Step-by-Step Replacing Rear Axle Seal & Bearing w/ABS (1st gen Tacoma or 3rd gen 4Runner)

I recently discovered a dreaded gear oil leak on my 4Runner, and knew it meant only one thing - it was time to change the rear axle seals (and bearings and brake shoes since they were now saturated with oil). In addition to the story of the 4Runner repair, and later the Tacoma repair, I figured a detailed set of instructions for anyone wanting to tackle this themselves would be nice to put together, since it's hard to find that written down in one concise place (maybe even impossible before now).

This is of course based on two amazing resources - first and foremost are some videos by Timmy, which are great. Second, is the Factory Service Manual (FSM) description, but varies slightly (to make things easier) and doesn't require flipping back and forth between many different sections.

So let's get started.

Determine Why the Rear Axle Seals Started Leaking

This isn't always possible, but if you can understand why the rear axle seals started leaking in the first place, it will make doing the job successfully easier. There are many reasons they could start to leak, but the three "most common" reasons I've seen are:

1. A bent rear axle, which wobbles in the seal, eventually loosening it and causing it to leak. If your rear axles are bent, do not do this job without replacing them; otherwise, you'll be doing it again shortly.
2. Recent service to the truck that required the rear axles to be removed from the axle housing for the first time in a long time (for example, to regear). In this situation, the seals have a very set "memory" and removal of the axles means they can never quite regain the correct position again.
3. Incorrect installation of replacement axle seals (essentially, doing the job outlined in this guide incorrectly). Usually, the part that's done incorrectly is driving in the new seal, resulting in a seal that doesn't work as designed.

Gathering the Parts...

As you can imagine with a job like this, there are quite a few parts and tools you need to complete it quickly and safely! I've tried to break down what's required vs. optional for you, though of course someone else's situation might mean suggest differently than I have. If in doubt, I'd purchase items in this list and return them, so you aren't stuck in the middle of the fix, waiting for a part or tool you don't have.

Required Parts

• (2) Dust Seals (90313-48001) - one for each side of the axle
  • '96-'00 4Runner or Tacoma - P/N: (90313-48001)
  • '01-'02 4Runners or '01-'04 Tacoma use P/N: (90313-54001)
• (2) Axle Bearings - one for each side. These should be replaced because the grease in them can be washed out by the gear oil seeping past the rear axle seal. While there may be some cases in which existing bearings can be repacked with grease, it is beyond the capability of the average wrench, and many pros to make this determination. The safe bet is to replace the bearing.
  • '96-'00 4Runner or Tacoma - P/N: 90363-40020-77
  • '01-'02 4Runners or '01-'04 Tacoma use P/N: 90363-40068
• (2) Inner seals for axle housing (90310-50006) - these are the actual axle seals
• (2) Axle Housing Tube O-rings (90301-88077) - one for each side of the axle
• DOT3 or DOT4 brake fluid
• 3qt 80W-90 Gear oil for rear diff
• Crush washers for rear diff

Optional Parts

• (2) Toyota OEM Rear Axle Shaft (42311-35400) Note: these are the rear axles for a '01-'02 4Runners and '01-'04 Tacomas. Rear axles for earlier model years have been discontinued, but these are interchangeable as long as you purchase the correct dust seals and axle bearings noted above for the '01-'02 4Runners and '01-'04 Tacomas.
• (2) Snap rings for retainers (90520-36045) - Optional, but strongly recommended. Toyota says to replace these when doing the job.
• (4) Rear Axle Bearing Retainers (42423-20010) - two for each axle, make seal with Inner seals. Optional, as you can likely reuse your existing retainers.
• (2) ABS tone rings (43517-35010) - Optional, as you can likely reuse your existing ABS tone rings/gears.

Brake Parts

• (1 kit) Brake shoes (04495-35230) - contains components for both L and R brake shoe replacement. Optional, but recommended if you're doing the job because you've had gear oil leak onto the brake shoes (vs. as preventative maintenance).

