Right Rear Quarter in Primer!

Quick on the heels of completing the bodywork on the right rear quarter, I wanted to get the right quarter safely coated in PPG epoxy primer so work could smoothly progress.  Recalling the complicating events of priming the left quarter, I was a bit hesitant to dive into the work as I was not sure what equipment issues I may encounter.

However, save for a few relatively minor glitches, the priming work consumed the better part of a Saturday afternoon anchored by near perfect weather.  Humidity was low and the temp in the high 60’s with almost no wind to stir up little nasties.  And after a thorough round of degreasing, I started the process by masking everything I didn’t intend to prime.  Learning a bit from the left side work, I was able to get good masking coverage with much less material than before without sacrificing any protection.  Bonus!

Another rinse with pre-prep solvent and about an hour of dry time had the surfaces ready for a cut-in and thin base coat of primer.  An hour of flash time, and a second coat was applied and allowed to dry overnight.  The end result was rather pleasing as everything was finally in a single, uniform color and the true contours of the panel were finally visible.  Fortunately, save for a few pinholes in a few spots of filler, the surface will block out perfectly after high-build primer application and we will be in business!  A few days to allow the primer to thoroughly harden will be in store as preparations begin to fit the lower valence, quarter extensions and the rear deck lid.  Once this work is complete, things will start getting interesting pretty quickly as the car starts looking more like it should! 

Right quarter in full primer is a nice sight to behold.  Arguably, this is one of the best angles of the 69-70 Mustang body form.

 

With clean fender lip lines and crisp body creases, this view begins to show how nice this quarter will look when fully finished.

A very subtle and often missed detail is the upper trunk opening corners.  The filled seam is clearly visible in this shot and I love the look!

 

Another look at the front trunk lid corner opening smoothed and primed.

 

And finally, a nice look at the roof seam area of the sail panel.  perfect flow with no hint there is any joint in this area.

Smoothing Up the Right Rear Quarter

As I mentioned in earlier posts, the right rear quarter panel on my car was the most in need of metal work and filling as any other panel on the car.  However, knowing this going in, and coupled with a good plan of action, this heavily iterative and time consuming project went quite smoothly and the results reflect the effort.

As outlined in my post covering this process on the left quarter, I start by sparingly applying the “heavy” filler in all of the areas that have welded seams or require more robust filler as the base to build on.  I use a product called All-Metal for these areas as it is as close to a metal (more specifically body solder) behavior as any polyester filler available.  It has excellent sealing characteristics over clean welds and although it is rather demanding to sand, it can be feathered and smoothed rather well and provides an excellent base for the primary filler I use.

Once the All-Metal is sanded to shape, the process of applying thin coats of Rage Gold body filler begins.  Generally speaking, the first base coat of filler I apply is the heaviest and every subsequent application gets thinner and thinner and over smaller areas until the panel is straight.  There is simply no possible way (other than pure luck) that the filling and smoothing process on a show-worth body will be achieved in a single pass.

After each layer of filler is applied, I knock down the ridges and rough shape the surface with a Surform tool.  One thing I take the time to do is smooth up the fender lips such that they are much more presentable than the often nasty surfaces presented by the factory work.  This also helps create nice, clean wheel opening lines that really look sharp when done.

I will often use my DA sander with 80-grit paper to shape the first layer or two of filler as this is often just a way to establish a base to work from and not the final finished surface that will be established by hand.  This also provides a very nice platform to apply powdered guide coat and block the panel by hand just to see the first indications of how and where I will need to work the most.  From this point on, every successive pass with filling and blocking will be done with guide coat and a very careful application of DA and hand sanding until the final shape is almost complete.  At that point, absolutely ALL of the final blocking is done by hand and with many coats of guide coat to indicate progress and panel accuracy.

Because I had a lot of area to cover that would need various levels of work, I split the quarter into 3 work sections and tackled one section at a time.  I started at the rear where the highest concentration of welded repairs were required and smoothed up the entire rear half of the quarter in the first phase.  Then, with that zone completed, I moved to the front half of the quarter and repeated the repair process until the results were as perfect as I could make them. 

