Lock-Right Installation for Toyota 8" Carriers

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Author: Luke Miller Editor: Scott Wilson April 2000

Installing a locking differential is one of the most important modifications you can make to improve your vehicle's off-highway ability. The Lock-Right locker by POWERTRAX is an automatic locker designed to replace the existing spider and side gears in your standard open differential. The Lock-Right can be installed in your Toyota differential without the need for delicate setting of the gear mesh pattern, making it a viable task for the home mechanic. This article will detail the installation of a Lock-Right in a Toyota 4-cylinder differential. 4-cylinder refers to the type of engine that came in the truck, either 4-cylinder or V-6. The V-6 differential design differs slightly from the 4-cylinder design, but may actually be easier to install. The 4-cylinder model is POWERTRAX PN1610, for the Toyota 8.0 inch axle, with 30 splines and 2 pinions. V-6 diffs have 4 pinions, but still measure 8 inches with 30 splines.

The aim of this article is to supplement the instructions provided with your locker. The instructions provided by POWERTRAX are good, but are somewhat generic to cover a range of vehicles with the removable 3rd member axles. We will attempt to provide you with the more specific info needed for your Toyota 4-cylinder differential.

You will need the standard assortment of metric sockets, a ratchet and maybe a larger breaker bar to remove the bolts that are torqued down tightly, a hammer, brass punches, a long thin punch (3/16" or 1/8" diam.), torque wrench, center punch, and some way to hold the 3rd member. In addition you may need a flare wrench to remove the brake lines, and other tools you find useful along the way.

To begin the installation, you'll need to remove the third member from the vehicle. On the rear axle, this will require the following:
1. Secure the vehicle by blocking the front wheels.
2. Remove the rear wheels.
3. Drain the diff fluid. Just in case, first be sure that you can remove the fluid fill plug on the back of the housing (24mm).
4. Disconnect the emergency brake cable at each brake backing plate.
5. Disconnect the hard brake line at each brake backing plate. You will have to bleed the brakes when you are finished. Alternatively, you may be able to get the hard lines to bend enough to allow you to pull the axle shafts out far enough. It may be worth trying.
6. Remove the 4 nuts on the axle flange around the brake backing plate. At this point, you should be able to slide the brake/axle shaft assembly outwards a few inches. The idea is to pull the shafts out of the differential side gears to allow the 3rd member to be removed.
7. Remove the 10 bolts around the face of the 3rd member. At this point, you should be able to pull the third member out of the axle housing, provided you have pulled the axle shafts out far enough. Be careful, the 3rd member is extremely heavy and awkward.

For solid front axles, removal of the third member is slightly more involved and messy. Essentially you must strip the hubs and rotors off to allow you access to the spindle, which must also be removed. Then you can grab the outer axle shaft, rotate the birfield so that the machined flats are on the top and bottom and you can slide the whole inner and outer shaft assembly out a few inches to allow removal of the 3rd member.


Place the 3rd member in a position where it is stable so you can work on it. You may want to secure the lip of the housing in a vise, or set the housing in a coffee can.

1. The first step is to get familiar with the diff. The ring gear is set up with a small amount of "backlash", such that the ring gear can be rocked back and forth a few thousandths of an inch before the teeth make contact with the next pinion tooth. Play with this for a bit and get a feel for how much backlash is present. You will have to recreate this when you are finished. However, this is the only delicate bit of gear setup you should have to do for this installation.

The ring gear side carrier bearing cap and adjuster

2. You now need to mark the carrier bearing caps and the adjuster rings. The carrier bearing caps are specific to their current orientation, i.e. left to right and top to bottom. You cannot mix and match these, they must go back in the same orientation they came out. Using a center punch, mark each cap. I would recommend starting on the ring-gear-side cap, and mark the top part with one punch on both the cap and carrier section below it. Then switch to the other carrier cap opposite the ring gear, and mark it and the section below it with a different number of marks. With these marks, you should be able to take off and replace each cap in its proper orientation by matching up the marks.

