floor pan patches--butt or lap weld
 

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.

Re: floor pan patches--butt or lap weld
 

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.

Re: floor pan patches--butt or lap weld
 

"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.

Re: floor pan patches--butt or lap weld
 

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.

Re: floor pan patches--butt or lap weld
 

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.

Re: floor pan patches--butt or lap weld
 

Good tip. Thanks.

Re: floor pan patches--butt or lap weld
 

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

Re: floor pan patches--butt or lap weld
 

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