Floor Replacement Questions

[matthon]

So, I need to learn myself on replacing this floor in order to put the seats in and sit down.

I read thru many threads, but need some clarity.

Previous owner cut out sections and replaced with galvanized signs and sprayed black something on top.

I have an AMD floor, and will soon have the two rear pans. There are two small areas under the rear seat where fiberglass was placed on top. Not concerned about those at the moment, but I will investigate.

Bought a spot weld cutter set, and multiple jackstands. Have a crappy HB welder that I don't want to use at all.

This is not a restoration, but a return to service, but it doesn't mean I want to cut corners for the install.

I will be removing the rest of the floor by drilling out the spot welds, removing the metal wire channels, seam sealer, etc. I'll take the steering wheel off and the entire interior is out.

The torsion bar crossmember is rusted on the driver's side at the rocker. I have a parts car with a good crossmember.

Need suggestions on:
Where exactly to support the car?

What specific model welder to get?
Budget is a concern here, so I need to balance that with a decent tool.

Replace entire crossmember, or repair?

Inner rocker needs repair on same side, what type/size/thickness of material to buy, and from where?

Is the correct process to drill holes in the new floor to spot weld it in?

I'd prefer to use a rust converter on the inside of the floor supports, then primer/paint, suggestions on brands?

Should I grind down the tops of the rails to the bare metal and use the primer you can weld thru? Brand?

When should the 4 speed hole/hump be cut/installed?

Should I paint the floor top/bottom after install with something specific or is spay paint sufficient?

I've looked at reviews on seam sealer, and I put some on a wish list, not sure what brand at the moment.

Anything I didn't think to ask?

I'm confident I can do this, just need some direction.

 

[BeepBeepRR]

Here are a few pictures of AMD half pans I installed on my old Belle. The cheap old Harbor freight 90 amp welder is what I had. It would have helped if I didnt suck at welding. However I have a great grinder that makes the welds look decent lol. I had 4 jack stands under the car. 2 on the rear axle and 2 up front on the lower control arms. But then moved them back to the frame rail just before the front door. The 90 amp HF welder is just what it is a cheap welder that will do the job. Its not a pretty weld maker but that could just be my sucky skills.

 

[Glenwood]

I think I had mine supported by 8 jack stands. Being a convertible I was concerned about flexing when I removed the rusted floor. I think any welder will probably do the job if you know how to weld properly. The better ones seem to have a steadier arc and smoother wirefeed, so I opted to replace my cheapie unit that had only 4 settings with a lincoln dual 180. It gave me decent guidelines to follow for settings according to metal thicknesses, etc. It helped build confidence as i was just learning, so I could no longer blame the unit lol!

my opinion for your questions:
Budget is a concern here, so I need to balance that with a decent tool. (mine was $1000 CAD. Don't need to spend that much.)

Replace entire crossmember, or repair? Depends how bad. If the metal is thin around close to the tb socket, replace it.

Inner rocker needs repair on same side, what type/size/thickness of material to buy, and from where? (19ga seems to be the norm for these. 18ga might be okay, but use a vernier to check the thickness)

Is the correct process to drill holes in the new floor to spot weld it in? (That's what I did. Floor pan was in and out a bunch of times to fit, then mark from below so you know where to drill)

I'd prefer to use a rust converter on the inside of the floor supports, then primer/paint, suggestions on brands? (Ospho is one)

Should I grind down the tops of the rails to the bare metal and use the primer you can weld thru? Brand? (I did using something from Napa. Otherwise it can rust in beween the layers)

When should the 4 speed hole/hump be cut/installed? (my guess is after the pan is fitted and secure, because I plan to this in the future. drivetrain should be installed to check the placement)

Should I paint the floor top/bottom after install with something specific or is spay paint sufficient? (I painted under mine. can't remember what I did on top before noise matting)

I've looked at reviews on seam sealer, and I put some on a wish list, not sure what brand at the moment. (I used something from Napa)

Here's a link to where I was working on the floor.

https://www.forbbodiesonly.com/moparforum/threads/can-of-rusty-worms.104526/page-17#post-910544502


Good Luck!

 

[JimCoronette]

Where in NY? I'm an hour north of NYC, South of Albany.

 

[Evan Frucht]

Real spot welding is done with a special tool called a "spot welder" in which you would not drill holes on the panel. When panels are attached with a mig welder instead you must drill holes, because a mig welder doesn't have the ability to penetrate and press, like a spot welding tool does. Same end result really. Only a slight visual difference (no little dimples.) To answer the question, YES you drill holes in the new pan.

