Installing Your Own Locker

Note: All specifications mentioned in this article refer to a Dana 44 differential.

Want to lock your front or rear axle but think the install job is a little out of you league? Think again. With the right tools and a little patience you can install one with not much effort. The key is to have all the tools ready and handy when you start so you will not be kicking yourself halfway through the install because you can't find your gear marking compound.

After I picked up my new Detroit locker I was a little short on cash to just drive into a differential shop and get them to install it. Getting a locker installed can cost a pretty penny, around CAD$400 to give you rough idea. At that time I began to research what is really involved and made the choice to try and install the locker by myself.

Tools

Before I took on this project I needed to purchase some very important tools. These tools are not cheap but they are necessary for an accurate installation which will ensure your gears and new locker have a long life. These tools include:

1. magnetic base dial indicator
2. 2 jaw bearing puller (just in case)
3. dial calipers
4. foot lbs torque wrench

Before starting the project you should have the above tools as well as these following items, which will make your life a lot easier and the install go a lot faster:

1. small brake cylinder hone
2. 2 high quality carrier bearings w/races
3. 2 'CR' carrier bearings
4. full set of shims
5. inner axle seals
6. 4 feet of 2" diameter pipe
7. rubber hammer
8. GM gear marking compound and brush
9. vise
10. ATV silicone gasket maker

Disassembly

After I pulled the axle shafts I marked the main bearing caps to ensure that I reinstalled them in the same direction and the same side as they came off. (Note: Some bearing caps are pre-marked - look for a 'K' or possibly another letter stamped into the cap and the diff housing. One side will have the 'K' sideways, the other normally oriented. These will match the ones stamped into the carrier.) With the caps set aside to ensure they wouldn't get damaged I started thinking of a way to pull the old carrier out. The carrier was a little tough to get out because of the carrier bearing preload. It took a while for me to pull it out but I eventually managed to. Since I did not have a case spreader I had to use a crow bar and a rubber hammer. I simply placed the crow bar under and behind the carrier and used the rubber hammer and tapped the end of the bar towards the ground.

Removing the carrier.

As soon as I moved the carrier out a little I removed the bar and inserted it behind the top of the carrier and tapped again. After I repeated this process a few times the carrier popped right out. When you are doing this make sure the bar does not come in contact with the ring gear teeth. Also make sure you have something soft (other than your foot) on which the carrier can land when it pops out of the diff housing. It is heavy with lots of sharp points.

After you pull the carrier you should replace the inner axle seals with new ones. If you have a factory service manual it will invariably tell you that you need the special seal widget #598-x52a or something like that. I used a three foot tube that was 2" in diameter. I slid one end down the axle tube through the knuckle then tapped it a few times when it came in contact with the seal. After the seals were both out I cleaned out the axle tubes the best I could with degreaser and a lot of shop towels. With the housing and tubes all cleaned up I tapped in the new seals very carefully making sure I didn't damage the rubber part. A seal installer kit can be bought just about anywhere for around CAD$30 and makes the job very easier.

Knocking out the inner seal with a pipe.

The cleaned differential housing, reading for new parts.

The cleaned differential housing, reading for new parts.

With the carrier in the vise I unbolted the ring gear. After all the bolts were removed I replaced two of them that were opposite from each other. I only threaded the bolts in a few turns just to make sure the ring gear didn't fall when I tapped it off with my rubber hammer. As soon as the ring gear came free I removed the two bolts and set the ring gear aside.

If you are not replacing the gears with a different ratio do not mess around with the pinion and leave it in. If you remove the pinion you are opening a whole new can of worms.

If your pinion seal is not really doing its job anymore you should replace it with a new one. I didn't bother replacing mine as I had replaced it last year when I rebuilt my axles with new gears. Some people say not to mess around with the pinion seal because it you will mess up the pinion preload. If you do need to change the seal mark the pinion nut to ensure you tighten it the to the same position you unbolted it. After the nut is of, slide off the yoke and change the seal. Note: diffs that use a pinion crush sleeve require the installation of a NEW crush sleeve.

