H150F rebuild and enhancement - and everything else along the way (dropping the gearbox, doing the clutch, etc) (2 Viewers)

[DivByZero]

For the last year my clutch has needed doing, but it finally hit critical a few weeks ago and I couldn't delay any longer. I started this job yesterday, thought I'd post here while it's still on the go and update as it advances. I'm pretty time poor, but I'm making my life harder here, because I'm not just going to replace the clutch. I've decided I want to fully refurbish my H150F gearbox, new synchros, bearings, sleeves, etc... plus a few upgrades. I started doing some research a year ago, and gathering parts. I did a big write-up on various findings in this thread:
H151F Rebuild - https://forum.ih8mud.com/threads/h151f-rebuild.1202461/page-2#post-14929700

I've been studying the differences between all the H15x gearbox variants and how they've changed over the years, up to the current 70 series models, the details of which are mostly in the thread above. I got a bit carried away with deals on facebook marketplace, and at this point I have basically every variation in my garage in one state or another. My goal here with this gearbox rebuild is to build up the best possible box for the humble 1HZ engine that's possible. For me, this means the gear ratios of the H150, with some of the triple synchro changes on the 1992/08 to 1996/08 H151, plus the 2nd gear metal bearing upgrade, without the cost-cutting changes they made in 1996/09 to go to single-piece cast parts rather than forged, with the reduced depth synchros that came with it (which are less effective), or the cost-cutting changes that followed to the shifting system. Sure you could stick a 70 series gearbox in, preferably one from a few years back without the different gear ratios of the H152, but you've still got all those cost-cutting changes, plus the lack of a triple synchro on 1st gear, which was only ever provided on the H151. This would represent the best possible H150 gearbox that could be made using original Toyota parts.

That's all great, but rebuilding the gearbox is actually only one part of this job. Before I can do that, it needs to come off the car. In this thread, I'm going to walk through the entire process, beginning to end. Here's my 80:

HZJ80R - Early 1996 model. In my opinion, the best version of the 80 series ever built. Time to make it a bit better. First though, gotta drop that box. I don't have a hoist, and I'm not pulling the engine, so how to get the gearbox and transfer off in the driveway? I found surprisingly little info about this out there, but I had plenty of time to think about it. I'll outline my method, which I haven't seen described elsewhere, but I find it makes the job pretty simple. We're going to start inside the messy cabin.

First step - pull the front seats. I tried to get away with just pulling the drivers, but it'll make your life much easier to just do both, especially if you've got a front bench seat like mine here.

Next step, remove the lower plastic panel that goes directly behind the gearstick, and remove the two steel brackets that connect its supports from the body to the dash. Then go ahead a pull the front carpet out. You'll probably have to pull the two plastic guards that run along the bottom edge of the door jam too. It should end up looking something like this:

Well, hopefully your floorpans look a lot better. That's a job for another day.

At this point unscrew the gear knobs by turning them to the left, and take out the five screws connecting the rubber gearstick surrounds to the floor (including the sneaky one hiding under the bend in the transfer shifter). You should now be looking at something like this:

Now it's time to get the shifters themselves out. You'll have to pull up those second rubber boots to get at the assembly below. Mine were torn, I'd suggest you make sure you've got replacements for these ready to go. There are four bolts that hold the shifter for the transfer case linkage in. You can pull up the rubber boot to get your impact on these:

The bolts for this shifter have a funny spacer below them. Make sure you get the spacers out as well as and the bolts.

For the main gearstick, it's pretty simple. There's a steel retainer at the top there which you can see in the above image. You press down on it with your fingers and rotate it anti-clockwise. It'll pop out with about 1/8 of a turn. After that, gently rotate the gearstick anti-clockwise too, and it'll pop out of the shift mechanism.

You've now exposed a hole directly into your gearbox. You should cover that up so you don't get dirt and muck in there through the rest of the process. Get some wipes or cloths or the like and shove them down into the hole to keep it plugged.

Now let's finish off that transfer lever. This shaft doesn't go into the box like the main gearstick, it's connected to a lever on the transfer case via a linkage. With the bolts undone, you should be able to maneuver the mechanism to a position like shown below, then get two spanners to remove the bolt on the linkage:

With that bolt undone, you'll be able to remove the shifting assembly. Put the nut back on the end so you don't lose it. We're not quite done here though, have a peek into the hole and remove the gasket for the transfer linkage, and four funny corner supports that go with it:

We're now done inside the car. Time to head underneath. You'll want your impact here, you'll be using it quite a bit. If you don't have one, get one. A good impact/rattle gun makes all the difference. First thing is the prop shafts. They both have to go off. You should probably mark the flanges on both ends so you can put them back with the same orientation. I didn't bother, since I was going to give them a going over and just check the manual afterwards for the correct phase, but if you want to make life easier you can just mark them. If you don't know what prop shaft phase is, definitely mark them. The prop shafts are pretty straightforward, eight bolts each, four on each end. Well, technically four nuts on one end, four nuts and bolts on the other, but whatever. Get in there and remove them. Don't hit yourself in the head or separate the two halves of the shaft at the sliding yoke.

