Bryan Irons
Words and photos by Bryan Irons
The ever-transpiring game of off road “catch up” has us strapping on bigger tires, bolting on heavier armor, applying more power and upgrading driveline components to our rigs in order to keep up with the crowds in the woods with turn key trail slayers and home brewed monsters alike.
As such, the “chicken or egg” quandary often rears its ugly head. Heavy armor? Yes, have plenty of that, as the scales tell no lies. Power? Ya, a nitrous huffing, fuel injected leviathan that makes enough torque to twist a Prius like tinfoil. Tires? 150 lbs a corner of 37” Pitbull Rocker and BAD Beadlock are at the ready. Axles? Well, between the weight, power, tires and gearing… we can snap rear Dana 44 shafts at will, and the well of junkyard spares were gobbled up long ago. It’s time to fix that.
If the first thought you had was “time to swap in one ton axles!” we’re going to disappoint you greatly, but with good reason. A Scout Dana 44 ended up in the rear end of our trail steed with a width only a few inches narrower then our front axle, and the same 5 on 5.5 bolt pattern. At a narrow ”ish” 58” wide from wheel mounting surface to wheel mounting surface, it was perfect for fitting though tight trails while maintaining enough ground clearance. We really didn’t want to change these dimensions much.
After a few brown pops infused brainstorming sessions, we dreamed up as a high strength, 4.10 geared, disc brake equipped Dana 44 with a width of around 60”, and a 5 on 5.5 bolt pattern. Now it was time for action, but we’re married and don’t have a big enough allowance, so we’re going to have to pick up pieces one at time. For the base of our axle foundation, we scooped another rear Scout Dana 44, after all, we know the axle design works for us, and we just need to spruce it up.
It may seem odd to start with a bearing package, but Jantz Engineering just south of the border is renowned for innovative ways of keeping a Dana axle together. Namely, their K4 installation kit which allows for a much larger Jeep JK Dana 44 ring and pinion to be placed in our old school Dana 44 housing, for a claimed strength increase of 44%. Jantz kits require specific ring gear carriers, but the installation bearing kits are complete and use only top shelf brands such as Koyo, NTN, SKF and Timken.
A 35 spline ARB Air Locker was ordered next in a 3.73 and down (numerically) carrier size (PN RD147). A selectable locker such as the ARB takes wheeling trips to the “Epic” plateau by locking both left and right axle shafts together for maximum traction at the flick of a button and the slight hiss of air. We have heard stories of leaking gaskets and air seals, but in our experience, avoiding this headache involves starting with a straight housing, keeping it that way, and proper installation techniques. To date, we have had exactly “zero” issues with any of our ARB installations.
To match the 35-spline locker, we need 35 spline shafts… there are “Scout” specific 35 spline shafts, but this can end up costing more then our aforementioned allowance allows. Plan ‘B’ was to scoop later model (think Jeep TJ and XJ) Dana 44 cut to length, 35-spline Chromoly Yukon shafts from Randy’s Ring and Pinion (PN YA WD44-35-32.0). The beaucoup beefier 4340 alloy shafts would ensure we would have to try pretty hard to snap them, and the additional beef from jumping from 30 to 35 splines will make it a true feat of utter stupidity if we do.
The Scout Dana 44 housing outer bearing pockets use standard “set 10” bearings, which work for our new 35 spline shafts, BUT the distance between the bearing and the axle flange is about 1.25” longer with the new TJ/XJ style axle shafts. This little SNAFU meant we needed a solution for the brakes. A trip to the local junkyard yielded a set of late 90’s Nissan Maxima calipers with a built-in emergency brake. A set of Suzuki Samurai front rotors fit like a glove with some CAD (Cardboard Aided Design) mounting brackets to match. The bracket sets were cut at a local shop out of 3/8 steel plate. Some drilling, tapping and coat of paint allowed the brackets and calipers to bolt to the factory outer housing and hold the calipers securely.
Also, from Randy’s Ring and Pinion we ordered a set of 4.10 axle gears (PN YG D44JK-411RUB) for a Jeep JK as described in the Jantz instructions. The pinion shaft OD of the JK gearset is on par with its big brother the Dana 60, and the ring gear diameter much larger and closer in strength to a Dana 50, and we were happy to get this kind of strength upgrade. The ring gear bolts are also stepped up a size, so be warned, you may have to drill out your locker/carrier mounting bolt holes to fit.
With the internals sorted, we needed to turn our attention to mounting the axle and keeping it safe. TMR customs in Newmarket, Ontario had everything we needed for our metal fix. Their 2.5” U-bolt eliminator kit (PN 1363) allows for a 2” stretch and negates our U-bolt hanging under the axle, which can catch on the trail in our “Spring Under Axle” configuration.
We also sourced out a super beefy differential cover (PN 1188) from TMR. In the past, we have built these in our shop but couldn’t achieve the same quality as TMR and ended up chasing leaks for far too long. TMR cuts, bends and welds the 3/8” thick covers before machining the mounting surface perfectly flat. The mounting holes are cut flat and new stainless hardware is supplied. All Made in Canada!