Any welder will work it just needs to run on gas. If you see yourself wanting to do more welding projects in the future get a Miller brand welder. If you don't care much about the quality of the tool, harbor freight might be OK, or also there is Lincoln... little cheaper than Miller. If you only plan to use for thin gauge metal you don't need a very powerful one. The only reason to get a large, powerful one, is if you plan to weld together 1/4 or 3/8 thick steal.

For paint, you need a 2k Acrylic Urethane. I would not recommend spray paint which is solvent based and has no durability. TCP GLOBAL has a line called RESTORATION SHOP. I really like it and it's dirt cheap. It can be bought through there website but I found the total price with shipping is a bit cheaper from their ebay store. About $120 for a whole gallon kit including hardener and extras. Enough to do a whole car in and out if you wanted.

For primer I use SPI brand. I like urethane but their epoxy primer is extremely popular. Cheap and as good as it gets.

For seam sealer. No choice but 3M Urethane seam sealer. You use it with a caulking gun. Its bullit proof and the newest technology as far as composition and formula (from what I hear)

It's a common practive to spray weld thru primer on an area that will be trapped before you weld it. Such as between the edge of two panels that are going to be spot welded together.

If you don't have a spray gun, I hear that one of the harbor freight ones is actually decent quality with good reviews.

Take a picture of the cross member damage so we can help you decide on that. First thought is that unless the rust is really localized in one or two spots just replace the whole thing.

 

[gkent]

Too many questions in one post !!

Forget the spot welder, buy the small Eastwood Mig - it will do all your sheet metal as well as the crossmember.

I have a good Blair spot weld but BUT prefer to use an air file. The spot weld cutter is too easy to blow through the bottom panel. Also, you don't always nail the center of the spot weld and end up having to take another shot at it and that is tough to do with that style cutter AND one way or another you'll have to grind that area anyway. Just use the air file and be done with it.

 

[dvw]

Floor pans are great place to learn sheet metal repair. If the rest of the car is up to snuff it'll be plenty sturdy. Could enven be done on setting on the ground. I'd remove the torsion bars. This will remove the load from the torsion bar cross member. Then remove the rest of the floor. Now you can determine the condition of the cross member and the inner rocker. Does it need a patch or more? The rocker is easy because its a simple shape. You don't need much of a welder as the material isn't very thick. As long as it uses argon (not flux core) it should work. Get it to this point then I can help you further.
Doug

 

[gkent]

As long as it uses argon (not flux core) it should work. Get it to this point then I can help you further.

You don't use pure argon in a mig. Argon is for tig, co2 or co2/argon is for mig. co2/argon yields less spatter.

 

[dvw]

You don't use pure argon in a mig. Argon is for tig, co2 or co2/argon is for mig. co2/argon yields less spatter.

You are correct. My intention here was not to use flux core. General gas used for IG welding mild steel is 75% argon/25% CO2 mix.
Doug

 

[gkent]

Is the correct process to drill holes in the new floor to spot weld it in? (That's what I did. Floor pan was in and out a bunch of times to fit, then mark from below so you know where to drill)

The car was mostly welded by a robot so the welds are usually a consistent distance in from an edge as well as a consistent distance apart. I often think you're better off NOT welding in the original place as the metal would be weaker in that spot - usually from cutting into it with the spot weld cutter. Put the new welds between the originals - particularly if this is not a concourse resto.

 

[matthon]

Great info to get me started and possibly order supplies. A friend might have a welder I can borrow, I'll have to see what it is exactly.

The plan is to pull the engine/trans, torsion bars, and what's left of the floor.

Then I'll clean up the rust and get better pics of problem areas.

Unfortunately it's too damn cold here to do anything.

This was the floor pan riveted in by the previous owner.

 

[JimCoronette]

Great info to get me started and possibly order supplies. A friend might have a welder I can borrow, I'll have to see what it is exactly.

The plan is to pull the engine/trans, torsion bars, and what's left of the floor.

Then I'll clean up the rust and get better pics of problem areas.

Unfortunately it's too damn cold here to do anything.

This was the floor pan riveted in by the previous owner.

View attachment 711347 View attachment 711350

I'm going to be doing a torsion bar crossmember for my buddy in the future.

My strategy would be to drill the spot welds out in the floor (just hog them out with a drill) and use the original floor as a reference to line up the new xmember.

I would have to cut out the outer floors over the xmember to get to the 4 spot welds where the xmember attaches to the rockers.

 

[dvw]

Tough to install the torsion bar cross member with the floor in place.
Doug