Rear Wheel Tub Prep & Fender Lip Rolling

Rear wheel tubs are kind of a pain in the butt for the home-restoration artisan to tackle.  Generally speaking, they are the dirtiest parts of the car, have lots of difficult-to-repair issues and are generally not very friendly from a work space perspective.  Mustang rear wheel tubs are not different, but the time had come for me to finally tackle the tubs on my Boss 302 once and (hopefully) for all.

The first order of business is getting all the undercoating and various levels of crap dislodged from the tubs to see what the base material looks like.  Some of my regular followers will recall the trick I use to remove 40 year-old undercoating quickly and rather painlessly.  In short, I use my air chisel dialed down to low air pressure (~25psi) to “shatter” the coating and then vacuum up the debris.  This method works so well in fact, it is truly amazing how little thought you give to further undercoating removal once you try it.  In any case, after about ½ hour dedicated to each tub, the undercoating was removed and vacuumed up and I could have a look at what the tubs looked like “nekid”.

As fortune would have it, both rear tubs in my car were in remarkably good shape!  Other than the damaged corners which were a “known” when I started the project, the metal was in excellent shape and the center seam was easily cleaned with a little sand blasting work.  From there, I dove into the job of cleaning the bulk of the tub surfaces with my angle grinder and a box full of 60-grit discs.  For the inner surfaces of the fender lips, I used an abrasive brush and wire wheel to clean everything down to bare metal and followed it up with a coat of phosphoric acid-based metal prep to get the surface cleaned of any residual corrosion and prepared for the next phase of the project:  Fender lip rolling.

Rolling a fender lip is a bit of a misleading description.  Actual “rolling” of a fender lip is usually done on a fully assembled car to make room for oversized tires and involves a tool specially designed with a hard-faced roller to gently fold the inner fender lip toward the inner wheel tub.  The fanciest fender “roller” tools bolt to the wheel hub and are quite nifty, but they are of little use when the body is on a rotisserie during restoration.  As such, folding the fender lips on a raw body shell requires a different technique but the results are much easier to achieve in my opinion.

The key to success when folding fender lips is patience and light, purposeful blows with a hammer to gently “persuade” the metal to its new location.  Also, in 99% of the cases, you do not need to fold the entire lip as the tire doesn’t require the same clearance at the front or rear as it does at the top during full suspension compression.  At the same time, folded fender lips are much harder to keep clean and without proper maintenance, can accumulate debris that will work to promote rapid corrosion propagation if left unattended.

I started folding each fender lip with light blows from my 16oz ball-pein hammer.  A ball-pein gives the metal just enough stretch to fold cleanly and not be lumpy along the flange.  I use a wooden paint stick (free @ Home Depot!) as a gage to determine when I have the right amount of fold by placing it against the wheel tub and folding the lip until it is just snug against the stick.  This leaves just enough gap to allow corrosion protective paint to be applied by brush and will allow debris to be washed away if needs be in the future.  Each lip took about 45 minutes of gentle hammer work to get just right and the results are very nice if I say so myself.  A little filler along the flanges will even hide the spot-weld divots and make for an exceptionally smooth wheel opening.

Once the rear fender lips were completed, I moved on to coating the wheel tubs with Zero Rust for corrosion protection.  I decided to apply the Zero Rust with a brush this time as I needed to make sure I got the lip areas fully coated and the resultant brush strokes would be of no consequence when you consider that the entire wheel tub will eventually be primed with DP40LF, seam sealed, painted flat black and finally coated in textured bed liner material as a final finish.  I would have preferred to spray the coating, but the space constraints in the confines of the wheel tubs prevented using my existing spray equipment effectively, so I stuck to the brush and made do with that even though I am embarrassed that there are brush marks to be seen at all!

So there ya go!  Wheel tubs cleaned and prepped.  Wheel lips rolled for fat meats and everything coated to keep it nice for the rest of my lifetime.  Next on the agenda is to finish the axle tunnel and front trunk floor and get the entire outside trunk floor area in primer.  I’m on it!

