Full Floor pan replacement question

[72Charger72]

So I have been a little slow as of late getting to replacing my floor pan because Im not sure exactly what to do with the seam along the firewall.
I have most of the 9 million spot weld drilled out and have looked on the Net and You tube but havent really found anything detailed explaining how to deal with this seam in a full floor pan replacement...most vids about patching etc.....etc...Any help or advice or good links are appreciated.

[Troy]

It's just a flanged joint isn't it? I replaced 3/4th of the pans in my 70 Challenger and a full replacement would have been a million times easier. Part of that firewall to floor pan seam was rusted (I swear Mopar only put seam sealer in theses cars to give water a convenient place to run) and I had to actually fabricate the firewall part along a large portion. There may be some issues at either end where you have 3 or 4 pieces overlapping. I'll take a look today to see how I did it.

Troy

[72Charger72]

Thanks Troy...yes I figured the full floor would be easier than cutting and welding a million times...I have a seam buster coming this week and just wasnt sure how to attack the seam and re-seat it with new floor pan.

[Cncguy]

I drilled all the spot welds with a carbide spotweld cutter, then I used a 2" putty knife to break the welds. I only used the panel separate knife tool on very difficult welds that wouldn't pop. Yes it destroys the putty knife but saves the panels.

[72Charger72]

I drilled all the spot welds with a carbide spotweld cutter, then I used a 2" putty knife to break the welds. I only used the panel separate knife tool on very difficult welds that wouldn't pop. Yes it destroys the putty knife but saves the panels.

Thanks CNCGuy how did you tackle the firewall seam?

[randy73]

It's just a flanged joint isn't it? I replaced 3/4th of the pans in my 70 Challenger and a full replacement would have been a million times easier. Part of that firewall to floor pan seam was rusted (I swear Mopar only put seam sealer in theses cars to give water a convenient place to run) and I had to actually fabricate the firewall part along a large portion. There may be some issues at either end where you have 3 or 4 pieces overlapping. I'll take a look today to see how I did it.

Troy

LMAO, seam sealer was only used to guide the water.

[Cncguy]

I drilled all the spot welds with a carbide spotweld cutter, then I used a 2" putty knife to break the welds. I only used the panel separate knife tool on very difficult welds that wouldn't pop. Yes it destroys the putty knife but saves the panels.

Thanks CNCGuy how did you tackle the firewall seam?

I drilled from the engine side of the firewall most or all of the welds can be gotten from this side. It is best to drill the panel you don't want to save, in this case I needed the full floor so I drilled firewall. But if I were trying to save the firewall, and the floorpans were rotted out I'd probably make a cut an inch away from the seem and get as many welds as I could from the floorpan side. If that makes sense.

[72Charger72]

I drilled all the spot welds with a carbide spotweld cutter, then I used a 2" putty knife to break the welds. I only used the panel separate knife tool on very difficult welds that wouldn't pop. Yes it destroys the putty knife but saves the panels.

Ran into a few questions today and thought I would ask rather than be sorry. Anyone feel free to chime in!
Working on rear seam first...
1) It appears along with spot welds they did some seam welds on the back of the rear seat pans. How do people take care of these? Grind?
or just break through with a seam breaker?
2) Whats the process for dealing with the wire hiders along the rails? The floor pan goes under these but they are so thin I am worried about ruining them?
3) Sometimes I go all the way through with the spot weld cutter? How to you address this adding in the new pan? Just drill a hole over an inch or so?
Pictures are in order of questions thanks!

[Midnight_Rider]

But if I were trying to save the firewall, and the floorpans were rotted out I'd probably make a cut an inch away from the seem and get as many welds as I could from the floorpan side. If that makes sense.

I am at this exact point in replacing the driver's side pan in a 71 RR. If the car he's working on (72 Charger ?) is the same, he'll want to be real mindful of that brace to the frame rail on the under side of the pan when he makes that cut -- mine goes right through the area where the screw holes are for the dimmer switch.

See if this pic loads...

[72Charger72]

But if I were trying to save the firewall, and the floorpans were rotted out I'd probably make a cut an inch away from the seem and get as many welds as I could from the floorpan side. If that makes sense.

I am at this exact point in replacing the driver's side pan in a 71 RR. If the car he's working on (72 Charger ?) is the same, he'll want to be real mindful of that brace to the frame rail on the under side of the pan when he makes that cut -- mine goes right through the area where the screw holes are for the dimmer switch.

See if this pic loads...

Thanks Midnight_Rider Yes Im working on a 72 Im going to mark all frame rails out before cutting but a photo is worth a thousand cuts!

[72Charger72]

Started floor removal and guess Ive answered my own question about Media Blast vs Acid Dip. This was acid dipped a year ago and after floor pan removal you can see plenty of rust and crap in the frame rail so I guess neither option is a perfect solution.

[randy73]

Started floor removal and guess Ive answered my own question about Media Blast vs Acid Dip. This was acid dipped a year ago and after floor pan removal you can see plenty of rust and crap in the frame rail so I guess neither option is a perfect solution.

