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shawny2087
12-24-2004, 11:11 PM
im replacing my floor pans in my 88' dodge daytona turbo with 22ga weldable sheet metal and im kinda new to welding but im using an HH140 with C25 gas and .024(should i be using .030?) wire and id like to know what would be easyer and stronger for me? butt welding the new metal to the car floor or a lap weld and what would be the best settings to use

Planet X
12-25-2004, 12:37 AM
Lap joint.

evaporator
12-25-2004, 01:04 AM
Lap joint, plus you can pre-position that joint with some sheet metal screws (then remove after) or pop rivets to get it just right. You could punch holes sround the perimeter and do plug welds, also. Knock as much of that rust back (Flap Discs on angle grinder and wire wheel) as you can, and I'm always concerned about new rust in the overlapped seam, so seal the **** out of it, top and bottom, when you are finished. I've put angle iron across the opening to stiffen up the new panel, also. Your most professional patch will be the butt joint, but we're talking lots of blow-through until you develop a "touch". The alignment clamps you can get at Harbor Freight work pretty good for holding the patch in while maintaining a 1/16" gap. I personally like to use a couple of their magnets, spot, move 'em , align, spot again, etc.

dda52
12-25-2004, 01:23 AM
.024 is the wire you want to use. It'll be better with the real thin stuff.

shawny2087
12-25-2004, 12:24 PM
ok ill stick with .024 and maybe a lap joint will be better for me but ive heard that when dong a lap joint moisture can become stuck in between the joint and rust out the floor again. if i seal up up well with like POR15 then tar would that pervent it??

243
12-25-2004, 12:44 PM
I would suggest butting the panels rather than lapping. Rust will form between the two pieces as you were told already. POR15 is a great product but you may not get full coverage between the lapped joint and still ruin your work.

Also, did you use pre-formed pans? You may be able to find factory pans at Raybucks or a similar body panel supplier.

Run short 1/4" beads, skipping from one side of the panel to the other. Cool the welds with wet rag.

Then again, if this is just a repair to keep you tennis shoes off the pavement, lap joints would be fine. And if this the case, you can glue the panels in and not worry about welding at all...wait, this is welding forum :)

Planet X
12-25-2004, 12:47 PM
ok ill stick with .024 and maybe a lap joint will be better for me but ive heard that when dong a lap joint moisture can become stuck in between the joint and rust out the floor again. if i seal up up well with like POR15 then tar would that pervent it??

That is a good point, if a butt joint will give you sufficient strength perhaps spend some time with them, they should be doable as well.

Sberry
12-25-2004, 12:50 PM
I make the laps real small, most of it is asorbed during welding leaving very little lap on the back for water to collect in, then spray on undercoat. A 1/8 lap makes it so much easier to weld.

evaporator
12-25-2004, 01:08 PM
Work the seam over with a heat gun (hair dryer if you don't have one) real well then POR 15 on each side. It'll be sealed for a long. long time. If you wanna be real careful, after you've dried it out, let it cool, then spray (heavy) aerosol rust converter into the seam all around., Let dry, then POR 15. I use the converter Wal Mart sells in the auto department (Kleen Strip makes it). I like it better than Extend.

Steve B
12-26-2004, 11:23 PM
On these lap joints, are we welding only on the top, leaving an open lap underneath or are we welding the bottom too?

shawny2087
12-28-2004, 02:17 PM
I would suggest butting the panels rather than lapping. Rust will form between the two pieces as you were told already. POR15 is a great product but you may not get full coverage between the lapped joint and still ruin your work.

Also, did you use pre-formed pans? You may be able to find factory pans at Raybucks or a similar body panel supplier.

Run short 1/4" beads, skipping from one side of the panel to the other. Cool the welds with wet rag.

Then again, if this is just a repair to keep you tennis shoes off the pavement, lap joints would be fine. And if this the case, you can glue the panels in and not worry about welding at all...wait, this is welding forum :)

not there big holes like for ex. one is about 18"L X 4-5"W and im using 22ga weldable coldrolled sheet metal i could not find pre fromed pans any where

evaporator
12-28-2004, 05:18 PM
22 gauge is too light for floor pans (or body work for that matter). I'd go no thinner than 18 gauge for floors.

