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Floor Pan R&R

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Bfix Staff
Bfix Staff

Joined: 13 May 2004
Posts: 48

PostPosted: Tue Aug 31, 2004 11:21 am    Post subject: Floor Pan R&R Reply with quote

One of the cardinal rules of owning an Early Bronco should be "Donít put house carpet and rubber pad in the front". If not that at least "When you buy an Early Bronco with house carpet and rubber pad in the front check under it for rust". In the Bronco I got for my wife the previous owner did not follow #1 and I did not adhere to #2. When I pulled the carpets out of an otherwise almost rust free uncut 1967 Bronco I found floorboards that were totally rotted. Big ugly brown scaly boils. A few taps with a screwdriver and I knew there was no hope of saving any of it with a brush and POR.

I had heard the horror stories and since this Bronco was to be a more or less daily driver/fun mobile for us I wanted to make sure the job was done right. I asked around and found a PSVB member experienced in the job at hand and dumbÖuh..helpful enough to offer me a hand. I have to thank Eric (Neasham) for his expert help and advice. If anyone is ever lucky enough as to talk him into helping on a Bronco project their in for some first class work. The first thing he had me do was cover the windshield and speedo housing with cardboard. The sparks will fly and you don't want to have any pitted glass.

Here is what the drivers side floor looked like. I removed a piece with the Sazall "just to look". If anyone has the little inspection plate on the hump next to the t-case shifter I would like to know. We had never seen one before and it looks like a factory or very good aftermarket job.
The pan's I got from Tom's Bronco parts. They did not have the stamped in stiffener rib's or the dimple for the body mounts they were just the plain sheetmetal. Eric had a slick way to dimple them that I'll show you later. They fit very well and had some sort of plating, from the way it burned and smelled it was probably zinc. Wear a mask when welding. If I was going to have to do it again I would have gotten the one's with the dimple and the ribs, but I'm NOT going to do it again.

Obviously you will need to remove the seats and have a welder (if it's not a MIG forget trying). A Plasma cutter would be nice, a grinder and plenty of disc's, a torch, Sawzall, and anything else you can talk your wife into letting you buy.

You need to get out the two body mount bolts. Mine were totally rusted and I had to grind the head's off and drive them out. I'll put in new bolts and washer's when I'm done. Then you put your pans in the floor and make a mark all the way around. You have to remember that this is NOT the line you cut on. This is a reference line only. You make a mark about 3/4" to an inch below the mark you just made. What happens if you don't, is the pan sits lower when you remove all the old metal and your going to have a big gap to somehow fill. You want to do a 'lap' joint not try for a perfect butt fit. This photo shows the original line we made and how low the pan sits after the old floor was removed.

Check and see where you brake line, fuel line and wiring are. Even with checking and being careful we nicked the plastic fuel line. I just cut it and we used clamps to seal it off at the tank and will replace it later. I don't like the plastic fuel line that well anyway. We used the Sawzall to cut out big pieces and as much as we could without cutting the 'hat' sections that re-enforce the floors. Once you get the big pieces cut out from around the support's the 'fun' begins. What I found to work for me, you you might come up with something better, is to mark the top of the rib and just start grinding down through till the spotwelds loosen and peel back the old floor from the support. Cut off that sections and start grinding again. Either a small air grinder with a thin blade or a disc grinder. I have a Makita and Eric had one he got from Harbor Freight for $19. I was impressed with it. For the money if it had held up for just that job it would have been great but he's had it awhile and it's still 'grinding' away. If you do it this way it will start looking like this.

Notice in this picture where the e-brake cable, brake line and wiring run. You might also be able to see where the e-brake cable is worn real bad. I'll be ordering a new one and before I put it in put a rubber sleeve over it to help it last longer.

Ok, so you keep grinding away the old rusty metal. Always check it twice, do a little at a time and think ahead of how you want it to be when your done. After all the old metal is gone your floor should look something like the next two pictures.

If your support members are rusted out and need replace you probably should have checked them first. Otherwise your body would be sagging about now, so, insert the following at the beginning of this article. "Inspect your crossmembers from underneath prior to any cutting. If they are rusted out and need replaced support the rocker panels so the body won't sag.

When you get to this point its time to do a bunch of cleaning. Wire brush all the rust you can find, scrape, pick, hammer and use that new Shop Vac you bought. Whatever you have to do to get rid of it. Completely grind off all the spotwelds and any other area that will keep the replacement panels from sitting flat and snug.

The next step is probably the most important one of all. Send your wife to the store for "blank" (insert number of helpers) nice thick T-bones. You should already have a good beer in the cooler. If you have trouble with this step sell the Bronco and buy a Jeep.

Next fire up the BBQ and cook the steaks the way you like them. Remember to use the BBQ as cooking over an acetylene torch leaves an funny taste and does not cook evenly. Eat the steaks and drink some beer then get the hell back to work!

