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!

Axle Housing Updates

The month of June has come and gone and I’m happy to say it’s been a very good month, even though my work volume on the car doesn’t outwardly reflect it.  Early in the month, I was fortunate enough to take a “real” 2-week vacation with my lady to visit my family in northern Germany and enjoy the many sights available in and around the area.  I hadn’t had a vacation to speak of since about 1996 or so and this trip reminded me how important it is to breathe the throttle once in a while to recharge and put everything back into perspective.  It worked….and I’ll not wait so long to do it again.

The last two weeks of June were spent catching up on business matters that developed while I was away and cultivating some new contacts that have the potential to advance this build more than I could have imagined.  While I won’t spoil the fun just yet, the next several weeks should generate some very exciting things, with a bit of “eye candy” to boot!

As has been the norm for the past few months, I have been concentrating on getting the rear suspension and axle set up under the car.  The custom Bilstein rear coilover dampers are finished and I am selecting rear spring rates as I write this.  I have also sourced all of the components and tools I will require to get the rear trailing arms upgraded to spherical rod ends to allow the 4-link to behave like a proper 4-link should.  While the expense to get the rear suspension system upgraded according to plan has been much more than I had anticipated, I am firmly convinced the results will be worth every cent.

On the “plus” side of the equation, I have been able to complete all of the required axle housing modifications.  The 4 link brackets are complete, the factory welds cleaned up, and the brake line tube tabs shaved.  But there are two modifications I made that I am particularly pleased with that are the feature of this entry.

First, I have always been irritated by the general lack of convenience in servicing gear lube in a 9-inch axle assembly.  Ford was kind enough to provide a place to put the lube, but never a place to drain it out.  I you’re like me, the cost of a few quarts of synthetic gear lube is worth the price of admission given the peace-of-mind I get from knowing the condition of the axle at any given time.

Additionally, the attractiveness of being able to jack the car up from the center of the axle housing is rather undeniable.  That is, until you see the mess a floor jack makes of the finish on the lower housing once all the convenience of the method is spent.  Since I will be powder coating my axle housing, I wanted to devise a way to have my cake and eat it too.  To that end, I designed and machined a combination axle drain and jack point that serves both purposes well.  Now, with a simple urethane jack pad on my floor jack cup, I can lift the car without damage to the housing finish AND drain the axle lube at any time with no more effort than I spend draining engine oil.

Next, I have always disliked Ford’s method of venting the rear axle housing.  The hose nipple and rubber whip hose protruding from the top of the axle tube always appeared very “busy” to me and generally unfinished.  Especially when you consider the nifty way they jam the free end of the vent hose into the upper rear shock bracing to keep it out of the way.  Nope…..that won’t do at all.

Borrowing alternate solutions from other manufacturers and builders, I decided to install a simple, tidy, sintered stainless steel vent fitting that would eliminate all of the production mess and provide adequate venting.  These vents are inexpensive and easily available and can be found on numerous aftermarket axle assemblies.  I chose an all-stainless steel vent for the uniformity of appearance as well as the durability factor and installed it in the location where the original vent nipple was placed.  A simple drilling and tapping operation and the deal was done.

So, as modifications go, there’s nothing earth-shattering here, but in the long run, I expect them to provide small conveniences where before there were none.  Just a few more details to set it apart.

A little time on the lathe is all it took to spin up this combination axle drain bung/jacking point.  Here is the final machining operation:  tapping the hole for the 1/2 x 20 drain plug.

The completed drain plug ready to go.  Note the flange at the base to allow a nice weld surface without distorting the tapped hole.

So simple yet so effective.  Here is the completed bung with the drain plug installed.  The weld flange can be easily seen at the base.

I positioned the bung on the bottom of the housing after drilling a 9/16" hole in the housing at the exact location I wanted the bung positioned.  Then I simply used the drain plug to hold the bung in place by screwing it into the bung from inside the housing.  You can just see the end of the plug inside the threaded hole in this shot.

A few minutes of welding and the bung is in place (still hot when I shot this picture!).

From inside, you can see the nice, clean drain hole with absolutely no intrusion into the housing like many alternative ideas advocate.

Complete and ready for sandblasting and powder coat!

This nifty little sintered stainless steel axle vent is all that will be visible rather than the nasty factory hose barb and rubber hose the factory provided.