...and Tools

As far as tools go, there are several specialty service tools (SSTs) that you'll need to complete the job. While these tools are technically optional, and you may be able to fabricate some stand-in yourself, I cannot stress enough how much easier they made this job. If you're tackling this yourself, buy all of these tools - especially the Rear Wheel Axle Bearing Puller & Tone Ring Tool/Installer - it is frankly one of the most well-designed tools I've used for its purpose. They will double the cost of the job, but it's still less than half of having Toyota do it, and you have the tools for next time and other jobs!

Specialty Tools

• 20 ton press  (sometimes Harbor Freight is cheaper)
• Rear Wheel Axle Bearing Puller & Tone Ring Tool/Installer (ebay) - used with the shop press to both remove and install various components on the rear axle. Amazing tool, worth twice it's price, and you're supporting a fellow gear head in the process. Plus, this tool works across much of Toyota's truck lineup - 1st, 2nd, and 3rd gen 4Runners ('84-02), 1st gen Tacomas ('96-04), older Hilux, T100 ('92-97), and 1st gen Tundras ('00-06). It's also available with a late model adapter (ebay), adding 2nd & 3rd gen Tacomas ('05-present), 4th & 5th gen 4Runners ('03-present), 2nd gen Tundras ('07-present), all FJ Cruisers, and all Sequoia's. And there's an eBay Store with more variants, sweet.
• 3” ABS cleanout, with cap - to seat the new rear axle bearing.
• OTC 4507 Seal Driver Kit - to seat the new rear axle seal.
• OTC 4579 Slide Hammer/Seal Puller Kit - optional, to pull the old rear axle seal; I recommend purchasing this puller - I didn't the first time I did the job, and the seal is a PITA to remove without it.

OTC Seal driver and the *amazing* Rear Wheel Axle Bearing Puller & Tone Ring Tool/Installer.

OTC 4579 Seal Puller Kit - this slide hammer makes pulling the old seals easy and prevents any damage to your axle housings. It feels expensive, but is worth it (and versitile for other projects).

Standard Tools and Supplies

Of course, in addition to SSTs, you'll need a reasonably well-equipped shop to tackle this job. Here's the additional list of tools that I used to complete the job, as well as having additional tools at my disposal in case I needed them.

• Floor jack.
• (2) 6 ton jack stands.
• Misc sockets (I recommend this set from Williams, a Snap-On brand)
  • 10mm socket - to remove the ABS sensor from the axle housing.
  • 14mm deep socket - to remove nuts holding brake drum to axle housing.
  • 24mm socket - to remove diff fill/drain plugs.
  • Ratchet, Extensions, and breaker bar as necessary.
  • 5/8" deep socket - to use in the press when pressing on various components.
• 14mm box end wrench (set) - to remove nuts holding brake drum to axle housing.
• 10mm flare nut wrench (set) - to remove brake line fittings from rear drum.
• Snap ring pliers - to remove/install the snap-ring for the outer retainer.
• 3mm, 4mm, 5mm Allen wrench (set) - to measure placement of the inner retainer on re-installation.
• Assortment of vacuum caps - to prevent brake fluid from leaking out of rear lines once disconnected.
• Brake cleaner - to clean the brake components, as well as axle, throughout the process.
• Grease - for installing new parts.

Doing the Job

With all the parts and tools gathered, it's time to get to work. Perhaps obviously, the job is mostly a bunch of removal of parts, and then a bunch of installation of those same parts - or rather, installation of replacement parts. This list of steps is just that - a list of steps (which makes it a great resource to print off and reference when you're doing the job). If you're curious about what a step looks like, I suggest reading the story of my shop day, or watching this video to see how something is done.

As of Sep 2021, I've added photos to this guide, as it just seems useful.