This was an area that was particularly complicated in that the amount of filling that was required was very thin but in many spots that simply were impossible to detect with the naked eye or even by hand.  This is where the religious and generous use of guide coat is the only way to get this type of area straight and actually saves tremendous amounts of time in the process as well.

The final zone was the “top” of the quarter and involved essentially two areas of interest:  the trunk corner seam and the roof seam at the sail panel.  These are rather curvy locations that require very careful and slow sanding to get the contours perfected.  The roof seam area also represents the heaviest filler application anywhere on the car due to the recessed seam area once filled with factory applied body solder.  However, the technique is pretty much the same here as it is anywhere else, and the generous use of guide coat will pay huge dividends along the way.  In my opinion, this sail panel area is one of the sexiest areas of the 69-70 Mustang body with the long, deep curves running almost the full length of the quarter.  That’s hot!

So, now that the right quarter is smoothed up, the next steps will be to prep the panel and quarter end caps for masking and then shoot the works in a coat of trusty PPG DP40LF epoxy primer.  Once that is done, we’re off to the next panel!

First bit of filler than I apply is All-Metal and is used to seal any welded patch area or any area that required welded pins to pull damage.  This filler is very hard and works more like body solder than Rage Gold so I use it sparingly to provide a base to work from.

Shaped & sanded with 80 grit paper to rough out the shape and we are ready to apply standard body filler for the rest of the job.

Here, you can get an idea how thin the All-Metal filler is when dressed down.  Maximum thickness in any spot is only on the order of .050".

Both the rocker panel welded seam and the area where the crease was removed get a thin coating of All-Metal.  These areas have been sanded and are now ready for a very thin skim of Rage Gold to finish.

A thin skim of All-Metal filler is applied to the seam welded joint at the base of the rear windshield and sanded smooth with 80-grit.

The first coat of Rage Gold is rather heavy with the understanding and intent of seeing most of it deposited on the floor as dust, leaving behind a very solid foundation for subsequent filler application.

I regularly employ Surform tools to shave the filler to rough shape just after the filler kicks to the heavy gel phase.  This is a bit like hard cheese and shaves very easily with these tools.

In the early filling stages, I rough out the initial shape with 80 grit paper on my DA sander and then finish the job by hand with various sanding blocks.

I absolutely LOVE dry powder guide coat!  Not a single layer of filler avoids a generous application of guide coat to allow me to easily see the shape and accuracy of the panels before, during and after sanding.  While the camera flash makes the guide coat look very light, in practice, these filler areas are stained quite dark and provide huge contrast when sanding.

Finishing body filler by hand is the only way to get things dead flat.  In this shot, I am sanding in an "X" pattern, starting at the top right of the panel and moving down to the bottom left and then reversing the direction, beginning in the top left and ending at the bottom right.

Having started at the back of the panel, I finished the rear half first, before moving to the front of the panel.  This shot shows several iterative layers of filler were needed to get the shape I wanted in the early stages.

The bulk of filling work at the rear of the quarter has been completed in this shot.

The final bit of work on the rear of the panel was fitting the panel contours to the die cast fender end cap.  The fit of these panels can be all over the map and this one required a bit of extra work to get the contour just right.  The green masking tape prevents body filler from sticking to the end cap while I apply it to the quarter.

Once the filler reaches the gel phase, I use a razor knife to cut the filler along the thin gap between the quarter edge and the end cap to create a straight line that is much easier to finish.  Once this bit is fully cured, We sand the filler to the proper contour and get ready to tackle the front and top of the quarter.

Like the rear of the quarter, the front is prepared in the same iterative way as all of the other filler work I have shown.  Thin applications of filler and careful sanding with guide coat allow the panel to flatten out very nicely.

And there we are!  The front and back half of the right rear quarter are complete.  All that remains is the roof seam at the top of the sail panel and the rear trunk corner.

With the first application of filler on the sail panel, I start by shaving the contour to the rough shape I want using a Surform tool and sand to shape with 80-grit paper in the DA sander.  This first coat is just a bulk-filling application as this joint between the roof panel and quarter is quite deep by design and requires a good bit more filler than most any other place on the body.  Recall in an earlier post that this seam had already been filled with All-Metal to seal the weld seam and fill the body solder trough.

