5. In the Pro Rock housings I decided on 5.38 gears, which is plenty low for big tires. I began to worry that the stock 27-spline pinion would be the weak link with the 40-spline axles. Of course, it is upstream of the torque multiplication, but I knew my transfer case was going to have 32-spline outputs, so why go back down to 27-spline? I had initially gotten some Spicer gears from Drivetrain Direct (left), and then I found that Yukon gear offered even bigger 35-spline pinion Dana 60 gears, but only for high pinion, and only in 5.38s. So I decided to do a test. I'll put the Spicers in the front, and I ordered the Yukons from Randy's Ring and Pinion and will run them in the rear. When a high-pinion axle is run in the back of a vehicle, it is turning on the coast side of the gear, and as such is weaker and more prone to break, but the bigger pinion shaft and stiffer Pro Rock housing should help keep the gears flush. In order to run the 35-spline pinion, I also need to run a special yoke that is only available for a 1350-series U-joint, where in the front I will run a Spicer 1410 yoke that I got from High Angle Driveline. The larger 1410 will give me more angle of movement over the 1350, but the rear driveline will most likely have High Angle's 1350 CV at the transfer case and not need as much angle at the pinion. In addition, the 35-spline Yukon gears (which are made in the U.S.) need special bearings and the shims are installed in a special billet shim case due to the larger diameter, but the pinion seal is the same as stock.
6. In order to keep all four of my tires turning, I decided to go with Detroit Lockers in both axles. They are the only company I found that offers off-the-shelf lockers for 40-spline axles, unless I was to go with a spool. Plus I have been running them in my Chevy Army truck, Ultimate Avalanche, and Tacoma for a few years now and really like the always-ready-to-wheel mode. Minor issues with Detroits include difficulty turning in some applications, which I shouldn't have since I'll be running both front and rear steer; locker breakage should an axle or joint fail, which is less likely with both the Dana 60 locker and the 40-spline shafts; and noise from on-the-street unloading, which is something I've never been bothered by.
7. When running kingpin-style axles, you need to sometimes rebuild the kingpins and bearing. The kingpin rebuild kits are still available and I got mine from Drivetrain Direct, but the lower kingpin that bolts to the bottom of the knuckle is getting harder and harder to track down. I found that Parts Mike is a great source for standard Dana 60 parts as well as Dana 44s and other drivetrain components.
8. When ordering my Superior Chromoly shafts, they asked what U-joints I was going to run, and I answered "CTMs." Again I've been running these billet 300M joints in the Avalanche and the forged version in the Tacoma with no problems. The Avalanche has even had them in the rear steering axle where they get tons of abuse both on the trail and on the street towing. In fact, I have gone through four different ring-and-pinions in the rear of the Avalanche but never have I changed the U-joints. I'm not gonna lie, I have seen them break in competition rigs, but that was under severe abuse and before a recent redesign. There are other U-joints on the market, but until the CTMs let me down, I'll be running them in my trail rig.
9. Part of the reason I chose the Dedenbear knuckles (here with black paint over their normal orange powdercoat) is because of the five-bolt mounting system for high-steer arms. As I've said before, I'm not the best driver, and I've been known to kill a few tie rods, so using these billet high-steer arms from OTT Industries will get the tie rod up high out of harm's way, and the five-bolt mounting system helps in locking the arms in place. I will get the arms drilled for the tie rod once I know exactly where the hole should be.
10. Another issue with the big 40-spline shafts is the need for a larger spindle to clear the bigger shaft. This requires the use of a larger-than-stock outer hub bearing, but the standard inner hub bearing is retained. When building a five- or six-lug axle, Dynatrac actually uses a shorter-than-standard spindle and stub shaft. But since most folks running eight-lug axles could be putting them under a heavy vehicle, Dynatrac kept the standard spread and used the 12-inch stub shaft. I decided on eight-lug since if I ever tow this buggy, I'm sure my tow rig will have eight-lug tires and wheels and that keeps spare tires and wheels universal in my garage. By going to the Chevy kingpin knuckle, we also had to track the somewhat rare Chevy brake caliper stands. We found some new old stock units at Boyce Equipment, but along with the lower kingpins we think someone should consider remaking these units.
11. Another issue is brakes, hubs, and drive flanges. Dynatrac is having custom hubs made to clear the larger spindle bearings, and I chose to run stock 12 7/8-inch rotors and single-piston calipers since these will most likely be parts I need to replace some day, and I can find them at most any auto parts store. Plus, they should offer plenty of stoppage for a medium-weight buggy. Running drive flanges in the front will require perfect driveshaft angles to reduce vibrations while at highway speeds (yes it will be on the highway, but that step is for a future article). If by chance I do have vibration, I could always pull the slugs and just let the hubs spin while on the road, at least until someone comes out with the 40-spline selectable hubs that are in the works.
12. So there you go, a set of axles that should take the abuse and be strong enough that the weak link will hopefully be gravity. Next month we'll move upstream and discuss the rest of the drivetrain, and after that we'll start building the chassis.