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.

Tail Light Panel and Trunk Floor – Part 1

The last major structural repairs that must be completed on my Boss 302 before “regular” restoration work can commence involve replacement of the trunk floors, rear tail light panel, rear quarter extensions and repair of the front trunk floor/axle tunnel flanges along with a small amount of rust repair on the right rear wheel arch.

It sounds so simple to condense it down that way, but this amount of work is quite extensive and will take a few months to complete, if not longer.  In fact, as the pace of restoration work has slowed over the last few weeks with non-Boss related activities, the chances are that this particular project will continue deep into the winter before it is complete…….so let’s get started!

At one point, before my ownership, this car was the “meat” in a traffic accident sandwich and suffered light damage to the rear and somewhat heavier damage to the front sheet metal.  Luckily, the rear quarters were not buckled in the incident, but the tail light panel, and rear center trunk floor and lower valence were folded noticeably and the temporary repairs were very poorly executed.  The end result was rust invasion between every panel such that the only way for me to repair them was total panel replacement.

I spent several weeks studying the landscape of this repair, carefully mapping out every step I would take in making sure the end result would be well-fitting, straight and pristine sheet metal.  Once I was comfortable with where I was going, and the repair panels were in hand, I was off to the races.

One significant change to my plans was actually a welcome reduction in the scope of work I had envisioned.  The lower rear section of the right quarter panel was where the rust repairs were required.  Originally, I planned to install a complete patch panel along the entire lower rear quarter panel section, however on closer examination, I discovered I had a lot of good metal around the area and the repair could be condensed to a small patched area instead.  This leaves the vast majority of the original quarter panel completely intact which is a bonus by almost any definition.  The one caveat to this repair is that it will have to be done while I have the right side trunk floor out to allow proper access to the back side of the repair areas.  No biggie, just planning.

With a solid plan in place, I pulled out my trusty red paint pen and set off marking the cut lines that would allow me to efficiently remove the bulk of damaged sheet metal in the shortest time.  Next, I squared and leveled the chassis on the rotisserie and placed my jacking posts under each rear torque box to maintain this position and to provide substantial support to the chassis while the repairs were being made.

Using a white paint pen, I started marking the spot weld locations that would need to be drilled to allow the fender extensions and inner jack mount, spare tire mount and rear bumper brackets to be removed.  Then out came the “screaming wheel of death” and the sparks started to fly!  After about a half hour and three cutoff blades, I had the tail light panel out of the car.

With room to work, I could now drill the spot welds and remove the jack and spare tire mounts, both rear bumper brackets and both rear fender extensions with relatively little trouble.  This also allowed me plenty of room to scrape the little bit of remaining undercoating off the inner rear quarter panels to make all future work even easier as well as provide a nice smooth surface for Dynamat adhesion when the finish work begins.

I cleaned up and straightened the fender extension flanges with a little angle grinder work and some hammer and dolly taps and began fitting the fender extensions using the factory body locating holes in each quarter panel flange.  I was pleasantly surprised at how well the fender extensions fit (for a change) and I like the one-piece design of the new panels over the rust prone 2-piece design of the original extensions.  Of course, restoration purists will throw up all over this idea, but from a practical perspective, the idea is a good one and I am glad for it in my case.

I spent quite a bit of time making sure the fit of the new quarter extensions was as good as it could be and clamped them in place just as if they were being installed.  Then I carefully marked each spot weld location so I could remove the e-coat only where the welds would be needed.  Did I mention you can never have enough good vise-grip style welding c-clamps?

And that’s where we are.  The next phase will be to remove the trunk floors and start preparing the flanges for the new parts.  In there somewhere, I will start the process of fixing the front trunk floor section as well.  All in all, there will be a lot of tack welded and Cleco’d pieces put in place before the repair work can be finalized.  Off I go!

Front trunk floor/axle tunnel is pretty rough.  Rectangular hole in the upper left is the area cut out by the factory for the staggered shock mount.  I will be repairing this section with new metal and eliminating this hole as it is not required with the rear suspension I am using.

Right side trunk floor is a mess even with the jack and spare tire mounts already removed.  You can just barely make out the buckling at the very rear edges of the panel from a previous bump.

Left side trunk floor is pretty rusty and wrinkled as well.

Using my red paint pen, I marked the locations where I would cut the tail light panel and quarter extensions with my cutoff wheel.  Here is the left extension marked for cutting.

Right side fender extension with cut line marked.

Right rear corner cut line.

Left rear corner cut line.  Some of the wavy sheet metal is visible here.

The white freckles in this shot are spot weld locations marked with white paint pen.

More spot welds located.

Spare tire bracket and jack brackets removed.

A few minutes with a cutoff wheel and the rear tail light panel was out!