The side opposite the ring gear

3. Also mark the adjuster ring on each side, again with a specific mark for each side. Mark them just below the adjuster lock. This mark will allow you to return the adjuster to its proper position to properly preload the carrier bearings and get the backlash back to its stock setting. The adjuster rings are now specific side to side, so mark them so you won't mix them up. In the above pictures the adjuster rings have been marked.

A view of the carrier bearing race with the bearing cap and adjuster ring removed

4. At this point you have marked everything such that you should be able to replace these parts at the end of the install and return the settings to stock specs. Remove the adjuster locks, and the carrier bearing caps. To be doubly cautious, I would recommend keeping the parts from each side of the diff separate. Tap the adjuster ring on the ring gear side upwards to remove it. Then remove the bearing race and mark it as being from the ring gear side. The race must go back on the side it came from.

The ring gear side carrier bearing race (aka "the cup")

5. Remove the adjuster ring from the opposite side and mark the bearing race accordingly.

6. The carrier is now floating free, and you can remove it from the housing. Set it in a position to allow you to work on it, being careful not to damage the now-exposed bearings. This may be a good time to clean the gasket off the mating surface of the 3rd member, being careful to get all the scraps out of the housing.

The pinion shaft will not come out without removing the ring gear

7. On the 4-cylinder Toyota carrier, the ring gear does interfere with the removal of the pinion shaft. Looking at the pinion shaft, it is quite obvious that you could not slide it out of the case with the ring gear in place. This means you'll have to remove the ring gear from the carrier. Mark the position of the ring gear relative to the carrier so you can get it to go back on in the exact same position it is in now (so the same hole in the ring gear lines up with the same hole in the carrier).

The locking tabs need to be bent back and the ring gear bolts removed

8. Using a hammer and punch, bend back the locking tabs on each of the ring gear bolts. Unless you bought new locking tabs, be careful with these, as they will be reused, and you can break off the tabs with too much overzealous bending. Then remove the ring gear bolts. Since I'm overly cautious, I removed the bolts in a star pattern, removing bolts on the opposite sides of the ring gear in succession.

The ring gear has started to separate from the carrier, using the brass punch to pound around the edge of the ring gear

9. Now the first of many disconcerting parts of the process. You will need to pound off the ring gear, as it is a slight press fit on the carrier. Definitely use a brass punch to avoid marring the ring gear (brass is softer than steel and will deform before marking the steel). It will take some real pounding to get the ring gear to budge, but be persistent and alternate around the edge of the gear to remove it evenly.

This is one end of the hole containing the retaining shaft pin Here the retaining pin has been driven far enough one way to allow the pinion shaft to slide free.

10. The next step was the worst for my particular installation. You must remove the pinion shaft retaining pin. This is a long pin that runs through the carrier housing and the pinion shaft. It will require a long, thin punch to fit down into the hole where the pin resides. This pin took a lot of force to move, as it is a very tight fit. In my case, I managed to get the pin to move an inch in one direction, but no further. At this point, I pounded the pin back to where it had come from and took a 7/32" drill to remove the ridge of steel that had built up in front of the pin.

After doing this (removing as little steel as possible) I pounded the retaining pin back and made a bit more progress. After repeating this process with the drill a few more times, I was finally able to get the retaining pin out far enough to let the pinion shaft slide free. This was a very time consuming bit of work, and required lots of hard pounding in my case. I hope yours goes better.

A side gear and thrust washer (arrow)

11. Now you can slide the pinion shaft out of the carrier, and remove the two side gears and two spider gears. The only parts here you will reuse are the thrust washers behind the two side gears, one per side.

12. The parts you just removed should be inspected. The pinion shaft should be in good condition, not galled or grooved. The two thrust washers should be in good condition as well. If these parts are not acceptable, you'll need to get new ones at the dealer. I deemed mine "good enough" and decided to reuse them. Keep your fingers crossed that the case and carrier bearings are in good condition, as replacing any of these with require the ring and pinion to be setup from scratch. As a note, there is no thrust block used in the Toyota 4-cylinder diff, so ignore the locker's instruction book in reference to this part.

Click HERE to follow the reassembly..

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