THE REAR END - Part 3

A "Diamond" in the Rough!!!

Starting with a bare housing, fresh out of Red Feather, Colorado, Bender and the BTF crew fit it under the chassis and began laying out the suspension.  After deciding on link location, the difficult part of every build came when it was time to build the upper link truss.  There are a ton of ways to do it, but Bender and Matt worked together to create a truss that not only looked great, but was strong and practical too.

On the next pics, you not only see how beefy the welding is internally in the Diamond Axle housing, you can also see the weld lines "inside" the truss.  That gusseting adds a lot of strength yet allows the whole package to be lightweight.

Of course you cannot miss the nice touches of branding such as the BURLY BTF logo as well as the custom "Diamond" that Matt created to add some "flair" to the whole thing.  Riding on top of the truss are the beefy 5/16" link tabs.

Here, you can see we chose to use front spindles for the rear full floater.  After trying out the weld-on spindles on the RockHer I, we'll not go that route again.  This way, the parts are common on all four corners...uh, oh...I just realised I might be in for some trouble...there are no caliper cutouts on those beautiful tube ends that the spindles bolt to...funny how you can look at it in person and not catch the problem until you see it in a picture!  anyway, the tube end that Diamond Axle fabricated are the Chevy 6-bolt style and have blind holes that are tapped so you can install bolts, but not see them on the inside.  NICE!

Next, to the True Hi 9 center section.  When they ship from True Hi 9, they come pre-assembled except for the copper ARB line that runs inside the housing on the center section.  I had never done one of these but after looking at it for a few minutes, I decided this was something I could cleanly handle.

Before starting with that, I checked out the gear pattern that True Hi 9 had set up as well as measuring backlash and runout to be able to compare to after running a few events.  The backlash was .009 and the pattern was great.

The next thing I did was admire the new forged Pinion yokes that I picked up at Randy's Ring and Pinion. I've always run cast yokes with good luck BUT, there's two things wrong with that.  There is something stronger (forged) and something with more bling (forged)...so I called up Randy's and ordered them.  As you can see, this yoke has been massaged a little with a die grinder to allow the axle to articulate to full swing.  I should note that the yoke pictured here is from the front, the rear didn't need nearly the same massaging but the pictures didn't turn out so I used these instead. They are U-Bolt style for 1350 joints.  The black piece just above the yoke, is the Currie "Daytona" pinion support that is far stronger than a traditional 9" pinion support.  With the abuse these diffs will take, we're not cutting any corners.  A stock pinion support is a no-go with us.

Back to the internal ARB airline...first thing was to layout the routing of the copper line.  I fit the "seal housing" (the part that transfers the air from the copper tube to the locker) in place on the carrier and then carefully hand bent the copper line to run around the ring gear in the shortest distance.  It happened to be down toward the bottom of the diff and I had to be careful to be sure it was close enough to the diff to be able to clear the super tight Diamond housing, yet not so close that it would rub on the ring gear as it spun.  When I routed it, I found a way to take it within an 1/8" of the ring gear and yet it was impossible for the line to touch because the sides of the True Hi 9 third member held it away.

I marked the copper line with a sharpie, about 5/16" beyond where it passed through the housing while the copper line was "resting" in the position I bent it too.  I removed the line and then cut it with one of those small tubing cutters that you spin around and around while tightening the wheel.  With this line, you would NOT want to use any other kind of cutter.

While that was out, I greased up the two O-rings that go in the seal housing, placed them in their grooves, and put it back on the center section.

As I started to tighten it down, I remembered that we are using the braided stainless steel ARB airlines from Russell Performance in place of the blue airline that comes with the ARBs. Though we've had good luck with the blue airlines, you can never be too sure, so we again chose the route that offered more durability and more bling! This upgraded airline uses "-3" AN fittings on the ends of the hose so it uses a different adapter.  I pulled the copper one off and placed the aluminum on on that came with the Russell kit and put it together..

The next part was to lock the "seal housing" to the carrier.  That uses a small spring clip that is quite simple in design and very easy to install. You'll notice in the picture below, the red arrows.  Brain Ellinger gave me a piece of advice.  Check the bends at those points and be sure they each are 90 degrees.  If not, take a set of pliers and bend them carefully to get that corner square or the clip will not hold as well.  We had no issues, they came from ARB just as they were supposed to be.

To lock the seal housing in place, the small clip fits through a groove on each side of the part, and clips down over the outside of the seal housing, locking it securely.

A couple more shots of the diff before doing the airline...the close-up shows the "spline" area within the differential that actually grips the axles when they are installed.  The big shaft that cuts vertically through the middle is called the "center pin" and is what often holds the spider gears.  It is a common part to break if an axle snaps and the inner piece of that axle is forced inward, in turn slamming into the pin.

The next thing was to install the inner housing axle seals. Here, I am showing the seals riding on the axles and they do actually do that, BUT, they are installed into the housing internally from the inside.  These seals are what keeps the fluid from leaking out of the differential and down the axle tubes. The third picture is me choosing the correct seal driver to be able to install the seal into the housing.  It's a simple process of beating the crap out of it with a BFH... Big F'ing Hammer.  While driving the seal in, you must be careful and be sure you drive it in straight.  You can ruin a seal and your day if you're not careful.

By the way, the seal has that "bell" shape on one side to help make it easier to center the axle correctly when sliding it in place.

Below you can see the axle seal surfaces that ride on the seals we installed. They are different lengths as the "center pin" is not necessarily in the "center" of the diff housing.  It is actually off-set by a few inches to allow for the pinion to clear.  In our rear application with the True Hi 9, the shorter seal surface goes on the driver's side.  If it was a front differential, the short surface would be on the passenger side.

Before installing the center section and seals though, I scraped all of the slag and dirt and debris off the inner housing, scoured it with a wire brush, blew it out with a blowgun, then wiped it out with a brakeclean soaked rag...then, for good measure, I ran a powerful magnet along the inside to pick up anything I might have missed.  Funny how a few tiny pieces had evaded the first cleanings and ended up on the magnet.

Here is the sexy drive flanges we all salivate over.  A drive flange is what connects the outer splines on the axle to the wheel hub. These are the chromoly flanges from Rock and Roll OffRoad and install with a single large "C" clip that is more like a slinky than a c-clip, and then 4 Allen bolts. 

Here is "the BOY" working on the rear hub...he sure spent a ton of time over there with that drive flange ;-)

Here's what the whole package looks like from underneath.  Notice the SAWEEEEET diff guard that BTF designed to help protect the True Hi 9 as well as help Becca slide up and over the obstacles that she might actually catch the normally vertical surface of the hi pinion 9" center section on.  Also, notice the small "ramp" Bender added to the front of the diff tube.  It's kind of hard to see, but it is the rounded black plate just to the left of the pumpkin.  That also helps Becca slide the Red Bull RockHer II over stuff she'd normally hang up on.

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Blue Torch FabWorks, Inc

Red Bull RockCrawling Team

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