Assembly

When installing your new Detroit locker there are three things that you have to be aware of: carrier bearing preload, backlash and gear mesh pattern. Carrier bearing preload is the amount of force that is pushing the carrier bearings against the bearing caps. The only real way to measure this is by the amount of effort it takes to place the carrier back in the housing. If the carrier just slips into the housing then you need to add shims, if you have to tap it in quite hard then there is too much preload and you must remove shims. The perfect amount of preload is when you can't push the carrier into the housing but need to tap it lightly with a mallet. Now it is time to start putting everything back together. The first thing I did was bolt the ring gear onto the Detroit. I simply threaded the bolts in and torqued them down to 50 ft. lbs in a criss-cross pattern. After the bolts were all torque down to 50 ft. lbs, I re-torqued them to 80 ft.lbs in the same criss-cross pattern. Now for the tricky part…the carrier bearings and shims.

This is where the extra bearings and brake cylinder hone come in handy. When pressing on and pulling off the expensive bearings/shims to check the pattern and backlash you run a high risk of damage, which can be a expensive mistake. I used two cheap 'CR' bearings to get the right shim combination so I didn't risk damage to the Timkin bearings. To make the install a lot easier I picked up a brake cylinder hone and put it in my drill press. I then bored out the center of the CR bearings so the bearings slip on and off the Detroit with ease. This way I could pick and chose the shims to get the perfect pattern without having to pull off the bearings with a jaw puller.

Preparing the "sacrificial bearing" which I'll use to check the pattern and backlash.

A good general rule is to start your shimming using the same size shims that were on the old carrier. This will give you a good starting point. I did not want to deal with pulling off the old carrier bearings to measure the shims that were used so I just eye-balled them and made a guess at there thickness by comparing the new shims to the ones on the carrier. I did this because if I made a mistake in the shim thickness it wouldn't be a big deal because I didn't have to press on and off the bearings to test fit them. Nice and easy, hey?

When checking for the pattern make sure you apply the marking compound to at least 5 or 6 of the ring gear teeth. Then check the pattern by running the pinion teeth over the ring gear teeth around 10 times. When running the gears together make sure you add enough pressure to the pinion and the ring gear so a good pattern indication will be present. For pictures of the correct and incorrect patterns check the Yukon Gear & Axle installation manual that is available online at www.ringandpinion.com.

It turns out that the first time I assembled the Detroit in the housing the preload was way too high. It was late at night and I wasn't thinking when I was tapping the carrier in. After about 5 minutes of tapping the Detroit was finally in. So I checked the pattern and it was not acceptable. I now needed to pull the Detroit out and play around with the shims, the only problem is the Detroit is in the housing so tight I couldn't pull it out. So this is what I did, I hung the housing by the Detroit to preload it while I tapped on the housing. This worked really well and the Detroit came right out.

This is what you have to look forward to if the preload is too high.

After you get the right shim combination, carefully tap on the new bearings with the shims in place. Then put some fresh gear oil on the bearings and on the inner axle seals. Now you are ready to put the Detroit in for good…you hope!!! With the new bearing races in place install the Detroit and bolt on the main bearing caps. Make sure you put the caps on the correct sides and use the proper orientation. The cap bolts should be torqued down to 80 ft. lbs. After the Detroit is in you should check the pattern one more time and then check the backlash with your dial indicator. My end pattern turned out to be slightly toe in on the coast side and the backlash ended up to be .006". these were both acceptable according to the Yukon manual.

The backlash is the free movement between the pinion and the ring gear. Simply dial in the ring gear and move the ring gear up and down while holding the pinion yoke still. The amount of acceptable play for a Dana 44 is .005 -.007" and other applications can be found in back of the Yukon Gear and Axle manual.

The gear pattern.

Measuring backlash.

The diff. cover with the magnet for collecting the shavings.

Now that you are ready to finally put the diff cover back on there is one thing you need to do. Detroit lockers tend to deposit small metal shavings in your gear oil, which is not the best mixture. To keep the metal shavings under control it is recommended that you glue a little magnet to the inside of the diff cover. This way all the free shavings will eventually get stuck to the magnet, which will keep you oil brownish, not silver in colour.

With the magnet glued in with some RTV, put a bead around the diff cover going both on the inside and outside of the bolt holes. After this all that needs to be done is bolt on the cover, torque down the bolts and fill it with oil.

Well you are done. Have fun with your new locker and remember to carry your extra axle shafts when you go wheeling!!!