Introduction.
There are several reasons you may want or need to rebuild and set up a differential:  1)  Replace bad bearings.  2)  Replace the ring and pinion gears.  3) replace the stock carrier with a locker or spool.  Rebuilding a differential is not too difficult with the proper tools, but it is the kind of thing that you tend to incorrectly the first time.  It is also not the type of thing you want to try when you are impatient or in a hurry.

The basic process is divided into 6 steps:
1) Disassembly and inspection.
2) Installation of new bearings and gears.
3) Setting the pinion preload.
4) Setting the ring gear backlash and preload.
5)  Setting the pinion depth (or resetting it if necessary).
6)  Final assembly

Tools:
You will need basic hand tools like wrenches, a hammer, mallet and drift punches.  You need foot pound and inch pound torque wrenches and a vernier caliper or micrometer for measuring shim thickness.  In addition, you will need a gear puller or a bearing separator or bearing press, a dial indicator with a magnetic base, a tool for holding the pinion flange and a tool for turning the carrier bearing side adjuster nuts.  The pinion holding tool is made from a 2 ft piece of 2x2 angle stock.  Drill two holes to match the holes on the pinion flange.  Then grind away a semi circular piece between the two holes to make room for the socket to remove and tighten the pinion nut.  The side adjuster nut tool is made from a 1 x 3/16 piece of steel bar.  Drill two 3/16 holes in the bar spaced to fit the holes on the side nuts.  Install two 3/16 inch x 1 inch bolts in the holes.  A refrigerator close by stocked with adult beverages is recommended for maintaining the proper attitude.

Reference:
Refer to the Toyota Chassis and Body manual for proceedure details and part numbers.

1) Disassembly and inspection.
1.1  Unstake the pinion flange retaining nut by grinding off the staked portion of the nut with a cut off wheel, angle grinder or Dremel tool.  You don't have to grind off the staked part, but it makes it easier to get the nut off.
1.2 Remove the pinion nut.  Use the pinion flange holding tool to prevent the pinion from turning.
1.3 Remove the seal, outer pinion bearing and preload adjusting washer and shims.  Keep the shims together.
1.4 Match mark the carrier bearing caps using a center punch and remove the caps.

1.5 Lift the carrier out.  If you are reusing the bearings, tag the races so that they can be reinstalled on the same bearing. Warning:  The edges of the gear teeth are sharp and can give you a nasty cut, so be careful and don't handle the teeth without gloves.
1.5 Remove the spider gear center shaft retaining bolt and then remove center shaft, spider gears and side gears from the carrier.  Use zip ties to keep the thrust washers with their associated gears.
1.6 Remove the pinion gear.
1.7 Remove the pinion bearing races from the housing using a large drift and a 5 pound hammer.

Be sure to retrieve the pinion depth shim from behind the inner pinion bearing race.

 

1.8 Remove the ring gear retaining bolts and tap the rind gear off of the carrier with a soft mallet.
1.9 Remove the inner pinion bearing from the pinion gear.  There are several ways to do this.  One is to use a bearing press and a bearing separator plate. With a press, it is possible to remove the bearing without ruining it.   Another is to use a gear or bearing puller.  You can also drive it off the pinion shaft with a drift and large hammer.  Both puller and hammer methods tend to destroy the bearing.

1.10 Remove the carrier bearings using a bearing puller.  These can be pulled without damaging them.  You need something to press against with the puller.  You can use a section of steel bar stock with a inserted through the center of the bearing for the puller screw to push against.

1.11  Clean all the parts in solvent and inspect all of the bearings and bearing surfaces for wear, pitting and galling.  Replace any worn or defective parts.

2) Installation of new bearings and gears.

2.1  Heat the ring gear to about 200 degrees F.  Rapidly press the ring gear onto the carrier and align the holes.  If necessary tap the ring gear on with a soft mallet.  Install the ring gear bolts (note that the beveled end of the bolt head faces to the outside of the ring) and nuts and torque the nuts to 76-86 ft lbs.  Increase the torque in 3 successive steps and tighten opposite bolts across the ring gear in a pattern.

2.2  Install the inner pinion bearing on the pinion gear.  This can be accomplished with a bearing press, a vice or with a hammer and drift.  You need to use a short piece of pipe that is approximately the same diameter as the inner bearing race to avoid crushing the bearing roller cage.    You can also use the old inner bearing race as a spacer to seat the new bearing.  If you forget and bend the roller cage, you can straighten out the little bars separating the individual rollers with a hammer and punch.  (Yes, I learned this the hard way).  Just make sure that the bearing is completely seated.  You can feel and hear a change in hammer noise when you drive it all the way on to its seat.

2.3  Install the carrier bearings.  You can use a bearing press or a drift and hammer.  Again, be sure that the bearing is seated.

2.4  Install the pinion bearing races into the differential housing.  For the inner pinion bearing, be sure to place the pinion depth shim into the housing before the race.  If you are just rebuilding the differential or even replacing the carrier with a locker and reusing the same gears, there is a good chance that the original pinion depth shim will be correct.  Even if you are replacing the ring and pinion gears, you might as well start with the original pinion depth shim and hope that you get lucky.  Drive the races into their seats with a drift punch and hammer.  I use the old race to drive them the last little bit of the way in.  Make sure that the races are completely seated.
 

