Right Rear quarter trunk corner repair-part 1

It's been a week of craziness.   Christmas coming in a week and a day has my schedule pushed to the max.  Plus we're on "baby watch" for my #2 grandson, which reminds me I need to get him some baby Mustang swag.   I'm slowly checking off the "to-do" list from work and home.   The children's Christmas program was today.  It all came together and went off without a hitch.    Of course, the 3 year old "angels" provided a level of comic relief as they adjusted their wings and did everything else to keep themselves from getting bored.  Afterwards, I headed home somewhat tired and ready to veg out and watch the Colts and then follow that with the Lions.   Somewhere and somehow, I decided to at least get started  on the next repair that I knew was going to be a challenge.

This repair is going to be an interesting one since there is not a repo part for it.  I don't think that a full rear quarter repair had enough metal to do what I  need done...not to mention that it's a $400 plus part.  Granted, I do have some serious "dolly and hammer" work on this quarter, I don't want to replace original metal I don't have to.  I also knew this would tax my metal-working skills to the limit.

The first order of business was to get the car turned around so that the area I would be working on gave me better access.  Thankfully, it wasn't raining.  So I rolled the Mustang outside on to the driveway, did a pirouette, and put it back in the garage front-end first.

The next step in the process was to evaluate how much of the metal I needed to remove.   This is the offending area to be repaired.  It is located on the top right-hand side of the trunk opening on the body as you're standing at the back of the car.  It's a strange place to have this kind of rust damage considering the other side has no rust whatsoever.

I taped off the area to be removed to act as a guide for the cutoff wheel...

I found 2 spot welds and carefully drilled them out. 

Then I took my 3" cutoff wheel and cut around the edge of the tape.  I had to be careful not to cut through the underlying substructure...

It took a little "creative" work to get to the area I couldn't access with the cutoff wheel.  I used a combination of my air saw and a chisel with hammer to persuade to part loose.  The lip got distorted with all the prying and hammering, but this is the offending rusty piece after removal...

This is the underside of the part.  It's pretty rusty.

This is the substructure of the upper right trunk corner after I cleaned it up a little.  It had some rust pitting, but overall was in acceptable condition...

Here's another view looking at the opening from the rear of the car.  The one thing I noticed before cutting is that there isn't one flat contour on the body at this transition.  It has a curve, either concave or convex on every plane.  This will be a fun piece to make.

The next step was to make a template of the area for cutting out the new metal.   I decided to make this in two parts since I don't have the means to make it out of one piece.  This is when a planishing hammer, English wheel, and a stretcher/shrinker would come in handy.   This template was a rough cut of the rear quarter top section

Here is another view.  This is going to be a challenge since you can see the bends in that will have to be formed in different planes. 

Since the lip section of part that I removed was ready to break off, I went ahead and removed it.  I would deal first with the part that would be the outer body section.  I tried to cut it so that as much of the transition radius from the body to the lip remained.  You'll see why later.

Here's the back side of this piece...

I then used the original piece to trace the pattern to make the template more exact to the part.  I cut it a little larger than needed so that I had enough metal to work with..

The next challenge was how to make the lip section that formed the trunk opening.  It had multiple contours.   I took a page out of my old drafting and design days and decided to make the template using an orthographic view.  That takes a 3-dimension object and projects it as a 2 dimension object.  To do that, I carefully flattened the piece which was a trick with the majority of the rust along the edge.  I didn't want to loose too much of the edge and hence the profile of this piece of the part.  When it was flat I traced the part onto cardboard and allowed for the nonexistent edges that disappeared from rust...

Here's the template after tracing and cutting.  Again, I left more metal than needed as just-in-case insurance...

Now the fun begins.   I put both templates into position on the car to see how close (or far off) I was.  For the first cut, it didn't look too bad.  But cardboard and steel don't have the same forming properties.  I'll do the final trimming and shaping with the metal.

Here are the two pieces in metal ready to be bent to shape... 

The first piece I formed is the top of the quarter panel.   Here is the part after multiple trimming with the air saw and 2" air sander.  The black color is after the Eastwood rust converter dried...

