Tail Light Panel and Trunk Floor – Part 2

Well……as much as I whine about sand blasting, I can’t deny its unmatched usefulness in auto restoration.  So, while the weather continued to offer opportunity to do so, I put on my “big-boy pants” and set to it once again to properly clean the flange areas of rust scale and better evaluate the wheel opening corners and inner wheel housings.  I already knew I was in for a repair on the right side rear wheel opening, but as I soon discovered, the left side would not escape the same fate.  Looks like the scope of work between the left and right side of the car will be a virtual match.  Whoopee………

The “up” side to this discovery is that I had already prepared for most of this additional repair, so all I need is one more patch panel to cover this newly discovered damage.  As a bonus, I can purchase one single patch panel that will cover the left rear wheel opening corner patch as well as the curb damage on the front wheel opening (more on this in a future entry).

With clean(ish) metal to work with, I leveled the car on the chassis support posts and started marking all of the spot welds locations on the left trunk floor in preparation for removal.  This is where a bit of pre-planning helped quite a lot, as all of the spot welds are not easily accessible with the spot weld cutter.  Also, a secret to making the job go much easier was to cut away as much of the old panels as possible such that I was left with only the spot welded flanges to work with.  I chose to use my pneumatic sheet metal nibbler for this as it is quick and capable of maneuvering in tight spaces much easier than my air saw.

With the bulk of the left trunk floor panel out of the way, I cut the spot welds free and popped the panels out rather easily.  The two areas that require a different approach are the welds along the inner wheel house and along the lower quarter edge between the wheel opening and the rear valence area.  In the inner wheel house area, I marked and drilled the welds from inside the wheel opening and gently separated the panels with a thin putty knife.  On the lower quarter flange, I found I couldn’t approach the welds straight-on with my spot weld cutter due to interference with my rotisserie, so I sized things up and decided to carefully grind through each spot weld with my cutoff wheel so I could pop the flange loose without running the risk of drilling a hole through this rather narrow flange.

It’s worth noting that all of the welded flanges in this area of a Mustang have weld-thru seam sealer between them and this provides significant resistance to separation of the flanges even after the welds are cut.  Another caveat is that you can be absolutely sure that anywhere Ford put this weld-thru seam sealer between the flanges is now quite rusty.  There’s absolutely no escaping this fact and it’s one of those dirty little secrets that nobody wants to let out of the bag and unless you plan to completely disassemble every last welded seam in the car, this is something you simply must deal with.  This is one area that has me thinking a chelation “dip process” could be very effective.  But that’s another story altogether……..

With the left trunk floor out of the way, I removed the rear trunk floor flange with rather unceremonious application of my trusty Sawzall which allowed me to remove the small section of flange left attached to the rear subframe horn.  With all of the offending sheet metal now removed from the left side, I was delighted to find the left rear subframe rail in pristine condition!  If ever there was an automotive “miracle” this discovery just might be it.  For as much weather that this car has endured, and the state of the trunk floor in general, the fact that the subframe is in such good condition almost defies explanation.  Thank goodness for galvanized metal!  Here’s hoping the right side is just as good.

In the meantime, I will start grinding the spot weld buttons smooth, metal working the flanges flat and starting the quarter and outer wheel opening rust repairs.  I have also found a number of additional stress cracks and valence bolt hole damage that requires repair as well, so the next few weeks will be pretty full.

Though it's tough to tell in this photo, I have started by marking all of the spot welds that need to be cut to remove this trunk floor section.

Here is a view of the rusty mess and you can see some buckling evidence of the rear punt the car took sometime in it's life.  I have already scraped off the sprayed undercoating that lined a section of the inner fender in this shot.

The right side looks a tiny bit better, but this is the side where the rust has eaten through the outer skin at the rear of the wheel house.

After slapping myself around a bit, I sucked it up and rolled the car out to the drive for some sand blasting mayhem.  In the end, it was the best decision.

Looking back up from the trunk floor to the top of the left rear quarter, you can see there was absolutely no pant or primer on the majority of these surfaces.  We're gunna fix that soon!

I love my dad!  Always there to help and always an ace at everything he does!  He's the reason this job got done before dark!  As you can see, he plays the Sandman quite well!

Have I mentioned that stinkin sand gets EVERYWHERE?

After a short blast from the inside, you can clearly see the rust perforation in the right rear quarter.  No surprise.

I didn't blast everything totally spotless as I plan to do another chelation experiment very soon on the inner quarters.

I rather like this view.  It really looks like I'm getting somewhere.  Nice clean, solid metal in beautiful grey primer.  And then.......

.......ya get this by stepping back a few paces.  Quite a contrast and probably the best indicator of what the current job entails.  Once it's done, she should be nice and solid again!

SURPRISE!  After the first several spot welds were cut and the floor pulled back, I couldn't believe how nice the inner frame rails were!  However, I quickly found that cutting away the extra material with my nibbler made removal of the panel much easier.

How about that!?  No problem at all working with these rails!  Hopefully the right side will be equally good!

With the bulk of the metal removed before I started drilling out spot welds, it was relatively easy to get the welded sections out.  Here, the entire left trunk floor is removed.

Note that every place there was a spot welded seam (except on the galvanized rail flanges), the factory weld-thru seam sealer has promoted rust between the panels.  One of the "dirty little secrets" of classic Mustang restoration.

The last section I removed was the rear trunk floor cross panel that spans the full width of the trunk from apron to apron.  Again, I cut out the bulk of material with my trusty Sawzall and left only the spot welded section to remove.

Here is a good shot showing the way I support the rear frame rails in the rotisserie as well as the small section of material that remains to be removed from the rear subframe horn.

Here is the head-on shot of the rear of the subframe with all of the rusty metal cut away.  Nice!

And there we have it.  A pile of rusty crap that used to be a left trunk floor.