Floor pan removal and replacement?

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JeremyAB95

JeremyAB95

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I'll be replacing the floor pans and trunk pan on my Duster and from what I understand they're just plug welded in.

Is there any reference material for body work like a structural repair manual or something? I need to know what I'm getting into and know all the attach points, etc. I have the 1970 Plymouth Service Manual, but the chapter in that for body work only has entries about the doors and glass and trim.

Wisdom and relevant data would be much appreciated.
 
Lots of material on the web and even this site. I suggest get a good spot weld cutter, grinder and a welder.

I just did the floors on my 66 dart, first time and was eaiser that expected.

If could do it again i would have done full floor pan rather than 4 patches.
 
340.. Curious if you removed your gas line while cutting and welding? I too am contemplating doing my own pans but I'm afraid of blowing myself up.
 
340duster340 said:
Lots of material on the web and even this site. I suggest get a good spot weld cutter, grinder and a welder.

I just did the floors on my 66 dart, first time and was eaiser that expected.

If could do it again i would have done full floor pan rather than 4 patches.
Click to expand...
I did find a useful post and an article in Mopar Muscle about it, but is there any technical data? I have more body work coming down the pipeline, but the floors right now are the priority. How did you weld it: stick, gas, MIG?
 
The full original section (entire floor and entire trunk bottom) were spot welded in. Replacement is often done in smaller sections. So you plug weld where they hit original spot welded edges and onto the frame, but more likely overlap and stitch the cut parts. Front of floor pan is a downward flange - not easy to get to all the welds. While there could be a procedure for changing the entire floor, that's not going to help if doing sections.cause rust eats each one a little different. Best thing is to search posts for someone that started similar to where you are at. I did left and right fronts plus some of the lower firewall. Here's a couple posts from my build.
Cinnamon 75 Duster \
Cinnamon 75 Duster \
 
Good Morning Guys,

I own a welding company for 23 years and have done more floor pans than I care to remember in 30plus years of adulthood.
*Practice on welding on spare same thickness metals before you start if welding is a weak subject for you. You cannot start welding and immediately be a super star. Wear safety glasses always and a welding shield and good leather gloves. On TV you see people all the time welding with out safety gear and is stupid. Watch U-tube for welding in body panels for visual guidance help as well.

*First off- remove all the interior up 24" from the welding area- anything you leave in the car including carpet can continue to smolder for days before it burst into flames. All interior removed is recommended for safety reasons.
*Fuel lines and fuel tank removed or at least safely capped off is recommended. Fire extinguishers (at least 2- one near the car near where you are working and one near the doorway if someone needs to come in if there was afire. I know, I know - its a bit over kill, but safety is not laughing matter. Cover all glass with welding blankets or thick cardboard and good duct tape. Glass is ruined so easy by hot sparks.
*Remember to remove anything that cannot withstand up to 1200 degree burns. some of the molten metal and rust / slag get up to 900 degrees.
*If you cannot cut the spot welds with a spot weld cutter like a Blair rotary cutter bit. just flat grind over the weld thru the metal you want to remove with a hand grinder.
*Use a "whizzer" or otherwize known as a cut off wheel to cut the majority of metal out of the way leaving only the frame rails.
*The new metal needs to be cut and shaped a bit because they are never perfect.
Line up the panels and pre drill like 3/8" holes where the old spot welds are and using a MIG welder, fill the circles thru the base metal (original frame metal) and make sure the two pieces of metal (original frame and new floor) are as tight together as possible.
*seal your joints like the factory did- dont use silicone... it does not last. 3m makes a good paintable seam sealer like $7.00 for a caulk tube size and can be bought at like napa or auto body supply company..
Good luck and hope I helps some.
I commend you on trying this process and going out of your comfort zone. Good for you!
Joe
 
Syleng1 said:
Good Morning Guys,

I own a welding company for 23 years and have done more floor pans than I care to remember in 30plus years of adulthood.
*Practice on welding on spare same thickness metals before you start if welding is a weak subject for you. You cannot start welding and immediately be a super star. Wear safety glasses always and a welding shield and good leather gloves. On TV you see people all the time welding with out safety gear and is stupid. Watch U-tube for welding in body panels for visual guidance help as well.

*First off- remove all the interior up 24" from the welding area- anything you leave in the car including carpet can continue to smolder for days before it burst into flames. All interior removed is recommended for safety reasons.
*Fuel lines and fuel tank removed or at least safely capped off is recommended. Fire extinguishers (at least 2- one near the car near where you are working and one near the doorway if someone needs to come in if there was afire. I know, I know - its a bit over kill, but safety is not laughing matter. Cover all glass with welding blankets or thick cardboard and good duct tape. Glass is ruined so easy by hot sparks.
*Remember to remove anything that cannot withstand up to 1200 degree burns. some of the molten metal and rust / slag get up to 900 degrees.
*If you cannot cut the spot welds with a spot weld cutter like a Blair rotary cutter bit. just flat grind over the weld thru the metal you want to remove with a hand grinder.
*Use a "whizzer" or otherwize known as a cut off wheel to cut the majority of metal out of the way leaving only the frame rails.
*The new metal needs to be cut and shaped a bit because they are never perfect.
Line up the panels and pre drill like 3/8" holes where the old spot welds are and using a MIG welder, fill the circles thru the base metal (original frame metal) and make sure the two pieces of metal (original frame and new floor) are as tight together as possible.
*seal your joints like the factory did- dont use silicone... it does not last. 3m makes a good paintable seam sealer like $7.00 for a caulk tube size and can be bought at like napa or auto body supply company..
Good luck and hope I helps some.
I commend you on trying this process and going out of your comfort zone. Good for you!
Joe
Click to expand...
Good stuff. I had the doors open when welding, so the panels were out of the way. I had cut the front of the carpet while the seats were still in. Don't know what I was thinking not pulling the rest of it out before welding, would have taken a whole 5 minutes....:BangHead:
 