After cleaning all of the nasty undercoating off the surfaces of the rear wheel tubs, I was stunned to see the underlying metal in excellent shape.  Nice!

The shinier "reddish" area in the center of the tub shows the area that was originally covered in undercoating.

Both wheel tubs were in equally good shape after all was said and done.  This left a lot to work with and made the sand blasting work very straight forward and relatively easy.

Sand blasting could be concentrated on the seam area and the fender lips.  The rest of the surfaces would be easily prepped with sanding and surface conditioning discs.

After a few hours work with the angle grinder and a box full of 60-grit sanding discs, the wheel tubs were cleaned and ready for metal prep chemical etching.

Rolling fender lips is a common technique to gain more tire clearance.  Here, you can get a general idea of what the fender lip looks like before any rolling/folding is done.

Working the lip with light blows evenly distributed along the lip surface, I eventually had the lip nicely formed with absolutely no damage to the outside skin.

Here is another shot of the finished rolled fender lip.  Not there is a small gap left between the wheel tub and the lip to allow paint to be applied to the area and cleaning of debris in the future.  Ignore the body hammer in the background!  This is NOT the hammer I used to form the fender lips!  It was just looking for some temporary recognition it didn't deserve!

I used Zero Rust coating thinned down a bit to coat the inner wheel tubs.  I applied it with a brush to make sure I got the folded fender lips properly coated and the brush strokes will never be seen as them will eventually be covered in textured bed liner material.  Also, this shot shows the rolled fender lip in pretty good detail.

I left the areas at the front corners of the wheel tubs bare as I will soon be making repairs in this area.  No point making it anymore difficult.

Right side wheel tub coated and dry.  Note the folded fender lips are pretty easy to distinguish here too.

Left side wheel tub coated and dry.

Project: Night Mission

Today is the day.  The day I quit teasing my loyal blog readers, family, friends, co-workers and fellow Mustang enthusiasts and finally reveal what this whole project is all about.  But before I do, a little background explanation is in order.

As many of you know, my Boss 302 and I have been a pair for almost 30 years and in all that time, I have had a vision of what this car would be and I can honestly say, that vision has wavered extremely little after all these years.  I lovingly refer to this as the longest term relationship of my entire life (much to the chagrin of my S.O. Cindy who I’ve known longer than I’ve owned this car!).

The car would be white…….SCREAMING white just like every racecar I have ever driven in my career.  A pure white says something to me at my core.  Can’t explain it…..it just “does”.

This car would be done “my way” and in a way that I had never seen done before.  In no way had I any intention of building ANOTHER boring “concours” Boss 302 restoration.

The car had to be unique among its peers.  I wanted to build an “all-Boss” Boss 302 that was modernized in such a way as to make the car perform like it never had in its prime.  If that pissed off the purists and MCOA judges……even better!

I wanted to build a car that had its own unique identity but was never too far from its lineage.  It had to be identifiable as a Boss Mustang from 100 feet away as well as up close inspection.  I wanted to avoid something that was a caricature of the original car like so many of the “skinned and stuffed” cars that are in vogue today.  No mini tubs, back-half tube chassis, no hacked Mustang II front suspension crap, and no fuel injection.  Is it a “real” Boss 302?  Yep, in my mind it is and then some.  The VIN has the “G” in it and the door tag has the “W” code as well.  That’s all I need to know.

The car had to be loaded with details.  LOTS of details.  I wanted those details to be such that one walk around the car at a show would only scratch the surface and any hardcore car geek would find his/herself coming back to the car time after time after time to absorb yet another detail.  In all this, I wanted to build something that genuine car-guys could find something to “take-away” and fuel ideas to use when building their own cars.

Visual “pop” was mandatory but the styling had to stay true to the classic styling of the original.  The only thing “radical” was the extent of its subtlety and the laundry list of small changes that blend into a personal interpretation of what this car is.

