Racing Rearend Build - Building the Ultimate Rearend

The rear cover has been machined to accept an O-ring which should provide much better sealing than standard paper gaskets. Paper gaskets work well in the shop, but they seem to start to develop annoying leaks at the racetrack when the oil gets hot and the metal casings start expanding. Also notice the aluminum wedge that’s used to securely hold the bearings in place.

After our visual inspection, driveline specialist Jim Cook put everything back together. The main gear ratio is a quick change standard 4.86:1.

The axle tubes are anodized aluminum. If you don’t like the blue, you can also get them in a less attention-grabbing black. Like the magnesium bells, there’s plenty of material here so that they should stand up to moderate abuse with no problems.

Here’s another nice touch we noticed. Bulldog includes a few extra-length bolts to fasten the two bells to the center section. These are perfect for attaching the torque arm brackets to the bell.

Even if you’ve ordered a brand-new rearend, it’s still a good idea to check the endplay in the pinion as well as the free play on the ring gear wear button. Thread the wear button down until it just makes contact with the back of the ring gear, then back off ¼ of a turn before tightening it down with the lock nut. You can’t see it in this photo, but the end of the wear button has a dimple machined in it to help trap oil between the button and the ring gear.

The machined aluminum nuts that hold on the quick change cover plate include flanges machined right in. This eliminates the need for washers which always seem to fall off and get lost in the dirt when you’re making a gear change in the pits.

With the rearend back together, the pinion plate can be bolted on. This rear is going into a Dirt Late Model that was built by Stuckey Enterprises. The company provided all the mounting hardware like the pinion plate.

The Joe’s hubs are machined from billet aluminum. They don’t really save much weight versus cast-aluminum wide-five hubs, but the billet aluminum is less prone to developing cracks. Also, if you take a hard hit in the wheel, the billet design will bend a bit. It will still ruin the hub, but in the same situation the ear on a cast unit can break off completely without absorbing much of the energy of impact—which can then be transmitted into the rearend where it can damage other components.

Here, we’ve already bolted up the brake rotor bracket. It’s designed so that you can bolt the rotor directly to the bracket or set it up to be a floater to cut down on brake drag when the rotor gets hot.

Like the Bulldog rear, the Joe’s hubs also have several very thoughtful features that can make a racer’s life easier. For example, the press fit for the rear seal is quite loose. It’s actually just tight enough to seal the hub when filled with oil. The seal itself is really held in place with the clip you can see bolted on top of it. This allows the seal to be easily removed without damaging it when it comes time to clean the bearings (and repack if you are using grease), and now it can be reused multiple times.

Joe’s also sent us these bearing spacers. They use a collar, held in place with set screws, to help reliably set the crush on the bearings for the right amount of drag. This setup does require a bit of trial-and-error, but once you get it right it should stay that way and speed up your weekly maintenance.

Bulldog also included these gun-drilled 31-spline axles. They’ll be installed when we finish up the hubs and birdcages on the rearend next month. Make sure not to miss it. CT