yeruncle
12-30-2004, 03:14 AM
Shawny - don't know how big a hole you're covering. This is what works for me. I have switched to 16 ga.( or heavier ) for floor work. Small holes - up to 12" or so cut patch with a healthy overlap (1' - 1 1/2"). After forming patch,grind foor clean, then coat bottom of ENTIRE patch with WATERPROOF fiberglass filler. Glue the patch in place, put a brick or two on it to hold it, then scrape all excess filler off all around edge of patch and floor with a gasket scraper before it sets ( wipe it with a little laquer thinner on rag to really clean it ). When your patches are in (set up and dried), tack all around, then weld edges - skipping around with 1/2" or so welds 'til it's done. It's surprising how little filler is lost by welding heat ( it will catch on fire while you weld occasionally - just blow it out! - don't inhale this crap - and keep moving heat to different spots) and this is the secret of having the strength of the lap without worrying about rust between layers. When you're done, clean it up and check lap joints from underneath. If any gaps have formed while welding, fill them from bottom with the WATERPROOF filler. When you're done, wipe down all edges and por 15 the inside and out side. Por 15 may not permanantly adhere to filler underneath, but it still won't rust, and you can respray it with spray can stuff if it really bothers you.
On larger patches, you may need some thicker bracing (unless you can roll some beads into them). The flatter they are the weaker they will be, thus the need for bracing with some strap iron.
These larger patches are done in the same manner, but only use the WATERPROOF filler on the edges. The por 15 will be fine on the bottom and looks better on these larger panels.
Sounds terrible, and it's a pain, but after 40 years of fighting winter salt damage, it's the only thing i've found that really holds up! It's not pretty, it's not for show cars, and if you live in Arizona or similar climate it's overkill. But for pitbull miserable winter salt slop areas it's the real deal. HAVE FUN!!! :D

shawny2087
12-30-2004, 01:44 PM
well the floor is 22ga it looks like, but ill go out and get a 24"X48" sheet of 16ga thats no problem. i think ill try that fiberglass thing. i build fiberglass moldings for mobil audio systems so i know how to work with that pretty well. also will a tin snips be able to cut through the 16ga sheet metal because i dont have a shears or nibblers or really anything else to cut it.

Zrexxer
12-30-2004, 02:12 PM
also will a tin snips be able to cut through the 16ga sheet metal because i dont have a shears or nibblers or really anything else to cut it.You're not going to have much luck cutting 16 ga with tin snips. And I think it's way overkill for the application - just as a visual reference, 16 ga is roughly the same thickness as a quarter.

drizler
12-30-2004, 04:12 PM
If you are going to do the resto thing or if you live in the salt pit like I do remember to put down some rust converter if you can't get all the rust. Picklex is expensive but they say its the best. Zero rust is cheaper than POR and much reputed to be better. That word on fiberglass is absolutely right. You need to make sure that the first layer of bondo on any exterior weld it the fiberglass bondo stuff. Then you can finish with the cheap crap. Don't forget the back of the panel for the same treatment if its exterior. Some epoxy primer under the Zero or por would be a nice touch too. Theres no such thing as overkill in rust country, expecially since the cars got so tinny.

evaporator
01-02-2005, 12:16 AM
"i dont have a shears or nibblers or really anything else to cut it."
...a hand held jig saw with a fine tooth metal blade will cut it easily. You'll have to support it close to the cut as you go to keep it from fluttering. Snips are out.

yeruncle
01-02-2005, 01:33 AM
Shawny - 16 ga. is 1/16" thick. Forget the snips! I just cut about 22 panels of various shapes and sizes for a floor mess I'm into with a 4 1/2" electric grinder and cut off wheels - all items from har.frt.. Not expensive and real slick, quick too!! (Outdoors is best - LOTS of sparks and dust) You won't believe what you can cut with these things!! :cool: ( Couldn't finish - weather just beat me to death - all panels are "glued in though).

P.S., eat your wheaties before you start bending and shaping 16 ga.; but once done it's not going anywhere, and it does away with need for a lot of bracing!! Good luck. :D

P.S., again. I also tried some rust encapsulator from Eastwood about two years ago. It's about same price as por 15, but I tried the spray can (frightenly - expensive in that form). I sprayed it on exterior upper auto panel (it was flat black) over bare metal with a quick laquer thinner wipe down at 30 degees!!! It was an experiment, and it's still there ( out doors every day and season since then) and looks great as it's NOT ultra violet sensitive like por 15. ;)

Teeps
01-02-2005, 11:12 AM
16 guage is exactly the thickness of the exhaust tubing I'm installing.

T304L SS 3.5" Diameter.

Seams thinner than a quarter, but maybe not. 16 guage is definately 1/16th, .062", I can't see going any thinner on a floorboard, unless you like to push your feet through like flinstones!!!!!

Just my .02 I've never had to install one of these.