Prep the Vehicle

1. Jack up rear end with floor jack.
2. Place a 6 ton jack stand under each side of the rear axle, ensuring that the wheels and tires are in the air.
3. Chalk the front tires so the vehicle doesn’t move.
4. Ensure that the emergency brake is OFF.
5. Remove the rear wheels.

Disconnect Parking Brake and Brake Line

1. Remove the small compression clip that attaches the e-brake cable to the rear brake drum
2. Remove the small pin and wobble washer that holds the e-brake cable to the rear brake drum.
3. Pull the e-brake cable away from rear brake drum.
4. Using at 10mm flare nut wrench, loosen the rear brake line where it enters the rear brake drum. Note: be sure to use a flare nut wrench to get a better grip on the compression fitting.
5. Prep a vacuum cap to place on rear brake line once it is removed, and place a rag under the brake line to catch any brake fluid.
6. Remove the rear brake line and place a vacuum cap over the end so that brake fluid does not leak out (as quickly).

Remove the ABS Sensor

1. Using a 10mm socket and any necessary extensions, remove the bolt holding the ABS sensor.
2. Pull out the ABS sensor, which is held in place with a small o-ring. This will provide resistance as you pull it out.
3. Place a plastic bag around the ABS sensor to keep it clean while you work.

Removing the Brake Drum

1. Remove brake drum. Note: this may require some tapping with a mallet, or loosening the automatic adjuster if the drum is too tight / rusted to the axle housing. If neither of those methods work, use two, M8-1.25x50mm bolts threaded through the drum to press it off.
2. Use brake cleaner and catch container to clean off the rear brake drums.

Drain the Rear Differential

1. Using a 24mm socket, loosen the fill plug at the top of the rear diff, to ensure that you will be able to refill the diff once it is drained.
2. Using a 24mm socket, remove the drain plug at the bottom of the rear diff.
3. Remove the fill plug at the top of the rear diff, to drain the oil more quickly.

Remove the Axle from Housing

1. Use a 14mm socket (and/or box end wrench) and breaker bar to loosen the four (4) 14mm nuts that hold the brake drum to the axle housing.
2. Once all four nuts are loose, remove them completely.
3. With all four nuts removed, pull brake drum and axle out of axle housing.

Press Axle Out of Inner Retainer and ABS Tone Ring

1. Place the axle, drum side down, on a surface where you can pound out one of the four studs that secure the brake drum to the axle housing. Note: if you have an old brake rotor, it can be used as a good platform on which the brake drum can stand/balance.

   

2. Screw one of the 14mm nuts that was removed earlier onto the stud opposite the bell crank until it is even with the end of the stud. Note: you can pound out any stud, but this is the one that is the easiest to access on both sides of the brake drum.

   

3. Pound out the stud opposite the bell crank. Note: as you do this, the bearing may also pop slightly out; this is OK.
4. Remove the nut, then pull the stud out the other side of the brake drum.
5. Move the red ABS tone ring capture plate from the Axle Bearing Puller into place by sliding it under the ABS tone ring, via the space made by removing the stud.
6. Slide the main cylinder of the Axle Bearing Puller over the axle shaft, so the square side aligns with the red capture plate.
7. Secure the studs from the red ABS tone ring capture plate through the Axle Bearing Puller using two washers and a nut on each corner.

   

8. Secure the axle assembly in the press with the brake drum down, and the other end of the Axle Bearing Puller captured by the press plates. Note: If using the Harbor Freight press, place the cross-member at the 4^th position down from the top.
9. Ensure that the press is aligned with the end of the rear axle before driving the axle down.
10. Place a crash pad under the press so that as the brake and axle assembly fall to the ground, they hit some padding, rather than a hard surface.

    

11. Begin pressing the axle down. Note: you should hear a crack/snap/pop or two as various components ‘release.’ This is normal.
12. Continue pressing until brake and axle assembly falls out the bottom of the press. Note: the ABS tone ring and inner retainer will be captured by the red ABS tone ring capture plate.
13. Remove the axle from the press, as well as the Axle Bearing Puller tool.
14. Remove the 4 nuts securing the Axle Bearing Puller tool to the red ABS tone ring capture plate. Remove the captured ABS tone ring and inner retainer. Set aside. Note: this retainer will become your outer retainer on re-assembly.