The car would evolve into an expression of “me.”  A three-dimensional representation of the images in my mind’s eye and the manifestation of what I can accomplish with my brain, my hands, and my heart mixed with a little blood and sweat (and crap-loads of cash!).

The car has to “go” as good as it looks.  It will be heard as well as seen.  It must make NOISE!  Glorious, unbridled noise, just like any politically incorrect, knuckle-draggin’, unapologetically red-blooded AMERICAN muscle car is supposed to.  It will handle and stop without compromise and it will do so with purpose……..built in.

A few years ago, I started this blog at the suggestion of a few good friends as a way to document and share the work I would be doing to keep my mind active and to maintain some sanity after long, frustrating days in my (mostly) professional life.  I had no idea how much I would enjoy everything about this project as well as sharing the work and countless hours I spend on so many nights doing what I love to do.

Earlier this year, I came to know a phenomenal designer who inspired me in ways I had never dreamed and set me to thinking about my work in ways I had never considered (THANKS Murray, you are THE MAN!).  Pretty soon, I had commissioned his undeniable talent to put together a rendering of everything I had ever dreamed this car would be.  And in so doing, it inspired me to pursue the execution of this car in ways I had never imagined before.  For the first time, I could see the project in finished form and I now know EXACTLY how this car will be executed.

The bottom line?  If I stick to the plan I have outlined and build this car as intended, perhaps more than few people will come to appreciate it.  Perhaps it will become known to thousands.  Perhaps it will become the catalyst to yet another glorious adventure.  In the meantime, I invite everyone to have a look at the rendering and try to pick out the myriad of little changes that have been made.  They are everywhere! 

So here it is:  The Night Mission Boss 302.  Why Night Mission?  It’s really simple.  This is a car that was conceptualized and is being executed outside of my “day job”.  It’s what I lose sleep over.  It’s what I dream of every day.  It is my “mistress” when everyone else around me sleeps.  It is my therapy and I think it “fits”.  I hope you enjoy!

Sven

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.

 

4-Link Coilover Suspension Completed!

As if on cue, the trees are just starting to show the slightest hint of fall and accordingly, I have been able to complete the modifications and corrections to the 4-link rear suspension.  The summer has indeed been a busy one on many fronts and this major project has consumed the bulk of the time spent at work on the Boss over the last several months.  Of course, I had not planned on such a major rework of what was supposed to be a good suspension option, but such is the reality of it and here we are.

The condensed version of modifications and corrections includes replacing every single pivot point with spherical rod ends to eliminate MASSIVE roll bind problems in the kit design as well as free up the entire rear suspension throughout the full range of motion.  Secondly, the rear coilover dampers were less than impressive and as such, were replaced with very nice custom Bilstein coilover dampers made just for this application.  And finally, I selected a proper coil spring that would match the proven front coilover combination more exactly.  Sprinkled in there too was a hardware upgrade along with a few minor touches I have documented earlier in this blog.

For this final round of work, I had to reconfigure the upper coilover mount to reduce the mounting bolt size to the requisite ½” the new Bilstein coilovers employed.  This was a rather simple welding and re-drilling operation but of course, I discovered it also would include a pretty major correction of the hole location on the right side as it was a full 1/8” higher than on the left.  Apparently I’m not supposed to bitch about “close enough” so I just welded the S.O.B. up and put the damn things where they belonged within a few thou and decided I was comfortable being “anal-retentive” or something along those lines…….

Next up, I had to cut off all of the gooey rubber bushed ends of the trailing links and thread them with left-handed threads to allow the length of each arm to be fully adjustable without the need to remove the whole arm to adjust.  Loosen a jam nut on each end and turn to adjust the arm then lock down the nuts.  It couldn’t be simpler.

Then came the tedious task of machining spacers to capture each spherical rod end in the center of their respective mounts.  28 of them to be exact (whew!).  While I was there, I made provisions to add seals to each rod end to keep dirt, water and any other evil crap out of them under operating conditions.  These are nifty little devices I used extensively in my former racing life and are made by Seals-It.  I highly recommend them on any application that requires a spherical rod end.  The price is right and they can extend the life of the rod end many times over.

