Quarter Panel Replacement Question

[Rich Ackermann 174]

To anyone who has replaced their Fastback quarter panels. I am getting ready to replace my 70 fastback original quarters with Dynacorn Skins. The skins replace the old panel from the front door jamb lip to the rear quarter extension lip, and from the rocker, wheel well lip, and drop down on the bottom of the quarter to about two inches over the top of the quarter shoulder. See the picture attached.

My quarters are mostly good and only need to be replaced from about halfway down the quarter, this would include the section at the door jamb/rocker in front of the wheel well, the wheel well lip and the lower quarter behind the wheel well where it meets the dropdown and the tail panel and valence.

So my question, is it best to use the entire replacement skin, which means cutting the old quarter panel over the shoulder (just below the quarter window and thru the top of the trunk deck area), or is it better to cut the old panel a few inches down the side of the panel below the top of the quarter, and trim the new skin down to meet it? Seem to me, that it would be easier to patch them together on the side of the panel where you have a more "wide-open" surface area to work it.

I would appreciate feedback, from anyone who has done this before.

Thanks

[mustangstofear 608]

It's  best to weld it on thw way you have,  less warping.  I would  flange the original  Qtrs,  then lay the skin on top.

[Rich Ackermann 174]

2 hours ago, mustangstofear said:

It's  best to weld it on thw way you have,  less warping.  I would  flange the original  Qtrs,  then lay the skin on top.

Got it. I am planning on TIG welding it and moving around the seam to keep the heat down.

Do you recommend flanging it with an overlap instead of overlaying the new panel on the old and cutting thru both the new and old and then butt welding the seam?

Thank so much!

[unilec 57]

I would try to retain as much of the original panel as you can, also you need to fit the door on to retain the correct body line. Do you have a pic of the original panel?

[mustangstofear 608]

I would  flange the original Qtr and install the  new on top. 

[Mike65 475]

When I replaced the quarter skins on my 69 Coupe I came down about 1" from the top body line & cut the quarter off, then once I had the fit I was happy with I cut the top of the quarter 1" higher then needed & then flanged it & slide the flange of the quarter skin under the old quarter panel did one last trial fit & screwed it together. When I was happy with that fit I started welding it on.

 

[dcm0123 15]

9 hours ago, mustangstofear said:

It's  best to weld it on thw way you have,  less warping.  I would  flange the original  Qtrs,  then lay the skin on top.

Do this. Will be easier to blend in the two panels because the surface will warp less as it states above. Not sure about flanging the edge. If you cut the old panel about 1" below the seam but weld it as you want to, leaving the corner on the old panel will result in less warpage on that section as well but will require more filler to blend the weld seam in.

It was already installed in my car when I purchased it but needed to be finished. It was cut and overlapped about 1" down from the edge as Mike65 did it. The panel warped and required quite a bit of filler to smooth it out.

If there is any of the original quarter flange left under the rear edge where the new quarter meets the tail light extension, I suggest you remove it so the old flange is at the same height as the new otherwise the fender extension may not sit flat. I would do the same with the front edge otherwise the door gap may not be right when you are done. Use the spot weld drill to cut the welds and grind flat. Install the rear valance panel before welding to make sure the end lines up with the edge of the quarter.

Do not make the mistake I did- grind all lead out of the seam of the old quarter to the roof panel and then fill it with Fiberglas reinforced filler. If you do not and you have any rust under the lead, it will cause the lead/paint to bubble.

[mustangstofear 608]

Welding the  qtr on the top will produce  less warping than  down the  side. 

[barnett468 418]

When I am doing a concourse car and the seams are still good, I section in the piece I need then butt weld it, but this is a pita.

[Ridge Runner 1,112]

Back when you couldnt get replacement panels i also butt welded them ,overlap the pannel and cut through both pieces at the same time about 6 inches at a time ,flush fit the new panel to the remaining old piece and tack about 1 inch apart cooling eack tack as you go to keep it from warping . Once fully tacked go back and fill in by stitch welding in between each tack and cooling as you go . Shift your welds around on the new pannel to keep away warpage 

[unilec 57]

If you look the sharp bends at the door and rear quarter of the old original quarter panel then look at the replacement panel bends there is no comparison and you will notice it when the door is in place and the rear extension is fitted, so like I said try to retain as much of the original panel as possible.

[Rich Ackermann 174]

Thanks all for taking a moment to share your experience and expertise. You have all given me lots to think about as I prepare to take on this new challenge... quarter panel replacement. I will let you know how it goes.