Steering gear box rebuild (4 Viewers)

Feb 25, 2007
This is the second time I’ve seen the inside of an 80 series gearbox. I bought a used box this summer and rebuilt it with the help of a good friend and Lexus mechanic. Then we swapped it onto the truck in place of the original box, which was leaking from the input seal. Unfortunately, I managed to blow the input seal a couple weeks ago after mucking around with the adjusting screw. The leak was catastrophic, to the point where I had to park the truck because the system would pump itself dry on the trip to or from work. I ordered up a steering gear box reseal kit from Kerry (gotmud) last week, picked it up today and put the box back together tonight (I disassembled it last night). I figured that a full write-up was in order so I took many photos along the way. I sandblasted the box first which cleaned up the outside very well. I repainted the box once it was back together. I also only replaced one Teflon seal (at the bottom of the gear box housing), as they were a huge pain during the first rebuild and they don't seem to wear or age at all.

So without any further ado, on to the fun stuff!

Part numbers:
Toyota gear box reseal kit: 04445-60050
Power piston plunger guide nut: 44154-30020
Input shaft seal part number (not from Toyota See post #28): 18-32-7-DL


Step 1: Removing the pitman arm.

This was a challenge on both rebuilds, but a 20-ton press managed to pop the arm off (as well as scaring everyone else in the building!) after removing the 32mm nut. I don’t have a press at home, but I was able to get some help for that again this time.



Step 2: Removing the sector shaft.

Start by removing the adjusting screw lock nut. A 17mm wrench and standard screwdriver are required here.

Note the seal washer:

Next, remove the side cover. Take out the four bolts holding the side cover on. I used a 14mm socket on an electric impact gun.

With the bolts removed, use the screwdriver to tighten (clockwise) the adjusting screw. This will push the side cover out of the box.


Nice needle bearing:

At this point, the sector shaft can be tapped out of the box with a soft-faced mallet

More needle bearings, and notice the power piston teeth in the foreground.

There is a seal, snap ring, metal ring, Teflon ring, and rubber O-ring in the bottom of the box. Remove them all, but leave the bearing in place. You may need to sand the corrosion off the box housing below the seal to allow you to get the metal ring out.

Step 3: Removing the worm gear valve body assembly.

Remove the power piston plunger guide nut. This should only require a 10mm Allen wrench, but in both cases I've seen it has required a cold chisel and some patience. I've listed the part number above as it is a cheap replacement.

Next, take out the four bolts holding the valve body head to the gearbox. I used the 14mm socket on my electric impact again.

Turn the input shaft all the way to the left. This will push the power piston to front of the gearbox. When it bottoms out on the front of the box it will start pushing the valve body out of the box. You can also use a screwdriver to coax it out.

This is the complete worm gear valve body assembly. Note the Teflon ring that can be replaced

This the metal tube that the ball bearings recirculate through (hence recirculating ball steering)

This worm gear moves the piston back and forth, which twists the sector shaft and pitman arm.

The inside of the gearbox. Don’t forget to replace the two little O-rings.

All the parts you have removed so far

Continued below...
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Feb 25, 2007
Step 4: Disassembling the worm gear valve body assembly.

Separate the power piston and the valve body head by spinning the input shaft. Make sure you don’t loose any ball bearings if they come out.

Remove the two #2 Phillips screws, the metal clamp, and the two-piece metal pipe.

Tip the piston over and pour out the ball bearings. Put them in a container so you don’t lose them!

Make match marks on the face of the valve body housing, lock ring, and preload nut.

Loosen the lock nut with a punch and unscrew it.

Loosen the preload nut with a punch and unscrew it.

I used the punch to start loosening it and then used the workbench as a brace to unscrew it the rest of the way.

While holding the punch and the worm gear shaft steady, turn the valve body housing to remove the preload nut.

More nifty needle bearings. There is also a replaceable Teflon ring on the inside bore of the preload nut.

With everything removed, you should be able to tap the input shaft out with a soft mallet. Note the bearing inside the housing. The typically leaky input shaft seal sits behind the bearing.

Use a punch to remove the seal and bearing

The input shaft has four Teflon rings that aren’t serviced in the reseal kit, so don’t wreck them. I was tempted to remove the snap ring and take apart the rest of the stuff just to see what was there, but I figured I was already in deep enough!

Everything sitting on the workbench

Step 5: Clean all the parts up well before reassembly.

Step 6: :beer:. If you’ve made it this far you’ve earned it!

Continued below…
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Feb 25, 2007

Step 7: Reassembling the worm gear valve body assembly

Press the input shaft oil seal and bearing back in. Make sure they seat properly at the bottom of the valve body housing. A large socket (~24mm), wooden dowel, or brass drift are all equally useful for this.


Put the input shaft back in the valve body housing. Use plenty of ATF to ensure everything slides in properly, and be careful of the Teflon ring if you replaced it. Then put the needle bearing and preload nut back in place.

