Replacing the Roof Skin – Part 1

Easter weekend and I have an extra day to spend in the shop and what better excuse would I need to start the removal of the rusted and damaged original roof skin on the Boss than that?  But first, a little background…..

Having committed to replace the roof skin some months ago, I wanted to make sure, in every practical way, that the original fit and finish of the window openings and body contours would be as perfect as they could be.  As such, I decided to make simple templates to allow matching the window openings and to have a place where exact measurements could be made to verify the fit of the new roof during installation.  So, the first order of business was to make these templates and measure everything before any of the roof skin removal work began.  Ted and I had a pretty solid plan laid out for the proper templates and we set about making them in an evening using the scrap cardboard I had left over from the shipping box the new roof skin arrived in.

With the templates made, I began marking the exact cut lines I would follow along the edges of the original roof to allow me to remove the bulk of the damaged skin in a single piece to allow work on the welded flanges to be much easier.  Using my trusty paint markers, I traces the entire perimeter of the roof about 1.5” inboard of the seams and flanges.  Then, with a box of fresh cutoff wheels in the queue, I very carefully cut along my painted cut lines, making sure to only allow the blade to penetrate the skin just enough to cut without damaging the under-structure beneath it.  This slow progression was particularly taxing on the cutoff disk life and it took about four fresh cutoff wheels to complete the job.  But, after less than an hour of work, the major portion of the roof skin was cut away and work would then shift to the careful removal of the perimeter flanges.

I wanted to preserve as much of the front and rear window opening flanges as I could to allow me to compare them to the contours and features of the new roof skin.  Since these were rather straight forward spot-welded sections, it didn’t take long to cut the spot welds free using my Blair spot weld cutter tool.  As each window flange was cut free and some small burs removed, I compared each one to the new roof skin to see how things were shaping up in these areas of concern.  What I discovered was an absolute stunning fit which quickly offered a welcome measure of comfort that the rest of the new panel would be workable as well.

With the front and rear window flanges removed, I could now start evaluating the condition of the underlying structures of the roof to see what, if any, additional repairs would be necessary before the new roof could be installed.  To my utter amazement, the structures were in fantastic shape with only the 40-year-old surface rust that is expected on surfaces that never received any form of protective coating during manufacture.  In fact, once the cobwebs and mouse turds were brushed free, the metal was nearly perfect in all respects.  This was good news I really needed and provided great confirmation that I had made the right decision to replace the original roof with new metal rather than risk a repair to the original.

At this point, the drip rails were all that remained to remove and I knew in advance these would provide a challenge in that there were an extraordinary number of spot welds along each rail (about 45 on each side), and the welds were smaller and more closely spaced than what is normal around the rest of the car.  This pretty well eliminated the possibility of using a conventional spot weld cutter in this area as there just wasn’t the room necessary to fit the tool in the confined space.

The solution to this problem was to revert back to my trust cutoff wheel to very carefully grind through the spot welds just enough to allow them to be popped loose with gentle prying/peeling on the loose end of the scrap roof skin.  On first blush, this sounds like a horribly barbaric means to address spot welds (Ted thought I was positively off my perch), but as long as each weld is clearly marked before you start, and a very careful and light hand is used on the cutoff tool, you will be amazed at how quick and effective this method of spot weld removal can be with absolutely minimal impact on the thin, underlying base material.  In fact, once I got going, each drip rail required less than 15 minutes each to remove and that included cleaning up any burs left behind.  Sometimes you have to see it to believe it, but the technique works and works extremely well.

Now that the old roof skin was completely out of the way, I spent a few minutes grinding down the remaining spot weld nubs around each window opening and across the top of each quarter panel seam.  Then, it was time to test fit the new roof skin to see where we were in the grand scheme of things.

Much to our amazement, the new roof skin almost dropped right into place with nearly every flange settling nicely and cleanly.  We clamped the panel around the flanges and started assessing the fit more critically and found that only small tweaks would be required to get the roof to fit almost perfectly.  The critical contours appear to be spot-on and after some small tweaks to get the roof shifted toward the driver side by about 1/8”, we should be in excellent shape when the time comes to lock it down for good.  To say I am stunned at this stroke of fortune would be an understatement!

Now comes the tedious task of addressing the surface rust on the inner roof structures and getting everything prepared for welding.  Every flange will require exceptionally tight fit to be properly and cleanly welded into place with maximum effect and best appearance and many hours of prep work will be required to get there.  So, the next few weeks work has been defined and we are off and running in that direction.  Part 2 is on the way!

To ensure the fit of the new roof skin would match the original as much as possible, patterns were made to match the front and rear window openings and to allow exact measurements to be taken at precise locations around the opening so fit could be verified.

