Tail Light Panel and Trunk Floor – Part 6: Lap 2 – Right Side Left

On my first evaluation of the right rear quarter panel quite some time ago, I figured on having to install a rather large patch panel in the lower section of the quarter to repair the rusted out rear wheel opening corner as well as fix the many dents and dings in the panel.  This idea has always sat rather poorly with me as I really wanted to do my best to keep as much of the original quarters intact as I could.  So after many nights sitting and studying the extent of repairs that would be required, I decided to spend several hours working out as much of the damage as I could with my array of hammers and dollies before deciding on the extent of metal replacement that would be necessary.  After several evenings spent massaging the metal as best I could, I was very pleased to see a rather straight panel before my eyes!  Now we’re talkin’!

All of a sudden, I was in the enviable position of being able to simply duplicate the same repair procedures that I performed on the left side of the car on the right side.  This made planning the repairs a lot easier and, with a little luck, a good bit quicker as well.  So without letting time get away from me too much, I set about my first task of filling the side marker light in the same way I had before.  Using the same pattern I had made for the left side marker light patch, I made another patch and carefully fit it in place.  This time around, I decided to give myself just a bit more gap around the edges to make weld penetration easier to achieve.  With the fit just as I wanted it, I clamped the patch into place with my welding clamps and my trusty patch panel clamps to keep the gaps nice and even all around.  I worked the shape of the patch a little bit with the hammer and dolly to get the fit as tight and flush with the surrounding metal as possible.  Satisfied I had the best fit I could manage, I started by tacking the patch in at random locations around the patch and cooling each tack with compressed air until I had tacks around the entire periphery spaced about ½” apart.  I concentrated a bit more effort on tacking more heavily each corner of the patch on this go-round based on lessons learned on the left side patch.  Then, I ground all of the tacks smooth to allow one final check of the fit before final welding.

Satisfied I had the fit as good as I could make it, I started the slow process of “connect-the-dots” tack welding and cooling randomly around the patch until the entire patch was welded in.  Another period of weld grinding and smoothing left a patch with excellent weld penetration and clean fit.  I did allow for a little extra weld coverage on the back side to make absolutely sure I would have no future issues with cracking around the patch.

Next, I headed off to removing the right trunk floor section, again suing the same methods used on the left side repair.  First, I cut away as much metal as I could to allow me easier access to the areas where I would be drilling out spot welds.  I began by cutting the welds at the front trunk floor flange, followed by the rear trunk floor flange.  Then, I located each spot weld along the rear frame rail by lightly grinding along the rail flange location to make marking the welds much easier.  Then, using my trusty paint marker, I marked the location of each remaining spot weld along the rail flanges as well as on the inside of the inner wheel house and lower drop-off flanges.  After a solid evening center punching and drilling spot welds with my Blair Rotabroach spot weld cutter and grinding the few that could not be drilled with my cutoff wheel, the trunk floor panel came out cleanly.  And, as fortune would have it, the right side rear frame rail was in equally good, if not better, condition as the left.  I almost couldn’t believe my eyes to be honest.  Again, the rust scale in the inside lower quarter area was a virtual copy of the left side, so the next step will be to assembly my chelation apparatus and remove the rust that is there using the chelation process described earlier in this blog.  More to come very soon!

Following the exact same procedures I used on the left side, I fit the corner marker light patch panel and clamped it into place.  Note the slightly increased panel gaps to allow better weld penetration.

Here is the outside view of the patch.  I had to do a small bit of hammer and dolly work to get the edges to fit the parent panel.

Here, the patch is tacked in at 1/2" intervals.  Notice the corners have been tacked almost completely around.  This prevented the corners from pulling under as I cooled the welds.

Here is the fully welded patch just as I started grinding the welds flush.

The finish-ground patch is hardly detectable and looks good.

I added a little bit of weld on the back side of the patch in a few areas to ensure that no cracks would develop over time.

Next, I cut away the extra material from the trunk floor panel to allow easier access to the remaining spot welds.

In this shot, you can see that the rear trunk floor crossmember has been removed from the rail horn and upper floor flange.

 

After lightly grinding along the upper rail flanges, I was able to easily locate and mark the spot welds I would need to cut in this area.

Along the inside of the wheel house, I marked and cut all of the spot welds with my Blair Rotabroach.  This flange is usually pretty bent up as part of the manufacturing process, so a good bit of straightening is required to allow proper spot weld cutting.

Can you believe it?  Another perfect rear subframe rail under all that rust!

Here is the lower inner quarter panel rust.  An almost identical copy of the rust on the left side.  Here, I will fire up the chelation process and go to work getting this rust gently removed.