It's a good time to hit those zerks with the grease gun while you've got the prop shafts off.

Next step, the front sway bar. Remove it from the two rear brackets then the two front brackets. Again, don't hit yourself in the head.

This is halfway done. Get it all the way off and out of your way. We need to make some space down there for when we drop the box.

 

[DivByZero]

Now we remove this bash plate from under the transfer case:

You'll notice how grubby this area is here. I've got a slow oil leak at the front extension housing for the transfer case. Been that way for ages. I'll be fixing that up when the transfer is off the car. Theoretically it could be done with it still fitted, but it's pretty filthy under there and I didn't want to risk getting dirt into my transfer case.

At this point I started disconnecting sensors from the gearbox and transfer case, but it turns out I didn't have to. A little bit later I discovered they all come back to one connector you can get to just above the starter motor. Disconnect this plug and you can leave everything else exactly how it is when you drop the box:

It's now time to remove the clutch slave cylinder. Just two bolts, easy peasy. Tuck it up on the frame rail out of the way. Don't let it dangle on the hose.

Now let's unbolt the starter motor. One bolt and one nut from memory. I do this from the top of the engine bay, but you could probably reach around underneath too. Keep the starter connected to its wiring and move it out of the way. Disconnecting the battery is probably worthwhile too.

 

[DivByZero]

Now it's time to actually drop the gearbox and transfer case. If you had a shop and/or a hoist you'd probably do this differently, but I'm going to show you how I did this at home, in a safe and controlled manner, without any expensive gear and without damaging anything (especially myself!). I went to the local hardware store and picked up a 2.4m span of 40x90mm structural timber. You guys in the US of A will have to work out how many washing machines that is. I then got a bit of chain and a big ass d-shackle from my recovery gear, and my trusty ??ton block and tackle which is twice as old as I am, and I did this:

Yep. In my opinion this is actually the best way to do this. The gearbox has hooks on the side for a reason. When you pull an engine you lift the engine up on them. When you drop a gearbox/transfer assembly, you lower it down. The hooks are at a pretty good point of balance by design, so the gearbox can just kind of float there weightless. The block and tackle gives you a continuous chain where you can make absolutely precise adjustments to height. No idea what the gearing is on this thing, but I'd guess (and this could be way off) that I pull through 1m of chain to adjust about 1cm of height, with absolutely no effort. Now when I've pulled engines in the past I've used an engine crane, but actually hung this block and tackle off it to give me better control. You could try and do something like that here, but the engine crane legs going under the car would get in the way. I just wound down the drivers and passenger side windows, pulled the steering wheel (it's one screw and one nut), and suspended this span of wood on each closed door. Gives me a gantry with no legs. Perfect.

Getting to the point where we're ready to drop the box takes a few steps. We are going to hook up that block and tackle now though, for safety. We're about to start removing key bolts and structural supports. We need to support that weight so it doesn't drop on us. Start by taking a length of chain and getting it around both the support hooks on the side of the gearbox.

This was easy to do from inside the cabin putting my hands down into the tunnel. All we do is put the hooks through the links in the chain, keeping the length very short. You don't want much slack in this at all, just enough to get the hook of the block and tackle under. If the chain hits the sides of the shifter cutout when you pull on it, it's way too long.

We're now going to install the block and tackle. First wrap a chain around the middle of the piece of wood. Keep it short, and secure it together using a bolt. Remove the steering wheel. Fold the mirrors back. Wind both front windows all the way down. Rest the wooden beam across both doors. Access the cabin from a rear door (the front seats are gone so this is easy) and hang the block and tackle, hooking it to the chain on the wood and the chain on the gearbox. Raise the hook until it just takes the weight. It should look something like this:

At this point, we're going to do something random. Remove the bolts for the fan shroud on the radiator and pop it up a little bit:

This is actually in the FSM. You see, we're going to lower the gearbox a bit soon when it's still attached to the engine. If you don't do this, the fan can foul on the shroud and break.

Now it's time to go to town on the bolts that attach the bellhousing to the engine. Here's a pic of a removed bellhousing so you can see the bolt pattern:

The ones there at the bottom are easy. The ones at the edges can be a bit tight but definitely doable. The ones at the top centre there are completely impossible without lowering the engine/gearbox/trans assembly at the rear. For now, we're going to tackle the easy ones and come back to those top two. Take your impact and zip off all the bolts you can get to. 17mm from memory. There are also these two bolts holding in the exhaust mounting bracket you need to get:

With those out of the way it's just the remaining bolts and the transmission crossmember keeping the gearbox/trans in. Note though that I've only cracked the bolts. In fact, I ended up putting the bottom two back in hand-tight. We don't want to put all the weight on the remaining bolts or over-stress them, especially as we lower the gearbox to get to the top two bolts. Keeping all the bolts at least part of the way in means bolts shouldn't get overstressed and shear.

