Installation of a Lock-Rite (by PowerTrax) Fully Locking Differential into a Ford 9 inch Carrier.

This was not intended as a FAQ, but I got a little long winded when I wrote it. Hopefully someone out there in CyberLand will enjoy this page, and maybe even find it useful. Send comments to Dan. See disclaimer below.

Click on any of the pictures for a larger, high resolution version. Slow connections be warned! The larger versions are much larger.

Installation of a Lock-Rite Locker into a Ford 9 inch rear diff is pretty easy. The entire endevor took me about 3 hours, not counting my initial attempt to install a Lock-Rite made for a Dana 30. The boys down at Fort Collins 4x4 are still trying to figure out what part they gave to the poor soul who wanted the Lock-Rite for his Dana30, and I'm sure he is too!

The first step is to remove the 3'rd member, a pretty straightforward process. Jack up the back, secure firmly on jackstands (or in my case old cement blocks and 2x4's), remove the wheels and back drums. The drums should pull off easily. If they don't, you may need to tap lightly to free it from the axle, or back off the rear brakes. Don't set the emergency brake or you'll never get them off (unless your brakes are really shot). Then, remove the plate that holds the axle in place (on each side). There are 4 bolts that need to be removed. The axles have a hole big enough for a socket and extension, line up the hole to the bolts. When the 4 bolts are removed, you can pull gently on the axle (where the wheel bolts on) and it should slide out easily. Be careful when removing the axle, there's a rubber seal thats pressed into the housing. You don't want to bang on that seal with the axle shaft or you'll ruin it.

With both axles removed, you can now removed the 3'rd member. Disconnect the driveshaft at the rear diff, then remove all the nuts that hold the third member in place. It might be a good idea to have a pan ready, as oil will run out the bottom. Let it drain. Pull on the 3'rd member. Pull some more. Get some screwdrivers, pry on the 3'rd member. Pull. Curse, pull some more. When you get it out and drop it in your lap, you'll realize its kinda heavy.

You'll need to remove the carrier, the assembly that hold the ring gear. The Lock-Rite manual emphatically states that you should mark everything, so that you can put it back together exactly like it was before you took it apart. This is because the caps that hold the carrier bearings are NOT interchangable, and because you don't want to change the position of the ring gear with respect to the pinion gear.

Here's a picture of half the carrier, after its been split open. One side gear is still in place, along with the two smaller spider gears. The other side gear is leaning agains the carrier. The side gears are splined on the inside, and are what the axles fit into.

This is an exploded view of the carrier showing the orientation of the Lock-Rite upon installation.

Another view.

Here's how the side gears fit against the gears of the Lock-Rite. The teeth of the existing side gears fit into the grooved slots of the Lock-Rite gears. There are springs between the two Lock-Rite gears that press them apart. When little or no torque is applied, only one side gear is engaged with its Lock-Rite gear. As more torque is applied, the Lock-Rite gears are forced into contact with the side gears by the nifty profile riding on the shaft. Thats the same shaft that used to hold the spider gears, and it goes right back into the same spot with the Lock-Rite installed.

Another view of the same thing.

A face-on view of a side gear and a Lock-Rite gear.

Since the Lock-Rite uses the existing side gears, its propper funtion depends on the condition of those gears. The manual had a few diagrams that illustrated how badly worn the side gear teeth could be and still allow the Lock-Rite to function propperly. Basically, if the side gear teeth look rounded and very pollished (no more factory grind marks left), then they should be replaced. My side gears were kind of on the border, so I replaced them. This picture shows the old gears and the new gears, it should be pretty easy to tell them apart. Two new Ford side gears and next day air shipping cost me a total of sixty bucks from Fort Collins 4x4. I didn't want to be walking any longer than necessary, and I wanted to make sure all this effort wasn't wasted on worn out side gears. I've not been dissapointed.

I found the bolts that held the ring gear to the carrier were very hard to get loose. In fact, I gave up with the breaker bar and wrench and used an air impact wrench, much easier. Re-torquing them to 90 ft-lbs was a challenge, since I didn't have a very good way to hold the carrier in place. I wasn't sure what the torque specs were on the carrier bearing caps, so I guessed at 50 ft-lbs. If you have any spare physicists sitting around, they come in handy to hold things, but they consume their weight in beer pretty quickly (see below).

Overall, I've not been the least bit dissapointed in the the Lock-Rite. However, this is my first and only experience with rear lockers. It has made the bronco noticably squirly on the street, especially when I back off the throttle, but this I expected. Also, I've been pulled over by the neighborhood cop because of my 'excessive wheel squealing'. Okay, its a new toy and I was playing with it. Some cops just don't have a sense of humor. I guess it didn't help any that it was 3AM. Driving on packed snow and ice in 2wd is a blast, as long as you don't really want to go anywhere. 4wd is no problem at all (remember, open front). In fact, I'd rather drive the bronco on the ice than my Wife's 92 Jeep Cherokee.

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The author has no affiliation with PowerTrax, he merely likes their product. All views expressed here are the views of the author and noone else. Damned lawyers!