Has anyone welded new floor pans into their Spider? If so, did you use a MIG welder. Did you use .023 wire, or will .030 work? I'm looking at getting new floor pans welded in, and the cost to have someone else do it is almost twice as much as buying a machine and doing it myself. I've done some welding, mainly stick, but I understand the basics of stitch welding a floor pan in. Any advice would be appreciated.

If you have limited welding experience the floor pans are a good place to learn. Lap welds are easier than butt welds and will be hidden by the carpets. Also welding flat will make the learning proces easier. Welding out of position can be frustrating. My preference is solid wire .023 with C25 gas. Lots of people get good results with .030 Flux core but I have no experience with it. Metal needs to be clean, really clean! And fit tightly. Which means wire wheeling or sanding enough to clean. But not thin the metal so much causing excessive burn through. Lots of people get by with a 110v machine on sheet metal but if you have the funds and 220v in your shop a 180 amp or more machine Will give you a lot more versatility. Lots of good tutorials on YouTube. Just stay away from the bad ones

The thing I found frustrating when welding fiat metal is that it tends to be crapy metal. Blow thrus can happen easy. Modern metal is much easier to use and you'll probably use new metal with the 45 year old, I would suggest start with the machine setting and dial back a bit until you get the feel of mig welding the different metals. .23 wire worked fine for myself with 75 argon 25 co2 gas.

This video seems to be more cutting and patching but pretty clear instructions, tho not on a spider
https://youtu.be/C0M5tUQSaps

A few years ago i had the same "problems"... a lot of holes where none are needed and much more rust
I never had welded before and asked the same questions. One of the best advise i got was to buy a verry good welding machine.
The one i bought has a lot of "electronic helpers" wich avoid learning all the stuff about feedrate, intensitiy etc.
If You think this is overdone try strating with a cheap one These machines are good for people who have experince in welding.

First I borrowed a cheap one from a friend who is welding for years and he was able to work with it - when i tryed to weld with his machine next to his perfectly done welding spot a new hole was born ( it was really frustatiing ).
I suggest to borrow or buy a good welding machine

There are some Tools wich are "required" ( and will help you a lot) PANEL HOLDING CLAMPS
(
https://pelatools.com/garage-equipment/ ... gK6GfD_BwE)
, a cheap but complete Set of Welding Grips
(https://www.bandel-online.de/WERKZEUGE/ ... gLU9fD_BwE)

I was afraid to cut to much metal out of the body ( i think it is normal ).
When you start welding the area needs to be really rust free. Even if you think the metal is shiny and rust free, put rust remover on it and wait till there is chemically no more rust ( i use Pelox re wich is very famoius in Germany. Then welding is fun

A famouse method of welding sheet to your floor is to cut a metal sheet to cover the replacement area but with a bit larger dimensions aprox 2cm , lay it on the area, weld a small welding spot in the corners to fix it, and then use your angle grinder and cut along one side through both metal sheets. Than use the panel holding clamps to fix this side. Do this for all the other sides and youll have a perfect starting point to begin. be patient, the welding spot needs to cool down before you can add a new one next to it.

I hope it is understandable

KWL82 wrote:This video seems to be more cutting and patching but pretty clear instructions, tho not on a spider
https://youtu.be/C0M5tUQSaps

Funny enough, I watched that video and even made a comment on it.

basso wrote:A few years ago i had the same "problems"... a lot of holes where none are needed and much more rust
I never had welded before and asked the same questions. One of the best advise i got was to buy a verry good welding machine.
The one i bought has a lot of "electronic helpers" wich avoid learning all the stuff about feedrate, intensitiy etc.
If You think this is overdone try strating with a cheap one These machines are good for people who have experince in welding.

First I borrowed a cheap one from a friend who is welding for years and he was able to work with it - when i tryed to weld with his machine next to his perfectly done welding spot a new hole was born ( it was really frustatiing ).
I suggest to borrow or buy a good welding machine

There are some Tools wich are "required" ( and will help you a lot) PANEL HOLDING CLAMPS
(
https://pelatools.com/garage-equipment/ ... gK6GfD_BwE)
, a cheap but complete Set of Welding Grips
(https://www.bandel-online.de/WERKZEUGE/ ... gLU9fD_BwE)

I was afraid to cut to much metal out of the body ( i think it is normal ).
When you start welding the area needs to be really rust free. Even if you think the metal is shiny and rust free, put rust remover on it and wait till there is chemically no more rust ( i use Pelox re wich is very famoius in Germany. Then welding is fun

A famouse method of welding sheet to your floor is to cut a metal sheet to cover the replacement area but with a bit larger dimensions aprox 2cm , lay it on the area, weld a small welding spot in the corners to fix it, and then use your angle grinder and cut along one side through both metal sheets. Than use the panel holding clamps to fix this side. Do this for all the other sides and youll have a perfect starting point to begin. be patient, the welding spot needs to cool down before you can add a new one next to it.

