Floor repair

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Apr 30, 2005 | 11:29 PM

tip49

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Cargo Master

Joined: Sep 2004

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From: Alberta Canada

Floor repair

After much anxiety I cut the rusted portion of my cab floor today. I have been working on getting the replacement section ready, 14 ga steel. I'm having problems with blow through and warp. I tried to stay with the stock tranny cover, and used the existing dropped lip grafted around the opening fastened to the new section. I switched my mig over to gas assist today, to try to weld up some of the holes. About 70% successful so far. I'm using a copper shield behind the hole. What is the largest opening I should be trying to close before using patch panel, 1/8" ?

Any tips for getting all pin holes closed ? If not can I seal with caulk or seam seal?

Tom

May 1, 2005 | 10:45 AM

Christopher2

Fleet Mechanic

Joined: Jun 2004

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From: Minnesota

I did the same thing you are doing. You will blow through the pin holes if you try to weld them. I used a 110 welder on low and kept blowing through. I cut back until I got to good metal. I was lucky enough I got to good metal around the the lip of the tranny cover.
I used real silicone caulking not the siliconized latex crap. It is a little more expensive but will not be peeling off a properly prepared surface in 5 yeasrs. It stuck to the clean metal very well and I was able to primer and paint over it.

Quote:

Originally Posted by tip49

May 1, 2005 | 10:52 AM

LEckart

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From: Kansas City area

I assume you're using Mig. When I switched from .35" wire to .23" wire it helped alot on sheetmetal. You have to proceed slowly, tack welds spaced as far apart as possible, then back and forth to close up between each tack. I also found that if I spent more time preparing the patch panel and made sure I had a good fit with a very small gap the welding went much easier. You also have to be careful when grinding the welds to not heat up the metal and cause warpage. Takes patience which I am generally short on. If I had a situation with a gap wider than 1/16" I usually made a filler piece. Most of my blow through occurred where the original sheetmetal was thin and it helped it I cut if back to good metal. Seam sealer is a good safety measure to make sure it is completely sealed.

May 1, 2005 | 11:08 AM

Christopher2

Fleet Mechanic

Joined: Jun 2004

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From: Minnesota

That reminds me I also cleaned up the surface of the rusted metal with a grinder and some flux. That made the weld much easier to do even if the wire does say for painted and rusty surfaces.

May 1, 2005 | 01:29 PM

tip49

Thread Starter

Cargo Master

Joined: Sep 2004

Posts: 2,757

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From: Alberta Canada

floor weld through

Thanks for the input guys; I am using .025 wire, but may try the .023

I may end up using u channel bracing front to back on both sides of tranny opening, also across back portion in front of ribbed sectioned.

Tom

May 1, 2005 | 02:45 PM

bobj49f2

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From: SE Wisc. (the Rust Belt)

I would suggest that you epoxy prime the metal before using sealer. Some sealers like to cause rust after a while and the epoxy primer will form a barrier. Paint will not stick to pure silicone caulk or any surface you inadvertently touch if you happen to have some on your hands. When you apply paint you may end getting fisheyes, small areas where the paint will pool away. You should try to use a sealant that is paintable, it should be listed on the label.

May 2, 2005 | 01:18 PM

AXracer

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Joined: Oct 2004

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From: Durham NC

If you just do short tacks, less than 1/4" long spaced as far apart as possible and allow the panel to become cool enough to touch before coming back to tack in between, you'll get much less warping. When filling blow thru, don't try to start filling the hole right on the edge or it will just keep getting bigger. Instead start outside the hole on solid metal and fill back into the hole. We welded holes as big as 1/2" in my firewall without using a filler piece by using a copper buck behind them. Make sure your copper is TIGHT against the seam where you're welding. Use clamps or strong magnets to hold it tight.