Our last, and most nerve-racking piece to pick up was a complete axle truss, again from TMR. While generic brackets for Dana 44’s are available, we wanted all the beef we could get. Since Dana 44 housings come in many different shapes and configurations, we selected a JK specific Dana 44 truss (PN 1293) and modified it slightly to fit our Scout unit. We took our time and welded the brackets on slowly so as to not warp the housing. Look for an upcoming issue in 4WDrive where we take a closer look at the process.
End of the day thought… Could you build a stronger axle for less money? Yes, most certainly but you will have to make trade offs. Without the ability to finance a crate axle, we had to build ours piece by piece as money and time would allow. In the end, we landed on the perfect unit for our needs. One that will get us further down the trail without hearing the sound of shrapnel flying behind the differential cover. Now onto how it all went together…
Bryan Irons
Jantz Engineering – http://www.jantz4x4.com.
TMR Customs - https://www.tmrcustoms.com
ARB – http://arbusa.com/
Yukon Gear and Axle - https://www.yukongear.com/
Randy’s Ring and Pinion - https://www.ringpinion.com
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Our housing came stripped down for us already. If yours does not, take the time to measure and record any shims as you blow the unit apart and are left with just the bare pumpkin. Mark the bearing caps for location and orientation if not done so already.
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We decided to start by installing the centre section components. In our experience, having a carrier in the pumpkin helps keep the housing straight when welding on a truss. The Jantz instructions are broken down well, with many tips for the process such as notching out the bearing pockets as seen here to help pop the pinion bearings out during setup.
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Don’t concern yourself with the size of the gear on the end but take a peek at the added beef of the pinion shaft itself on the JK piece (left). Larger splines, bearing mounting surface and overall diameter all make this axle so much stronger.
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Jantz supplied shims go under the pinion head bearing for proper gear mesh depth. If you are at the point of installing your own gears, go get yourself a cheap shop press and put the hammer away.
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Check for any clearance issues with the new pinion in place as some grinding may be required. We were in luck and everything fit well.
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Bryan Irons
The Yukon ring gear is double drilled for both ½” and 7/16” bolts. We decided to keep our “bigger is better” mantra and drilled the ARB air locker mounting holes out to the larger ½” size using a ½” bit and a steady work surface.
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Bryan Irons
Before bolting on the ring gear, we took a file to the mounting surface to take away any burrs. Take a sharpie and draw around the entire surface to check for any high or low spots.
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Bryan Irons
With the ring gear bolted up, we switched over to ARB’s installation instructions and used the ARB supplied bearings. Shims for the ARB are unlike those of a standard Dana setup as they go on the outside of the carrier bearings. Our trick is to place the left side shims and air line attachment in first, and then tap in the right-side shims so as not to accidentally hit the air line.
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As with any gear setup, checking the pattern and making shim adjustments is critical to bearing life, noise, and gear wear. We found the installation instructions supplied with the Yukon gears to be very thorough and complete with diagrams. Getting this pattern took us six or so tries.
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Once the gear pattern is correct, it’s time to set pinion bearing backlash. The JK setup typically uses a crush sleeve. We are not fans of the evil sleeve and prefer using shims and a spacer, which are supplied by Jantz, as they hate them as well!
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Having the proper tools to measure bearing preload is critical. Our dial indication torque meter (not wrench) was not a cheap but it is a critical purchase. No, you can’t borrow ours.
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ARB’s instructions outline where to drill and tap a hole for the air line to exit the housing. With the ring, pinion and locker setup complete, routing the air line is the last step. Before final assembly, clean the housing out of any metal pieces that may have snuck in.
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Bryan Irons
Time for new inner axle seals. With the older rear Dana 44’s, there is an inner seal that resides in the housing, and an outer seat that rides on the axle shaft. This keeps oil in the differential, and grease on the wheel bearing. Don’t forget this inner seal and make sure to drive it in squarely. We had to use a hole saw to get the right fit.
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It is easy to see the difference in shaft extension between the factory Scout unit (left) and the new Yukon 35 spine shaft (right).
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Bryan Irons
Don’t forget the shaft retainer (black) before pressing the bearing on. With us omitting the drum brakes, we needed to add a shim that is the same thickness as the backing plate. This is to ensure that the proper preload is placed in the bearings. We just cut the old backing plate down to the same size as the shaft retainer.
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Bryan Irons
The shafts are bolted in and it’s time to work on the TMR JK truss. The laser cut pieces fit together like Lego. Some grinding and tweaking was required because this Dana 44 housing is obviously not the same as a JK housing.
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Bryan Irons
At the same time the truss was being SLOWLY welded on, the leaf spring mounts were assembled and tacked into place.
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As mentioned, take your time welding this all together. We did not weld to the cast steel (not cast iron) housing. We feel that if you are going to be welding to the centre section, a proper axle jig should be used to alleviate any possible warping. Now would have been a good time to clean up the shop…
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With everything welded and cooled, check your gear pattern and backlash again. Ours was still within spec so we bolted up the monstrous TMR cover.
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The junkyard Nissan calipers got a rattle can rebuild, some new seals installed, and pads bolted in. The new Zuk rotors are cheap and fit like a glove.
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With Wonder Woman threatening us with the whip, we cannot tell a lie; this axle turned out GREAT and the last step before bolting it in was paint. We spent many late nights in the shop building the axle at home piece by piece as money and time would allow, and we’re confident it will stand up to the brutal punishment we have in mind.