I hope it is understandable

I've welded before, though never on anything as thin as floor pans, and I've only done MIG a couple of times. I was mainly curious about the wire gauge for that thin of a metal. I've seen places that say to only use .023 to avoid blow through, mainly Eastwood trying to sell their speciality welders. I've also seen places where they've said that .030 is fine, such as the ChrisFix video that KWL82 shared here.

My main thing was to pick the brains of people who have actually done it on their Fiats, so thanks for the advice and info.

The .030 he talks about is Flux core wire, 030 solid wire is too heavy for body sheet metal. Think welding 10 gauge with 1/8 stick electride. So to be clear, .030 Flux core gasless wire. Or .023 er70s6 solid core wire with 75/25 argon/Co2 shielding gas for body sheet metal.

I used this wire and never had blowouts – that is why i wrote about the machine type ( it is solid wire 0,8 mm thick ): https://www.ebay.de/itm/Schweissdraht-S ... 1242486163.

I welded everything on my Fiat Spider with it:
the rear (all panels upper and lower inner and outer), rebuild all fenders, bottom, undercarriage, frame on both sides ( complete rebuild ), trunk, bonnet, rocker panels, outer sill on the right side, the frame Rails, wheel wells left and Right, fuel tank molding,
...everything.... it took one and a half year to rebuild my spiders body.
I write about my restauration here in the forum if you like to see how i made it...

Well basso your results speak for themselves. Your experience is different from mine but I have looked at your restoration thread and your work is exemplary! May I ask which welding machine you purchased and are you using 75-25 gas?

Of course, my welding machine is a REHM Synergic.Pro² 230-4 Quattro-MIG and it has funny electrical stuff to "not care a about learning how to weld" – sounds funny but it is my experience.

I dont know if it is ok to post the link - if not please delete it
https://www.rehm-online.de/en/schweissg ... s-310.html

Im not sure about the gas, it is called "SAGOX 18", 18 % Kohlendioxid (Carbon dioxide) , 82 % Argon and i used an bit more than necessary ( just to be sure ).

regards
Basso

Good to know about the welder and gas you use. Your results are truly excellent. I ended up going with a Eastwood Welder after seeing their restoration YouTube channel. It's basically a long ad for their products, but they get good results.

https://www.eastwood.com/mig-welder-110 ... utput.html

I've ordered my metal, well the metal I can order right now. I'm just waiting on it to come in and then I'll get my gas and start welding in new steel to get my restoration truly started.

I have been getting good results with 030 flux core wire and the basic 90 amp wire feed welder from Harbor Freight (got it on sale for $79). You'll be stitch welding and unless you have a safe indoor area to weld in using a gas shielded MIG setup is a bit moot since outdoor air currents will blow away your shielding gas so badly that you'll need to set the gas flow rate high and go through a ton of it.

I use a slow feed rate between 3 and 4 along with the low amperage setting. Be sure to keep the wire guide fresh replacing it at least at every 2 lb spool change and more often if you weld too close and end up getting a lot of slag inside the welding tip heating it up and wearing the wire guide more quickly. The wire guide is what electrifies the wire so if its egged out or loaded up with carbon/slag then you won't get a consistent arc and weld. A package of 10 disposable wire guides/tips are $10 or less so at about $1 each why skimp on that and risk wasting a $12 to $20 spool of wire while making poor quality welds?

Get some copper welding spoons or make your own out of scrap copper pipe. Backing the weld area behind the joint with a copper spoon can make the job much easier for someone just getting into welding plus it makes filling screw holes such as when deleting the luggage rack a breeze. On mine they had put something that added about a dozen screw holes to the trunk lid since it had five chrome strips screwed down on the paint along with the 4 points where the legs attached. The previous owner removed the rack and tossed it without plugging the holes so water just poured into the trunk every time it got wet.

I am not a welding guru but was taught by an old timer almost 50 years ago and when he started welding he had to make his own flux rods for stick welding by wrapping the bare 1/8 and 1/4 inch rods with newspaper soaked in the flux solution and allowing them to set up a few days before using them. We have it very easy today with all the new fangled automated stuff out there. Before the flux soaked paper mache flux coating came out you only had bare rod electric stick welding which required a lot of practice to master. The arc welders many times were just big hollow core transformers weighing in at about 1/4 ton with moving hollow cores to adjust the output and cooled by a chimney with no fans. Art was still using one of those old GE Franklin Arc Welders in his shop until he passed on about 10 years ago at pretty close to 100 years old.