Tail Light Panel and Trunk Floor – Part 5: Left Coilover Mount & Trunk Floor Install

I am happy to report; the left trunk floor is complete!  And I would be remiss if I failed to mention that the NPD-supplied trunk floor panel was another excellent piece that required no modification short of trimming the lower edge of the drop-off (which is desirable and expected anyway.

To begin this phase of work, I decided the time was right to install the left rear coilover mounting bracket included in the Heidts 4-link suspension kit I am installing in my car.  Under normal circumstances, this mount would be a bit tricky to weld in place with a complete trunk floor.  However, since the trunk floor was completely out of the way, I decided to install this mount while the opportunity was ripe.

I started by running the bracket through my blast cabinet to clean off the mill scale and slight surface rust that had developed on the surface.  Then, I treated the bracket with a dose of phosphoric acid to clean and etch the metal.  After a few hours of dry time, I clamped the bracket into place per the instructions included with the Heidts kit.  With all measurements verified, I clamped the bracket solidly into place, saddling the lower frame rail and welded it into place.  The lack of a trunk floor panel made welding the inside edges of the bracket quite easy.  The job of welding the inner edges of the bracket would have been nearly impossible with the trunk floor in place.

Next came the trial fit of the trunk floor itself.  I tend to spend a lot of time getting repair panels to fit as close to perfect as I can.  As a pleasant surprise, the trunk floor panel fit amazingly well straight out of the box.  I started by dollying the flange that meets the inner wheel house until the fit was just right and the panel would seat firmly against the inner wheel house.  Then I aligned the rear of the panel with the frame rail and clamped it into place.  After a few small adjustments, I was ready to mark the location of the frame rail flanges on the panel so I could drill spot weld holes where required.  At the same time, I clamped and marked the lower quarter flange edge so it could be trimmed for a perfect fit.  With the panel marked, I marked each spot weld hole with my trusty paint marker and began punching and drilling the necessary holes.

I treated the bare metal flanges to a thin coat of SEM weld-thru primer (won’t be doing this again) and let it dry.  Next time, I will mask the individual spot weld areas to prevent any primer from coating these surfaces.  In my experience, the welds are much cleaner and easier to make without any such weld-thru primer in the way.  Lesson learned.

Using my painted reference outlines for alignment, I clamped the drilled panel into place and carefully adjusted its position until the fit was perfect.  Then, in my usual “clamp-the-hell-out-of-it” fashion, I clamped every flange as much as I could to bring every surface together as tightly as possible.  Particular attention was paid to the inner wheel house flange as this proved the most difficult flange to get fitting properly.  In the end, every flange fit exceptionally well and I was set to weld.

About an hour later, the left trunk floor panel was fully welded into place and looking like it was made to be there.  About another hour and a half of careful grinding, and all the welds were smooth and the repair was complete!  This pretty much wraps up the left rear corner repairs on the car and now I will move the whole operation over to the right side for a series of repair operations that will be virtually identical to what I’ve done on the left side.  Feels good!

Heidt's coilover bracket fresh out of the blast cabinet.

A good coating of phosphoric acid will be a good prep before installation.

This gives you an idea how accessible the bracket is without the trunk floor panel in the way.  Even these welding clamps would not have been able to be used in this way if the trunk floor was in place.

Coilover bracket welded in place on the outboard side.

And the inboard welds can be seen here.  Note the top weld and the curl around the corner.  These welds would simply not have been possible without this kind of access.

Fitting the trunk floor panel was remarkably easy.  A little flange work at the wheel house and some small adjustments at the rear and the panel fit was excellent.

Here, you can see that I traced around every flange to give me reference marks for drilling spot weld holes and to help me realign the panel when it comes time to clamp it in place for final welding.

The NPD trunk floors have extra material on the lower drop-off flanges to allow you to fit the panel perfectly to the lower quarter flange shape.  If you look closely, you can see this flange has been marked for trimming.

I coated the flanges with a light coat of SEM weld-thru primer.  I believe it would have been better to mask each spot weld location to leave it in bare metal.

With all of the spot weld holes drilled, it was time to fit the panel in place and clamp it securely for welding.

I was more than pleased with the fit of the lower drop-off flange to the original quarter panel.  This fit is arguably much better than the factory had done originally.

The fit around the inner wheel house is critical for good overall panel alignment.  Here, the fit is almost perfect.

Clamps?  You betcha!  The use of lots of clamps is key to getting the fit as good as it can be.

Here is my collection of clamps located along the lower flange edge.

And here is the front flange edge clamped up as well.

Plug welds along the top are nice and symmetrical.

Lower drop-off flange welded up!

Here are the welds securing the inner wheel house to the trunk floor flange.

Trunk floor welded and ready for finish grinding.

Top frame rail welds ground smooth.

Inner fender and coilover bracket welds ground.

And finally, the lower drop-off flange welds smoothed up as well.