Two of the “spacers” are actually stand-offs for the lower coilover mount.  Since these needed to be longer to accommodate the new lower coilover mount, I decided to spin these up out of stainless for a nice appearance and corrosion resistance.  I am truly delighted with how these worked out.  I finished the lower coilover mounting configuration with a safety washer at the rear to prevent the lower shock eye from pulling off the mount if the spherical bearing were to ever catastrophically fail.  Another old racing rule of thumb that has stuck with me over the years.

And at last, I was finally able to assemble the entire system and work out a few setup details and take some measurements to see where we landed.  I am happy to say the suspension articulates extremely well, the roll bind has been eliminated and the total radial deflection of the rear axle over the full suspension travel as defined by the panhard rod swing arc is a miniscule 0.052”.  Not a bad result and way more desirable for me than the complexity of a Watts-link.

The one area I chose to leave alone is the chassis and axle mount locations for the trailing links.  This leaves the anti-squat geometry a bit of an unknown variable until I get the car sitting on the suspension at proper ride height and full load, but that will be a problem for another day.  Chances are it won’t be enough of an issue to make me want to do much to change it anyway since this is a street car as opposed to a dedicated track car.  Time will tell.

So now I am off to sand blast the housing a prep it for paint and assembly.  Once that is done, I will be heading back to the body for some work in the axle tunnel and trunk area and then back to the front for some major work on front suspension, steering and engine bay upgrades.  And oh yes……..that surprise I have been hinting at is getting very close to show time!

Upper rear coilover mounting points required welding and re-drilling to 1/2" from 5/8".  Turns out, I needed to correct the location of the right side mount hole while I was at it anyway.

 

 

I spent several days machining the proper spacers that would properly locate each spherical rod end in the middle of their mounts.  At the same time, I made room to install Seals-It seals on each side of the monoball to keep the crap out of them for longer life and smooth operation.

 

While not just a simple spacer, the lower coilover standoffs were machined from stainless as a single piece.  Looks pretty nice and works very well.

I upgraded all of the fasteners in the entire system while I was at it.  You can also see the Seals-It sealing washers more clearly in this shot as well.

The top coilover mounts got sealing washers too. 

Here is a simple yet very valuable safety trick.  I installed captive washers at the rear of the lower shock mounts to help ensure the shock would be retained in the event of a catastrophic failure of the monoball.

Looking at the left rear from the back shows how simple things look from the rear.  The springs will ultimately get powder coated black so as to tone them down a bit.

A view of the right side coilover setup from the rear.  Most of this will be hidden by the fuel tank.

Left side view of the completed 4-link coilover suspension.

Right side view of the completed system.

2013 Boss 302 Quik View

I finally had an opportunity to spend some quality time in a new "Gotta Have It Green" 2013 Boss 302 last week and the experience was worth a few lines here.  With only 2800 miles on the clock, I felt safe that the car was in prime condition to show me what it was made of and my personal evaluation would be honest .  The adventure started at the local car cruise where the screamin-green paint attracts gawkers like moths to a flame.  For three solid hours, the car was never without at least 3 admirers ranging in age from 4 to about 90.  Apparently it has a presence, and means something different to each person.  People "get" this car, without a doubt.

First impression:  What a huge disparity in interior quality compared to the visual “pop” of the exterior.  Looks like Ford regressed 10 years on interior design and materials.  Speedo is hard to read, tach is a little lazy and driver offset toward the middle of the car seems excessive (e.g., I never felt properly “centered” behind the wheel).  The surfaces are very cheap and "plast-icky" with dime-store fake machine-turned silver inserts across the panel.  I am not sure I will ever understand what happened here.

