Installing ARB's Toyota 8" Air Locker

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Author: Scott Wilson April 2000

Here we will install an ARB Locker into a Toyota 8" V6 housing. In this installation we do not use true V6 gears, but rather the 4 cylinder gears with a special spacer on the pinion gear. We are using all new gears, locker, and bearings in this installation.

Empty V6 Housing Prep the Mounting Surface

Prep-work involves removing the stock gears, carrier, and bearing races. The old gasket material also needs to be cleaned off the mating surface.

Drill the hole for the air line Tap the hole for the fitting

Many shops will wait to drill & tap the hole for the ARB air line until the differential is in place. This technician prefers to drill the hole while the old differential is in place, or the housing is empty. This eliminates the chance of leaving metal shavings in the good unit.

Notice the spacer & shims Press or Hammer the bearing on

Reassembly begins with pressing the new pinion bearing race into the housing. Once the shims are put in place on the pinion gear, the pinion bearing can be pressed in place. Here we used a spacer that gets installed with the shims on the pinion gear. You can see it clearly in the picture on the left. The spacer allows the 4 cylinder gears to fit into the V6 3rd member housing. The 4 cylinder gears are less expensive, and have similar strength to the V6 gears. Some will argue that the 4 cyliner gears are weaker in this housing, but without repeatable testing it is hard to say for sure.

Pinion gear in place

Often the correct amount of shim the pinion needs is guess work, and involves a lot of trial and error. Because you may have to remove the pinion and reshim it, do not install the pinion with the crush sleeve at this time. Our experienced technician took an experienced guess and got the amount of shim correct on the first try.

Bolt on the ring gear Press on the carrier bearings Put the carrier in place in the housing

The new ring gear can now be bolted to the ARB housing and the bearings pressed onto the ends of the ARB. With the bearings in place, the unit can be put into the 3rd member housing. The bearing adjusting nuts are put in place, and backlash adjusted within factory specifications. Notice the special bearing adjusting nut that is used with the 'business end' of the ARB. The stock bearing adjusting nut can still be used on the opposite side.

Check the contact pattern

A marking compound is now brushed on the ring gear, and the compound is run past the pinion gear. This is how the pattern is checked. The marking compound will show you where the ring gear and pinion are making contact with each other. Often you will see that they are contacting to high or too low on the gear. To fix this, the pinion must be removed and reshimmed.

If you're attempting to setup gears for the first time it is likely you will press the bearing on and off many times as you try to find the correct amount of shim. Setting up ring and pinion is not something the 'average Joe' should attempt. The tools needed (example: shop press) are not found in the average man's tool collection. For a long lasting set of gears a knowledge of what a good pattern looks like is also important.

Pinion seal in place

When you are happy with the pattern the crush sleeve can be put in place on the pinion and the nut tightened down. Once the preload has been determined (crush sleeve) the output seal can be put into place.

Notice o-rings

This picture shows the two o-rings on the ARB that keep the air where it belongs. If your aging ARB is spitting gear oil from the air lines, it is likely these o-rings which have worn away and need replacing.

Adjust backlash

With the pinion done, the unit is put back into place and assembled for the last time. Backlash is set with the bearing adjusting nuts, and then the keepers are put into place to ensure the backlash will not change.

Put air fitting in place Route air line

The special fitting that carries air to the ARB can now be put into place. The hard line must now be bent to the desired shape to get it to the hole drilled into the housing earlier. Take special care not to damage the line while prying it, and to route it so that it doesn't touch any moving components. The supplied fitting can now be screwed into the hole we threaded in to the housing earlier, be sure to use a sealant on the threads of the fitting to prevent gear oil leaks. Now the compression fitting can be put onto the hard air line and tightened down.

Be very particular about air line placement

Upon assembling the 3rd member into our axle housing we learned the air line was in exactly the wrong position for us. The air line was in the same place our filler plug wanted to be. The thought of inserting the plug anyway crossed my mind, but if I did that I would not know if I had caused the air line to come in contact with a moving part, which would result in a failure later. Removing the axles from the housing and removing the 3rd member in my garage sounded much more appealing than doing it on the trail, so I removed the 3rd member and reshaped the air line to avoid the filler plug. You can save yourself a headache by checking this before you finish assembling your axle.

Install air line

With the hard line in place and tightened down, the compression fitting can now be placed onto the soft line and tightened down.


THE FINISHED PRODUCT - At this point Martin used the air in the shop to test for leaks in any of the air lines. He put pressure into the line and we could hear the ARB activate. We also heard no leaks, so the install is complete and the 3rd member is ready to be placed into the axle housing.

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