Press Axle Out of Outer Retainer

1. Place brake drum and axle assembly on workbench, drum side down.
2. Insert stud removed earlier from the bottom of the brake drum to begin re-installation.
3. Place several washers (four or more) over the stud to act as spacers. Note: the washers should be tall enough to cover any unthreaded portion of the stud.
4. Using one of the 14mm nuts and a 14mm deep socket, tighten down on the stud until it has completely pulled back through to its original position.

   

5. Once the stud has pulled fully into place, remove the nut and washers.
6. Using a pair of snap-ring pliers, remove the snap ring that holds the outer retainer to the bearing. Note: it is OK to mar the axle shaft during this process, but do not mar the surface of the outer retainer.

   

7. Place the Axle Bearing Puller tool over the axle shaft and align the holes with the four studs. Note: if the bearing is not fully seated at this point, there may not be enough threads to capture the studs. In this case, turn the axle upside down and drop it on a piece of 2x4 (or other “soft” surface) to reseat the bearing.
8. Using two flat washers and a 14mm nut per stud, secure the tool to the backing plate.

   

9. Secure the axle assembly in the press with the brake drum down, and the other end of the Axle Bearing Puller captured by the press plates. Note: If using the Harbor Freight press, place the cross-member at the 4^th position down from the top, like before.

   

10. Ensure that the press is aligned with the end of the rear axle before driving the axle down.
11. Place a crash pad under the press so that as the brake and axle assembly fall to the ground, they hit some padding, rather than a hard surface.
12. Ensure that you have removed the snap ring from the axle so the retainer and bearing can travel up the axle shaft.
13. Begin pressing the axle down. Note: you should hear a crack/snap/pop or two as various components ‘release.’ This is normal.
14. Continue pressing until brake and axle assembly falls out the bottom of the press.

    

15. Remove the axle from the press.
16. Remove the Axle Bearing Puller tool (and brake drum) from the press.
17. Using a 14mm socket, remove the four nuts securing the Axle Bearing Puller tool to the brake drum. Remove the captured outer retainer. Set aside. Note: this will become your inner retainer on re-assembly.

Remove Axle Bearing from Brake Drum

1. Set brake drum on workbench with axle bearing on bottom. Note: hang the bell crank over the side of the workbench so it does not cause the drum to be wobbly when set down.
2. Remove the dust seal using a set of pliers by simply pulling it up towards you.
3. Place the press sleeve that comes with the Axle Bearing Puller, with the long side of the cylinder down, on the inner race of the bearing.

   

4. Place a steel plate on top of the press sleeve to evenly distribute the force around the edge of the sleeve.
5. Hit the center of the steel plate with a hammer to push the bearing out the back of the brake drum. Note: this will take almost no pressure - do not hammer hard.
6. Clean out the inner bore of the bearing case.

Install New Axle Bearing and Dust Seal in Brake Drum

A common statement is "the leaking gear oil has washed the grease out of the bearing and it's no good". Well maybe, maybe not. This comes down to a judgement call that in most cases is way beyond the capability of the average wrench, even pros. A bearing that feels rough is one thing, some degree of wear is another. A bearing that someone insists is still good should at least be repacked with fresh grease. The safe bet is just replace it.

1. Smear a bit of grease inside the clean bore where the bearing will sit.
2. Smear a bit of grease on the outer race of the new bearing.
3. At the press, prepare to press the bearing into the brake drum with the bore up under the press. Note: if using the Harbor Freight press, place the lower bar at the 3^rd hole, then stack a press plate, the press sleeve that comes with the Axle Bearing Puller, and the 4”x4” steel plate under the bottom of the brake drum.