I media blasted the hard to reach areas, sanded most of the rest and used paint remover on the rest, but have to say that sanding is the best option when possible.

[72Charger72]

Sorry miss-posted down below....
Ran into a few questions today and thought I would ask rather than be sorry. Anyone feel free to chime in!
Working on rear seam first...
1) It appears along with spot welds they did some seam welds on the back of the rear seat pans. How do people take care of these? Grind?
or just break through with a seam breaker?
2) Whats the process for dealing with the wire hiders along the rails? The floor pan goes under these but they are so thin I am worried about ruining them?
3) Sometimes I go all the way through with the spot weld cutter? How to you address this adding in the new pan? Just drill a hole over an inch or so?
Pictures are in order of questions thanks!

[Troy]

1. I ground them off.
2. The metal flaps? I cut them at the spot welds.
3. I spaced my own holes. If you try to mimic the original spots and weld exactly where the old ones were, the existing metal will be thin from the earlier weld and will probably blow through very easily. The other option is to drill all of the holes all the way through then don't put any holes in the new panels. Just weld from the back! This assumes you can reach all of them...

I sort of mix-n-match approaches to get whatever works best. When possible, I try to weld to the thickest, cleanest metal available even if it's not perfectly aligned with the factory weld. No one is likely to see the bottom of my car or under the carpet. Even if they did, most of these are covered with seam sealer and/or undercoating.

Troy

[72Charger72]

Thanks Troy
Grinding it is!!
And yes the thin flaps that cover the electrical running down the sides. Not sure what that's called?
What do you mean by cut? Did you reuse them?
For the spot welds that makes sense since! Thanks for the quick reply!
Still have some time left today to make progress!
And the I wondered why on the inner fenders people just didn't drill
All the way through and weld from behind looks cleaner and easier!

[Troy]

Depending on the car... those metal flap wire covers usually have about 3 spot welds in the bottom (towards the inside of the car). They may be covered in seam sealer. I reuse them if I can. They aren't structural so no worries about weakening them (or breaking a tab).

Also... if you really did want to duplicate the look of the factory welds, just grind all the new ones flat, put on a film of body filler, and "dot" it with a pencil eraser wherever you want it to look like there's a weld. Then you can weld wherever it's convenient.

Troy

[Midnight_Rider]

Aplogies to 72Charger72, sorry to butt in on your thread -- but could you (or anyone for that matter) tell me what's going on in the circled area? It looks like a plate of some kind? That was/is missing on mine, and I'm new to the B's and have no frame of reference. All I have there is a couple of holes where the studs would go?

[randy73]

There is a large C shaped (and heavy) piece on the underside, I was told it is to protect the rear passengers should the driveshaft break. The C piece sits right over the driveshaft.

[Midnight_Rider]

There is a large C shaped (and heavy) piece on the underside, I was told it is to protect the rear passengers should the driveshaft break. The C piece sits right over the driveshaft.

Thanks for taking the time to answer. Always delighted to discover more missing parts to track down, lol.

[72Charger72]

Aplogies to 72Charger72, sorry to butt in on your thread -- but could you (or anyone for that matter) tell me what's going on in the circled area? It looks like a plate of some kind? That was/is missing on mine, and I'm new to the B's and have no frame of reference. All I have there is a couple of holes where the studs would go?

All good Midnight_Rider we are all here getting and giving help if any of my posts can help someone else Im all for it!
I have just started that part of my floor pan replacement but its been way to hot to get in the garage. 103 all last week. When I checked last though thats a mounting bracket.
Two bolts underneath sticking out. I was trying to figure out how to remove that just before the heat kicked up.
I will check it again when I get home tonight. And add a couple photos from the under side.

[72Charger72]

There is a large C shaped (and heavy) piece on the underside, I was told it is to protect the rear passengers should the driveshaft break. The C piece sits right over the driveshaft.

I remember taking that piece off and it being heavy. I can look on my 71 tonight also. Im pretty sure I can get a photo or two.

[Midnight_Rider]

All good Midnight_Rider we are all here getting and giving help if any of my posts can help someone else Im all for it!
I have just started that part of my floor pan replacement but its been way to hot to get in the garage. 103 all last week. When I checked last though thats a mounting bracket.
Two bolts underneath sticking out. I was trying to figure out how to remove that just before the heat kicked up.
I will check it again when I get home tonight. And add a couple photos from the under side.

Thanks man, appreciated.

[72Charger72]

All good Midnight_Rider we are all here getting and giving help if any of my posts can help someone else Im all for it!
I have just started that part of my floor pan replacement but its been way to hot to get in the garage. 103 all last week. When I checked last though thats a mounting bracket.
Two bolts underneath sticking out. I was trying to figure out how to remove that just before the heat kicked up.
I will check it again when I get home tonight. And add a couple photos from the under side.

Thanks man, appreciated.

Here you go Midnight_Rider photos of the part and underside of floor pan. There is a small flat plate you will need also....The piece weighs about 10 lbs either lead or steel not quite sure.