The second application of filler to the sail panel is much thinner than the first.  We are getting very close to the final surface.

Shaved with the Surform tool and ready to be carefully sanded to final shape.

About 4 passes with Rage Gold filler were required to get the sail panel joint perfected.

Dent Repair & Metal Finishing on Right Rear Quarter

A month has passed since my last update, but activity has been steady and productive as the adventure begins on straightening the right rear quarter panel in preparation for filler and primer.  And with the exception of another week of international travel for work as an interruption, I have been working on the car pretty steady for the remainder of time.

In contrast to the left rear quarter, the right rear quarter had seen significantly more abuse over its lifetime.  In fact, some of the metal repairs that would be required were actually to reverse the effects of botched metal work that had been done in excess of thirty years ago and I was actually able to identify a shopping cart impact that left the front of the quarter clearly indented with perfectly symmetrical vertical divots from front to back.  Further to that, I had a deep crease in the lower front apron area and quite a bit of damage to the leading edge of the “hip” area at the front top of the panel.  Plenty of work to be sure!

First things first, however.  A huge benefit of the right quarter was that the spots of surface rust were far fewer than on the left.  This made scrubbing them away with a surface prep disc on my angle grinder a relatively quick affair.  As expected, there were several tiny areas where some micro-pitting was evident and I marked each of these areas for later attention from the Speed Blaster.

Once the surface rust was gone, I went over the entire panel from front to back with a clean 36-grit disc on my DA sander to clean up and prep the panel for a swab with diluted Prep & Etch to preserve the bare metal as the work progressed.  Then, I set about tackling the top section of the quarter where earlier work had been done (and quite poorly I might add) as this area would present some unique challenges to getting the metal straightened.

To begin, I used my giant Sharpie marker to stain the repair area so I could block over the surface to identify and clearly highlight the damaged area details.  This actually revealed a much more extensive and complicated repair area than I had estimated, but the details were clear and the path set to get going on the repairs.

Starting with my bulls eye pick, I slowly started raising the low areas along the roughly 20-inch gouge in the panel as well as the palm-sized dent in the “hip” and a significant ripple along the forward character line.  This is a very iterative and slow, painstaking process that rewards patience and gentle persuasion.  Slowly, the metal started to gradually move back into place and after several cycles of staining and bumping, I reached a point where I would need to use my stud welder/puller to remove the deeper section of the crease.  After several hours this process, the areas was returned to within 98-99% of its original shape and I could move on to the next repair areas, until all of the metal work was complete.

The next step was to return to the slightly pitted areas I had earlier marked so I could ensure every trace of rust was removed by using the spot blasting nozzle on my Speed Blaster tool.  This nifty tool allows me to very quickly and cleanly spot blast each small spot of pitting, leaving rust-free, clean metal behind.  This few minutes spent ensured I would not have issues with future re-development of rust in these areas and contributed to considerable peace of mind as well.

With the spot blasting work complete, I once again sanded the entire panel with 36 grit paper to establish a clean surface with sufficient “tooth” to allow the “heavy” All-Metal filler to be applied to seal the welded areas, and to allow the formal body work to begin.  By the time you read this, that work will be well underway!  Stay tuned!

Surface prep discs were used to scrub away the bulk of the surface rust spots on the quarter.  Far less work involved here than on the left quarter for sure!

The upper "hip" area of the quarter had the remnants of a poor attempt to push out a heavy crease that ended up with surface rust in it from end to end.  The lighter gray area above and below the long strip where I scrubbed the crease shows the huge shallow dip along almost the entire front section of the hip.  This is going to require hours of metal finishing to get back in shape.

This lower apron area also had a major crease along it's full length that ended in a nasty cleft in the leading edge of the flare.

After all of the surface rust areas were scrubbed clean, I went over the entire quarter with my DA and 36 grit paper to smooth up and clean the surface to bare metal and to provide the ever important "tooth" to the metal required for proper filler adhesion.

