Powertrain Part 2-Transfer Case, Differentials, Drive Shafts and Shocks

Money Pit Staff Writer

In this episode we start with transfer case, and no surprise here... Advanced Adapters is the best in the business. We have an Atlas Pro Series 3.8:1 in Rocksanne and it, too, has been flawless, and don’t forget—that’s with tons of horsepower and 49” tires on a 7500 lb car.

The Pro Series is intended for heavier Gross Vehicle Weight Ratings (GVWR), and high horsepower race applications. The New G2 Pro Series Atlas Transfer Case is equipped with a 1-1/2” idler shaft assembly offering several advantages in strength. This is the same transfer case that many Ultra4 teams have been running in their King of the Hammers race cars for many years with just a freshen up between seasons.

We ordered a 3.0:1 gear ratio with the Flat Tow option because we want to be able to flat tow the LJ to places where we won’t be wheeling. This includes an oiling system to keep the transfer case lubed during trips of more than 250 miles. We also ordered a VSS output that we can use for a speedo and to tie into the GM engine computer to better control the idle which will give the Jeep better road manners during slowing and stopping. 1350 front and rear yokes and a cable shifter rounds out our order.

The transfer case was relatively easy and quick to install with the body off the Jeep. The first thing we did was lay it front down on the bench and fill with the supplied oil. This is way easier than trying to do it later under the Jeep. Next, we set the clocking ring to the specs in the Tracer Kit instructions and lifted it into position and installed the bolts.
The cable shifter takes a few minutes to figure out, but good instructions pay off and soon it was done.
The next item is our Currie Extreme 60 and 70 differentials. We are very excited to be working with Currie Enterprises on this project because these axles are specifically designed for rock sports.
They have huge 3-5/8” diameter axle tubes. Currie designed cast iron center section that has the differential cover rotated up at an angle to keep it out of the rocks, full float hubs, locking hubs in the front, 1 ton knuckles with machined high steer arms, hardened steel skid plate, an axle bridge in the rear to attach your upper link mounts, 5.38:1 gear ratio, and Auburn electric lockers. Wow! We ordered our axles bare with no brackets.

The installation of the Genright Tracer brackets was fairly easy. GenRight supplies good instructions and lots of pictures to keep things moving. We lifted the rear diff with the engine hoist set it up on 3 stands at about 3 feet off the floor. No bending over and we could rotate the entire unit on the stands to make welding much easier.

The rear took about 3 hours to tack everything in place including upper and lower link mounts, shock mounts and sway bar mounts. Another hour or so to weld it up and it was ready for paint.
Well almost. Paint prep is more than just blowing the dust off. First, the best advice I can offer you when it comes to the finished product is to use a fog coat of splatter spray during the welding process to keep weld splatter from sticking to everything. This makes a huge difference in how the finish product will turn out. After welding there will still be some splatter, but it is easily scraped off. I like to use a file for this. The file is super hard and will clean much better than a chisel. Next, I used a flap disc to ease all the edges on the brackets and clean off any burs. Next up, a bath in lacquer thinner to remove any oils and residue and then a coat of etching primer. I let the primer set for a couple of hours and then sprayed on 2 coats of Rustoleum dark gray metallic paint for the finish coat. The complete process took about 8 hours to complete.

The front axle was next, and it is basically the same process as the rear but with a few more pieces to contend with, like a track bar bracket and steering.

GenRight offers a high steer kit that completes the Tracer Kits front axle assembly. This kit is beefy! Chromo heims, 1/4” wall tubing and 3/4” bolts are the recipe to make your steering worries fade. The kit includes a drag link that connects the steering box to the passenger side knuckle, a tie rod to tie the right and left sides together, and a Tracer specific Griffin aluminum radiator. That's right; even a special radiator is required to make this suspension tuck up as tight as possible at full bump. 
After all is said and done, the front axle took us about 12 hours to complete including paint. She is tight! Below is the front axle at full bump. Check out the super tight tolerances built into the Tracer design.
Note the flat stock we welded to the track bar tube to support the hydraulic steering lines as they make their way down to the assist cylinder. 
Now we can finally roll these axles under the frame and link them up. We set the axles on out roller carts and under they went.
and Billet Flex joints. They are both beautifully crafted in the USA with American made material. It does not get any better than that!
Summit Machine has a full line of high-quality builder parts for the off road industry and their work is second to none. When the links and joints arrived they were assembled together and protected with a fishnet rubber material to keep them looking great.
We literally removed the protection from the ends, adjusted the length to the dimensions in the Tracer instructions and bolted them in linking the differentials to the frame.

Next we installed the best drive lines in the off road business. J. E. Reel has been building off road drive lines for many years for some of the most successful teams on the course. We are excited to have Reel drive lines for our LJ!

2”x .25 wall tubing will keep the drive lines away from other parts in the build and out of the rocks. 1350 joints on both ends and slip yokes installed toward the transfer case will protect them from the rocks.  Using 1350 U-bolt kits the drive lines bolt right in with no issues.
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