Separating Sheetmetal Welds

[LanceLyon]

Hi everyone,

I'm sure many of you have gotten to the point in their restorations where they need to remove various sections of sheetmetal that are rusted. In the areas where sheetmetal is connected to a frame member it appears that the best way to remove it is to cut it as close to the frame as is reasonable, and then use a grinder to get everything flush and clean.

There are areas however, when sections of sheetmetal overlap one another, and are either spot-welded or connected with interupted welds. What is the best way to separate them in these areas? A case in point is the floor of the trunk area that is connected not only to the cross frame member, but also to the wheel arch, bumper brackets, skirt rail supports, rear bulkhead etc. I guess the question is, do you attempt to separate the connections, or simply cut the metal at the edge of the connections and attach the new piece to the now "doubled-up" piece? This applies to areas of the floor panels, sill pannels, side reinforcements as well.

Not coming from a bodywork background I am not sure what is "kosher" or what is smart! The last thing I want to do is to either create more work or cut away something that I'll regret!

Thanks in advance for your thoughts on this.

Lance

 

[Keoke]

Hi Lance, there is a tool called a Spot Weld breaker.They come in various diameters and can be used with a good 3/8 inch hand drill.These little buggers look like miniature hole saws but they perform like a miniature milling machine when used in the hand drill.They are available from specialty tool supply houses; Snap-On Mac tools and others.--FWIW---Keoke

 

[Skip & Lynne]

hi Lyon the first thing I did was to make sure what I was trying to save was worth it. Most of it wasn`t and if it wasn`t going to be worth saving I used a high speed grinder with a thin cutting wheel and scarificed the bad stuff and then just cleaned things up. I spot welded my new sills togther wrong (no epoxy primer) and had to open them up again and I just used a drill with a bit slightly lrger than the spot weld and they came right apart. Hope this helps

 

[Skip & Lynne]

scuse the spelling I am in bed with the flu anyone want some

 

[Cutlass]

I tried the inexpensive spot weld removers. The teeth break quickly. There are more expensive, one piece spot weld removers that supposedly work very well. On my BJ8, I've removed all floors, including trunk (boot), sills, rockers, front door hinge faces, using a high speed cut-off tool with 3" diameter, 1/16" thick wheels, much in the same manner you described. If I had it to do over again, I would have bought a high quality, one piece spot weld remover. It's hard to get to some of the spot welds with a cut-off tool, and there's always some of the "good" metal removed. Finally I'm nearing the end of my now eight month chassis repair. If you're up in the Atlanta area, I'd be glad to show you what I've done, on the condition that you learn from my mistakes, and don't tell everyone how stupid they are.

By the way, I learned that pre-priming metal that is to be tig welded later makes welding very difficult. On my sills and rockers, I'm leaving access holes to insert Waxoyl type rust inhibitors after painting. FWIW.

 

[Keoke]

Cutlas, Snap-On and Mac tools are not Inexpesive and all good shops use tools of Comparable quality.---Keoke /ubbthreads/images/graemlins/yesnod.gif

 

[Randy Forbes]

I second the use of a quality spot-weld cutter. In my opinion, the ones made by Blair are the best. They have a new one called a Rota-Broach (I think) and it works FAST!

On some of the Healeys and MGs I did floor replacements on, I would use a torch (nowadays, I would go Plasma) to cut as closely to the flange as possible. Then I would use a pair of "lineman's" pliers to peel up the remaing metal left on the flange; similar to opening an "old fashioned" coffee can. The flange would remain intact and the "popped" spot or seam welds would clean up nicely with a 4-1/2" grinder.

Putting the new floors in using plug welds closely mimics the factory spot welds.

Good luck, and have fun /ubbthreads/images/graemlins/wink.gif

 

[bob hughes]

The technique used by Randy has also been recomended in Practical Classics, one of the magazines over here that is dedicated to car restoring. I don't think that they were using plasma cutters but the principle is the same, trim back to the lapped joint then peel off the old metal from the flange you wish to save, between spots, then clean off with a grinder and dress up ready for the new material.
Bob /ubbthreads/images/graemlins/cheers.gif /ubbthreads/images/graemlins/england.gif

 

[Johnny]

Ahh what fun. There really is no easy way, unless you have a cutting torch. I used various methods, scroll type saw with metal cutting blades (worked well on fenders etc). I also used to drill out spot welds, even bought Eastwood's spot well drill, worked okay for awhile. But my favorite tool, and is now the first thing I grab, is a large chisel type sheet metal cutter and a ball pean hammer. The chisel has a wide thin blade, cushtioned hand protector (a must) and I must say worked better than anything else. I think I bought it at Eastwood, or maybe Harbor Freight. Good Luck.
/ubbthreads/images/graemlins/hammer.gif /ubbthreads/images/graemlins/hammer.gif

 

[LanceLyon]

Thanks, Everyone!

I picked up a "Blair" this morning on the way in to work, and I'll give it a try tonight.

You guys and this forum are always a great support.

Thanks, again,

Lance