Fortunately, only a little metal work was required on the top of the fender to get it into fine shape.

Using my trusty big Sharpie marker, I marked the entire damaged area of the hip so I could start sizing up the extent of the metal work that would be required to get this previously repaired area back into shape.

A few light passes with the sanding block and the damage was revealed.  Essentially, the entire area was one huge low spot with more heavy damage concentrated along the middle of the crease and lower on the front hip area.  These more heavily damaged areas are easily seen in this shot as they are the spots still colored in black marker.

After a few short minutes of work, the metal is starting to gradually move back into place.  However, there are many hours left to get this area corrected.

In this shot, most of the front hip area has been bumped back into shape with only small detail work left.  Notice how little black marker ink is showing in this area.  It is quite obvious I am working from front to back in this particular area.

The front hip metal work from a slightly different angle. 

As I moved back into the heavy crease, it became obvious I would need to gently pull this damage with my stud puller in order to get the metal to move enough to bring it up to the proper level.

After about 6-8 hours of gentle metal persuasion, the upper fender is pretty darn good.  It will need a very thin skim of filler to get it perfected, but that is pretty straight nonetheless.  Also, I have worked out the lower apron crease and a few other smaller flaws I found along the way.

For an extra measure of insurance, I chose to run over each former surface rust location with the spot blaster to make absolutely sure there would be no rust remaining in the metal pores.

Looks like the quarter panel came down with a case of the measles after spot blasting.  In this case, it is a very good thing!
 

 

Cleaned up with another pass of 36 grit paper on the DA and the quarter is looking much better than it did when I started!

After sanding, you can just make out the shadow of the heavy crease that once occupied this area of the upper quarter panel.

Rear of the quarter after metal finishing looks quite good.

 

And there it is!  The right quarter is ready to begin the slow process of filling and blocking on the way to a sealing coat of epoxy primer.

 

Left Rear Quarter in Primer!

Well, this part of the work on the left rear quarter panel is kind of anticlimactic………and that is actually a GOOD thing.  Generally speaking, priming a body panel is a relatively straight forward process and the success (or failure) of the primer coat is largely determined by the amount of preparation you put into the panel ahead of time. 

As I have documented over the last several weeks, a lot of time and effort has been put into getting the left rear quarter as straight and clean as possible before shooting the panel in epoxy primer/sealer.  As the day approached to finally get the panel in primer, I was checking and re-checking every detail to do as much as I could to ensure success.  And for the most part, success is what I enjoyed.  However, as I have committed to tell the “whole” story on this blog, I did have one relatively minor “oops” that caught me out that required a little extra effort to fix and a second round of primer/sealer to get everything straightened out.

On the first “cut-in” shoot of all of the edges, wheel and window openings, I queued up my small touch-up 3M PPS cup for the job.  This cup is small and very maneuverable in tight places and allows me to get primer in the detail areas quickly and efficiently.

With the cup full and the HVLP turbine spooled up, I started covering the cut-in areas as quickly as I could to conserve primer and avoid excessive film thickness.  If I had been paying better attention at this point, I would have recognized I was going through the primer too fast to be normal and would have avoided a larger problem later.  But, the signs of trouble were subtle enough and I managed to get the cut-in work complete just as I ran out of primer, so the brief window of enlightenment closed as quickly as it opened.

After letting the cut-in work flash off for about an hour, I switched my gun over to the large 3M PPS cup and started mixing up enough primer to coat the entire quarter with a little bit of material to spare to catch any light spots I may have missed.  With everything checked out, I started spraying from the bottom surfaces up, trying to move quickly enough to avoid applying to much material.  Ya…….that’s how it SHOULD have worked anyway.

After getting the full coat of primer on the panel, I noticed again how much material I seemed to be using and how much more overspray I seemed to have (which is very rare when using a turbine HVLP spray system).  As I started quickly inspecting the freshly coated surface, I began to notice very small sags in the primer at almost every spot where the gun had been triggered or where each pass had overlapped.  What the…..?????!!!!

