I have to replace a cross member on one of my old MB's and have to break the tack welds to get it out. Is there an easy way to do this if you don't have a torch?

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1982 300SD
1967 250S
...what was I thinking......

If you're talking about spot welds, Eastwood has a variety of products that will work.

Sopt Weld Cutter

I've used the drills for removing body panels and they work fine. Depending on how many welds you're removing, you may want to order two. The ones I got wore out after about 50 holes.

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

I reckon the first question to ask is are you talking about spot welds or tack welds? If you're looking at a tack weld...an angle grinder or die grinder either one will likely be the best choice...even better often than a torch. Some tack welds are postioned such that you can get to them with a reciprocating saw. Beyond that you may be looking at some time with a cold chisel and ball peen. Hopefully this gives you a few possibilites given your space limitations and gets you going...I know outfits don't leave us a heap of wiggle room for doing stuff like this

Jim

I'm replacing a front cross member that is welded at the front of the frame and along the radiator mount. It's under the mount that I have to separate. I don't think it's seam welded. It looks like it's spot welded.

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1982 300SD
1967 250S
...what was I thinking......

The normal way is to get a spot welder drill. It has a pilot bit and a cutter and you drill through both pieces of metal with the pilot bit. When the cutter bit starts cutting you only go through the first layer of metal. This is about the only way you can do it neatly. Standard fixture in the auto body shop buisiness to remove spot welded panels etc.
Your problem may be getting one large enough for your job. If you have the room you might be able to just drill through them. Your outside area of cut must go past the edges of the weld to separate the two pieces of metal.

The cheapskate way it to use a decent sized drill bit, roughly the size of the spot weld, and drill into the spot weld. Stop before going all the way through the second layer and use a hammer and chisel to pop the weld loose. Probably not as good as a dedicated spot weld drill, but will work. When welding the new piece on, you can drill a hole in the new part (or use the previous hole drilled in the old part) and use a wire feed welder to weld in the hole and "spot" weld the pieces together. Grinding down the excess weld will make it look good. They do make a dedicated spot welder, but how many do-it-yourselfers have one of those.

As KCM said.......I have used a small drill bit to make a pilot hole straight through the centers of the spot welds then come back with a large bit about the diameter of the spot weld to cut through the top layer. Has worked for me on several of my classic cars in the past. Then drill holes in the new part
about the same factory spacing as the old welds and weld through the holes with a Mig Welder to form a plug. Grind them off with an angle grinder to make them look like a true spot weld.

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FRED

Daily Driver: 98 E300TD 199K
Hobby Car: 69 Austin Mini
Past Diesels: 84 300SD, 312K
87 300SDL, 251K
94 Chev. K-1500 6.5Ltr.TD, 373K

I actually mangled it pretty badly and will now have to replace the sheet metal. I got a bit ahead of myself. I'll have to go to a junk yard and have them cut out the piece I need and weld it in myself. Fortunately, I picked up MIG welding yesterday and it doesn't seem that hard.

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1982 300SD
1967 250S
...what was I thinking......

There is a nozzle for migs that is cutaway on two sides. Or another way to look at it is it has two areas of the nozzle protruding.
So when you spot weld with it you can press the two pieces of metal together before you activate the gun. A person could modify an old nozzle as well.
One more nozzle variation is a tube welded diagonally on the side if the nozzle. You insert a steel rod until it touches the metal. Pull your trigger and it welds the protruding rod to the sheet metal. Then you can pull the dents out. Just grind the rods off when you are finished. Again with a little effort you can make your own if unavailable in your area.
Just thought I would mention as they may not be common. But what do I know. Either way they are useful and not rocket science.

They actually make a very useful tool for doing this in the body shops, a "Stud Gun" and it also has other tips for doing heating and shrinking/stretching operations in dented areas, as well as tips for installing rivets for landau tops. The stud gun replaces the old screw in dent pullers of the 60's and back. I bought one 8 or 9 yrs ago, and its paid for itself several times over, I got the good one that came with a hand pull T-handle in it and a slide hammer, only thing I might ever need for it is a clamp attachment for grabbing groups of studs when doing big pulls with hydraulics.

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Chris
64 190D R.I.P.
80 240D W/617 engine -for sale
82 240D -for sale

Being a new welder, I'm having a hard time visualizing what you are describing. Do you have a picture or drawing? I bought a Lincoln welder so maybe they have one? I assume you use the two sides of this tip to create your welding pool and thus melt out the plug?

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1982 300SD
1967 250S
...what was I thinking......

For drilling out spot welds, a good substitute that should work very well (since it has a flat cutting surface rather than a taper as in a conventional drill) is the Bullet point drills by Black and Decker. I think DeWalt also has them. I've seen them in Walmart.

Here's a pic:

http://www.bcae1.com/images/jpegs/plexibanddbit.jpg

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked