105 Sector Shaft upgrade - Steering box rebuild (1 Viewer)

[Box Rocket]

I don't often do instructional threads but I'm gonna give it a try here. Hopefully this will make sense. I used a few other threads about rebuilding the steering box rebuild as a reference for doing this upgrade and those other threads helped a lot. The only real difference I'll have here is the addition of the 105 sector shaft.

The parts to do the upgrade can be sourced a few different places, but Cruiser Outfitters, and Wits End both stock the parts and have "kits" with the parts and seal kits. There might be others out there too, and of course dealer parts counters should be able to get you all the parts also.
I got mine from Cruiser Outfitters since they are local and I could pick it up at the shop.

The parts you will need for the 105 sector shaft upgrade are:
-105 Sector shaft
-105 pitman arm
-new pitman arm nut and split washer
-new sector shaft stake nut and adjustment screw
-steering box seal and o-ring kit
-ATF or power steering fluid
-moly grease

Tools needed:
-Flat Screwdriver
-17mm wrench
-14mm socket
-32mm socket
-10mm allen wrench
-snap ring plyers
-dead blow mallet
-Adjustment screw stake nut SST (I'll show you what I used later in the thread)

DISASSEMBLY
I was using a spare steering box that I had on the shelf, but if you don't have a spare box you'll need to remove your steering box from the truck. Obviously.

Step 1: Once you have the steering box out of the truck and on the bench you need to remove the pitman arm. The pitman arm nut is a 32mm nut so you'll need that size socket if you don't have one already. At a minimum you'll need a pitman arm puller. Depending on the condition of your box and arm you may need a press to get the pitman arm off.
Steering box FZJ80 by Adam Tolman, on Flickr

Step 2: Remove the sector shaft. To do this you need a flathead screwdriver and a 17mm wrench. Remove the adjustment screw lock nut using the screwdriver to make sure the adjustment screw doesn't spin.
Steering box FZJ80 by Adam Tolman, on Flickr

There's a seal washer under the nut. Your new seal kit hopefully includes a new seal washer. If it doesn't, you'll need to reuse this one if it's in decent shape so don't lose it. You'll reuse the nut.
Steering box FZJ80 by Adam Tolman, on Flickr

Next you need to remove the side cover. There are four 14mm bolts that hold the side cover on. Remove the 4 bolts.
Steering box FZJ80 by Adam Tolman, on Flickr

Once the bolts are removed, tighten the adjustment screw with the screwdriver and it will push the side cover out.
Steering box FZJ80 by Adam Tolman, on Flickr

Steering box FZJ80 by Adam Tolman, on Flickr

The side cover has an o-ring that will get replaced and there are needle bearings inside. Typically these don't need to be replaced but make sure yours are rolling smoothly and replace if needed. I didn't need to replace the bearing.
Steering box FZJ80 by Adam Tolman, on Flickr

With the side cover removed you can tap the sector shaft out of the box with a dead blow. It should come out with a few light taps.
Steering box FZJ80 by Adam Tolman, on Flickr

Steering box FZJ80 by Adam Tolman, on Flickr

Here's the stock 80 sector shaft next to the 105 shaft. There's a noticeable difference in size as well as spline count. Note: the splines on the 80 shaft look to have a slight twist starting. If the splines on your sector shaft have any amount of twist to them, the shaft should be replaced. Twisted splines are a warning that the shaft is close to failure. Unfortunately the only way to really check the splines for twisting is to remove the pitman arm. Sometimes you can see some twist in the splines without removing the pitman arm by holding a straight edge up to the box and check the splines against the straight edge. Also note in this photo: the steering box seal kit with part number.
Steering box FZJ80 by Adam Tolman, on Flickr

The twist in the splines is more visible in this photo. The twist will nearly always be right at the top edge of where the pitman arm sits on the splines.
Steering box by Adam Tolman, on Flickr

Time to move to the next step.

 

[Box Rocket]

Inside the box you'll see more needle bearings as well as the power piston teeth. As with the side cover needle bearing, check for smooth bearings and replace if needed. Again, mine were in good shape and didn't need to be replaced.
Steering box FZJ80 by Adam Tolman, on Flickr

There is a seal, a snap ring, a metal ring, a Teflon ring, and a rubber O-ring in the bottom of the box. Remove them all, but leave the bearing in place. Use a punch or seal puller (if you have one that will fit) to remove the seal and expose the snap ring. Remove the snap ring. The metal ring is next and should come out easily but if there is corrosion inside the box you may need to use a little emery cloth to remove the corrosion so you can get the ring out. Under the metal ring is the rubber o-ring and Teflon ring that should come out without issue. Note the order that these come out so you can put new ones back in in the right order when you reassemble.
Steering box FZJ80 by Adam Tolman, on Flickr

Steering box FZJ80 by Adam Tolman, on Flickr

Step 3: Remove the worm gear valve body

First you need to remove the power piston plunger guide nut. This is were you need the 10mm allen wrench.
Steering box FZJ80 by Adam Tolman, on Flickr

Now remove the 4 bolts that hold the valve body cover to the side of the box. Once the bolts are removed, turn the input shaft all the way to the left. It will bottom out and start to push the side cover out of the box.
Steering box FZJ80 by Adam Tolman, on Flickr

The valve body assembly will all come out with the side cover. The metal tube you can see holds a bunch of ball bearings. The ball bearings fit into the grooves on the worm gear shaft. This is what this style box is called a "recirculating ball" steering and the worm gear is what will move the power piston back and forth and the teeth on the piston is what turns the sector shaft and pitman arm.
Steering box FZJ80 by Adam Tolman, on Flickr

I did not get a photo of it but on the steering box under the valve body cover you just removed are two small o-rings. Replace those with new o-rings from your kit.

 

[Box Rocket]

Step 4: Disassemble the worm gear valve body assembly.

Separate the worm gear from the power piston by turning the input shaft. Be careful of the ball bearings inside that could come out. Don't lose any that come out.
Steering box FZJ80 by Adam Tolman, on Flickr

Now remove the two screws holding the ball bearing tube. #2 Phillips screws. Keep track of the metal strap that holds the tube. The tube is two pieces. Set those aside also. Put the ball bearings in some kind of container so you don't lose any.
Steering box FZJ80 by Adam Tolman, on Flickr

Steering box FZJ80 by Adam Tolman, on Flickr

Steering box FZJ80 by Adam Tolman, on Flickr

Next, make a mark on the valve body housing, the lock ring and preload nut so you can line them back up during reassembly.
Steering box FZJ80 by Adam Tolman, on Flickr

Remove the lock nut. I used a small punch and hammer to loosen the nut.
Steering box FZJ80 by Adam Tolman, on Flickr

Now remove the preload nut. I used a small punch in the holes on the nut to spin the nut.
Steering box FZJ80 by Adam Tolman, on Flickr

There's another needle bearing inside the preload nut.
Steering box FZJ80 by Adam Tolman, on Flickr

Under the needle bearing is a metal ring (bearing race) and you can see a Teflon ring inside the bore of the nut that you'll replace.
Steering box FZJ80 by Adam Tolman, on Flickr

Now you can remove the input shaft. It might need a couple taps with a mallet to get it out. The Teflon rings on the input shaft are not included in the seal kit so the ones on the shaft will be reused. Don't damage them.
Steering box FZJ80 by Adam Tolman, on Flickr

Inside the input shaft housing is a seal and bearing that need to come out. This seal is often the one that leaks.
Steering box FZJ80 by Adam Tolman, on Flickr

The bearing and seal removed
Steering box FZJ80 by Adam Tolman, on Flickr

Now you've got everything apart, clean everything up before moving onto the reassembly.

 

[Box Rocket]

REASSEMBLY

Everything will go back together pretty much in the reverse order you took it all apart.
Steering box FZJ80 by Adam Tolman, on Flickr

Reassemble the worm gear valve body assembly.

Put the input shaft bearing back in along with a new seal, making sure they seat properly in the housing. I used a 24mm socket to drive the seal into place.
Steering box FZJ80 by Adam Tolman, on Flickr

Apply some power steering fluid or ATF to the input shaft (particularly on the teflon rings) and put the input shaft back into place in the housing. The PS fluid/ATF should lube everything up so it slides in easily. Then put the needle bearing, the bearing race ring and preload nut back into place.
Steering box FZJ80 by Adam Tolman, on Flickr

Steering box FZJ80 by Adam Tolman, on Flickr

Tighten the preload nut so the marks you made line up. I couldn't get it to turn past the marks so it should stop very close to where you made the marks. Now re-install the lock nut and align the mark on the lock nut to the others.
Steering box FZJ80 by Adam Tolman, on Flickr

 

[Box Rocket]

Now you get to put all the ball bearings back in the power piston. Before you do that, replace the o-ring on the input shaft housing. You can see the o-ring on the housing in this image
Steering box FZJ80 by Adam Tolman, on Flickr

Now spin the worm gear back into the power piston. You can put most of the balls back into the two holes in the power piston. As the hole fills with the ball bearings, turn the worm gear back and forth and the balls will settle inside and make room for more. Be careful not the turn the worm gear too far and let the balls fall out.
Steering box FZJ80 by Adam Tolman, on Flickr

Steering box FZJ80 by Adam Tolman, on Flickr

When you have most of the balls back into the piston, take the two halves of the metal tube and apply a little moly grease to both sides. Then set the remaining balls in one half of the tube and place the other half of the tube on top. The grease will hold the balls in place.
Steering box FZJ80 by Adam Tolman, on Flickr

Put the metal tube back into place on the piston and place the metal strap and two philips screws back on to hold the tube in place on the piston.
Steering box FZJ80 by Adam Tolman, on Flickr

 

[Box Rocket]

The next step is to reinstall the worm gear valve body and power piston assembly back into the housing. On the end of the power piston is a rubber o-ring under the Teflon ring. Your seal kit should come with a new o-ring and teflon ring to replace the old ones. Put the new o-ring on in the groove and place the teflon ring on top of the rubber o-ring.
Steering box FZJ80 by Adam Tolman, on Flickr

Note: this photo is out of order. I actually replaced both of these rings before putting the ball bearings and tube back together.
Steering box FZJ80 by Adam Tolman, on Flickr

Once you have the new rings in place you can install the assembly back into the housing. But first use a generous amount of PS fluid or ATF on the piston and Teflon ring to help it go back together more easily. Be careful when putting the piston back into the housing so you don't damage the teflon ring. If you damage the Teflon it will have to be replaced. The piston will get to this point fairly easily. But notice the Teflon ring isn't past the last edge in the housing. You need to be most careful here. This took me a little time to get the Teflon past the edge in the housing without damage. The new rubber o-ring is thicker than the old one that came out since it hasn't been squished into the housing for a couple hundred thousand miles and this makes it more difficult for the teflon to move past the edge.
Steering box FZJ80 by Adam Tolman, on Flickr

I found that with some more PS fluid and slowly twisting the piston clockwise I could get the teflon ring past the edge without damage. Once you have the piston in all the way, reinstall the 4 bolts that hold the assembly to the housing.


Now reinstall the power piston plunger and guide. I forgot to take photo of the pieces of the plunger and guide. There are 4 pieces and an o-ring on the plunger. The piece that goes in first is a T shaped cylinder with the male end in first. Then the pin goes next into the female end of the cylinder you just put in. Next is a spring. Last is the plunger with the 10mm allen wrench hole. There is an o-ring on this plunger that should be replaced.
Steering box FZJ80 by Adam Tolman, on Flickr

Now it's time to install the sector shaft. If you're upgrading to the 105 shaft the new sector shaft probably didn't have the adjustment screw and nut in place. You can try to remove the old ones from the original shaft but I was not successful. The original nut is a stake nut and the stake flanges need to get pushed back so the nut can be removed. Even with a chisel I couldn't get the nut to spin after pushing the stake tabs back in.
Steering box by Adam Tolman, on Flickr

I got a new nut and adjustment screw. I suggest getting a new one of both of these when you purchase your parts in the beginning. It's probably not the best move to reuse the original stake nut anyway.
Steering box by Adam Tolman, on Flickr

This is where you'll need a SST to tighten the nut. I made my own SST by drilling out a 14mm nut so the adjustment screw could pass through, then welding the nut to an old socket. I little dremel work to shape the weld so the SST could have as much purchase on the nut needing to be tightened.
Steering box by Adam Tolman, on Flickr

Steering box by Adam Tolman, on Flickr

since the new nut did not have staking tabs, I used blue Loctite on the threads and installed the nut and adjustment screw into the new 105 shaft.
Steering box by Adam Tolman, on Flickr

Steering box by Adam Tolman, on Flickr

Before inserting the new sector shaft, reinstall the new o-ring, teflon ring, metal ring, snap ring and seal into the end of the housing. The photo is the old ones as they were removed during disassembly.
Steering box FZJ80 by Adam Tolman, on Flickr

The FSM says some moly grease should be applied the to teeth on the sector shaft before installing it. Center the teeth on the power piston, then insert the sector shaft lining up the teeth.
Steering box by Adam Tolman, on Flickr

 

[Box Rocket]

Since I have two steering boxes out of the truck being rebuilt I painted the side cover red on this one so I know which has the 105 sector shaft without having to count splines. I know a certain shop also paints the side cover red on their rebuilt boxes. This isn't meant to copy them, just helps me know which is which. I had some red paint or white paint and white didn't seem like the right choice. So red it is.

Put a new o-ring on the side cover and put it back into position with the adjustment screw. Use the adjustment screw to pull the side cover back into place. Note: turn the adjustment screw counter clockwise (lefty-loosy) to pull the cover into place.
Steering box by Adam Tolman, on Flickr

Now reinstall and tighten the 4 bolts that hold the side cover on.
Steering box by Adam Tolman, on Flickr

Now you need to set the preload. I don't have a dial indicator so I set the preload by feel. It's pretty easy to tell what is too tight on the adjustment screw. Start by tightening the adjustment screw all the way. You won't be able to turn the input shaft. Then slowly loosen the adjustment screw ( I did about a 1/4 turn at a time) and checked the tension on the input shaft by turning it lock to lock. I set it just where the input shaft would turn smoothly lock to lock without any hitches and no more loose than that. I ended up at about 5 in/lb. I think that's close to any spec I've seen published.

Using a 17mm wrench and a screw driver to hold the adjustment screw so it doesn't move, reinstall the new seal washer and reuse the lock nut on the adjustment screw.
Steering box by Adam Tolman, on Flickr

That's pretty much it.
Steering box by Adam Tolman, on Flickr

I sprayed a coat of fresh black paint on the housing and now it's ready to go back in the truck. This is the first steering box I've rebuilt so hopefully it all works out. The process was not that difficult. If I missed something or did something different than you have done it, I apologize. I tried to follow the FSM and other steering box rebuild threads that are here on MUD to compile the steps and photos. Hopefully this is helpful for someone that wants to tackle a rebuild/upgrade on their own.
Steering box by Adam Tolman, on Flickr

 

[Box Rocket]

Please feel free to add any info if anyone has details or tips to share.

 

[MrMikeyG]

I tried to embark on the 2019/2020 "budget" version of this. I sourced parts from all sorts of strange places, and then sent the box out anyway.
I got mine back from West Texas Off-road with some strange bracket still attached. (I still need to email them about this) The steering box arrived well packaged and seemingly in good order. My choice was one of trying to minimize downtime when I finally do a steering system refresh. I will rebuild the existing box myself though.
Nice job on this Adam. There are 1 or 2 other really nice steering box threads, but you've added a couple of images that help out a lot I think.

 

[Box Rocket]

I tried to embark on the 2019/2020 "budget" version of this. I sourced parts from all sorts of strange places, and then sent the box out anyway.
I got mine back from West Texas Off-road with some strange bracket still attached. (I still need to email them about this) The steering box arrived well packaged and seemingly in good order. My choice was one of trying to minimize downtime when I finally do a steering system refresh. I will rebuild the existing box myself though.
Nice job on this Adam. There are 1 or 2 other really nice steering box threads, but you've added a couple of images that help out a lot I think.

Thanks. I’m definitely no expert on this job but figured I could document what I did since I was doing it anyway. Hopefully if there are any holes or gaps in what I did, others will chime in and add to the thread.

My goal was minimizing downtime too which is why I did this on a spare box I’ve had. When it goes in the truck I’ll rebuild the other one probably with the original sector shaft if it’s not twisted and have it as a trail spare.

 

[NorCalFJ100]

This is absolutely awesome!! Great job detailing everything! Let us know how it works on the rig!!!

 

[-Spike-]

Great thread! Here's my contribution, most if not all of which was passed on to me by Kevin (Tools R Us), RIP.

Loss of preload on the input section roller bearings is the leading cause of slop in the box, which is why excessive slop can't be fixed without disassembling the box. The tiniest bit of play in that bearing is multiplied many times. It is adjusted via the preload nut mentioned above in the 3rd post, 5th pic. AFAIK Toyota never published the bearing preload spec for the 80 box, that section is non-rebuildable according to them. Kevin 'Tools R Us' (who I always called upon for arcane knowledge such as this) suggested using the 60 series spec, as the mechanism is very similar, IIRC it was ~3-6 inch/lbs. He used a beam-type inch/lb torque wrench (I bought this one on Amazon) to measure the preload, and while he made an SST by welding a socket to half of a spare steering shaft universal joint, I just put an appropriately-sized 1/4" drive socket in one end of the uni joint and clamped it in there with the existing bolt to interface the input shaft with the torque wrench. I bought this adjustable pin wrench for the adjusting nut, which IIRC I had to grind a small spot on to make it fit around the mechanism- although Kevin told me he just used a hammer and punch. (I bought him the pin wrench after that conversation, but I doubt he ever got around to using it.) With the assembly in a vise so the shaft can rotate freely, adjust the preload nut until you get 3-6 inch/lbs of moving resistance.