Then I decided to calm down and give this a “think” for a while and start documenting every tiny detail that may have been out of the ordinary.  After all, the primer was already on the surface and the best thing I could do at this point was let it dry fully before I could do anything remedial.  So, with that, I started my review of every detail.

Pretty soon, I was confident that absolutely everything up to the actual process of spraying the first cut-in coat was as perfect as I could make it.  However, the first subtle hint of an issue manifested itself in a slight “catch” in the trigger pull of the spray gun while adjusting the spray pattern.  While an almost imperceptible difference in the gun, this small detail would ultimately prove to be the single item that caused the domino-effect of the whole issue.

The bottom line is that this “catch” was an indicator that the needle was not seating fully into the spray nozzle as a result of debris and paint residue collecting in an almost hidden area of the trigger assembly that is not mentioned in the gun maintenance and cleaning instructions (and YES, I read them!).  The end result was a small amount of material was flowing through the gun all the time, so even when the gun was not triggered, primer was still flowing ever so slightly, and thereby adding thickness to the base coat and causing several small sags and few runs as well when all things flowed out.

So, after sleeping on this discovery overnight, and given the fact that I wanted to let the primer cure fully before going after the goofed spots with the DA, I set about doing a complete teardown, cleaning, lube and reassembly of my trusty spray gun.  This allowed me to revise my maintenance schedule based on these new discoveries to ensure I never have this problem again.

A few days of cure time on the primer had the scene set to start repairing the problem areas with a combination of shaving and sanding with the DA and a small hand block with 80 grit paper.  The rest of the panel was scuffed with medium Scotch Brite pads and everything was cleaned thoroughly with prep solvent and then tacked off in preparation for round 2 of the priming exercise.

In my usual preparatory fashion, I checked off each “pre-flight” detail as I always do with the extra sensitivity to gun condition firmly implanted into the process.  With all boxes checked and the surface freshly masked, cleaned and tacked, I was ready to give it another go.

This time, the gun performance was stunningly improved and the primer laid down very nicely.  In what seemed like only a few minutes, I had the entire quarter finished and was involved in cleaning up the gun.  At this point I started to question just how long and slow this particular problem had been developing?  Had I been working “around” this issue for months and just not noticed the deterioration in performance?  Who knows?  At the end of the day, the left rear quarter looks great and I am moving operations to the right rear quarter for the same treatment.  Hopefully, without the speckle of drama.

Prep work is complete and the bare metal surfaces are cleaned and ready for masking.

 

The roof was previously primed for protection and this required scuffing with 80-grit paper to prepare it for the primer blending process into the previously primed area.

 

This is a close-up of the bare metal surface I prefer when applying primer.  Most of this surface is created with 80-grit discs on a DA with light pressure.

 

All masked up for the first round of priming.......or so I thought!

 

First step would be priming these "cut-in areas around the window, trunk, door and wheel openings.

 

Shake, shake, shake..........shake your primer!  It really is the only way and this inexpensive pneumatic shaker is ridiculously handy.  Get one!

Objective evaluation of this shot reveals the first hint of trouble:  that surface is far too gloss and "wet" than it should be and is worse in some spots than others.

 

After the first coat was completed, I started noticing more little hints that things were not quite right.  In this shot, the primer has flashed about one hour and it still shows some obviously wet areas that should have started to dull by now.  Uh oh...
 

Out comes my inspection light and my worst fears are confirmed.  Patches of slight to moderate sagging are evident on several areas of the quarter.  *Insert long string of colorful expletives here!*
Careful investigation would reveal a very subtle spray gun fault that was responsible for the entire issue.  Yep......fixed that.

  

Even after a few days of cure time, the panel remains too glossy for a "normal" primer application.  I have my work cut out for me, but a few days of careful shaving and sanding of the problem areas and a complete tune-up of my spray gun and we were ready to give it a proper go.

This image shows a much more agreeable coat of primer.  Not nearly as glossy and heavy looking as on the first round and it's laying very flat and smooth.

 

From another angle, the finish is clearly superior to the first attempt.  Funny how things go when your equipment is up to par!

After the masking was pulled following only a hour of flash time, the surface look great and is noticeably smoother than before.  We got this!