Cowl Panel Replacement - Episode 5: First and goal to go, but there’s a penalty on the play

Last time, I left off with the cowl install essentially complete with the remaining work involving the prep and install of the cowl end enclosures, apron brackets and rear fender mounts.  In the last few weeks, I have managed to tackle the majority of those tasks along with embarking on a rather extensive research project targeted toward replacing my old, ailing MIG welder (which I will cover in a separate posting).

To begin, I decided to protect the inside of the cowl kick panels with a rust preventative coating.  The product I chose to use is called Zero Rust based on its ease of use, good laboratory performance reports, its ability to be easily sprayed and the many positive end-user reviews and durability examples.  Since all of the places I envisioned using this product are out of sight when the car is completed, I chose the standard black color, although the range of colors is quite extensive depending on your particular requirements.

The most obvious thing I noticed about Zero Rust black was how heavy a single quart of this material is, indicating (to me anyway) a very high solids content.  It also has a rather heavy body to it and that makes brush application a challenge on many surfaces.  I started my application of the product with a foam brush (lasted about 5 strokes) and quickly moved to a conventional disposable bristle brush to paint the kick panels.   Note to self:  Home Depot foam brushes SUCK! 

 I used two coats on all surfaces but was rather frustrated at the thickness of the coats required to cover properly.  After a bit of research, it seems the black colored Zero Rust may be slightly thicker than the other colors (like red oxide) and could stand a little bit of thinning to ease application (more on this in a bit).  Indeed, some of my other blogger friends have used the red oxide colored Zero Rust and successfully brushed it on with apparently little hassle, so there must be something to this.

I let the inner kick panels dry for several days with the help of a heat lamp and then set off on the hateful task of sealing the entire cowl panel and ends.  I spent a lot of time evaluating the various iterations of available seam sealers on the market and decided that I wanted nothing to do with those that could be formed with a wet finger and cleaned up with water.  Generally speaking, these are limestone-based products and are usually referred to as “general purpose” seam sealers.  Naturally, a paintable, flexible seam sealer is desirable in most applications involving structural panels like this.  After much research, I settled on 3M #08405 Flexiclear Body Seam Sealer for most of my sealing requirements.  This stuff is kinda like household silicone sealant on acid.  Truth is, I think this stuff could glue together greased, day-old mayonnaise and not break a sweat.  The down side is this sh*t sticks extremely well to EVERYTHING including human hair, skin, eyelids, t-shirts, zippers, shoe strings, cat fur, carpet, light switches, toilet seats, coffee tables, light bulbs, tennis shoes and chocolate chip cookies (ask me how I know).  This stuff is bad-ass expensive and just plain bad-ass.  In the immortal words of Forest Gump……”that’s all I have to say about that”.

Anyway, with the inner kick panels fully sealed and protected, I switched my focus to the rear fender brackets which were thankfully included with my new cowl.  These brackets are an exact duplicate of the original parts and fit the cowl very nicely right out of the box.  After a few seconds on the wire wheel to remove the e-coat where I needed to weld, I was able to position each one exactly based on the previous measurements I made from the old pieces before their removal.  A few minutes with my (now) very fussy MIG and they were welded in place and solid.

Next, I focused on getting the rear inner fender aprons remarried to the new cowl via new Dynacorn apron brackets I bought from NPD.  As you might expect, I wasn’t thrilled with them at all due to their significantly thinner material and everything-but-fit condition.  Not to be accused of failing to give it a shot, I massaged these damn brackets for several hours until the fit was almost perfect and they looked quite nice.  Then after one more sanity check with them clamped into place, I took them off, threw them in my pile of “what-not-to-do” parts and exhumed my original brackets and set to work refurbishing them for re-installation.  I just couldn’t bring myself to accept the thinner gauge material after all.

Fortunately, my original brackets were in decent shape and I was able to remove them with little drama early on.  I did have to weld up a few stress fractures in the corners and tidy them up in the blast cabinet, but once I was done, I had a pair of brackets original to the car and fitting perfectly by most accounts.

With the rear apron brackets ready to install, I carefully marked the location of each required plug weld using a paint pen.  I carefully ground off the e-coat under each weld and dusted them with SEM Copperweld primer and welded them in, dealing my old MIG the coup de grace.  At this point, I had decided it was a mercy killing long overdue…..  I protected the back side of each plug weld with Zero Rust paint while they were easy to access and called this phase of the project done.

With my immediate welding tasks out of the way for the time being, I moved to the preparation of the cowl end enclosures.  As I mentioned in earlier entries, these panels were in astonishingly good shape when I removed them.  In fact, following several minutes work in the blast cabinet, they looked exceptional and ready for a coat of phosphoric acid to prep them for paint.  The following day, I decided to experiment with thinning the Zero Rust paint before application.  As it turns out, I really liked the performance of the paint much better with a slight thinning and will experiment more with the technique in the future.  Fortunately, I discovered that Zero Rust can be thinned with my standard PPG DT-870 reducer with fantastic results  (BONUS!).  As if that weren’t enough, I found I can also use PPG K-201 hardener with Zero Rust to speed the hardening process in sprayed application at a ratio of 5:1:1 (5 parts Zero Rust to 1 part DT-870 reducer to 1 part K-201 hardener).  These two bonus features alone make this product much friendlier to use than the comparable product POR-15.

With a slightly thinned Zero Rust mixture ready to go, I applied three medium coats to the inside of the cowl end enclosures and let them dry overnight with the aid of a heat lamp.  Next, I trial fit the enclosures to the cowl and adjusted the fit until they were as close to perfect as I could make them.  Then, I carefully marked the top cowl flange where each plug weld needed to go and center punched them to make them easy to drill with the spot weld cutter.  Once the plug weld holes were drilled, I went around each flange with my angle grinder and sanded off the e-coat and Zero Rust everywhere there was a weld location.  With the flanges in good order, I clamped everything back into place to check the fit one more time.  Now, if I only had a welder…….

Zero Rust paint applied to the passenger side cowl box.  I ain't bad with a spray gun, but this shot proves I STINK with a brush!

Driver side cowl box coated with Zero Rust.

3M Flexiclear seam sealer is awesome stuff.  It takes on the color of the base material and seals extremely well.  Once dry, it is paintable in any color you choose.

Passenger rear fender mount welded in place.  Welds are looking progressively worse with my ailing  MIG welder.

Driver side rear fender mount welded in.  How much longer will this 'ol welder live?  Or perhaps, how much more can I take?

After wrestling with new Dynacorn rear fender apron brackets, I ended up refurbishing my original brackets.  Here I have marked the locations of each plug weld on the cowl with a paint pen.

Rear fender apron brackets welded in place and welds ground smooth.  This will be the final job for my old MIG as it's just not doing the job anymore.

Fresh out of the blast cabinet, the cowl end enclosures look great and ready for phosphoric acid treatment and Zero Rust paint.

I decided to thin the Zero Rust slightly for the end enclosures and really liked the way the paint responded.  I will be using this technique more as the project moves forward.

With the en enclosures fitted, I marked the top flanges with a paint pen to locate each plug weld location for drilling.

I center punch each weld location to allow the spot weld cutter to accurately center and run true.  The Blair rotabroach cutter makes perfect plug weld holes every time and can easily be controlled to go no deeper than the top layer of material.

With all of the weld holes in place, I sand off the e-coat and paint around each weld area to ensure a good weld surface.

With all of the prep work complete, the end enclosure is clamped back into place one last time.

Fit along every flange is checked for fit.  Looks good!

Top flange fit is exceptional.  Now, where's my new welder........