Now, some of these bolts can be tricky to get to, but it helps to have wobble extensions, and a few creative ways of working. I find it's best to work out the right extension length, then see if you can reach up and fit the extension itself onto the nut, without your impact or breaker on the other end. Once you've got the nut on the extension, you can reach up and fit your impact/breaker to the extension and crack the nut. Here was me doing a tricky one above the exhaust bracket before I lowered the box. In retrospect it would have been better to just wait until the box was lowered but I was under a delusion at this point that I might be able to get away without doing that.

At this point it should just be the top two bolts and the transmission crossmember. So let's remove that crossmember.

A bunch of bolts to remove the crossmember, then a few more to remove the rear engine mount from the transfer case. I like to thread bolts back in so I don't get confused what was what later, which I've done here.

 

[DivByZero]

The gearbox is now entirely supported by our block and tackle, and the remaining bolts holding it to the engine. We're now ready to lower the back of the gearbox down, so we can get to those top bolts. As you're lowering the gearbox, this is the spot you need to keep an eye on:

See there how the top back of the engine is starting to kiss the firewall? With the fan shroud loosened like we did above, that's your first point of contact. You're looking here at the point when the back of the gearbox was lowered as much as it could be. This is where you'll look to know when you've reached the limit. Lower it as much as you can to make your life easier getting to those bolts.

Now, because I don't like to trust a single point of failure, I had some short bits of pine as a backup under the engine:

I didn't end up resting the engine on these really, they were just there "in case" I needed something else to take the weight of everything and stop the descent. They're suspended between the radius arms. I adjusted their position as I lowered the gearbox with it anchored to the engine, just as a backup. Totally unnecessary really, but I'm paranoid like that.

Now it's time to pull that chain and lower the back of the gearbox. Afterwards, it'll sit a bit like this:

Which now gives you heaps of room to get an impact up there and get those last two bolts:

At this point I dropped the continuous chain for the block and tackle down into the tunnel, so I could control the descent of the gearbox and transfer case from below the vehicle. With all the bolts removed, I gave the gearbox a good solid pull backwards, and it separated from the engine:

Now it was a matter of lowering it... but onto what? I'd placed down some sheets of marine plywood across the ground in my driveway, since it's not continuous concrete, just two strips where the wheels go. On top of that I put a garage creeper I scored from @mudgudgeon before he went stateside. It's low profile, which is handy for this.

Now the easy bit, just pull the chain to gradually lower it down:

Great you say, but how are you going to get it out from under the car? Once again, recovery gear:

Hi-lift jack to test the flex on the front passenger side, and it just wheels right out.

 

[DivByZero]

Now since my clutch was knackered, I left the gearbox there for a minute and pulled the clutch and flywheel. Pretty easy with the impact, but the flywheel bolts are going to be the hardest. I had to fetch a new battery because my impact didn't have enough juice left to spin them off at first. You don't want to be using hand tools for that one, since the crankshaft will just rotate. The impact is the way to go.

The clutch was rooted and the flywheel wasn't happy. It'll be off to be machined during the week.

This was a good opportunity to solve a mystery too. I'd posted in the past about how there are two different flywheels for the HZJ80, and it wasn't clear what the difference between them is:
Two different flywheels for HZJ80? - https://forum.ih8mud.com/threads/two-different-flywheels-for-hzj80.1306450/
While 1HZ engines around the world got the 13405-17010, and apparently the 1HD-T engines in Europe got this too, just in Australia, and just for 1995/04 - 1998/01 model years, we got the 13405-17040 flywheel. The fitment for this flywheel is identical to the 13405-17010, and as I suspected, the difference is mass:

See the difference. There's less of a dip around the centre for the 13405-17040, which means higher overall mass. I guess they decided we needed a bit more stored energy for the rough use down under.

It's now time to take out the flex plate, which sits behind the flywheel, and take a quick peek at the rear main oil seal on the engine. I was planning to change this oil seal regardless, and I strongly recommend you do too. It's an easy job once you can get to it, but getting to the seal is a marathon. One bolt to remove the flex plate:

That rear main oil seal is weeping, so looks like it was good timing. Probably goes without saying we're going to clean things up around here too. It's a good time to clean that transmission tunnel on the bodywork too, which is a good idea if it looks anything like mine.

 

[DivByZero]

Now it's time to separate the transfer case from the gearbox. This is easily done, just a few bolts. The join between the transfer case and the gearbox is "dry", there's no gasket, no oil inside, just the bolts holding it together. There's a bit of a pry tab you can use for leverage here:

Don't forget to take the wiring harness off and the breather hoses too at this point.

Now we take off the bellhousing. A few bolts and a few blows with the deadblow hammer and off it comes:

Now things are disassembled and easier to move around by hand. If your back is ok, one person can move the gearbox and transfer separately without too much fuss. A cart or a trolley is the best for anything other than a quick move onto a bench or the like though, you don't want to be running laps carrying these things.