Also there's an o-ring sealing the outer end of the input shaft, you have to completely disassemble the shaft to get to it. 'Usually doesn't go bad, and it's a bitch to get to' is what Kevin said, and it's not sold as such by Toyota that I'm aware of so you have to source it by size, but of course mine took a s*** immediately after rebuilding the box, and now spews fluid all over the place. I've been waiting to fix it until I got motivated to swap for the 105 shaft, and this thread just might give me the impetus to get it done in the nearish future.

I don't know how to describe this so it makes sense without seeing it, but Kevin also suggested using the sector shaft to stretch the new teflon ring installed in the end of the housing, mentioned by pic 11 of post 6 above, by inserting the taper on the splined end into the teflon ring backwards (said ring having been installed in the housing). I don't know if this would work with the 105 shaft, so maybe don't toss the 80 sector shaft out.

Another thing Kevin taught me was to round the sharp edges in the bore where the power piston has to pass through the sector shaft cavity, as mentioned in post #6 above. He explained this as he was rooting through his parts bins for a spare teflon o-ring for me, because I had nicked mine. Those edges are freaking sharp, and there's no downside to rounding them off. I used a dremel-type rotary tool.

 

[OGBeno]

Great work Adam.

 

[Delta VS]

Very nice, thorough write up Adam! Seems like this should end up somewhere in the FAQ area??

 

[Shipwreck]

Thorough write-up Adam!
A couple things that I found useful when I rebuilt mine:
I bolted the box to a 4x4 block of wood so that I could clamp the whole thing in the bench vise when needed. Like you, I also used an oil pan to work on the benchtop. I was most worried about losing one of those recirculating balls.
During the final preload adjustment, I first set mine by "feel" as you did, but then broke out my in./lb torque wrench to check the total per the FSM. (I had to fabricate an adapter out of either a torx or 12-point socket to duplicate the input SST).
Although it felt right, I was considerably lower than spec. I reset it to the higher end of factory spec and was surprised at how tight it felt. I kept thinking, this cant be right because I could barely turn the sector shaft by hand. I rechecked several times, and then decided to trust the factory. Once I got the box in the truck the steering felt better than ever and has stayed firm since then.

 

[Box Rocket]

Thorough write-up Adam!
A couple things that I found useful when I rebuilt mine:
I bolted the box to a 4x4 block of wood so that I could clamp the whole thing in the bench vise when needed. Like you, I also used an oil pan to work on the benchtop. I was most worried about losing one of those recirculating balls.
During the final preload adjustment, I first set mine by "feel" as you did, but then broke out my in./lb torque wrench to check the total per the FSM. (I had to fabricate an adapter out of either a torx or 12-point socket to duplicate the input SST).
Although it felt right, I was considerably lower than spec. I reset it to the higher end of factory spec and was surprised at how tight it felt. I kept thinking, this cant be right because I could barely turn the sector shaft by hand. I rechecked several times, and then decided to trust the factory. Once I got the box in the truck the steering felt better than ever and has stayed firm since then.

View attachment 2389123

Thanks for this info! I’ll likely recheck the preload again before the box goes in the truck. It’s possible I need mine to be a little tighter as it’s just lower than the 6.5-9.5in/lb shown in your image.

 

[ItsBavid]

Fantastic job. Thanks for dedicating your time to do this. It's great getting updated "how to" threads in here.

 

[Bludozer]

Like others have said, great detail. I'm a moron and was able to follow along. Nice work!

 

[Grandlooser]

My contribution having done this in recent history:

If you do happen to idiotically loose one of the recirculating balls, fear not. It's (I think) 5.5mm which is very common to find in bearings. I lost one of mine in the process and had to source a new one. The very first old bearing I cut open had 5.5mm balls in it. And I'm an amateur machinist, so I didn't just wing it, it was SPOT on exact dia. Via micrometer. Just an FYI.

 

[Bambusiero]

Very nice documentary - thank you!