If replacing the entire floor pan at once, I suggest adding some cross bracing between the sides of the passenger area before you cut to be sure you hold the factory dimensions. Depending on how the vehicle is supported, and whether or not the engine / tranny/ rear end is still in place, you can get a lot of flex if you start cutting without some reinforcement to hold it. If you watch this type of work online or TV, you can see how the bracing is done. And double what Syleng1 said about welding practice. I had 20 years of experience as a welding supervisor in shipbuilding and welding on thin material is an art that takes practice. Looks easy, but it's easy to screw up.
 
JeremyAB95 said:
I did find a useful post and an article in Mopar Muscle about it, but is there any technical data? I have more body work coming down the pipeline, but the floors right now are the priority. How did you weld it: stick, gas, MIG?
Click to expand...
definitely use a mig .
 
Syleng1 said:
Good Morning Guys,

I own a welding company for 23 years and have done more floor pans than I care to remember in 30plus years of adulthood.
*Practice on welding on spare same thickness metals before you start if welding is a weak subject for you. You cannot start welding and immediately be a super star. Wear safety glasses always and a welding shield and good leather gloves. On TV you see people all the time welding with out safety gear and is stupid. Watch U-tube for welding in body panels for visual guidance help as well.

*First off- remove all the interior up 24" from the welding area- anything you leave in the car including carpet can continue to smolder for days before it burst into flames. All interior removed is recommended for safety reasons.
*Fuel lines and fuel tank removed or at least safely capped off is recommended. Fire extinguishers (at least 2- one near the car near where you are working and one near the doorway if someone needs to come in if there was afire. I know, I know - its a bit over kill, but safety is not laughing matter. Cover all glass with welding blankets or thick cardboard and good duct tape. Glass is ruined so easy by hot sparks.
*Remember to remove anything that cannot withstand up to 1200 degree burns. some of the molten metal and rust / slag get up to 900 degrees.
*If you cannot cut the spot welds with a spot weld cutter like a Blair rotary cutter bit. just flat grind over the weld thru the metal you want to remove with a hand grinder.
*Use a "whizzer" or otherwize known as a cut off wheel to cut the majority of metal out of the way leaving only the frame rails.
*The new metal needs to be cut and shaped a bit because they are never perfect.
Line up the panels and pre drill like 3/8" holes where the old spot welds are and using a MIG welder, fill the circles thru the base metal (original frame metal) and make sure the two pieces of metal (original frame and new floor) are as tight together as possible.
*seal your joints like the factory did- dont use silicone... it does not last. 3m makes a good paintable seam sealer like $7.00 for a caulk tube size and can be bought at like napa or auto body supply company..
Good luck and hope I helps some.
I commend you on trying this process and going out of your comfort zone. Good for you!
Joe
Click to expand...
Good advice! Would you say stick or gas is adequate for doing the spot welding? I only own the equipment for that and I am unsure about spending money on MIG or TIG equipment unless it is absolutely necessary.

Thanks
 
supertruck said:
If replacing the entire floor pan at once, I suggest adding some cross bracing between the sides of the passenger area before you cut to be sure you hold the factory dimensions. Depending on how the vehicle is supported, and whether or not the engine / tranny/ rear end is still in place, you can get a lot of flex if you start cutting without some reinforcement to hold it. If you watch this type of work online or TV, you can see how the bracing is done. And double what Syleng1 said about welding practice. I had 20 years of experience as a welding supervisor in shipbuilding and welding on thin material is an art that takes practice. Looks easy, but it's easy to screw up.
Click to expand...
What would you say is the best way to properly brace it to keep from bending or warping? I can throw some jack stands under it, but I also keep loose wood around so I could screw together some temporary bracing to help spread the load out better if need be. What areas should I focus attention on when it comes to bracing?
 
To brace the flooring, run some angle bar in an X pattern between the door sills, tack welding it to the body. Maybe even an X for the front and one for the rear. This will prevent the body from twisting and sagging as you cut the floor pan out. Also add some stands under the floor area, not just on the front and rear frame rails. If you don't, you may get the new floor welded in and it looks great, then the doors don't close correctly an the car "crabs" down the road. Also, when welding you never weld in a solid bead on sheet metal. Make sure you weld the perimeter in short, spaced out sections, filling in the open areas in 5-6 trips around the perimeter.
 
There are thousands of YouTube videos on this type of replacement. Many are very good and detailed.
 
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