 

[DivByZero]

Reserved

 

[DivByZero]

That's where I'll leave things for today. I got further into the process, got the gearbox apart and started on that side of things, but I've run out of time to post about it. More coming when I have time.

 

[suzuguru]

Great write up so far. Glad the process seems to be going smoothly for you.

 

[DivByZero]

Picking up where I left off before. This'll all be about the gearbox for awhile, as we're about to get in and tear it down, then build it back up again. First of all, we've got to drain the oil. These oil plugs are notoriously easy to damage. I would NOT recommend using hand tools, and especially not any 12 sided sockets, you're sure to round the corners. Use a 6-sided socket with an impact to take it off, then drain the oil:

Now the next thing is some cleanup. Your gearbox probably looks similar to mine above - covered in crap. The oil isn't a problem as much as the dirt is here. We're about to crack open this case. Showering the gear assembly with fine bits of ground up rock and glass isn't a great move. Break out the pressure washer, degreaser, and a copper brush, and give the case a quick once-over. It doesn't have to be anywhere near immaculate, just get off all the looser material and muck. Wrap up the input and output shafts first, especially around their oil seals, and thoroughly seal off the breather pipe and the shift hole at the top, then go for it. Here's what mine looked like after 5 minutes or so:

Good enough. Let it dry for a bit, then onto the workbench. You don't need to work in sterile lab conditions, but the cleaner the better. My setup is less than ideal, I'm working out of a garden shed, but it works. Clean your work surface, keep hands clean (change gloves if they get contaminated), and you can work just about anywhere.

In this first bit, you're going to make a mess. There is still a lot of oil in that case you didn't manage to drain. As we separate the case here, it'll all spill out over whatever surface you're working on. Plan accordingly. In my case, there's a broken concrete slab below me running off into dirt, and the cabinet below is full of other gearbox parts, diffs, things like that. I didn't care much at all about the oil situation, just some extra rust proofing for whatever it hits. Even so, I had two spaces prepared, one to crack the case on, and another to transfer the internals to once the case was removed. You should plan to do the same, and pick a convenient spot to separate the bits where you can deal with the oil flood.

Anyway, on with it. Almost. Do you know what you're about to do? Have you done it before? Do you trust some random shmuck on the internet to guide you through it blindly? This is where you need to crack out the FSM and go through the steps one by one. Rebuilding a gearbox has a lot of steps, you need to keep track of what you've done, what's next to do, what parts went where, and so on. And you're about to be perpetually covered in gear oil. You need to have everything at hand ready to go. First of all, you need the steps in the FSM. The best, most complete instructions on servicing the H150F/H151F gearboxes are contained in the Jan 1992 supplement for the 70/80 series, RM290E. You know, this one here:

It contains all those invaluable steps you'll need to perform to complete this job. What, you don't have one? That's fine, just buy it from Toyota. What, they stopped selling it a decade ago? That's ok, just get it from ebay. What, it's rare and you can't find one for sale? Well that's ok, just download a scanned copy. What, nobody has ever shared a digital version of this manual on the internet before? Ok then, download this one:
https://forum.ih8mud.com/attachment...646411/?hash=e79bea28944c123a2b94bfcbc874be58
This is a pdf-ified and ocr-ified version of the supplement ripped from the 70 series repair manual I put up at https://toyotamanuals.gitlab.io/toyotamanuals. Since the supplement covers the 70 series too, Mr T scanned this one and made it available on the CD... which they also no longer sell. I have an original copy of this manual, but I print pages out anyway for a job like this, because you don't want to ruin your good manual flipping through pages covered in oil. You'll want to print out the entire manual transmission section, keep it with you, and get a sharpie handy so you can cross things off and make notes. I also strongly recommend bagging the parts as you go in sandwich bags. I had small ones but also massive ones I could throw the entire input shaft into for example. And a box of nitrile gloves, wipes, degreaser, a phone to take pictures, etc. Basically this is the point where you think out everything you need and make sure you have it all together.

This is the part where I should give you a full list of all the tools you're going to need. Some of this stuff is gear you probably won't have lying around unless you've done work like this before. Here's a quick list now I'm making off the top of my head that I'll probably amend later:

-20+ ton shop press with extra arbor plates
-Large bearing splitters
-Assorted pullers
-Bearing press kit
-Brass hammer/drifts
-T40 Torx impact socket
-Assorted prying tools (prybar/crowbar/flathead screwdrivers)
-Snap ring expander (NOT the pin type, one with flat edges)
-Magnetic pickup tool
-Pin punch (can substitute)
-Plastic/deadblow hammer (can't use brass on the aluminium case directly)
-Feeler gauge (for inspection)
-Outside micrometer (for inspection)
-Impact wrench (for disassembly)
-Torque wrench (for reassembly)
-All the usual hand tools (sockets, spanners, etc)

You'll also need a bunch of parts. I basically went scorched earth and pretty much bought as much as I could new, but you don't have to do that. At a minimum you'll need oil seals and reverse idler thrust washers, you should get new synchros (otherwise what's the point), and you should really get new hub sleeves. After that there's more flexibility. I'm not going to work up a parts list right now, but I've snapped pics as I went of parts as I did reassembly. Maybe I'll do a summary at the end, we'll see.

Enough talk, let's tear down a gearbox. For this, we're starting from MT-8 - Basic Subassembly Separation. We've done a bunch of these first steps already, but we need to do step 4, remove back-up light switch. This needed some oversized spanner I didn't have handy so I broke out one of the most evil tools in the toolbox, the shifter:

It was bigger than 24mm, my largest spanner. Maybe a 27mm? Whatever the size, the shifter took care of it. Bagged and tagged. Seriously, bag and label as you go. Notice I put the step number on the bag above. Makes it much easier to not get lost, especially if you end up having to take a break after tearing this down to wait for parts.

 

[DivByZero]

Now it's step 6 and 8 (we've done 5 + 7 already) - the shift lever control retainer. First, rattle off the restrict pins, one on each side, then do the 6 bolts holding down the plate, and get a prybar. There's handy tabs, use them to pry off the retainer:

With that off we're going to skip step 9 about the reverse restrict pin, that can stay in place. It's on to step 10a, removing the oil pump cover assembly. First take off the 5 bolts to remove the pump cover. The manual makes it sound like it'll just fall out, but mine was stuck on tight from the oil seal. I had to give it a bit of a pry to get it to release. Be careful though, there are two pins behind this you could easily lose, look ahead to the next step, 10b.

On to 10b, if you're lucky like I was, the oil pump gear will stay behind on the shaft where it was rather than come out with the assembly. There are two small pins that go into slots of the gear and into the output shaft. Turn the gear so the slots are horizontal to stop the pins falling out, slide off the gear, then remove the two pins, preferably with your magnetic pickup.

Step 11 - Remove transfer adapter. Do the 11 bolts as per FSM, easiest to rattle them off, except one sneaky one at the back, where the case angle doesn't allow you to get an impact in easily. Get your breaker bar to shift that one. At this point the FSM says "If necessary, tap the transfer adapter with a plastic hammer". By which they mean, this thing is stuck on hard, forget the plastic hammer, get a pry bar. There's a handy tab near the top you can use to easily separate the gasket most of the way around. At which point you will release a flood of gear oil that'll cover your workbench. Be prepared.

Now pay attention - this is where you can lose another part. Don't just go yanking the transfer adapter off. There's the reverse idler gear inside this adapter, and it's held in by bugger all. It may choose to come off with the transfer adapter, or it may choose to stay in the intermediate plate, or it may fall out in the middle. Reach in and support it whatever happens. You may now see either of these two:

 

[DivByZero]

Whichever scenario you're looking at, you need to immediately locate the woodruff key that goes into the reverse gear idler shaft. The assembly should look like this:

If the key isn't there, go hunting in the bottom of the transfer adapter and the intermediate plate, and the oily mess spread out over your bench. It'll be there somewhere. Now bag and tag the entire assembly, which was supposed to be step 14, but deal with it now.

Skip step 12, we'll worry about the oil strainer later.

Step 13 - Remove the magnet from the intermediate plate. It's just sitting there magnetically attached, yank it. And we've already done step 12.

Step 15 - Remove shift lever and shift lever housing.
15a - At this point ideally you have your pin punch handy. But if you don't have one or misplaced it and can't be arsed finding it, the back of a knackered drill bit will do fine in a pinch. Drive the pin out the bottom of the shift lever housing. At this point it'll disappear into the gearbox. We'll have to find it again in a little bit.

15b - This next part can be tricker than it sounds in the FSM. You need to slide the (now unrestrained) shift lever shaft through the intermediate plate and right out the back of the case. You may find it doesn't want to cooperate. The best approach I've found is to rotate the shaft while trying to wiggle it back and forth. You can also physically move the shifter back and forth (easiest with a tap from the plastic hammer) to help wriggle it along. I also found in one gearbox that the liquid gasket at the intermediate plate had intruded on this hole the shaft was supposed to slide through, and it produced a rubber lip that stopped the shaft going through. I had to scrape around in there with a screwdriver for a bit to remove some of the material. At any rate, the goal is to wiggle that shaft out by any means necessary. Once it clears the shift lever housing, that'll come free, bag it with the shaft. We'll add the pin to that bag when we recover it later.

Step 16 - Remove front bearing retainer. Rattle those 8 bolts off, and discover that the plate is stuck fast and won't budge. I did some gentle sharp taps with the plastic hammer on the nose of the retainer to provide some leverage to break the seal, after which it was easy to pull off. After this, there are two snap rings you'll be looking at. Well, three actually. The two the FSM tells you to remove is the one on the counter shaft at the bottom, and the outside ring for the input shaft. There's a smaller inner snap ring I also removed at this point, but if you don't it can be done later after disassembly. Now, snap rings like to fly across the workshop! You should wrap the snap ring in a shop rag or wipe or something, preferably with your hand there keeping guard, when you expand the snap ring. Don't hold it in the air open taking pictures like you see me doing in this image. Frankly I couldn't see how to wrap this one easily and I needed the other hand to work the camera, but take more care when you do it.

With that done, it's time to separate the main case from the intermediate plate.

Step 17 - Separate transmission case from intermediate plate. As per the FSM, it says to carefully tap off the transmission case with a brass drift. I don't think it's that simple. There's two things working against you here. There's a full bead of sealant between the case and the intermediate plate, and the outer races of those two bearing at the front of the case are holding in tight. You need to overcome both these forces to remove the case. We do have one semi-useful pry spot, just below where the back-up switch was fitted. You can get a large prybar in there to separate the case from the intermediate plate a fraction. With that done, I worked around the lip with a putty knife to cut the rest of the sealant.

At this point the case still isn't off. I chose not to use a brass drift, didn't want to mar the aluminium case, I chose for a longer task with more bashing using a plastic hammer. I found this spot here the best:

 

[DivByZero]

As you bash on the case, you'll see the bearings slowly disappear back into the case, until finally it separates:

Now immediately go and track down that pin you drove out of the shift lever housing back in step 15a. It'll probably be stuck inside the case or on your bench at this point.

Skip step 18, we don't need to remove that oil receiver from the case yet.

Step 19 - Remove oil receiver from intermediate plate. We'll do this one, because we don't want to damage this receiver when doing the next step. Three screws, quick job. Bag and tag it.

Step 20 - Mount intermediate plate in vise. This is where you'll need your second work area. If you're working by yourself like I am, this step requires some extra equipment. See, what we're going to do is put a couple of bolts and nuts on the two bottom holes in the intermediate plate, and mount the entire gear assembly and intermediate plate by them into a (very preferably swivel) bench mounted vice. Unless you have a couple of extra arms. It'll be basically impossible to support the weight of the entire gear assembly perfectly in place in the vice while you tighten it. If you have a second helper, this is definitely the time to rope them in, because they can just hold the entire assembly supported by the output shaft while you tighten it up. I didn't have this, but I threw together an improved gantry from bits of an old Singer industrial sewing machine table, with a ratchet strap for positioning, so my setup looked a bit like this:

Finally, take a minute to admire this marvel of modern engineering, and the hard work you've put into getting to this step:

 

[DivByZero]

Leaving things there for now. More updates when I can find the time.

 

[DivByZero]

Step 21 - Remove straight screw plugs, locking balls and springs.
21a - At this point you'll need that T40 torx socket. Rattle each of the four screw plugs out of the intermediate plate. There are three on top, one facing you on the side.

21b - You now need that so-called "magnetic finger". Really just any compact magnetic pickup tool will do, the kind you use to fish out screws you drop into inconvenient places in the engine bay. I got a fancy bendy one as per the FSM just because I didn't have one and thought it'd be useful. A straight telescopic pickup tool would work just as well for this though. Extract the four springs and balls from the holes.

Step 22 - Remove fork shaft snap rings
There are four snap rings on the two shift fork shafts closest to you, in the positions annotated in the FSM. We need to knock them out using a pair of flathead screwdrivers of the same or roughly equal length. We lock each tip into one side of the ring, then give a sharp tap on the top with a hammer. Be aware, you need to wrap some shop cloth or rags or something of the like around the snap ring! This thing'll fly across your workroom otherwise never to be found again. Try and use the minimum force you can get away with when tapping these off. If you're in the right spot, it shouldn't take a lot of force, and you don't want to scratch things up with your screwdriver tips. You could put some electrical tape around the tips if you wanted to take extra precautions. Remove each snap ring and bag them.

Step 23 - Remove shift fork shaft No.4 and reverse shift fork
23a - Rattle off the set bolt from the shift fork

23b - Now removing the shift fork is simple with the set bolt removed, but be careful with the shaft! There are two ball bearings which are going to be exposed when you pull out the shaft. One is in the connector that joins the two shafts together (reverse shift head), and a second is inside the intermediate plate between the two shafts. Be careful not to lose any.

Step 24 - Remove shift fork shaft No.3, shift for No.3, and reverse shift head.
24a - You may have already removed this ball bearing in the above step (shown in the image). If not, grab it now.

24b - Rattle off the next set bolt

24c - We've got a bit of a juggling act here. There's three separate pieces and locking pin we need to grab, so don't go yanking out the shaft in a hurry. First, slide it out just a little bit, and grab the locking pin with your magnetic pickup.

The FSM lists this as step 24d, but grab it first or you're sure to drop it on the floor. After this is done we can proceed with 24c.

 

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With that pin secured, now you can slide the shaft back and grab the shift fork and reverse shift head, then finally extract the shaft all the way.

Step 25 - Remove shift fork shaft No.1 (not 2 like FSM says) and shift fork No.1
25a - First remove the very long interlock pin between the front pair of shafts and the rear pair.

25b - Now rattle off the set bolt

25c/d - At this point you want to remove the shaft and shift fork, retrieving the interlock pin from the end again as per the last shaft. If you pop the shaft out though and mysteriously find the pin slot empty like this:

It probably got pulled out of the shaft when you used the magnetic pickup to pull out that long interlock pin in 25a. Go hunting through the front hole of the intermediate plate to find the pin.

Step 26 - Remove shift fork shaft No.2 and shift fork No.2
26a - First grab the interlock ball which was behind the shaft we just removed previously.

Notice this interlock ball is a different shape. You should be bagging these separately with each corresponding shaft so you don't get mixed up.

26b/c - Now just like we've done a bunch of times, rattle off the set bolt and remove the last shift fork and shaft. There's no interlock pin set into this shaft.

Step 27 - Remove reverse gear and hub sleeve No.4 assembly
27a - The shift forks/shafts are all removed. Now it's time to get into the gears themselves. First, drive off the snap ring holding on the hub using the double screwdriver technique.

27b - Now it's time to remove the hub itself. This thing is pressed onto the output shaft and needs a puller to remove. The FSM here has two sets of instructions - one for hubs with a "service hole", and one without. By service hole, they mean two sets of threaded holes are present and drilled into the hub itself, allowing you to attach a puller. If you have a box without these threaded holes, the FSM calls for a very specialty gear puller of some kind. I suspect you could instead pull the hub sleeve all the way off and get a long three jaw puller on the hub, at the risk of causing some marring to the teeth of the hub (best replace it in this case, with one that has the holes drilled!). In my case though, with the drilled holes, you really just need a puller set, like you'd use for a steering wheel or just about anything else. I used a $20 cheapie from ebay:

27c - With the hub removed, the gear itself is loose. Gently slide it off the output shaft with its synchronizer ring and needle roller bearing. Bag it. You'll need those jumbo ziplock bags for this, as you would have for the shift forks.

 

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We're going to skip step 28, the disassembly of the hub we just removed for now. Just bag the hub for inspection later. It's best to leave the hub assembled until it's time to rebuild it with new parts.

Step 29 - Remove rear bearing retainer. Pretty straightforward, remove the four bolts and the metal bearing retainer ring. Use hand tools for this, impact is overkill.

Step 30 - Remove two snap rings. As per FSM, get your snap ring pliers and remove the snap rings for the output shaft and counter gear bearings.

Step 31 - Remove counter gear
The first step here is be prepared for the counter gear to drop! You are unlikely to be able to support it with your hands as you remove the bearing race, and the bearing race is the only thing that's keeping the counter gear propped up right now. I put a lot of padding under the counter gear to stop it being marred when it dropped, as shown a bit in the below pic. If I was doing it again, I'd probably break out the ratchet again and fully support it. If you have a helper, get them to hold it in order to support it.

31a - The FSM calls for a fancy SST here to pull the bearing outer race. You don't need it. The counter gear bearing isn't in there overly tight. Get a screwdriver and lever it out using the snap ring groove, tapping on the handle with a hammer if you need to.

31b - Once you've got the outer bearing race pulled, you need to maneuver the counter gear forward a bit so you can get to the split bearing cage. It has two halves that lock into each other. The angles are awkward, but the goal here is to get a screwdriver into the tabs of the bearing halves and separate them. You can't pull the counter gear out until you pull these two bearing halves out the back of the plate.

Step 32 - Remove input shaft
Now the input shaft should have been sitting there patiently through the whole ordeal, but it's not actually secured by anything, and hasn't been for awhile. Grab the input shaft and gently pull it forward, and the whole thing should come off. Support the synchro ring as you do this. Also be careful! The input shaft has 12 loose roller bearings inside that ride on the tip of the output shaft. They should be supporting each other and held in place by residual gear oil, but don't go shaking it around the room. Bag the input shaft together with the synchro ring and try not to drop the roller bearings everywhere.

Step 33 - Remove output shaft
It's time to remove the output shaft. The FSM talks about tapping the intermediate plate with a hammer. In my experience this is unnecessary, at this point the output shaft should slide out quite easily. Remove it, and place it on your bench. At this point you should have the output shaft and counter gear separated from the intermediate plate, and a tray of parts bagged and tagged.

That's the end of the "Basic subassembly separation" section of the FSM. From here, we'll move onto disassembly of the output shaft.

 

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It's now time for the output shaft disassembly. This is in the FSM at MT-21, starting from step 1 again. We'll have the output shaft separated and ready to tear down, looking a bit like this right now:

Note that everything so far has been the same regardless of whether you're working on a H150F or a H151F box. Things will be slightly different in this stage depending on which box you have. I'm rebuilding a H150F box here, but I'll be doing some "upgrades" during reassembly, bringing some enhancements from the H151F into this box to make it better. I'll note them when it happens later.

The first thing the FSM starts with for output shaft disassembly is inspecting gear thrust clearance in steps 1 and 2. We skip that, since the plan is to disassemble the output shaft and replace our synchros and bearings regardless. We'll check thrust clearances during reassembly.

Step 3 - Remove ball bearing and first gear
3a - We use the double screwdriver technique here to drive out the snap ring.

3b - There's now a thrust washer to remove, locked in place with a pin. Be careful not to lose the pin! Position the output shaft with the "slot" in the thrust washer facing up, so the pin doesn't fall out. The thrust washer will probably be stuck on the face of the bearing by a film of oil. Gently pry it loose with a screwdriver to remove it, then use the magnetic pickup to remove the pin. Bag them both.

3c - This part sucked. Per the FSM, what they want you to do here is use a large bearing splitter to pull the first gear, which in tern will drive out the bearing. The SST called for is 09555-55010, which from the illustration is just a bearing splitter. I don't have the dimensions on it, but possibly perhaps, a 150mm bearing splitter would work here. The largest one I have currently goes up to 105mm, which wasn't wide enough. The issue is the distance between the two rods that hold the halves together. It needs to be wide enough to fit around the first gear synchro ring in order to drive off the gear. I meant to order a larger one that goes up to 150mm, but forgot to. I could have waited, but I'd done this before without one so I proceeded with what I knew worked. I'd recommend you source the larger splitter if you're doing this though. That said, here's what I did. I got a crowbar. Not a prybar, a full on crowbar, and hooked it in the narrow gap between the bearing and the gear:

The reason I did this, is that gap is too darn narrow to fit anything I had into. I used the crowbar to gently, gradually, carefully lever the bearing off the output shaft. I made sure all the force was focused forward onto the bearing, you don't want to press against the teeth of the gear, you could fracture them. This approach took several minutes of levering, spinning, levering, spinning, to nudge the bearing case forward a few hundredths of a mm forward at a time, until I moved it forward enough that I could hook my long arm three jaw puller into the gap, then I rattled it the rest of the way off.

That long arm puller is another $20 ebay job we'll be using quite a bit.

I would recommend sourcing a 150mm bearing splitter before you begin this job. It'll do this much quicker and simpler. This is the only step you need it for, but it would make it much simpler and avoid risk of damage screwing around trying to improv something.

We actually haven't finished this step yet. There's still another thrust washer, pin, first gear, first gear needle bearing, and first synchro we need to remove. At this point they're all loose on the shaft, go ahead and remove them. You should probably pull the thrust washer and pin first, then remove the gear. In the pictures I show below, I forgot this and pulled the gear, synchro, and thrust washer all together, then snagged the pin afterwards. This risked having it fall onto the floor.

With this all pulled and bagged, that's step 3 done, on to step 4.

 

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Step 4 - Remove hub sleeve No.1 assembly, synchronizer ring, second gear and needle roller bearing.
4a - Continuing down the output shaft, drive out the snap ring holding in the hub.

4b/c - Now for the first time of many, it's over to the 20 ton press.

With the second gear supported by a bearing splitter (75mm-105mm in this case, flat side facing the gear), we're going to press the output shaft down and out. Second gear will drive the hub assembly off the output shaft. It'll probably take a bit of force to break the hub assembly free, but be gentle and look closely at what's going on when you use the press, make sure things are straight and nothing is getting bound up that shouldn't. Get your hand below ready to catch the output shaft as it falls through, then slide off the gear and hub assembly together.

Note that plastic cage needle roller bearing for second gear. That's one of the things we'll be deviating from Toyota spec for, and upgrading to a metal cage bearing.

We skip step 5 about disassembling hub No.1 for now. Bag it, we'll worry about disassembling it later.

Step 6 - Remove hub sleeve No.2 assembly, synchronizer rings, third gear, and needle roller bearing.
6a - Now we flip the output shaft around and start working from the other end. First let's drive out the snap ring using two screwdrivers.

6b - Now the FSM here says to slide the hub sleeve onto the fifth gear as shown below.

The catch is, with no shift fork to restrain the hub sleeves, and with fifth gear being a smaller diameter than the sleeve, you'll probably find like I did that it basically is going to fall off into your hands as soon as you hold the shaft upright to press.

Place the sleeve aside for now, and move the output shaft over to the press.

6c/d - Now use the press to drive off the hub and third gear. Using the same 75mm-105mm bearing splitter here (yes, a cheap ebay job).

Bag and tag the lot.

Skip step 7 for disassembling the hub.

Step 8 - Remove hub sleeve No.3 assembly, synchronizer ring, fifth hear, and needle roller bearing.
8a - Same as before, drive out the snap ring.

 

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8b/c - Over to the press and drive out the lot. Remember not to let the output shaft fall.

The bearing cage for fifth gear is a split cage, so it comes out in two pieces. No real reason it has to be for this application, but that's how it's made.

At this point the output shaft is fully disassembled, and you should have a bunch of parts like this:

We're basically done with disassembly now. There are smaller bits we've taken off that we'll disassemble, inspect, and reassemble as we go. It's at this point you need to have your large collection of new genuine parts ready for replacements as we go.