Second Impression:  Once on the road, I couldn’t care less about the interior.  The car impresses in just about all areas.  Engine is no neck-breaker, but a nice balance to the car.  Surprisingly smooth power with glorious exhaust notes north of 7k rpm (right up to the 7500rpm fuel-cut in fact).  I think I would lose the side exhaust plates permanently………pass-by noise regulations and bitching passengers can get stuffed.  Don’t like it?:  That’s what public transportation is for.

The Recaro seats are a bit too snug in the bolsters for long-term driving, but otherwise work well.  Truth is, I could have been sitting on a banana box and not cared one bit.  The car is pretty impressive and a pant load of fun to drive.  The benefits of the substantially reduced weight over other market competitors is undeniable.

The rear axle was the low-point of the driving experience.  Howled like a banshee in heat.  How that got past the quality rolls at the plant is hard to understand, but it eventually grabs your attention so much it starts to take away from the driving experience.  This is especially noticeable at 75-80mph cruise.

I absolutely HATED the cross-gate spacing in the shifter!  Fore-aft throw was fantastic, but cross-gate detents and shifter positioning through the neutral gate sucked.  I sure hope this hasn’t become the gold-standard reference for anything with a 6-speed.  Talk about a Heaven and Hell experience all in one.  Misery.

Back to the engine.  The track key function is entertaining.  Cool in fact, and evokes rather ungentlemanly advances toward the throttle that few cars would tolerate........if you know what I mean.  The slightly lumpy idle once it’s up to temp is apparently a clever bit of split-phasing camshaft trickery I would find myself constantly entertained with.  It’s the coolest “retro” feature of any modern muscle car I have experienced.

The handling and braking of this car is spectacular and in every way worthy of the Boss moniker.  There is an amazing amount of mechanical grip in the car that is easy to modulate and gather up if you get too excited.  The brakes are equally impressive and put the whoa-down with absolute authority.  The balance between handling and braking is as good as anything this platform has ever seen and to say it is competitive to other market products would border on understatement.  And while I have never been a huge fan of Pirelli tires, the P Zero shoes on this one seemed a perfect match to the car.  The car is incredibly easy to acclimate to and could easily be a daily driver in my book.  I would love to see the difference the Laguna Seca option brings to the table.

So, in short, I hate this car.  After the driving experience in the Boss, I was condemned to slide behind the wheel of my crapped-out daily driver and suddenly felt I was on my way to a trailer park resort instead of the nice suburban home where I currently get my mail.  As depression set in, I realize I could own this car………rough edges and all.  But a $44k price tag before ransom would keep it out of consideration for a while yet.

Note to Ford:  What the hell is the “white” key for?  (BIG evil grin).

Rear Disc Brake Fitting, Brake Lines & Coilover Mount Bushings

As the rear axle evolution progresses, I am becoming more and more happy with the results.  After a few nights of diligent work, I am to the point where I will start prepping the axle housing for final color very soon, and that will make way for the final modifications to the 4-link suspension.  However, before I get too far in that description, there are a few interesting things I need to document here first.

“Cunifer” Hard Lines

Pronounced “Cue•knee•fur” – the word cunifer is actually an acronym referring to the metallic composition of the brake line tubing most people have never heard of.  Specifically, cunifer tubing is an alloy of copper (Cu), nickel (Ni) and iron (Fe) and has been around for over 70 years.  The material is extremely corrosion resistant, bends and flares very easily, and is very durable.  And while the material is a copper-based alloy it is NOT conventional copper plumbing tubing in any way, shape or form.

In hot rod circles, stainless tubing gets big play because it’s shiny, durable, and obviously corrosion resistant.  The good news is that many pre-bent brake line kits are available in stainless for restoration ease as well.  But what if you are doing something from scratch or want to clean-up the appearance of the installation over what the factory installed?  In most cases, you are on your own, and generally speaking, stainless steel brake tubing is harder to work with and expensive, especially for the do-it-yourself restoration enthusiast.  In fact, other than “off-the-roll” appearance, there really isn’t any advantage to stainless steel brake line material compared to cunifer. 