   

4. Set the bearing on top of the bore and ensure that it is as flat/even as possible.
5. Place the 3” ABS cleanout, with cap on the outer race of the bearing, and ensure the cap is centered under the press.
6. Slowly (using only finger pressure) apply pressure to the ABS cleanout to fully seat/press the bearing into the bore. Note: the bearing should go in relatively easily; you may not even need the press. Watch the ABS cleanout to ensure that no pressure is building up, and to ensure that the bearing is going in straight.

   

7. Remove the brake drum from the press and set it on the workbench, bearing side down.
8. Smear a bit of grease inside the bore where the dust seal will sit.
9. Insert the dust seal (by hand, no tools needed).
10. Smear a bit of grease on the inside of the dust seal, since it will ride on the axle once installed.

Re-installing Outer Retainer Ring and Snap Ring.

1. Clean the axle well with brake cleaner.
2. Place the axle on the workbench, studs down. Note: utilize an old brake rotor to hold it more easily.
3. Smear some grease on the axle, on the widest (polished) part of the axle.
4. Smear some grease on the inner race of the bearing.
5. Gently slide the brake drum over the axle, bearing side up. Note: be careful not to displace the bearing in this process, as it’s not pressed into the brake drum.
6. Smear some grease on the inner bore of the outer retainer. Note: recall that the retainers will SWAP positions on reinstall. The original inner retainer will become the outer retainer.
7. Slide the outer retainer over the axle with the bevel facing up (away from the bearing).
8. Place the press sleeve that comes with the Axle Bearing Puller, with the long side of the cylinder down, on the outer retainer ring.

   

9. Place the Axle Bearing Puller in the press, square end down, capturing the rectangular end between the lower crossmember.
10. Insert the axle assembly into the Axle Bearing Puller from the top, so that the press sleeve rests on the Axle Bearing Puller tool.
11. If necessary, raise the lower crossmember so that the assembly is fully supported and can be pressed down. Note: if using the Harbor Freight press, the crossmember will be at the third hole from the top.
12. Insert the press plates between the lower crossmember and the rectangular foot of the Axle Bearing Puller tool, to better support it (vs. simply using the crossmember for support).
13. Place and center a 5/8" deep socket on top of the axle - between the wheel studs - to press on.
14. Ensure that everything is vertically aligned, then press the axle into the outer retainer. Note: this should go smoothly until the retainer is fully seated.

    

15. Using snap ring pliers, install a new snap-ring into the groove that has been exposed once the outer retainer is fully installed. Note: It's seldom mentioned but most retaining rings are "directional". Retaining rings tend to have a slightly radiused or eased edge where the die punch/shear enters the sheet metal and a sharper more square edge where the die/shear cuts thru the sheet. The sharp edge should face the part the retainer is retaining.

    

    Correct installation of retaining / snap rings.

Re-installing the ABS Tone Ring and Inner Retainer

1. Place the axle on the workbench, studs down. Note: utilize an old brake rotor to hold it more easily.
2. Smear some grease on the axle, on the widest (polished) part of the axle.
3. Smear some grease on the inner bore of both the ABS tone ring and inner retainer.
4. Slide the ABS tone ring over the axle, with the “solid” side up (towards the rear diff).
5. Slide the inner retainer over the axle, with the bevel down toward the ABS tone ring. Note: this is the opposite orientation compared to OEM/removal. However, it is better given a redesign that has taken place to the axle seal since 2003.

   Background Context

   

   On the left, the new (2003+) seal design vs. old (pre-2003) axle seal lip design on the right.

   With the seal redesign, flipping the inboard retainer is probably not necessary, but it does no harm and could cover for a degree of seal deformation.