This is the same part from a different view.  You can see all the different contours of the part.  Of course, when you shape one contour, it changes the other.  Patience and a deft hand came in handy.

This picture is looking toward the back of the car.  Again, you can see the different contour changes of the body.  

OK.  Since I had the general contour done, it was time to form the radius along the trunk-side of the part.  I didn't want to do a square corner weld since that could end up with a mess...blow through, grinding through the corner, more welding, etc.  This is from experience.  Better to butt weld flat joints than corners on thin sheetmetal.

I had scribed a line when the part was on the car to give me a reference where the radius needed to start.   Then I chucked it in my vice and slowly bent it over using a couple of different body hammers...a pick to start the radius and a flat face for the final forming of the radius.

The challenge was the radius on the corner and the curved section.  I clamped the part in the vice with the bottom of the radius of the corner lip in the jaws.  After starting the lip, I kept moving the part so that I was working through the corner about an 1/8" at a time.   This was really tedious work, especially since I didn't want to loose the entire contour of the part.  Here it is with the edge radius completed...

I used a similar technique on the second piece in forming the near 90 degree angle that transitions from the body to the trunk lip.  It was sharper than it should have been when compared to the "good" side.  To round it out more, I used a 1/2" steel rod clamped in the vice to hammer a bigger radius into the part.  It's OK but I'm still not happy with it.  I'll fine tune it later.

What took time was the forming of the corner contour.   After getting the first bend in the long section, I clamped it in place on the end toward the rear of the trunk and along the flange that would eventually be plug welded to the trunk lip.  Then using a wide end and pointed pick body hammers,  I used the thicker inner trunk structure as my "buck" to hammer the shape into the piece.  This was a progression as I left the end clamp in place and moved the large clamp along behind the section I was working.   This is what I ended up with when I got to the opposite end...

When I got to the corner the metal was "bunching up".   To relieve the metal,  I cut 3 slits with the air saw to allow the corner metal to gather together...



The cuts aren't the best since they were in a location where there wasn't much "meat" in the metal.   I'll weld these up when the time comes...



A little more clamping and judicious body hammering and the shape is getting closer.   Here's another view from the top with the blue "back up" tape removed that was holding the top piece in position during shaping and fine tuning....

Now it was time to marry the two pieces together and see what adjustments will be required.  After adding the radius to the top piece, it took multiple trips to the vice and wood buck block along with good ol' fashion hand bending to get all the proper contours into the part again.   
 

The first mock up wasn't too bad.  I had to grind off the top of the vertical part about an 1/8" to accommodate the radius addition.

The corner was not matching up.  I took a flat-end punch and carefully tapped the radius of the inner piece at the "pie cuts" to get the shape in place.  I also went back to the vice a few times and hammered the corner around the steel rod I had chucked in the vice.   As the corner radius took shape,  the top edge also increase in height.  I then used the 2" sander to carefully contour the metal to match the top piece.  It obviously took several different techniques to get the corner into some resemblance of a proper shape.

I still have some tweaking to do in that corner.   I may also work the radius of the bottom piece so that it isn't as sharp.  I don't want to use body filler to shape the area.  I'd like it as close to the other side metal-wise as I can get.   I know I'll end up with some filler, but less is more.

I realized that I had been in the garage for over 4 hours.  It was time to grab a bite to each and catch up on football scores that were disappointing.  Both the Lions and Colts lost.  At least the Colts still have a shot at making the playoffs.  Considering the changes and challenges they faced this year, it would be pretty cool to see them make it in.

The next part of this little project will involve welding these pieces into position.  I'm still trying to decide how to proceed with that.  I'm leaning toward tacking the two pieces together and then fitting it as a unit into the body.   My other option would be to weld in the top piece and then fit the lower piece to it since it's more critical for the top of the quarter to have the better fit and finish.   I'll have a while to think on it before I get back on it again.   I am anxious to see how the finished product will look, especially when compared to the original opposite side.   Hopefully, there will be no noticeable difference...hopefully.