3) Setting the pinion preload.

3.0  Considerations when installing new ring and pinion gears.  There is more than 1 way to set up the ring and pinion gears.  If you have new R&P gears, chances are that you will need to set the pinion depth.  There are 5 different pinion depth shims that vary from approximately .010 to .018.  One way is to set the pinion depth first.  You can do a preliminary check of the tooth contact pattern first by hand tightening the pinion bearings to provide some preload, temporarily installing the carrier as in section 4 and then setting the backlash.  Then you can check the tooth contact pattern as described in section 5 and change the pinion depth if necessary before setting the pinion preload.  This  might save you some time by avoiding re-setting the pinion preload every time you reset the pinion depth.  This is important if you do not have the entire set of preload shims and only want to set the preload once.  The second way is to set the preload first.  If you have the full set of preload shims, a micrometer and know the correct pinion preload shim size, you can just change the preload washer size according the the change in pinion depth.  The Toyota manual sets the pinion preload first and assumes that you have a full set of shims, so that is the way I will describe it here.

3.1  The pinion preload is set by selecting the right combination of preload washer and preload adjusting shims.  There are 9 different sized washers from .108 inch to .118 inch and you can use up to 4 shims that are 0.010 inch thick.  The easiest way is to buy all 9 of the different sized washers, find the one that works and return the unused washers.  Another way would be to use a thick washer (.118) or a couple of washers across the range of thickness and sand them to the necessary size.  Start with the original shim and washer pack as long as they are in good shape and show no evidence of wear.  Lubricate the bearings with gear lube and assemble the pinion gear in the housing and slide the shim pack over the threaded end of the pinion.  The beveled side of the preload washer faces the gear end.  Add the outer pinion bearing, oil slinger and then the pinion flange, washer and nut.  (Do not install the pinion seal until the the last final assembly steps.)  Snug the nut and test rotate the flange.  If the flange turns with resistance, the shim pack needs to be thicker.  Add another 0.010 shim (up to a total of 4) and try again.  If the flange spins freely with no noticeable resistance, torque the nut down to about 60 ft lbs and rotate the flange again.  If no resistance is felt, it is time to start trying progressively thinner preload washers.  After each successively smaller washer, torque the nut to 60 ft lbs and rotate the flange.  Stop when the flange no longer turns freely and you can just begin to feel some resistance to turning.

3.2  Once you find this point, then torque the nut to 145 - 173 ft lbs and measure the preload with an inch pound torque wrench.

The preload limit for new bearings is 16.5 - 22.6 inch lbs.  For used bearings, the preload limits are 7.8 to 11.3 inch lbs.  If the preload is too low, the preload washer needs to be slightly thinner.  If the measured preload is too high, use the next size thicker washer.  You can sand the washers to adjust the thickness.  Use silicon carbide paper on a flat surface with solvent as a cutting fluid.  Make about 50 strokes turning the washer every 10 strokes and measure the shim with a micrometer.  If you don't have a micrometer, just stop and try the fit more often by trial and error.

3.3  After you remove about .0005 inch reinstall the washer, torque the nut and measure the preload again.  A change in thickness of .001 results in a change of about 10 inch pounds of preload, so go slowly and carefully (unless you have the whole set of washers).  When the preload is within the correct range you are done.  If you don't have an inch pound torque wrench, you can improvise using a 0-20 lb fish scale.  Measure the distance from the center of the pinion shaft to one of the holes on the flange.  Then attach the scale to one of the holes and measure how many pounds it takes to rotate the pinion.  Multiply the measured pounds times the radial distance in inches to determine the torque in inch pounds.

4) Setting the ring gear backlash and preload.

4.1  In order to set the ring gear backlash and carrier preload, it really helps to have the housing solidly mounted to a stand or to your bench.  It just doesn't do to have it rolling around on the table.  I mounted the housing to an engine stand using some brackets, but you could also bolt it to the bench top with a couple of pieces of angle iron screwed to the top.  Drill a couple of holes in the angle stock and suspended the housing over the edge of the bench and bolt it to the angle stock using the housing flange holes.

4.2  Lubricate the carrier bearings with gear lube and install the outer races and carefully lower the carrier assembly into the housing.  It can only fit one way.  Push inward on the outer races to seat them against the bearing rollers.

4.3 Install the adjusting nuts into the housing.  It is really easy to install these incorrectly so be careful.  The best way to tell if they are correct is to turn them.  If they turn easily, they they are threaded correctly.

4.4  Install the bearing caps.  Match the marks to be sure that the caps are on the right places and gently press the caps down on the bearing and adjuster nut.  Check that the threads of the adjuster are properly engaged in the cap.  You should be able to press the cap all the way down to completely seat it and still be able to turn the adjuster easily.  Install the cap bolts hand tight.  If the bolts won't go in, you are off by a thread or two, so remove the cap and try again.  Do not tighten the bolts until you can press the cap all the way seated by hand and still turn the adjuster nut easily.  It will be difficult to set the backlash and preload if the adjuster nuts have been cross threaded.  Once you are sure that the caps are seated, tighten the bolts just enough to slightly compress the split washer.  As long as you can still turn the adjuster nuts easily (with less that 15 ft lbs of torque) you are fine.  If it is too tight back the bolts off.