Tail Light Panel and Trunk Floor – Part 4: Left Rear Quarter End Cap

This blog entry will be refreshingly short and sweet.  After finishing the corner repairs, I needed to get the rear of the quarter panel back into solid form before I could install the trunk floor panel.

In an earlier post, I mentioned how pleased I was with the quality and fit of the replacement quarter end caps I purchased from NPD.  There are many who would complain about the fact that this one-piece stamping takes the place of two at the lower trunk opening corners, but I am quite happy about this feature and think the repair is that much easier to make with less chance of rust down the road.  We’ll see if I have the same opinion when the tail light panel installation comes about.

Anyway, the key to getting these end caps to fit the quarter as intended is to use the original body alignment holes as guides before clamping the panel in place in as many locations as possible to make sure the fit is tight and right.  I use large, round steel drifts to align these holes properly.  Once I am satisfied with the fit and location of the panel, I clamp everything in place using as many clamps as I can manage.

I started the installation at the trunk opening corner area to make sure the trunk lid sealing bead was nested under the original panel correctly.  Once this fit was established, I tacked the plug weld holes in the original spot weld locations to lock things down and moved on to the rest of the panel to get everything tacked in before final welding.

With the panel fully tacked into place, I could move my clamps around to provide support as I started plug welding each hole, moving around the panel randomly to reduce warping.  One rather tricky area to weld was along the top edge of the quarter panel.  The original spot welds were very high on the panel (almost to the outer skin surface), leaving considerable open space above the patch panel that would need to be welded closed.  By using a strip of copper plate clamped behind each hole as a backing and heat sink, I could carefully plug weld the patch and fill the hole at the same time without distorting or burning through the body surface, even though the plug welds extended right to the very edge of the character line.  While I was at it, I also took the time to repair a small stress crack that had migrated to the outer skin.

With all the welding done, I was able to grind each weld smooth, making the fender extension seating edge a perfectly flat fit against the extension itself.  Now, with the structural integrity of the rear quarter vastly improved, I could move on to the trunk floor installation without fear of pulling the rear quarter out of shape.

Body alignment holes can be very accurately aligned using long steel drifts and plenty of locking clamps.

Here is a close-up of the drift used to align the body alignment hole and one of the many clamps I used to keep everything right where it needed to be.

Here is the drift locating the top alignment hole.  Also note the gaps at the top of each weld hole above the edge of the panel.  This was due to the factory spot welds being very high on the edge.

After tacking the panel in place, I started the final welding at the top, where the trunk opening lower corner and seal bead meet.

To fill the gaps shown a few photos back, a copper backing plate was clamped behind the holes along the top of the panel to allow a complete weld without "whiskering" out the back or burning through the quarter skin surface.  While I was at it, I repaired a small stress crack, seen just to the left of the photo.

Working all the way to the bottom with careful plug welding, the panel fit turned out spectacular.

Here's a view of the fully welded end cap in place and ready for weld smoothing.

And here's the finished installation.  The quarter panel now has significantly better structural integrity and will not move around when the trunk floor is installed.

Tail Light Panel and Trunk Floor – Part 3: Wheel Opening Rear Corner Repairs

As I mentioned in my last posting, the left rear corner of the wheel opening was found to be peppered with tiny rust holes, discovered after sand blasting the areas in preparation for the trunk floor repairs.  This changed the pace of the trunk floor repair a bit in that I had to make this repair before I could go any further in repairing the trunk floor, since the trunk floor drop-off must be welded to the inner wheel opening flanges.

I spent quite a bit of time studying the overall scope of this repair along with the repair panels available for the job as well.  Fortunately, all of the sheet metal I would require was indeed available.  However, I would need to buy a complete outer wheel house and quarter patch panel to get all of the stamped parts necessary to do this work the right way.  Another trip to NPD to emasculate my wallet………

One of the “tricks” to effective rust repair is making sure your repair will be made far enough beyond the rust damage to get you into good solid metal on every edge.  It is very easy to assume a few small pinholes of rust on the outer surface equate to a small repair, but as you will see below, this is generally quite different from actual fact.  Experience has taught me that a general rule-of-thumb is the “spread” ratio of rust is roughly 3:1.  In other words, for every ¼” rust hole you can see at the surface, the actual damage (e.g., what you can’t see) is actually equivalent to a hole at least ¾” in diameter and the required repair will have to accommodate this larger specification to get into good solid metal.

In consideration of the above, it is still prudent to start small and expand the scope of the repair by small nibbles until all of the damage can be removed without sacrificing a bunch of good metal.  Once I had a good idea of how extensive the repair would need to be, I marked the general area with my white paint pen and transferred this same marking to my patch panels for future reference.  Next, I grabbed my handy dandy “screaming-metal-eating-wheel-of-death” and carefully cut the rusted corner of the outer sheet metal about ¼” inside of my painted line.  Then, I marked and drilled the few spot welds along the front and lower flange areas and off the piece came.  In keeping with my 3:1 rust spread ratio above, the extent of rust damage was indeed much more significant than the outer skin would show.

