iam getting ready to weld in some new rear window channel, i always here to butt weld and then grind off smooth, my question is if you grind off smooth doesnt it take the strength out of the weld and how do you keep it from warping when grinding and welding

If you have a full penetration weld (can see the bead on the backside) you've created / replaced all the material the same as if it was a continuous sheet of metal. It's as strong or stronger than the parent metal.

The trick to prevent warping is to tack the repair patch in multiple places, then finish weld in a stagger pattern - distributing the heat around the area. Don't let one spot get too hot. Same with grinding.

John D is right. Tack the panel in place every few inches and take your time.

I just replaced the rear window channel on my el Camino last weekened. I used the patch panel offered by OPG. I didn't need the entire panel so I split the panel lengthwise and lap-welded it. I only cut-out the rust and left the original channel mostly-intact as much as possible (I only needed the channel itself, everything below the window trim and above the front bed moulding is rust-free). This 'little' job was by far the most difficult task on my car to date. Stitch welding the shelf, patch panel and what was left of the original channel while lying on my back was a major pain. But I'm pleased with the results and I'm happy to have this behind me. Just go slow and it should turn out fine.

Tim

Pay really close attention to the geometry when welding the rear window channel in place. You need to tack it lightly and test fit the glass before you finish the welding.

I had to replace the entire channel under my rear glass.


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Chad Landry
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'68 El Camino, 357, L31 Vortec heads, 700R4,
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