When was the last time you saw stainless steel brake lines on a production car?  Even an exotic, high-end sports car for that matter?  Fact is, in 99% of brake applications, they don’t use stainless brake tubing.  In fact, more high-market car manufacturers use cunifer tubing than any other.  Rolls-Royce, Porsche, Audi, Aston Martin, and Volvo all use cunifer brake line tubing exclusively.  Japanese and US car manufacturers are the remaining hold-outs that continue to use conventional coated steel (not stainless) tubing due to the pervasive “low-bidder” mentality that dominates these markets.

Luckily, cunifer tubing is easy to get in the aftermarket and is priced between plain coated steel and stainless steel tubing.  It can be easily polished to a copper-silver shine (if that’s what you like) and will accept all standard brake hardware.  Due to cunifer tubing’s slightly softer surface than steel, an additional measure that should be taken is that the outer surface of the cunifer tubing should be protected with a stainless steel spring shield to avoid damage from rocks and road debris.  Plus it looks kinda cool as well!  I have chosen cunifer tubing as the preferred material for all of my fluid hard lines in the Boss and formed the rear axle hard line using this material.  I will be using much more of this material as I move forward in routing new brake hard lines around the rest of the car and will likely use it for the fuel hard lines as well.  In any case, it’s worth a look.

Cunifer brake tubing is wonderfully easy to form with simple tools.  Note the protective stainless steel spring around the tubing to prevent damage from road debris.

Here is the rear brake distribution block with the newly formed cunifer hard line in place.

  

The hard line is routed around the periphery of the 3rd member for a clean look.

Here is a look at the passenger side of the hard line.  Bends are smooth with no hint of kinks.

Rear Disc Brake Trial Fit

As the modifications to the axle housing approach completion, the time had finally come to trial fit all of the Street or Track, LLC rear disc brake conversion parts I had collected for the car to ensure everything fit as intended and clearance issues could be addressed before applying final finishes to the rest of the parts.  This would also mark the first time I could test fit the axles and complete set of brake lines to the housing as well.

I am happy to say that the brake kits installed quite nicely and the installation instructions were quite easy to follow.  I played with caliper position a bit but quickly discovered there was only one position that would allow adequate clearance to all components, so that’s what I stayed with.

Once I was satisfied with the caliper installation, I fit all of the rear brake lines (hard and soft) to ensure proper fit.  Here again, the Street or Track parts worked superbly and I could now move forward with final prep of the housing before sand blasting and coating.

This is the Street or Track rear disk brake kit mocked up on the left rear of the axle housing.  This is the "busiest" corner of the car and I discovered the fit to be perfect for my 4-link suspension.

here is the left rear brake kit installed (without brake pads).

The right rear brake kit is equally nice an installation and a considerably less crowded corner than the left.

Left rear disc brake conversion mock up is complete!

Coilover Lower Mount Bushings

In the process of engineering the upgrades to the 4-link rear suspension I am installing, I moved to a custom made Bilstein damper.  In doing so, the mounting fastener diameter went from 5/8” to ½”, which necessitated bushing the mounting holes in the axle brackets down to the proper size.  As luck would have it, I found commercially available bushings at a local hardware store that fit the bill perfectly.  With a quick pass of a 5/8” drill through each hole, the bushings slipped right in and I was able to weld them in with little trouble.  Another quick pass with a ½” drill and the lower mounts were ready for action.  Check!

Using a commercially available bushing, I was able to weld it into the original 5/8" mounting holes.  This was necessary to mount the new Bilstein coilover dampers as they use 1/2" fasteners instead.

Going Forward

Now that the mechanics of the axle housing are basically complete, my next area of concentration will be to finish modifying the rear trailing arms and fabricating the spacers required to properly locate the spherical rod ends that will replace the rubber bushings they were originally configured with (yuck!).  Following that, and a few more trial fits, the axle housing should be ready for color and the brakes can be finally fit.  By this time, Fall should be approaching and the focus will shift back to the rear bodywork area and then the fitting of the front coilover suspension.  Busy winter ahead!  …….and still a few surprises to come!