4.5 Find the zero preload position.  First make sure that you have plenty of backlash (.010 - .025) because you don't want to be tightening the side adjusters if the gears are in contact.  Tighten the pinion side adjusting nut until it is snug and then tighten the ring gear side adjuster until it is snug.  Turn the ring gear:  It should be noticeably tight.  Then back off the pinion adjuster just until the point where the nut turns more freely.  Next back off the ring gear side adjuster 4 holes or "clicks".  Install the dial indicator to indicate off of the outer bearing race on the ring gear side as shown in the picture below.

Now start slowly tightening the adjuster on the other side (pinion side) while watching the dial indicator.  Stop turning when the dial indicator just begins to move (.001-.002 inch).  Remove the dial indicator and tighten the ring gear adjuster 4 clicks.  This is the "zero preload" position.  Set up the dial indicator to measure the backlash at the heel (outside edge) of the ring gear teeth.  Tighten the pinion side adjuster 2 more clicks and check to see if this increases the backlash.  If it does go back to step 4.5 and find the zero preload position again.  If it does not change the backlask, loosen it 2 clicks back to the original starting point and go on and set the backlash.  It would be a good idea to mark the top hole on each side adjuster nut with a punch mark or spot of paint so you won't forget the zero preload positions.

4.6 Set the backlash.  Tighten the ring gear adjuster and loosen the pinion side adjuster an equal amount of clicks (holes) to move the ring gear toward the pinion and decrease the backlash.

Keep tightening the ring gear adjuster and loosening the pinion side adjuster until the backlash is .0059 - .0079 inch.

4.7 Add preload.  Tighten the pinion side adjuster 1 - 1.5 clicks and measure the overall preload at the pinion using the inch pound torque wrench.  The overall preload should be 3.5 - 5.2 inch pounds higher than the pinion bearing preload by itself.  If it is too high, back off the adjuster half a click.  Double check the ring gear backlash again.

4.8  Tighten the bearing cap bolts to 66 - 79 ft lbs.  Recheck the backlash and preload.
 

5)  Setting the pinion depth (or resetting it if necessary).

You thought your would almost be done now, but now comes the moment of truth.  It is time to check the tooth contact and if it isn't right, you get to change the pinion depth and go back and set up steps 3-4 again.    Mark 3-4 ring gear teeth on the "drive side" with red lead gear marking compound.  This marking compound is available at gear vendors.  Art stores also sell red lead oil paint and it looks and smells a lot like the gear marking compound.   The oil paint doesn't work quite as well gear marking compound, but it will do in a pinch.  Then hold the pinion flange so that there is some resistance to the pinion turning and then rotate the marked ring gear teeth across the pinion in the drive direction.  Only rotate the gear one turn, then read the tooth contact pattern.

I was hoping for a slightly more centered coverage but the pattern shown in the picture isn't too bad.  Ideally it would be centered left to right and top to bottom.  To move the pattern out to the "heel" of the tooth and down to the "flank", I would need a thinner position shim under the inner pinion bearing race to move the pinion farther from the ring gear.  Since this one is going to be my trail spare, I didn't fool with it.  I have had good results as long as the contact patch includes the center of the tooth and does not extend all the way to the toe or heel of the tooth.  If the contact is all the way to the toe (inside edge) then select a thinner position shim to move the pinion away from the center.  If the contact is all the way to the heel, select a thicker shim to move the tooth contact closer to the center.  If the contact pattern is way off, consider selecting a shim two sizes larger or smaller.  That way if you do over shoot the size, you only have to go one step back one step to get it right.

If you change the position shim, you have to readjust the pinion preload.  The position shims vary by .002 inch while the preload shims vary by .001.  If you increase the thickness of the depth shim, you have to decrease the thickness of the preload shim by the same amount.  This is easy to do if you have the entire range of shims available.  If you don't, it would be best to set the tooth contact first and then set the pinion preload.

6)  Final assembly

6.1  All that is left is buttoning it up with the final details.  Install the locking tabs that prevent the side adjuster nuts from turning.

6.2  If you are running the stock open differential, install the side gears, spider gears, their thrust washers and the center shaft.  Install the center shaft retaining pin screw.  I torque this to 25 ft lbs, but the manual doesn't specify a torque value.

6.3  Remove the pinion flange, install the pinion seal. then reinstall the flange.  I put a dab of RTV on the back side of the washer to prevent gear lube from seeping past the pinion splines.  Torque the pinion nut to 145 - 173 ft. lbs.

6.4 Stake the nut to prevent it from loosening.  I use a chisel to cut the lip of the nut on both sides of the notch in the pinion and then I use a flat punch to displace the lip into the notch.

That's it.  Good luck and happy cruising.

Please report any problems or errors to:

cglabe@uci.edu