 

A single pattern was made for the front window opening that could be simply flipped over to verify the other side.  Measurements were written directly on the pattern for reference later on.

Here is the front window patter flipped to the passenger side for fit.

The hole in the middle of that yellow circle is what started the entire roof replacement discussion (more later).  More importantly, you can clearly see the yellow cut line I marked with my paint pen and the clean cut created by the cutoff wheel.

This is the cut line around the rear window opening.

 

Here is the cut line around the top of the front window opening.

I kept the cutting depth rather shallow to avoid damage to the underlying roof structure.

I was expecting a disaster under the roof skin once it was removed, but to my amazement, the roof support structure was in excellent shape with only surface rust to be seen.

This is the spot that changed everything.  After breezing over this rust spot with a wire brush several months ago and immediately breaking through, I though the world was truly against me.  Since it was located above a structural beam and I couldn't see it from behind, I feared the worst was being hidden from view.

This is the same spot from underneath.  What it shows is the pit was exclusive to the outside surface and not disguising a disaster on the inside.  Though this photo makes the interior surface look worse than it is, careful inspection shows a lot of clean metal, a fair amount of red oxide primer over spray and a smattering of surface rust.  As odd as it sounds this was a fantastic discovery.

Again, worse in pictures than in person, the inner roof structural beams were in excellent shape with only surface rust to contend with.

Even in the rear quarter to roof flange area, the condition of the metal was excellent.

 

This little bump in the middle of the rear roof brace is actually an alignment aid used to get the roof skin properly positioned during production.  It will serve the same function when the time comes to fit the new roof skin.

We were careful to remove the front and rear window flanges intact so they could be used to verify the contours and fit of the new roof skin in this area.  They will also function as patterns to position the trim rivets when the time comes.

The Blair spot weld cutter does an excellent job cutting spot welds on a job like this.

By comparing the original window flanges directly to the new roof skin, we were able to verify the new roof skin would work very well for our needs.  Quite a comfort seeing such good fit on panels separated in manufacturing date and tooling by some 43 years!

The front upper windshield beam is in excellent shape as well.

Upper windshield corner looks great!

Diver side quarter panel upper seam doesn't get much better.

Using a unique spot weld cutting technique, the drip rail roof sections were removed quite quickly and with virtually no damage to the base material.  Cool trick!

With all of the spot weld nubs ground smooth, the new roof skin dropped on with amazingly good fit.

With only the window flanges clamped, even the quarter panel flange fit is superb.  A couple of strategically placed Clecos and we will be in business.

Beautiful front driver side window opening fit!

Passenger side front window fit is also excellent!

Exterior Floor Final Priming & More Roof Skin Adventures

Since our last update, I am happy to report things have moved along quite nicely on several fronts.

With our seam sealing (mis)adventures long behind us now, the focus was to get the exterior floor prepared for final priming in PPG DP90LF black primer.  After a few conversations with the nice folks at U-POL regarding the best platform to apply Raptor Liner, I was encouraged by the fact that a good epoxy primer like DP was lauded as an excellent base for the Raptor.  With that in mind, I purchased a quart of the DP90LF and we set about masking and priming the floor over the course of about two solid evenings.

As I have mentioned before, the PPG DPLF primer is just about the best thing since pants with pockets when it comes to primers.  After shooting the DP90LF, I have another “like” to add to the growing list and that relates to the very nice matte finish the DP90LF exhibits once it dries.  In fact, I like the finish so much, that if I were to look for a matte black top coat for just about anything under the car, I’d just have a single stage urethane mixed up to match the DP90LF exactly and never look back.

Anyway, after a few hours of careful spraying, the floor was completely primed and the smooth, molded look we were after was quite handsomely satisfied.  The lower floor looks absolutely fantastic if I say so myself.  So much so, that I am quite confident the application of the Raptor spray bed liner material will achieve the exact finish I am looking for and will make for a very pleasing look that will be extremely durable.  But for now, we will purposefully shift the focus to the roof skin adventure in order to give the DP plenty of time to dry to full hardness (and the weather to warm up a good bit more), before we venture off to spray the Raptor and finish up the lower floor.