With a little metal work, the rear quarter extension flanges were nice and straight.  This allowed me to fit the extension panels quite nicely.

Quarter panel extensions are aligned using the body alignment holes.  These are the three larger holes in the flange that are used when mounting the extension end caps.

As fitting comes closer to perfect, several clamps are required to prevent movement when working on specific areas.  You can never have enough vise-grip type welding clamps.

Right side extension was fit in the same way as the left.

This is a good shot of the fit I am always trying to achieve.  When spot welded in place, this panel will fit every bit as well as the factory parts.

Lower on the outer edges, the fit is equally good.

This is probably one of the trickiest areas to fit on the rear extensions.  Patience and clamping helps as you work the flanges to get the fit as tight as possible.

Heidt’s Subframe Connector and 4-link Mount Finishing & 9” Rear Axle Inspection

A lot going on the past few weeks, but I have managed to get some good “Boss time” in between diversions and am looking pretty good as the Fall season rapidly approaches.

I spent a few nights tidying up all of the welds securing the 4-link brackets and subframe connectors and sanding the surrounding areas to get everything ready for primer.  At the same time, I decided to scuff clean a few areas on the inside floor of the car where I noticed a few small spots that had lifted where I had primed over some Zero Rust paint.

Once I was satisfied I had properly prepared the bare metal areas around each weld site, I swabbed everything down with generous amounts of PPG DX-330 Acryli-Clean to remove any traces of dirt, grease or wax and, because I was working around so many seams and flanges, I decided to let the solvent dry overnight to make sure I would not have problems with bleed-out once I started priming.

The following day, I got all my paint equipment locked and loaded and prepped the surfaces with a good wipe with a tack rag.  With fresh primer mixed up in my gun, I shot all of the areas with a nice even coat of primer and followed up with a second coat about 20 minutes later.  I am finding I really like the DP-402 catalyst much better than the DP-401, not only because it’s quicker and easier to mix, but because I think the bond strength and resistance to lifting is better and it seems a bit more forgiving to shoot as well.  I think I have been converted…..

With the priming complete, I was happy with the look of the installation and particularly happy to consider the installation a complete success.  Next, it was a simple matter of flipping the car end-for-end in the shop in preparation for the Fall project of replacing the trunk floor panels, taillight panel and repairing the rear axle tunnel.

Since I had a little Labor Day weekend left, I decided to tear down my rear axle housing to see what horrors might exist in that area as I make preparations to complete the 4-link installation.  Much to my surprise, the damage that I expected (and was, in fact evident) was fairly minimal.  As expected, the third member was not the original to the car, but it is a genuine nodular iron “N-case” 9 inch with 31-spline axles, so it appears I have something to work with.  Unmerciful drag launches took their toll on the spring perches as evidenced by the fact that the leaf spring dowel holes were mangled and the perches showed stress cracks at the root of several welds.  Other than that, however, the housing appears to be the original and will be an excellent foundation for the rest of the 4-link rear suspension.  With a fresh Detroit Locker diff and a set of 3.89 gears along with a Daytona pinion support and new bearings and seals and this axle should be just about bulletproof.

Over the next few weeks, I plan to start the slow process of carefully planning the entire trunk floor repair work.  I’m a bit slow on the planning front, but before long, I will be making sparks again with the hope that the work will flow smoothly until the structural work is finally done later this Fall.

A wire cup brush chucked in my drill was the right tool to clean up the weld areas before priming.  However, I started by breezing all the weld edges with my angle grinder to make sure there were no sharp edges.

The 4 link bracket was most challenging to clean up but everything looked good to go after a few hours of work.

Front subframe connector mounts cleaned up well.

When I welded in the front subframe connector mounts, I scorched the primer on the interior floor just above the weld areas.  Here, I scuffed away the scorched primer with the angle grinder and followed it up with a DA sander to blend the edges.

With the spray gun locked and loaded, the priming could begin!  Here's a front subframe connector fully primed.

I love the fact that the 4-link setup looks so inconspicuous when it's all in one color.  Exactly the effect I hope to achieve when the car is completed.

Interior scorched spots are no more.

Rear subframe connector looks nicely integrated.......just like it belonged there.

9-Inch Rear Axle Teardown & Inspection

A genuine 9" nodular iron third member.  Not original to the car based on the date code, but genuine nonetheless.  Something to work with.

Brutal drag race starts have mangled the leaf spring dowel locating holes beyond use.  Fortunately, I will be cutting these off the housing soon.

The opposite side spring perch is equally hosed.

If you look closely at the root of the welds in these two pictures, you will see small stress cracks.  Another sign of a hard life.

Axle housing flanges look excellent.

I am pretty sure the housing itself may be original to the car.  It is in surprisingly good shape considering it's hard life and will be a great foundation to finish the rear suspension.