9-Inch Axle Powder Coated & Assembled

I have decided that long weekends are God’s gift to car guys.  At least to those that plan ahead a little to capitalize on the extra time wherever possible.  Most times, I am NOT that guy, but over the Labor Day Weekend, I finally WAS for a change!

In preparation for the final finish work on the axle housing, I tidied up a few details the week before the holiday weekend by fabricating a pair of axle bearing retainer shims to make up for the slightly wider axle bearings I used on my Moser 31-spline axles.  Without these shims, the Street or Track Cobra rear disc brake adapter brackets wouldn’t seat properly on the axle flanges (not good).  So, using a Fel-Pro replacement flange gasket as a pattern, I made two sheet metal shims of the appropriate thickness to properly space the bracket out to allow it to fully seat against the axle bearing flange and retain the bearing as intended.  Once this detail was addressed, the rest of the rear brake kit fitting was pure textbook.  Kudos to Shaun at Street or Track for a fine kit that fits as intended and looks factory once installed.

The final detail I had to address before moving on to sandblasting the housing was to move the right side brake line mounting tab up on the axle to avoid any possibility of interference with the rear coilover setup.  This was a rather simple and quick fabrication job to make a new tab and then a few minutes cutting the old one off and welding the new one on in the correct spot.  Following that, I had to tweak the brake line a slight bit and we were in business.

At this point, I had everything in order with the axle housing and was ready to begin the sand blasting process to get all of the crud seen in the build-up photos off the housing and ready for powder coating.  However, I had been toying with an idea on how to improve my blasting operation efficiency and decided to spend a few hours chasing down parts.  In short, I wanted to build an air “manifold” that would allow me to gang both of my air compressors together to allow a larger reserve of air and more flow volume to my pressure blaster in hopes it would respond.  I am happy to say the results were worth the effort as this was perhaps the best my pressure blaster had ever operated and I was able to blast non-stop (except for sand refills) until the entire axle housing was clean.

What I basically did was to take a three-way air manifold adapter I picked up at Home Depot and plumb it in reverse with two air feed lines going in one end with the third line plugged and then plumbing my quick connect for my sand blaster into the single outlet on the other end.  As simple as it looks and sounds, this little device dramatically cut down the compressor(s) cycling frequency and kept ample air supply available at all times.

The sand blasting operation went like clockwork and after about two hours of total time (including clean-up!); my rear axle housing was free of four decades’ worth of crap and looked pristine.  With time in the day to spare, I went straight to etching and phosphatizing the housing to ensure every last trace of rust was neutralized and the entire surface was etched and ready for powder coating after an overnight drying period.

In prep for powder coating, I went over the entire housing with a wire brush to remove any excess phosphate residue and masked all of the surfaces that needed to remain in bare metal.  Then I attached my hanging loop to one end of the housing and then I attached a lifting fixture to the housing to allow me to safely lift the housing off the hook in the spray booth and into the oven without killing myself.

With my powder coating equipment ready for battle and the oven steaming along at a steady 400 degrees, I laid down the first of two coats of powder and dropped the works into the oven for a full cure cycle.  After the second coat was applied and cured, I removed the housing from the oven and let it cool for a few hours while I tended to other chores.  When I came back to it, I removed all of the masking materials and fixturing and was extremely pleased with the final result.  My once putrid looking housing was now sporting a beautiful satin black urethane powder coated finish that is done no justice by my lousy photography.

With renewed energy, I spent the next few days assembling the rear axle housing into final shape.  I started the assembly by installing new ARP studs in the housing to secure the differential and followed that up by installing a stainless steel axle vent similar to those used in many GM housings.  Now, I am the LAST guy on the planet to give GM any credit for anything, but they certainly had a much cleaner axle vent solution to the hideous whip-hose device Ford used on the Mustang.

Next up, I installed my axle drain plug followed quickly by the fresh 9-inch nodular iron center section I rebuilt earlier in the Spring/Summer.  At this point, the assembly was getting a little hard to handle so I recruited my trusty ‘ol Dad to help finish this project up.

With Dad as my wing man, we fitted the axles and disc brake adapter brackets and drew everything down with fresh fasteners from NPD.  Then came a fresh set of Raybestos Premium Grade rotors and new Ford caliper brackets, followed by my rebuilt and powder coated calipers.  With the major hardware in place, we finished up the assembly by installing the brake “hard” line, distribution block and braided stainless flex lines, rounded out by a pair of Moser axle end covers for a clean look.

This particular assembly represents a significant milestone in this project as it is he first mechanical assembly that went back together since this project began two years ago.  I am happy to say I spared nothing in getting this axle done properly and with the best equipment and parts available, and I managed to get it finished in a way that reflects the project as I have imagined it.  I still have to prep and coat the trailing link and panhard bars in the same color (easy work) and get everything protected and stored.

Now that this work is in the books, I am already moving back to the body structure to pick up where I left off in the trunk floor area and wheel wells and complete the final repairs in the left rear rocker area.  The fall and winter work plan is looking good!

These two axle flange shims were fabricated to allow the disc brake adapter brackets to seat properly on the axle flanges with the wider bearings used on the Moser 31-spline axles I use.

The yellow arrow indicates the shim location.  This measure may be required based on the axle housing and bearing combination you have.  Careful measurement and mock-up is the key.

 

I had to move the brake line mounting tab up on the right axle tube to ensure there would be no interference with the coilover assembly.

This simple device allowed me to gang together my two air compressors to feed my pressure sand blaster.  The difference in blasting performance was astounding and may even get better if I were to use a 1/2" I.D. air hose between this manifold and the blaster.

The freshly blasted housing is quite inspiring to look at after four decades worth of crap was removed.

Another look at the freshly blasted housing with my 30-year-old blaster and some of my "sand recovery equipment."

After a good degreasing with acetone, I let the housing dry completely and then treated it with a 3:1 water/phosphoric acid solution to eliminate any microscopic rust left on the surface and to provide a nice, evenly etched surface for good coating adhesion.

Here is a look at the drain bung fully etched and phosphatized.  Soon after this image was taken, the entire housing was brushed with a fine steel cup brush to prep the surface for powder coating.

Here is the housing hanging in my powder booth after the first coat of powder has been applied.  Note the hanging loop at the top and the lift handle fixture across the center.

After two coats of cured powder, the result was a pristine housing by most any definition.

The first order of business was to load the rebuilt differential section into the housing using new ARP mounting fasteners.

The Street or Track Cobra rear disc brake mounting brackets are mounted using news flange fasteners from NPD.

Fully assembled left rear disc brake assembly.

Completed right side rear brake assembly.

One of the last install items was the brake line distribution block and hard and soft brake lines.

 nice finishing touch are these axle end caps supplied by Moser with a new pair of axles.  No one will ever see them in the end, but who cares?  I know they are there.

 

The finished axle assembly!  This picture does the effort no justice at all, but the truth is, it looks fantastic in person.  Almost a shame to put it under a car.........almost.