Floor pan replacement
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New User
Joined: May 2012
Posts: 16
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Floor pan replacement
Hi there, I'm new to this site and it has been very useful to me. My driver side floor pan is rusted out and time to be replaced. I'm not great at doing body work so any hints, tips, or tricks would be great. The cab support needs replaced as well.
Thanks for the help.
Thanks for the help.
Hotshot
Joined: Jan 2011
Posts: 13,143
Likes: 348
From: THIS IS SPARTA!, ...Mo.
I would get the truck on level concrete and support the cab at the front and rear of the rocker panel before you cut anything apart. This way, nothing will move on you and create fitment problems later. Measure, measure again, line it up, measure one last time, cut the panel big, line it up, trim it down a little, line it up again, etc, etc, etc.
Trim the panel a little at a time and sneak up on it. There's nothing worse than cutting too much off at once and having to make a patch for the patch. Take your time.
Trim the panel a little at a time and sneak up on it. There's nothing worse than cutting too much off at once and having to make a patch for the patch. Take your time.
Postmaster
Joined: Oct 2010
Posts: 4,656
Likes: 4
From: Northern and Southern Cal
How much cab mount /support is gone?
Here are some links that may help you.
If it's the body thats going.
LMC Truck Parts - Page 18
If it's the frame perches.
Frame Saver Truck Complete Kit Set of 6
There are loads of places to get body parts.
In the picture I attached, notice the support chanels at the front of the hole. If you can, try to save that.
Also if you do it on the frame as I did, put some sheet metal between the floor and frame to protect things like fuel lines, lest armageddon comes early.
Have fun.
Here are some links that may help you.
If it's the body thats going.
LMC Truck Parts - Page 18
If it's the frame perches.
Frame Saver Truck Complete Kit Set of 6
There are loads of places to get body parts.
In the picture I attached, notice the support chanels at the front of the hole. If you can, try to save that.
Also if you do it on the frame as I did, put some sheet metal between the floor and frame to protect things like fuel lines, lest armageddon comes early.
Have fun.
Lead Driver
Joined: Mar 2010
Posts: 5,250
Likes: 11
From: West Virginia
I'd recommend welding the cab support, but you can also trim outside the rust, cut the patch larger, and use body adhesive and/or rivets. sheet metal is a real pain to weld if you don't have much experience.
Lead Driver
Joined: Mar 2010
Posts: 5,250
Likes: 11
From: West Virginia
wow, in regards to the above picture, I would also say that in most parts of the country you can still find rust free cabs for $300 or so, maybe less if you are in the southwest. Its a good bit of work to swap a cab, especially if you are swapping your interior over into the cab, but when compared with welding in new floors, cab mounts, and inner/outer rockers, I'd choose a cab swap.
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Postmaster
Joined: Oct 2010
Posts: 4,656
Likes: 4
From: Northern and Southern Cal
wow, in regards to the above picture, I would also say that in most parts of the country you can still find rust free cabs for $300 or so, maybe less if you are in the southwest. Its a good bit of work to swap a cab, especially if you are swapping your interior over into the cab, but when compared with welding in new floors, cab mounts, and inner/outer rockers, I'd choose a cab swap.
But if his mounts/rockers are garbage you could be right.
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Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 83
From: NorCal
Been there. Done that.
The principles are the same so below are some pics from replacing the floorpans of my 65 Mustang.
Tools: Miller 140 with Autoset, Hobart plasma cutter, Blair spot weld cutters, Harbor Freight hole punch tool, DeWalt grinder with a flap wheel, Harbor Freight grinder with a cut-off wheel, body hammers, dollies, C-clamps, magnets, snips, drill driver, self tapping screws, scrapers, center punch, ballpeen hammer, Sharpies, straight edge. Patience.
Process:
Tools: Miller 140 with Autoset, Hobart plasma cutter, Blair spot weld cutters, Harbor Freight hole punch tool, DeWalt grinder with a flap wheel, Harbor Freight grinder with a cut-off wheel, body hammers, dollies, C-clamps, magnets, snips, drill driver, self tapping screws, scrapers, center punch, ballpeen hammer, Sharpies, straight edge. Patience.
Process:
- Buy the replacement panels so you know how far it will reach.
- Remove all bad metal. You want enough thick metal to weld to and ya can't weld to rust.