And that brings us to the latest chapter of the roof skin chronicles.  When I last left off, I was grappling with the decision to wait an additional 4-6 weeks for the roof skin I had ordered through NPD to arrive after making its enviable California-to-Florida southern tour of the United States before making the trek to the Michigan NPD warehouse where it would then be mine.  I guess I just couldn’t accept that as the way things had to be, so the day after receiving this news, I decided to go on a mission to see what alternatives there were to sourcing a new roof skin sooner than later.  And a good effort it was indeed!  Very quickly, I was able to find a very tidy deal on a new roof skin from another of my favorite Mustang parts suppliers:  Tony D. Branda Performance in Altoona, PA.  Of course, the “elephant in the room” was whether or not they actually had a roof skin in stock and if the shipping costs were going to torpedo the deal altogether.  So I made a quick call to them, and as I have come to expect, got a very knowledgeable gentlemen on the phone who went out to the warehouse and physically put his hands on the part to make sure it was what it should be.  When he came back to the phone a minute or two later with the good news, the shipping costs were estimated, and the deal was struck.  The trucking company would deliver the roof to my employer’s shipping dock and I would get a call when it arrived. This was Wednesday morning, March 20^th about 10:00am. 

Friday, March 22^nd, about noon I get a call from our shop manager with “your roof just arrived.”  Wha?  At this point the native Texan in me came to the fore and “Yer sh*ttin me” was all I could muster.  In less than 72 hours from the time I placed the order with Branda, my brand new Dynacorn roof was in my possession and ready to become integrated into my excruciatingly long and complex project.  THAT, my friends, is called SERVICE with a capital “S”!  And to top it all off, by the time the dust had settled, after my 10% off St. Paddy’s Day discount had been applied, the entire adventure only cost me an extra $37.60 more than my previous order.  I am lovin’ this.

Fast forward a day, and dad and I very carefully unpack the roof and inspect it from stem to stern.  Having had mixed results from Dynacorn panels in the past, I am naturally skeptical at what I will find.  The good news is the panel appeared, by all intents and purposes, to be nearly flawless!  For me, it’s hard to imagine such a large and delicate panel making such long trips without a hint of damage, but this one did and I am duly impressed.  A quick call to NPD to cancel the original order and the dilemma of the roof skin was solidly closed.

And so, the course of the next few weeks has been set, and the process of removing the old, damaged roof skin will begin in earnest.  I am desperately keeping my fingers crossed that what I find underneath the old skin is sound and without major repair requirements.  With renewed energy and a solid plan, I am on it!

With the 3M sealer dried, the entire lower floor was lightly scuffed (again) to provide a good bonding surface for the PPG DP90LF black epoxy primer.

Taping off the floor was comparatively easy since we wanted everything from rocker to rocker and firewall to tail light panel completely primed.

We purposely avoided priming the rear fender lips as they will require additional work before they can be finish-primed and the fact that they will be body color when completed anyway.

Good 'ol Ted "takin' care of biznezz"......masking off the rockers.

More masking around each fender opening.

Here, the firewall has been masked all the way back to the joint where the floor pan meets.  This is an excellent and convenient place to mask as it allows the floor to be treated differently than the firewall.  This allows the engine bay and firewall to be a different color than the lower floor without being visible from the top.  A very clean transition.

The trunk floor is masked from the inside to allow the edges to be "soft" in the way they feather into the interior.  Eventually, the trunk area will be sprayed with DP90LF primer as well.

Starting to cut-in the floor joints.  I ended up shooting the entire floor with my small 3oz 3M PPS cup as it was much easier to maneuver in the tighter spaces of the floor.  This used up quite a few disposable cups, and required several mixing cycles, but it proved to be the best way to go overall.

 

Cutting in the front part of the floor around the cross member and subframe connectors.

I sprayed the floor in "halves" to allow complete access to the intricate areas around the floor.

After rolling the car over to the other side, I sprayed the other half.

Another round on each side to touch up any light spots we could find and we were done!

I love the finish of the DP90LF.  This is an excellent chassis black color and I would not hesitate to match paint to this color and finish for final chassis painting if needs be.

You can start seeing how much smoother the seams look in this shot, especially with everything is a nice uniform black.

Trunk floor area also looks very clean and smooth.

"Yer sh*ttin me!"  A new roof skin!

Exterior Floor Seam Sealing Completed, Roof Panel Mysteries and a Moment of Silence for a Trusty Tool

Starting from ground zero can be a bit disheartening on so many levels, but for once, I was very happy to be starting from this distinguished point with a clear understanding of what NOT to do.

Recalling the last installment, our first attempt at seam sealing the exterior floor of the car went…..well…..badly.  The good news is, we learned a lot in a very short period of time and were able to get ourselves back on plane to start over with new confidence. And that’s exactly what we did!

As before, the exterior seams were carefully taped off to allow nice clean beads of seam sealer to be laid down, smoothed and allowed to tack a bit before the tape is removed and the sealer is left to dry.  This technique is fairly exclusive to the “custom” side of the hobby as the purists often get purposefully sloppy with seam sealer to duplicate the rough patterns and textures applied by the factory.  However, by taping and smoothing as described here, the seam is very smooth and slick, and when top coated with epoxy primer and later, sprayable bed liner material, the panels take on a very smooth, almost molded appearance that I find very attractive.  It’s quite tidy in fact, and that after all, is what we’re after!

