Welding in a floor patch. Tips needed. . .

[JohnN]

OK, I've finally worked up the courage to try and weld in a patch into the driver's side floor in my car.

The offending area is right at the pedal box and "only" extends 1-2" up the tunnel and a little towards the driver's door. I have the bad stuff cut out, and I've rough fit a patch piece I cut from a donor car. The rough cut patch extends a couple inches proud of the hole. The hole is as regular as I could make it (there are a lot of curves that make a straight cut difficult).

The problem I'm trying to resolve is how to hold the patch piece flush and positioned properly while I'm welding it in. . .

My current thoughts are this. . .I was thinking of mounting the donor piece "as is" and securing it with welding clamps an the occasional sheet metal screw. Then cutting through sections using the hole as my template and then use a magnet to hold the pieces in line while I tack weld the patch.

I'd then move on to another section and repeat.

Does anyone with experience have some magical trick to do this right the first time??

Thanks!!

John N

[gwb72tii]

can't you adhere a piece of copper or aluminum to the underside of the floor where you're going to weld to support the patch and provide continuity? then tack weld it, remove the support and finish the periphery weld.

just a thought...

[JackF]

eastwood has some clamps for this kind of thing. You could use a dew cleedo clamps too. Having done this as a rookie a few years ago on the 72 I will say that the best tip I can giveyou is to back up the welds with a piece of copper. Either cut a piece of buss bar out of an old electrical panel or get a 3-4" piece of I-2" copper. Pound it flat and hold it behind you tacks. It will make you into a better welder just by absorbing a lot of the heat. Small tacks all around and fill in from there.

To hold the piece in place you could pop rivet or screw a temporary backing strap or make small tabs to support the piece. Make sure everything is clean clean clean prior to firing up.

[jerry]

To hold the piece in place you could pop rivet or screw a temporary backing strap or make small tabs to support the piece. Make sure everything is clean clean clean prior to firing up.

+1,

either cut your patch piece with a couple extra tabs to hold it in place while you secure it with a couple tacks, then cut them off, or if you have already cut your patch piece w/o tabs, tack a couple on. i used this method to hold a spare tire well in place and it worked great. i cut the tabs off and welded over them w/o problems.

i also recommend borrowing or buying one of those auto-darkening helmets. they make welding a lot easier for us amatuers.

[ToddK]

Use the magnet to hold the piece in place. Tack a weld in a good starting place. Use a hammer, wire brush, magnet - whatever you need to manipulate the metal and tack around the opening. Then go back and fill in the weld. It's not that big a deal. Sounds like your over thinking it. Grind off the ugly when your done. If it's in an area that gets finish paint, tape it lower than the surrounding area and fill with body putty. I like to make complicated patches out of thin cardboard like a cereal box and duct tape. Once I get what I need, I transfer it to metal. Sometimes on floor patches you need to push the metal patch from the other side of where you are working. Use a floor jack to keep the new metal tight against the old metal. Always be mindful of the potential for fire. Stop often and check. If you are welding inside a garage, make sure you have a plan to get the burning car out before the whole garage goes up.

[clc]

Another timely post.

I have two long rust holes on my lower front valance, front clip. RobT (2002Haus) has a patch panel I can get. I was wondering the same thing about keeping the patch panel in place and tack welding.

[gwb72tii]

Jesus. Just a STUPID thought.

more inspiration

i'll repeat what someone else said

you're the biggest piece of crap on this board, i can't find anything of value you've ever posted

http://www.bmw2002faq.com/component/option,com_forum/Itemid,50/page,search/search_author,JhC/

[bluedevils]

Get a Mexican who works in a restaurant and who used to be welder in Mexico, offer him 20 bucks/hour and give him the patch floor, your welding machine and other supplies and come back four hours later, your floor will look like new.

[Kidasters]

I got a buddy of mine who is an ace welder one of the auto darkening helmets. They are excellent.

I think it was this one, but I'm not sure:

http://cgi.ebay.com/MILLER-PRO-HOBBY-RED-FLAME-WELDING-HELMET-231408-/360180519830?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item53dc6e9396

It was his payment for helping me (read as "Doing") weld a new floorboard in my mini.

[Guest Anonymous]

Here's a real good read on the subject;

http://www.garagejournal.com/forum/showthread.php?t=53534

[Davo]

Thanks for posting that. I just got a 55 Chevy that needs work in exactly the same area. I can't believe how much in the way of parts are available. The headlight brow section is $65

[TobyB]

I'm not clear, here-

are you trying a butt weld

or are you overlapping the patch?

In both cases, you can use screws or pop rivets-

but any more, I just make a tack, readjust, tack again,

recheck, tack again, ad nauesum until the patch is

so bound with 1/8" tacks it's solid.

Then I use 1/4" long beads (carefully, moving around,

still readjusting, cooling occasionally with a little water)

until it's welded up.

Any more, I butt weld everything.

But then, everything I own is a butt...

And by readjust, I DO mean with a body hammer and dolly.

Metal's always moving when you're welding it, and the

best of the best can make it dance right into place.

The rest of us go more slowly and adjust with care.

And also cool our work rather frequently- sometimes,

that makes all the difference.

t

[JohnN]

I'm guessing that all I would do is create a nice home for the rust worm. . .

Am I going to incur the wrath of the BMW gods if I go the 'cheap and cheerful' (overlapping patch) way ????

John N

[kcdonahue]

John,

I actually find it more difficult to go with the overlap method (I'm pretty anal)... Even using a crapload of self tapping screws to hold the patch tightly in place, I find that I still have to beat the crap out of the patch and panel with a BFH to get the two layers to meet so that I can weld them without burning a hole. After that I usually end up grinding the shit out of things further weakening the repair...

When I use a tight fitting patch panel that does not overlap, I find that when I take my time, using short 1-3 second zaps with the MIG, all around the perimeter of the patch I end up with a nice solid patch that is strong and presentable.

I usually use welding magnets to hold the patch in place while I tack it in. Just make sure that you are not welding directly over a magnet as it screws things up.... As Toby mentioned, you may need to cool the panel after you do some welding. I keep a crappy old terrycloth towel full of water (not dripping) close by to cool the welds after a few seconds of zzzzaaappppping.....

Hope this makes sense...

Capt. Morgan and Coke.

[gwb72tii]

I'm guessing that all I would do is create a nice home for the rust worm. . .

Am I going to incur the wrath of the BMW gods if I go the 'cheap and cheerful' (overlapping patch) way ????

John N

no

any patch that works and fixes the problem that meets your standard of correct is ok IMHO. its an old car.

post up pics when you do the repair please