- Saving crossmembers - drill holes from underneath along the crossmember edges and corners. Then "connect the dots" on top to avoid errantly cutting into the crossmembers.
- Lightly grind down the spotwelds and center punch all of them.
- Spot weld cutters work better if ya push them square into the panel. You can rock them around a bit once it starts to bite. Blairs seem to be longer lasting.
- I choose to butt-weld. After cutting out the cancer, put the sectioned pan on top of the new pan and loosely trace around it. Also identify where they will rest on a crossmember and drill 1/-8-inch holes for self tapping screws.
- Place the pan into the truck and trace around its perimeter where it will be butt-welded to the existing pan.
- Sneak up to the final dimensions... grind, grind, grind and sneak up to the final fit. Aim for 1/16-inch gap.
- Drill the pan for crossmember holes (about every 1.5 inches) and punch any flanges (like along the rocker) every two inches.
- Attach the pan to the crossmember with self tapping screws.
- Tack weld every two inches along the butt joint tacks along the rocker
- Ready for final welding? Burn it in. Jump around to avoid excessive heat in one area to avoid warping. You'll want to create a solid continuous weld made of spot welds at the butt joint.
- Grind, grind, grind. Avoid over-grinding and thinning the metal.
- Apply seam sealer to both sides of the butt welds and along the rocker seams.
- Paint (I like Eastwood Rust Encapsulator or POR-15). I went so far as to paint the underside of the seat pan in the last pic.
- Crack a couple of cold ones and celebrate!
Laughing Gas
Joined: Jan 2012
Posts: 1,106
Likes: 25
The principles are the same so below are some pics from replacing the floorpans of my 65 Mustang.
Tools: Miller 140 with Autoset, Hobart plasma cutter, Blair spot weld cutters, Harbor Freight hole punch tool, DeWalt grinder with a flap wheel, Harbor Freight grinder with a cut-off wheel, body hammers, dollies, C-clamps, magnets, snips, drill driver, self tapping screws, scrapers, center punch, ballpeen hammer, Sharpies, straight edge. Patience.
Process:
Tools: Miller 140 with Autoset, Hobart plasma cutter, Blair spot weld cutters, Harbor Freight hole punch tool, DeWalt grinder with a flap wheel, Harbor Freight grinder with a cut-off wheel, body hammers, dollies, C-clamps, magnets, snips, drill driver, self tapping screws, scrapers, center punch, ballpeen hammer, Sharpies, straight edge. Patience.
Process:
- Buy the replacement panels so you know how far it will reach.
- Remove all bad metal. You want enough thick metal to weld to and ya can't weld to rust.
- Saving crossmembers - drill holes from underneath along the crossmember edges and corners. Then "connect the dots" on top to avoid errantly cutting into the crossmembers.
- Lightly grind down the spotwelds and center punch all of them.
- Spot weld cutters work better if ya push them square into the panel. You can rock them around a bit once it starts to bite. Blairs seem to be longer lasting.
- I choose to butt-weld. After cutting out the cancer, put the sectioned pan on top of the new pan and loosely trace around it. Also identify where they will rest on a crossmember and drill 1/-8-inch holes for self tapping screws.
- Place the pan into the truck and trace around its perimeter where it will be butt-welded to the existing pan.
- Sneak up to the final dimensions... grind, grind, grind and sneak up to the final fit. Aim for 1/16-inch gap.
- Drill the pan for crossmember holes (about every 1.5 inches) and punch any flanges (like along the rocker) every two inches.
- Attach the pan to the crossmember with self tapping screws.
- Tack weld every two inches along the butt joint tacks along the rocker
- Ready for final welding? Burn it in. Jump around to avoid excessive heat in one area to avoid warping. You'll want to create a solid continuous weld made of spot welds at the butt joint.
- Grind, grind, grind. Avoid over-grinding and thinning the metal.
- Apply seam sealer to both sides of the butt welds and along the rocker seams.
- Paint (I like Eastwood Rust Encapsulator or POR-15). I went so far as to paint the underside of the seat pan in the last pic.
- Crack a couple of cold ones and celebrate!
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 83
From: NorCal
That floor pan took me one weekend and the passenger side was completed the following weekend. Being methodical without interruptions makes things go faster.
