How To: Installing A Detroit TrueTrac Locker In A Ford 9" Rear Axle

Installing a Eaton Detroit TrueTrac in a Ford 9" rear axle is pretty straightforward. Nevertheless, it is always nice to have a clear set of instructions to follow as a reference. I was so appalled by the abysmal lack of installation directions offered by Eaton for the Detroit TrueTrac, that I thought I would write a tech article on it. As always, this article is intended to serve as just a guide. So let's get on with it.

Removing The Ford 9" Third Member:

Removing the Axles: The first thing to do is park the vehicle on a level surface, and place chocks on the front wheels. Loosen the rear wheel lug nuts. Use a floor jack to jack up the rear end just high enough to remove the rear wheels. Support the rear axle with jack stands. Remove the rear wheels. Drain the rear end of all gear oil. Remove the brake drum, or rotor and caliper if you have rear disc brakes. The passenger and driver side axles are attached to the axle tubes by a flange with four bolts. Remove the the nuts on each of the four bolts (note: for some applications, it may be necessary to remove the drum brake backing plate or caliper bracket in order to remove the axles). Slowly slide the axles out from the axle tubes, and label each side accordingly.

Removing The Third Member: Now that the axles have been removed, remove all the bolts that hold the third member to the axle housing. Using a thin putty knife, carefully pry the third member away from the axle housing. Be carefuly not to mar the mating surface between the third member and axle housing. Once the third member is loose, carefully slide it off the axle housing studs. Be cautious not to hit the ring gear against the housing while removing the third member. Use a scraper or razor blade to remove the gasket/sealer material from the mounting surface of the axle housing. Do the same for the mounting surface of the third member. Be sure that all the gasket material has been throughly removed. Clean the inside of the bare axle housing of any sludge and debris.

Disassembling The Ford 9" Third Member:

Removing The Carrier Main Caps: First, remove the bolts in the center of each of the carrier main caps that secure the keepers for the carrier bearing race adjusters (see Figure 1). Next, loosen the bolts for the carrier main caps, so the bolts are only finger tight. You should then be able to unscrew the carrier bearing race adjusters (the inside of the carrier main caps is threaded, which the race adjusters screw into). Remove the main cap bolts and main caps. You should now be able to lift out the carrier assembly (see Figure 2).

Figure 1: Ford 9" third member


Figure 2: Ford 9" third member housing with carrier assembly removed



Removing The Ring Gear: Remove all the bolts that hold the ring gear to the carrier. The ring gear is pressed onto the shoulder of the carrier (see Figure 3). Ideally, a gear puller should be used to remove the ring gear from the carrier. If an appropriate size gear puller is not available, insert a small bolt into one of the ring gear holes, and use a dead blow hammer to tap the ring gear loose. Tap lightly, making sure to tap no more than a few times in a row in one spot. Work in a criss-cross pattern in order to loosen the ring gear evenly.

Figure 3: Ford 9" open carrier on the left, Detroit TrueTrac carrier on the right. Notice the shoulder on the open carrier at left, where the ring gear is pressed on.


Removing The Carrier Bearings: Removing the carrier bearings from the open carrier assembly is a very trick prospect, and requires a bearing puller. It is extremely easy to damage the bearings during this process. So much so that I recommend foregoing attempting to pull the bearings, and purchasing new carrier bearings. New carrier bearings cost ~$40, and can be obtained from most parts stores (e.g. NAPA part number BR50). When searching for bearings, specify carrier bearings for a 1970-79 Ford Torino with a 9" rear end. The bearing race OD is 2.891".

Installing The Detroit TrueTrac Locker:

Pressing On The New Carrier Bearings: Ideally, a bearing press should be used to press the carrier bearings onto the TrueTrac carrier. However, if a bearing press is not available, you can use a piece of wood and a dead blow to press on the bearings. Carefully place the bearing with the tapered side facing up, on the shoulder of the TrueTrac carrier. Make sure that the bearing is as even as possible. Place a piece of wood on the bearing, and lightly tap the wood with the dead blow. The bearing should easily be able to be pressed into place with minimal force. Be sure that the bearing is fully seated. Repeat this process for the other side of the TrueTrac carrier.

Installing The Ring Gear: A spare tire makes a handy impromptu stand while working on the carrier (see Figure 4). Ideally, a bearing press should be used to press on the ring gear. However, if a bearing press is not available, lightly tap the ring gear onto the shoulder of the TrueTrac. Reinstall the ring gear bolts. Slowly tighten each bolt no more than a couple of turns at a time, making sure to work in a criss-cross patter in order to draw the ring gear up the shoulder of the TrueTrac carrier. Once the ring gear is properly seated, remove all the bolts. Clean the bolt threads, and use red Locktite when reinstalling the bolts. Torque the bolts to 45 ft/lb in a criss-cross pattern (see Figure 5).

Figure 4: Ring gear properly seated on the shoulder of the TrueTrac carrier. Note the spare tire carrier holder. It may be low-tech, but it sure does work great.


Figure 5: Ring gear bolts replaced with red Locktite, and torques to 45 ft/lb.


Installing the TrueTrac Carrier: Place the races over the carrier bearings, and insert the TrueTrac carrier assembly into the third member housing (see Figure 6). Reinstall the carrier bearing main caps, and tighten the main cap bolts finger tight. Screw in the race adjusters, making sure the carrier is properly centered. Torque the main cap bolts to 20 ft/lb. Use a screwdriver and dead blow to adjust the race adjusters in order to set the appropriate ring and pinion lash and bearing preload. Once set, torque the main cap bolts to 80 fl/lb. Reinstall the race adjuster keepers and bolts. Torque the keeper bolts to 25 ft/lb (see Figure 7).

Figure 6: The TrueTrac carrier assembly, complete with bearing races in place, placed in the third member housing.



Figure 7: Reassembled Ford 9" third member, complete with Detroit TrueTrac locking carrier



Reinstalling The Third Member: Using high temperature RTV black silicon, run a thick bead of sealer around the mating surface of the axle housing. Be sure to run a bead of sealer 360 degrees around the studs. Reinstall the third member, and torque the bolts to 30 ft/lb. Reinstall the axles. To test the locker, turn one of the axles. The opposing axle should spin in the same direction if the locker is functioning properly. If all is well, fill the rear axle with gear oil. Replace the brakes, and rear tires. You are done!

Hopefully you found this helpful. Cheers.