[Comander1990]

Anyone else have a bronco with no rust besides these spots? Trying to figure out what caused it and if they make a replacement panel for that spot. The ones I see are for the truck cab and don’t match the bronco from the seat area back. I’m not that creative or have the tools to fabricate the parts from sheet metal. For the cab corner, I plan on buying a rocker panel and cutting off the section I need and patching that in.

 

[fodder]

That's pretty heavy surface rust for spots that shouldn't pool. Have you pulled up the rest of the carpet, front and back, to make sure it's not all like that?

 

[Comander1990]

I took some time today to look it over and I couldn’t find any other spots. Floor boards front and back as well as the trunk look amazing. The underneath has lots of undercoating on it so no idea what spilled or came though in this area to eat holes through. Anyone ever find an actual bronco outer cab floor replacement panel and not the truck panel?

 

[Fredensborg]

I’ll be hunting for some of these same panels soon…found this at LMC truck. Not sure of the quality.

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[Comander1990]

If you buy them soon, let me know how it works out. I wonder if there is any difference between the 80-86 and the 87-91? I might have to call LMC and find out.

 

[Fredensborg]

Will do, but I’m sure they have panels for the 4th gen Broncos too.

 

[Stitch's 95]

Wow. The rear floor in my 95 was in bad shape. Best I can tell the door drip rail leaked and there was also a leak in the top. It had the vinyl floor and it trapped the moisture under the floor and made a huge mess.

I feel like if you had a leak causing it there would be rust all over. I would check and make sure your door drip rail isnt leaking, but I'm inclined to think the rust is comming up from the bottom. I have no experience with it, but I have heard that the undercoating material is bad to trap moisture and cause things to rust. You may want to try and peel some of it back and see.

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[Rob_64-365]

Pretty typical that the seam sealer in the drip rail has started leaking from age, the water seeps in, and runs down the inside of the roof, down the A & B Pillars, pooling where the floor meets the rockers, resulting in rusting from the inside, to the out side. Mine was just like that, and the worst of it is at the outboard foot well of the back seat as it's the lowest point. I cut it all out, and repaired it, so seal up those roof seams & the b pillar slots so they are water tight, or this is the fate you will find.

 

[Comander1990]

Thanks for the ideas. The seam sealer in the drip edges, is shot. A little rust on them and chicks of sealer missing. That must be what happened.
Rob, what did you use for patching the metal back in?

 

[Rob_64-365]

I just used 18 gage metal sheets, & cut templates, pieced it in, bending it into shape in my vice with a hammer, nothing too special, it was mostly flat, and the rust was just the first inch from the edges that were bad, so I didn't need to buy a whole floor patch panel. Check my build thread out at the bottom of my post, I go in depth on an entire truck rebuild.

 

[fodder]

It's definitely worth repairing the drip rails and b-pillars, but that doesn't explain the rust you showed in the first post. Water doesn't pool outside the door seal...

Water from above could contribute to moist carpets, but it wouldn't be just the spot rusting alongside the door sill, as that's not where the water actually collects. Water comes in around the dash and base of the b-pillar. In between is basically the high spot and least likely to be wet.

You've got something else going on there.

 

[Comander1990]

That’s what I thought originally, I just don’t know what. It’s such a strange spot for rust, especially as severe as it is when the rest of the body is great.

 

[Rob_64-365]

The bolts for the seats to mount are wide open squares with weld nuts welded to the backside of the floor pan, they go into 8x12mm square holes, somewhat open to the elements, and after 30+ years, chances are that the gooey asphalt stuck on there to prevent water intrusion has exceeded its intended life cycle.

Then the screws that attach the rocker sill covers also allow water in, and they are self tappers, so a raw edge of metal is exposed, and water seeps in. Same thing around the transmission cover, that butyl seal can give out, especially if its been removed once or twice, and maybe not sealed up again. Over 30 years, things rust, and rust does creep, not like hair sniffing, but still... unless you live in a dry desert environment, thus isn't anything out of the ordinary.

If you pull your console, seats, seat belts, and carpet to get a good look at the whole picture as it really is, anything going thru that floor has a chance of water intrusion to happen. Pulling all of this stuff out gives you a much clearer picture to see what condition your floor is and and to repair it, than just lifting the edge of your carpet.