In any case, the 3M Urethane seam sealer worked extremely well and by using xylol (xylene) as our solvent, it remained quite happy and dried to a very nice finish.  A little trick I learned is to carefully read the ingredients of the sealer for clues on what type of solvent will generally work.  In this case, xylol was part of the ingredients of the sealer and worked perfectly.

Urethane sealer is pretty interesting stuff in that straight out of the tube; it dries to a paintable finish in under an hour above about 60 degrees F and 50% humidity.  However, when you endeavor to use a solvent to smooth the finish as we did here, it is best to allow a few days before paint to allow all of the extra solvent to flash off completely.

In any case, Ted and I were able to knock out the entire job in a few nights and our focus will not turn to preparing the lower floor for a couple of coats of DP90LF (black) primer and later the U-POL Raptor urethane bed liner material.

In other news, I have struggled with what to do with the rather sketchy condition of the roof panel on the car for several months.  I have purposely left this decision until last to give myself adequate “think” time to try to make the best decision possible for the car and ultimately, I have decided the roof needs to go.  I really tried to avoid this particular bit of work for many, many reasons, but the old girl deserves the absolute best and that’s what she’s gunna get.  Anything less at this point in the project is simply false economy.

With that decision firmly established, I trotted down to the local NPD warehouse to lay down the bones for a brand new roof panel.  However, fate would decree differently.  The nice gentleman behind the counter rounded in his chair after typing in my rather significant order and informed me that the roof panels were “temporarily discontinued”.  I was mortified.  After struggling with the decision for so long and avoiding the weighty time penalty it would impose, I was now being told I was too late.

But wait!  There’s more.  Mr. Counterman allowed that there was one in the California NPD warehouse, and if I wanted it, he could ship it out to the Michigan location at no charge.  At this point, I asked him to please call them and ensure that it was indeed there and if so, I would take it and pay for it in advance.  They did, I did, and the deal was struck.  In “about two weeks”, a new roof panel would be in my possession and the last major panel replacement work could begin.

Fast forward two days.  The phone rings and it’s Mr. Counterman looking for yours truly.  Apparently, my spendy new roof panel will now take 4 to 6 weeks to arrive and in the process, it will have to make a coast-to-coast tour from California to Florida and THEN make its way to Michigan.  Ya……..that makes perfect sense.

Anyway, Mr. Counterman asks if I still want the panel or if I want a refund.  After a moment of reflection, I decide to leave the order standing, but have now committed to trying to find another panel somewhere else without having to wait……even if I have to pay the shipping charges to get it.  Can’t anything be easy?

And finally, a moment of silence for a trusty old tool that has finally met its end.  My nearly indestructible Kodak digital camera has snapped its last images for this project and I feel a bit of personal loss at its demise.  To date, this camera has contributed every image shared on this blog and thousands more beyond that.  For the price, this camera was a far better tool for taking pictures than most of the similar devices I have experienced and I found myself resorting to it more often than not when I needed something that simply worked.  Adios amigo…..

Taping off the seams once again for round 2 of under body seam sealing fun!

Ted is an excellent hand at taping "his" end of the car.  He manages to stay just out of arm's reach, forcing me to endure MANY off-handed comments and copious whining.

After a few hours, we have one side taped off and we are ready to give the seam sealer another shot.

Success!  The sealer went on quite smoothly and the xylol solvent worked very well at feathering the edges.

After a few solid hours of carefully orchestrated teamwork, Ted and I had caught ourselves up to where we had previously discovered our earlier error.  After an overnight cure, the sealer was nice and firmly cured and we could move on to the other side.

With each seam taped off, we run about a 12-18 inch bead of sealer and then smooth that section with xylol before moving on.  Ted uses a butter bowl to hold a small amount of xylol to make it easier to chase the seams.

At long last, the other side is now sealed and we can move on to the harder-to-reach areas at the rear valence to finish things up.

Ignore the date on the picture!  Camera operator lacked sufficient talent to get that part of the new digital camera set up properly.  The good news is the rear wheel tubs are sealed and look very nice and ready for finish.

The rear axle tunnel area is one of the more complex areas to seal, but looks very clean when the job is complete.

Here, Ted has started scuffing the floor in preparation for the final coat of primer.

Synthetic scuff pads are great for scuffing the surface of the primer to get it ready for it's final coat.

And there it is.  The floor is now completely sealed and scuffed and we can now begin preparations to get the floor in a nice fresh coat of PPG DP90LF (black) primer.