, especially the floors and trunk pan. While my recent situation was not a rust issue but a Dumb PO who though it was a good idea to cut four holes in the drivers side floor to try to retrofit an incorrect seat frame. It was a PITA to weld in the patches without burning through. A lot of patience is required. Didn't help I was laying on my back under the car while welding either. But got them in, ground down and sealed with seam sealer and painted. Can't even tell they were patched. The guy who initially taught me how to weld taught me on very thin sheet metal, telling me the thick stuff is easy. If you can weld thin sheet metal without burning holes in it or warping it, you can weld up about anything.
Having welded my share of sheet metal, I couldn't agree more. You won't need a Lexicon of cuss words, you'll make them up as you go.

:D

 
If your trunk looks better than this, then you don't have a problem. lollerz

attachment.php


 
If your trunk looks better than this, then you don't have a problem. lollerz

attachment.php

while driving the Mustang you can hear better the engine sound and the smell of exhaust fumes

rofl rofl rofl rofl rofl rofl rofl rofl rofl rofl rofl rofl rofl rofl rofl rofl rofl

 
If your trunk looks better than this, then you don't have a problem. lollerz

attachment.php

lmfao! rofl ...

I too learned to mig weld in the 1990's, laying on my back, on a stone driveway, in the full sun, in the 95° hot/humid summer. I would lay under there (at that time it was my 1970 Bronco) in shorts and a t shirt and nothing could stop me. Burn marks all over me. Passion.

 
If those are the only holes you may want to just patch them. But if you find any more I would say replace the full pan. Its not too bad just takes time and patience in drilling out all the spot welds on the frame rails. I only have these 2 pic of when I was doing mine. I had a bunch but cant find them now?? And contrary to popular belief you do not need to remove the taillight panel to fit in a full size trunk pan. it will fit through the trunk opening, BARELY!

2s7hzqv.jpg


 
As soon as I get brave enough, I'll be replacing the trunk floor, tail light panel, trunk drops, and a portion of one quarter....oh, and fender aprons up front. I have no experience with this sort of work...going to get my feet wet replacing the radiator support on my ranchero. The radiator support actually looks like it's not that hard...it's the tail light panel on the mustang that scares me the most.

 
Here is a link to the work I did in my trunk a few yrs ago, if you are replacing the full floor pan, you will need to remove the tail light panel to get the pan in as one peace.

http://www.7173mustangs.com/thread-work-on-tail-light-panel-last-update?pid=118830#pid118830
The taillight panel don't need to come out to do a full pan. I did mine. Its tight, but can be done. I even replaced my trunk pan AFTER the car was painted....Brilliant I know!!
I heard it can be done, but not easy!!

 
If your trunk looks better than this, then you don't have a problem. lollerz

attachment.php

lmfao! rofl ...

I too learned to mig weld in the 1990's, laying on my back, on a stone driveway, in the full sun, in the 95° hot/humid summer. I would lay under there (at that time it was my 1970 Bronco) in shorts and a t shirt and nothing could stop me. Burn marks all over me. Passion.
Trunk? What trunk? you sound like me learning how to weld.

 
If your trunk looks better than this, then you don't have a problem. lollerz

attachment.php
is the chain for holding the spair tire ?
Actually, that handy-dandy dee-vice was the previous owner's solution to keep the front end of the gas tank in-place under the car. I'm guessing by the precision holes drilled by a torch, that was at least a 3 six-pack job. rofl

 
Well, this is going to be a pain. I have zero experience welding. I guess that's what makes it a project, huh?

In the meantime, I think I will wire wheel it to get the cancer out, and keep the heavy carpet in the trunk to cover the holes. Luckily it doesn't rain or snow here. It looks like the last guy put some sort of black coating on everything to hold the rust at bay. I'll take some pictures at lunch.

Do I need to drop out the gas tank before doing this so I don't blow myself up?

 
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