Now the floor should be prepared to fit the new floor pans. Make sure the new pans fit snug and look about like you want them to look when your done. Have someone hold he pan tight to the floor and from underneath mark when the body mount bolt goes and mark a line where the support is. After you take the pan up again it's a good time to coat the inside of the supports with something to help prevent rust. I soaked them in Hammerite, you could use POR-15 or something else. Anything is better than nothing. While that is drying it's time to work on the new pans. If you got the ones with the dimple and ribs you can enjoy another beer and skip ahead. For those of us who didn't read on and we'll catch up later.

Where you marked for the body mount drill a hole. I made mine7/16th, because that's the size bolt I had for the 'dimpling jig' Eric had me make. (see next picture)

It's a 1 1/4" socket, a 3/4" socket, a washer, a ball joint sleeve, a washer all put on a long bolt. You stack it up on your pan where the body mount hole is, MAKE SURE THE SMALLER (3/4") SOCKET IS ON THE TOP SIDE. When it's all together you heat the top side with your torch and when its red around the small socket tighten the bolt till you have a dimple big enough to recess the body bolt and washer. It only takes a few minutes and works great.

You end up with a 'dimple' that look's like this.

Where you marked the location of the lower supports you need to drill some hole so you can plug weld the pans back to the supports. Remember all that nasty grinding to get rid of those spot welds? You need to re-weld your pans there and plug welds are the best way to do it. And since this is the section for those of us that didn't get the pans with the ribs and the dimple, we also have to add some small 3/4X3/4 angle to the bottom of the pans to prevent "oil canning".

Drill a line of 5/16 or 3/8 holes just inside the lines you made where the supports are. Do both sides of the supports. Make sure that they are where you want them or you will be welding up a lot of holes. Cut some small pieces of the angle and weld them to the bottom of the pan. The next picture shows the bottom of the passenger side ready to install. You can see the scribed lines and the location of the holes.

Your now ready to weld in the pans. Set them in position and make double sure they are where you want them. Put a tack weld on one edge on the transmission hump. Keep holding the pan down tight and work your way across the tunnel putting a tack about every 6 inches. Double check the location and make sure it hasn't pulled away. The tunnel is the easiest place to grind off a few tack weld's if you need to re-position it. If every thing is OK you can start doing the plug welds. We took a piece of wood about 16' long and a 4 foot piece of 2x4 under the dash and used it to push the pan down tight for plug welding. It worked very good. After all the plug welds are done you can weld up around the edge of the pan. Make sure to wear some sort of face mask. You don't want to breath those zinc fumes. When the welding is done your floor should look like something like this.

As far as finishing it goes. I'll be coating the cut seams underneath with seam sealer, then a coat of Hammerite and finally a good undercoating. It's a great project for a couple of guys with nothing better to do on a Saturday than drink beer and work on the Bronco. The top will get cleaned up, primed and painted with Hammerite then the whole inner tub will be done in Herculiner. I liked the way Brian Cooke's Herculiner came out and I'm going to give it a try. Hope I can talk him into coming over to help.
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Bfix "What's a Bronco?"

Joined: 07 Jul 2006
Posts: 13
Location: Fayetteville NC

PostPosted: Fri Jul 07, 2006 7:04 am    Post subject: Reply with quote

That is exactly the same way I get things done;Freinds, beer and Steak. I did this mod on my last Bronco but this time I used Aluminum instead, so far so good. I did have trouble bending it though so I used an angle finder and had a local metal shop bend it for me. I still need to finish the tunnel but it sure drains good with out it being completely done. Great tech tip!

Mod Freak
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Bfix "What's a Bronco?"

Joined: 01 Jul 2002
Posts: 12
Location: San Diego

PostPosted: Wed Jan 30, 2008 5:01 pm    Post subject: Old topic but new question Reply with quote

Did you fair in the edges? I am going to be rhino lining but I dont know If I need to fair it in to look a bit better.

Also If I bondoed the edges will the rhino still be good to go?

72 351W
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Bfix Rockin
Bfix Rockin

Joined: 24 Dec 2007
Posts: 323

PostPosted: Sat Feb 02, 2008 9:33 pm    Post subject: Reply with quote

Ah, floor pans what a joy to find out you need new ones. My right foot and gravity teamed up together to tell me I need to replace them, I have battlewounds now Laughing
74' w/ 351 W
-5.5" lift
-35" KM2's
-3 speed on the column

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Bfix "What's a Bronco?"

Joined: 27 Jan 2009
Posts: 2
Location: Chino Valley, AZ

PostPosted: Sat Jan 31, 2009 7:20 am    Post subject: MIG welder Reply with quote

You state that if you don't have a MIG forget trying. I'm pretty ignorant on welding so why couldn't a wire feed arc type be used? Was MIG around when they built the floors? I need to replace the drivers side pan and won't remove it until I can access what I need to put the new one in.

Old Guys Rule
68, 302, d-44 front, alot of worn out stuff but
slowly getting better.
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