[Midnight_Rider]

Here you go Midnight_Rider photos of the part and underside of floor pan. There is a small flat plate you will need also....The piece weighs about 10 lbs either lead or steel not quite sure.

Wow! That's a big ol' hunk-o-cheese right there. Thanks for taking the time.

I've run into a few fitment issues with my replacement pan pieces. Hopefully you won't have any problems, but here's a link to my thread in case anything in there might be of help. Bear in mind this is my first rodeo with both panel replacement and welding, so I'm learning as I go -- there might be better ways to go about fixing things that someone with more experience would know but at least it should help identify some potential areas to keep an eye on.


http://www.dodgecharger.com/forum/index.php/topic,129581.0.html

[72Charger72]

Here you go Midnight_Rider photos of the part and underside of floor pan. There is a small flat plate you will need also....The piece weighs about 10 lbs either lead or steel not quite sure.

Wow! That's a big ol' hunk-o-cheese right there. Thanks for taking the time.

I've run into a few fitment issues with my replacement pan pieces. Hopefully you won't have any problems, but here's a link to my thread in case anything in there might be of help. Bear in mind this is my first rodeo with both panel replacement and welding, so I'm learning as I go -- there might be better ways to go about fixing things that someone with more experience would know but at least it should help identify some potential areas to keep an eye on.


http://www.dodgecharger.com/forum/index.php/topic,129581.0.html

No Problem Midnight_Rider My first rodeo with Pan replacement and Metal resto also. I had to learn to weld too!  Started by building my rotisserie!
heres the link to my build.
http://www.dodgecharger.com/forum/index.php/topic,109796.msg1610702.html#msg1610702

[72Charger72]

I drilled all the spot welds with a carbide spotweld cutter, then I used a 2" putty knife to break the welds. I only used the panel separate knife tool on very difficult welds that wouldn't pop. Yes it destroys the putty knife but saves the panels.

Thanks CNCGuy how did you tackle the firewall seam?

I drilled from the engine side of the firewall most or all of the welds can be gotten from this side. It is best to drill the panel you don't want to save, in this case I needed the full floor so I drilled firewall. But if I were trying to save the firewall, and the floorpans were rotted out I'd probably make a cut an inch away from the seem and get as many welds as I could from the floorpan side. If that makes sense.

Thanks again CnCguy and Troy for his insights on the wire hiders came out perfect!
I got the rear seam removed and floorpan off yesterday. Posted photos on my build page.
http://www.dodgecharger.com/forum/index.php/topic,109796.msg1621712.html#msg1621712

Now looking at the firewall to toe board seam. I reread CNCguys post but I have a brand new full floor pan that needs to be attached at the seam so cutting an inch away from it confuses me? I would assume I should just drill out spot welds and use a Seam breaker as gentle as I can to save the firewall side? Seems to also make sense to just drill out the spot welds from the firewalll side and weld from the engine side? A lot more room towork there?
Would love to hear how others have tackled this?

[Midnight_Rider]

Now looking at the firewall to toe board seam. I reread CNCguys post but I have a brand new full floor pan that needs to be attached at the seam so cutting an inch away from it confuses me?

If I am reading his post correctly, I believe he means cut the old toeboard out close to the firewall lip seam first... which will then give you access to drilling out the spot welds along the remaining floor pan lip from inside the car where there's plenty of room to move around?

[72Charger72]

Now looking at the firewall to toe board seam. I reread CNCguys post but I have a brand new full floor pan that needs to be attached at the seam so cutting an inch away from it confuses me?

If I am reading his post correctly, I believe he means cut the old toeboard out close to the firewall lip seam first... which will then give you access to drilling out the spot welds along the remaining floor pan lip from inside the car where there's plenty of room to move around?

Thanks Midnight_Rider! I get what he is saying now.
So pretty much the same as removing the rear seam. Remove spots
And gently work the seam apart.
I have one more day of vacation tomorrow.
So I was hoping to get that done it would be big big progress for me! 

[72Charger72]

Just wanted to share a great method I ran across to remove a spot weld without damage to the panel behind. Saw a video where a guy used a file sander and ground the spot welds. I used an 80 grit belt and took out 25 spot welds in about 15 minutes then used the putty knife to break the seam.  Way faster than spot weld cutting and less chance of damaging the panel behind...plus the belts last forever so its also cheaper than buying spot weld cutter blades.

[alfaitalia]

Exactly the method I've used.....ran across it on the youtube thingy....when looking for a video on tubbing arches of all things! How did we ever manage without the interweb. In days gone by I would have actually had to talk to people to find stuff out....yuck! At least with talking to you guys on here rather than in real life I don't have to put up with your ugly mugs and questionable personal hygiene!! LOL!

[72Charger72]

Exactly the method I've used.....ran across it on the youtube thingy....when looking for a video on tubbing arches of all things! How did we ever manage without the interweb. In days gone by I would have actually had to talk to people to find stuff out....yuck! At least with talking to you guys on here rather than in real life I don't have to put up with your ugly mugs and questionable personal hygiene!! LOL!

Saves on BEER Too!