   

6. Place the press sleeve that comes with the Axle Bearing Puller, with the long side of the cylinder down, on the inner retainer ring. Note: the small notch on the press sleeve will allow you to see how far the ABS tone ring and inner retainer need to be pressed.
7. Place the Axle Bearing Puller in the press, square end down, capturing the rectangular end between the lower crossmember.
8. Insert the axle assembly into the Axle Bearing Puller from the top, so that the press sleeve rests on the Axle Bearing Puller tool.
9. If necessary, raise the lower crossmember so that the assembly is fully supported and can be pressed down. Note: if using the Harbor Freight press, the crossmember will be at the third hole from the top.
10. Insert the press plates between the lower crossmember and the rectangular foot of the Axle Bearing Puller tool, to better support it (vs. simply using the crossmember for support).
11. Place and center a 5/8" deep socket on top of the axle - between the wheel studs - to press on.
12. Ensure that the small notch on the press sleeve is facing the press operator.

    

13. Ensure that everything is vertically aligned, then begin pressing the inner retainer onto the axle.
14. As the inner retainer is being pressed onto the axle, measure the amount of polished axle showing under the inner retainer, until 3mm of polished axle is showing. Note: use a 3mm allen wrench for this measurement.
15. Remove the axle assembly from the press and verify the 3mm measurement.

Remove Old Axle Seal

1. Remove the old axle seal from the axle housing by pulling it out using a seal puller.

Install New Axle Seal

Though there are only a few steps here, this is the most important part of this entire job, and the most common place that mistakes are made because it's easy to deform the seal during installation.

 

1. Spread a good amount of grease into the inside (oil side) of the seal to retain the seal tensioning spring during installation.
2. Using the OTC 4507 Seal Driver Kit, select a press plate that matches the outer diameter of the new axle seal. Note: the outer diameter of the seal is 274 thousandths of an inch, and you want to select a seal driver that is between 272-273 thousandths of an inch. Larger than that and it will not fit in the axle tube; smaller and it risks deforming the seal.
3. Oil the outer surface of the seal and insert it as squarely as possible with your fingers.
4. Lightly tap the seal using the seal driver until it fully seats. Ensure that you are pounding it in straight. Note: freeze the seal for 30 minutes prior to installation to shrink it slightly and make installation easier.

Ensure That the Axle Seal and Inner Retainer Align Correctly

1. Use a sharpie to make lines on the inner retainer.
2. Insert the axle assembly into the axle housing and tighten four, 14mm nuts to the four studs.
3. Spin the axle in the axle housing several times in order to ensure that the axle seal is contacting/rubbing the inner retainer (and rubbing off the sharpie marks).
4. Remove the four, 14mm nuts and remove the axle assembly from the axle housing.
5. Ensure that the axle seal is approximately in the center of the inner retainer, as indicated by the sharpie mark being removed in that position on the retainer.

   

6. If the inner retainer is not aligned correctly, use the Axle Bearing and Tone Ring Puller or Bearing Driver to pull/push the inner retainer and tone ring into the correct position - so that when fit into the axle seal, the center of the sharpie line is worn away.

Reinstalling the Axle into the Housing

1. Remove the large rubber o-ring on the outside of the axle housing

   

2. Install a new large rubber o-ring on the outside of the axle housing
3. Using a 14mm deep socket and 14mm box wrench, reinstall the four, 14mm nuts on the end of the studs that hold the backing plate to the axle housing. Torque to 48 ft-lbs.

   

4. Reinstall the ABS sensor, and 10mm bolt that holds it in place. Cinch it up snug; no torque spec.
5. Reconnect the brake line using a 10mm flare nut wrench. Cinch it up snug; no torque spec.
6. Reconnect the e-brake cable using the original clip.

Finishing Up

1. Reinstall the brake drum; use a mallet if needed.
2. Reinstall the rear diff drain plug with a new crush washer.
3. Refill the diff with 80W-90 gear oil.
4. Reinstall the rear diff fill plug with a new crush washer.
5. Bleed the brakes, since lines were disconnected. Note: Bleed in the following sequence: passenger rear, driver rear, passenger front, driver front.
6. Reinstall the wheels (torque lug nuts to 89 ft-lbs) and lower the truck.