Inner fenders - Rust, Defeated!

"Just give it a tap tap tappy!"

Minor frame box repair

After fighting with an inferior patch panel to repair the rusted battery apron, struggling, and ultimately failing and having to rip out the bad repair, I ordered a nicer replacement panel. This time around I decided just to grind out all the spot welds and replace the entire panel. Glad I did, since when removing the whole panel I discovered that the rust that ate the battery tray, core support, and battery apron had also eaten holes in the frame box underneath. So before I could focus one the battery apron, I needed to repair the frame first. It was not a huge deal, but totally required. I also took the opportunity to arrest some of the rust inside the frame box and wiring tunnel under the core support.

 

 

Battery apron repair

New battery apron, plug welded in

After completing the frame patch, next task was to replace the battery apron. I used my new sheetmetal punch to  make the holes for the plug welds. After fitting and snugging the panel, I plug welded it in.  Some self-etching primer was applied when finished. This also tied the core support back to the unibody, which had been flopping around while I chased the rust problem down.

Interestingly, I will not be putting the battery tray back in since we're relocating the battery to the trunk. My friends in the LS Mafia suggest the pocket might be the perfect place to locate a turbo! (Noted. No turbo in the plan, but hey, they're right about the fitment possibilities)

 

Driver's side inner fender rust repair

Rust repair patch, fitted to the driver's inner fender

The inner fender on the driver's side was not nearly as rusted as the passenger, but there was a strip where a flange was plug welded on, and trapped moisture had rusted it through. This did not warrant a full panel replacement, so I decided to fabricate a patch to repair it in place.

Inside the fresh air intake, under the cowl- repaired with fiberglass and epoxy

I also repaired the fresh air vent intake inside the cowl on the driver's side with some fiberglass and epoxy so that it would both not rust any further and not leak. This was to fix the pinholes that might let rainwater into the interior of the car when it rains, but without having to perform a complicated and time-consuming disassembly of the cowl and firewall portion of the unibody 

I finally welded in the patch and it looks good. Welding to the old metal can be tricky, but I am getting better at it, as evidenced by the increasingly neater welds.

Take that, Illinois!


More pics

Treating rust in the wiring box under the core support

Test fitting a fabricated frame patch

Using my sheetmetal punch

The fresh air vent after rust treatment, but before the pinhole repair

Fabricating the inner fender patch - test fitting to see if contours match

Using spray paint to mark where I need to cut

Adjusting fitment of the patch with a hammer and dolly

Finished patch

Long wintery gap, full of hand wavy. Now we're back at it!

Yeah, my last post was in December. Why no Mustang progress? So winter happened, no heat, compressor idle, and an electrician who is 5 jobs deep happened. I took some time off. It's been pretty mild in Illinois for the last 2 weeks though, so I put on my longjohns and jumped back in. Still waiting for the electrician though. As appropriate, we'll probably have shop heat by July!

Screwed up some sheet metal

This looks almost ok in this pic. I wasn't happy with it though.

Sorta. I cut the rusty battery apron so I could section in some new sheet metal. As luck would have it, the replacement piece was not very good quality- it fit poorly and was, I dunno, just weird. I went for it and cut it in, but there were some unsettling gaps. I mean I measured 4 times, templated, traced, all that. But after tacking it in place and removing and reworking, then tacking in place again I decided it looked like shit and tore it out. For giggles (and because the welder was burning through inexplicably), I gauged the metal, and found that it was weird because it was 20 gauge sheet, not 18 (crap). So I "saved" $20 on this cheaper panel. And it cost me more since I threw it in the trash after all that cutting and fitting, then ordered a better quality one. That's not even factoring my time spent trying to push a bad position. Dad was right. Just pay for quality and shut up, it's easier and cheaper in the end.

water in, water, detergent, and debris out!

Dead mouse count up to 7

I thought I had found all of the rascals, but when I blew some compressed air into the end of the cowl to do a quick clean-out there was nesting and skeletal mouse bits. I didn't expect the cloud of crap that blew out the other side when I started. Turns out the fresh air intake was filled in places one can't see with more mud wasp and mouse nests. After an hour, I chased the last of the debris out. I finished up by dousing the channels with detergent and flushing with water. I didn't have to open up the cowl, so a huge win there.

Found a new challenging thing (spoiler alert: more rust)

So why was I flushing out the cowl? While waiting for the new battery apron I decided to get back on the horse and start work on the driver side cowl, which rusted through where it mated to the firewall and the floor. I did not get a shit-cheap panel for this replacement (made sure this time) so we're ready to rock. I cut some of the firewall and some of the cowl back. I noticed once this was opened up that I had easy access to the fresh air intake. Since it'd be easier to work with that removed, out it came. Then the fun started. I noticed immediately that the flange for the cold air intake (the part that keeps water that gets in the cowl vent from pouring inside the car) was rusted pretty badly, with a few holes all the way around.

Fresh air intake flange - rusty but savable

This is a common weakness in the '65 Mustang. I just figured that since the cowl looked ok from the inside, it wasn't a thing. Given that replacing the cowl would be a gigantic crazy deal, I resolved to repair the fresh air intake with a sleeve epoxied in place. I ended up removing the cold air flapper, cleaning it up and repainting it with POR15. I removed the wiring harness since it was in the way (and we're replacing it anyway), then hit the panels inside the car with a wire wheel. I finished by arresting all the surface rust on the inside of the firewall and cowl with POR 15.

More pics

Cut out a bit of rusty firewall, saving the rib

Broke some spot welds, looking to replace most of the cowl side with new sheetmetal

removed the fresh air flapper -it was filled with debris!

prepping the air flapper for rust arresting epoxy

all done

cleaned up the inside of the firewall

firewall and cowl painted with POR15

fresh air intake cowl flange painted with POR15