Tighten the preload nut until the match marks line up. I tried increasing the preload but the really isn’t much room to play here and I ended up going back to “stock”

Install the lock nut and align it with the other match marks.

Now comes the tricky part, getting all the ball bearing back in the power piston. Put the worm gear shaft back inside the power piston. You should be able to get most of the ball bearings back inside the two holes by turning the input shaft back and forth. Make sure you keep the piston close to the valve head so the balls don’t fall off either end of the worm gear.

Once most of the balls are in the housing, grab the two halves of the metal tube and some sticky moly grease. Line the inside of the tube halves with grease and stick the balls inside the tube.

Put the other half of the tube on top of the first

Push the assembled tube back into the piston until you can get the metal clamp back in place. Install the two screws.

Step 8: Reinstalling the worm gear valve body assembly

Now that the worm gear valve body is back together, reinstall it into the gearbox housing. Use plenty of ATF to ensure nothing binds, and be especially careful of the Teflon ring. Make sure it isn’t caught on the edge inside the gearbox.

Install the four 14mm bolts and tighten them down to pull the valve body into the gearbox

Now reinstall the power piston plunger and guide. More ATF to lube the O-ring here too.

Step 9: Installing the sector shaft

Install the new O-ring, Teflon ring, metal ring, snap ring, and oil seal. Pay careful attention to the orientation of the oil seal.


Centre the power piston in the gearbox housing

The FSM recommends putting some moly grease on the teeth prior to installation. Install the sector shaft, making sure the teeth are centered on the power piston.

Put a new O-ring on the side cover and line it up on the adjusting screw.

Use the adjusting screw to pull the side cover down. Note the direction of the threads (lefty loosey in this case)

Install the four side cover bolts and tighten them.

Now the box is 99% back together, and you need to set the preload. It is possible to use a special SST socket on the input shaft to attach a dial torque wrench, but most of us don’t have access to either of those. I found that the difference between good and too tight was easy to differentiate while turning the input shaft back and forth from lock to lock. Adjust the screw 1/8th of a turn at a time until you get to too tight, then back it off a bit. Install the new seal washer and the adjusting screw lock nut. Be sure that the adjusting screw doesn’t move as you tighten the nut.

That’s it! :cheers:

A few power steering related links:



Fluid cooler
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Aug 17, 2004
Awesome! I am getting ready to do a rebuild + 105 shaft, and this may give me the ability to do it myself if I can find the time.

Great writeup :cheers:


not an addict
Jan 30, 2003
windy wyoming
excellent writeup. i just resealed my sector shaft about a month ago. was going to do the whole thing but getting that plug out was pretty much impossible on mine and i was sure the output was all that was leaking, so i stopped there.
Aug 25, 2009
Any idea on what the issue could be if the preload is different at opposite ends of the output shaft travel?
Aug 17, 2004
So let me ask a question: If your steering box has no leaks, and all you are doing is upgrading to a 105 series sector shaft, what is the value of the rebuild, which is essentially a gasket/seal kit if your box isn't leaking?

The sector shaft work seems very simple, and then adjusting the settings for steering play.

Obviously it's great to tear it all down and put it all back together, but if only the main seal is prone to leaking, and you replace that one by pulling the sector shaft, is there a reason to bother?

Feb 25, 2007
The input shaft seal (all the way at the back of the box) is the common leak point on these boxes from everything I've seen. Unfortunately replacing it involves this whole tear down.

If your box isn't leaking and doesn't make any sounds of distress when wheeling/driving I'd probably gamble with just the sector shaft replacement. On the other hand, if you've heated the fluid before and caused the painful groaning sounds you've probably toasted the rubber seals and o-rings to the point where they will eventually start leaking. The question is, when? Luckily, most leaks tend to be the slow seeping kind so you can plan when you're going to deal with them (unless you play with the adjuster screw too much like I did!)

Given that the Teflon seals haven't shown any signs of wear on either box I've opened and the metal ring and snap ring should be reusable, I'm going to see if some place like NAPA would be able to sell me only the rubber bits of the rebuild kit. I will eventually be re-rebuilding (yeah, for a second time :rolleyes:) the box I pulled off the truck, and since everything in it is fresh from the summer I'd like to only replace the input shaft seal if possible...
Aug 17, 2004
Makes sense - I bought a core from a fellow Mudder off a '97 (he had done the same to avoid rig downtime during the work), so I can easily send to West Texas Offroad.

They quoted me $100, so I'll be well under $200 for the total work. That is probably worth it to get a professional result. I may dig into my own once it is off my rig just to get familiar with the process should I ever need a trail repair.
Feb 25, 2007
Any idea on what the issue could be if the preload is different at opposite ends of the output shaft travel?

Have you torn into the box at all? Is the box still on the truck? (if so I'd suspect the steering stabilizer) How are you determining that there is a difference?

Off hand I can't really think of much that would affect one end and not the other. Maybe some odd wear on the sector shaft/power piston contact points, or on the power piston/gear box housing. I don't think there is much other than that which could cause those symptoms, but I'm just a guy with a (greasy!) camera. :D

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