floor pan patches--butt or lap weld

[69Tom]

OK guys, was wondering your opinion on this, as I've seen it done instructionally and by people on the web both ways.

My car is not going to be a show car--it's a driver. I will keep it as nice as I can, and original as I can. I am not undergoing a frame off restoration. I am fixing what I can when I can on it as a driver.

First off, I have a front driver's floor pan to patch. It's incredible I have to replace it, as the rest of the floor pans in the car look as if they're day 1 from the factory, as does the rubber mat. I guess water/salt from the driver's boots would get trapped under there each winter and it took it's toll. That's the only explanation as there's no leaks anywhere.

So, question is, should I lap weld the patch or butt weld it? I know I'd like it if it were butt welded and then ground down. However, I'm always worried about getting a close enough fit on the existing pan to the replacement patch. Plus my access to the underside of the car won't be incredible. I don't have a lift....

If there any downside to the lap weld? Is it frowned upon?

thanks.

[whitetop]

I would butt weld it. Once you start fitting the metal you will find it is not that hard to line up.

I would weld the top and not grind down the weld. Once you get the time and capabilities you can always go back and weld in the bottom side.

I think you will regret it later..that is if you plan on keeping the car and not just flipping it.

[Bill Pritchard]

"I would butt weld it. Once you start fitting the metal you will find it is not that hard to line up."

x2 [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]

Many years ago when I restored my wife's 69 Impala convertible, I needed to replace 3 out of the 4 floor pan sections. My brother-in-law butt welded them in in my garage using a 110V MIG welder and they turned out great.

[69Tom]

Thanks guys. OK, butt welding it is. Just need to get thin enough cutoff wheels so as to not create too big of a gap between new and old.

[scuncio]

When you have access to the other side of the weld, it can help to back up the butt joint with a piece of copper. The copper sinks some of the heat to prevent blowout.

[69Tom]

Good tip. Thanks.

[Schonyenko2]

What size wire do you have in the gun? I would suggest 0.23

[69Tom]

Yep, I have good ol' 0.23 in the gun Ken.