With the outer skin removed, I moved to the damaged section of the outer wheel house that was directly behind the skin.  This was where the real extent of the rust would become painfully obvious.  With careful evaluation, I was able to establish how far up the wheel house the patch would need to extend and then transferred this measurement to my new wheel house.  Then, I cut the wheel house patch on my band saw and cleaned up the edges on the belt sander and it was ready to go.

This brings me to another tried-and-true, but rarely mentioned rule about fitting patch panels:  ALWAYS make the patch before cutting the parent metal.  This ensures the patch will be properly sized and shaped to the task at hand before you ever cut the original damaged metal away.  With a patch that is formed perfectly, you can simply clamp it securely in place and trace the exact cut line you need to follow using the patch as the template.  If you configure your scribe to incorporate the required kerf offset, you can cut just under the line and use a 2” disc grinder to sand the base metal right to the scribed line.  This makes fitting patches for butt welding far easier than you might expect.

Once I had my wheel house patch trimmed and fit to the car, I used my trusty panel clamps to secure the patch in place at exactly the right gap for welding.  In a matter of a few short minutes, I had the patch butt-welded in place and the welds ground smooth.  This was now an excellent base to work from as I moved on to making the outer corner patch and welding it into place.

Since I had already marked my patch panel with the same basic shape as the damaged area I cut away, I could easily cut a patch that was a bit larger than the marks to allow plenty of extra material for custom fitting if necessary.  As it turns out, the patch required only a little bit of trimming and it was ready to go.  As with the wheel house patch, I let the patch determine where the cut lines needed to be on the original quarter panel and then I scribed my cut lines and made the final slight trims necessary for a perfect fit.  Again, using my panel clamps for secure location, I tacked the patch into place about every ½”.  I like to use a lot of tacks on the first fit as they not only act as a method of securing the panel, but also as very effective heat sinks in the process.  This is a big help in keeping warping to a minimum, particularly when using a MIG welder for such work.

Once the panel was fully tacked in, I carefully ground the tacks flush with the parent metal to have one last look at the fit before fully welding it in.  By grinding the tacks smooth at this point, it allows me to feel the fit of the patch and make sure the contours and edges match exactly as they should.  This helps keep the amount of filler required to bring the surfaces up to a minimum and give you one last chance to make corrections before welding it in permanently.  And as luck would have it, the fit was excellent and I set off welding the patch in fully, using long blasts of compressed air to chill the short, ½” stitches before moving around the panel randomly to complete the weld with minimal distortion.

After all the welds were complete, I ground the seams smooth and verified the welds had good penetration to the inside of the panels.  With everything in order, I was finally able to trim the inside flanges to replicate the factory profile and the repair was complete.

Using a paint pen, I marked the general size and shape of the required patch on the repair area.  This line is significantly outside the immediate damaged area to ensure the repair is made into good sheet metal.

I transferred my basic patch dimensions to my patch panel material for reference before cutting.

Removal of the damaged outer skin area starts with drilling out the spot welds along the front and bottom flanges.  Then the skin is cut to the inside of the paint lines with a cutoff wheel.

You can see the extensive rust damage under the skin and plenty of light passes through the pinholes in the inner wheel house.  But when the lights go out.....

.....the true extent of the damage becomes obvious.  OUCH!

Here is the back side of the outer skin section that was cut away.  What a mess!

In the same fashion as I marked the outer skin, the wheel house corner was marked and cut.

ALWAYS let the patch panel determine where the cuts are made in the parent metal.  Here the patch has been formed and metal worked until the fit is perfect.

Even this notch was reproduced in the patch and it's location verified before any cutting was done.

Here, I have scribed the cut lines and marked some indexing lines using my paint pen.  Then, I used my cutoff tool to cut away the damaged metal and the, using my 2" grinder, I trimmed the panel to match the scribed cut line exactly.

With the fit exactly as I wanted, I clamped the patch into place with my panel clamps and was ready to weld.

Here, all the welds are completed and they have been ground flush.

Here's a nice shot showing the outer patch panel tacked into place.

With the tack welds ground smooth, I can check one last time that the patch fits correctly before final welding.

The patch is fully welded using short stitch welds placed randomly around the patch and cooled with compressed air between welds to keep warping to a minimum.

With the welds ground smooth the patch will require very little filler to get everything smooth.

Weld penetration on both patches is excellent.  And best of all:  NO MORE RUST!

The repair was finished by trimming the flanges to match the factory shape.  Done!