How to Rebuild an 88/89 KM132 Manual TransmissionSTEP BY STEP W/PHOTOS
Posted 03 August 2015 - 01:45 PM
Please note: I am not a mechanic who works on cars day in and day out! I don't have an unlimited supply of specially tooling! I am an auto enthusiast/backyard mechanic like the majority of us on this site. I've done my best to document how I performed this particular rebuild using mostly standard hand tools and the factory service manuals as my guideline. If you see something in error, please respond via PM. If you see something that may be performed in a simpler fashion, again please respond.
I have been receiving many requests from club members asking if I would consider rebuilding their parts per the steps shown in these ‘how-to’ threads. Although I am humbled at your trust in my abilities to rebuild such critical parts of your vehicle, I respectively have to decline any such requests. With a family of four, a demanding career, and just the normal responsibilities in everyday life, I have difficulty in finding time to work on my own project vehicles much less take on additional work. However, I encourage you to review the thread in detail, try to gather the required parts and tools, and attempt to rebuild the items on your own. My goal in developing these threads was to give members the encouragement to perform these component rebuilds at home while gaining valuable experience, saving some $, and simply having fun with the hobby. I hope by sharing this information and by including my own trials and mistakes along the way, help to achieve these goals.
Background: This particular rebuild was to freshen up my 88/89 KM132 manual trans. This transmission had about 90k miles on it when removed from the vehicle. I didn’t recall any issues with this transmission when it was in my car. The purpose of the rebuild was simply to refresh the transmission with some new synchronizers, bearings, gaskets, and seals hopefully to result in many more years of operation.
Reference: PQ's thread in the SOS forum: http://starquest.i-x...6fee35e71adcd83
First and foremost: YOU NEED THE FACTORY MANUALS and the PARTS MANUALS! If you do not have these, get them. They are downloadable on several starquest sites and are also on ebay constantly for a very low price. NOTE: The 88 factory service manuals that are downloadable on the sites appear to be missing a few pages in the manual transmission section! For this reason, I was using my hardcopy 87 manual for most of the rebuild, particularly with the disassembly. This led me down the wrong path at one point, costing me a lot of unneeded time and developing a tool that I didn’t need….follow along for more detail.
Parts required: Please follow the thread to list the required parts for this rebuild. At a minimum you will need the input bearing, center bearing, output bearing, and both countershaft bearings (the input and center bearings are specific to the year of the transmission). You will need all six synchronizers. I recommend that you purchase new shift forks as well. You will most likely need a few shims for your countershaft (follow along with the thread). Plus gaskets and seals. There are several needle roller bearings in this transmission…I’ll leave that up to you on whether or not they need replaced. I replaced all but one of mine (was NLA from Mitsu) although my originals were in good shape and probably could have been reused. You will possibly need a new rear retainer as well.
Source of parts: manualtransmissionpart.com has many aftermarket parts for our transmissions. They have full rebuild kits…although don’t buy the 88/89 rebuild kit! It doesn’t have the right center bearing in it which is one of the most expensive parts in the kit. Although you can buy the input, output, and countershaft bearings from them. They have all of the shift forks, one of the needle roller bearings, seals, and synchronizers. Note: our 1st and reverse synchronizers are slightly different than the ones this site sells…thus I bought these from Mitsu…although I don’t believe there would be a problem using theirs (follow along in the write-up).
For most of the other parts, I went directly with Mitsu. One item of concern is the countershaft shim….they don’t make a shim kit! You must purchase each shim separately…and they come from Japan! To make it worse, they are expensive and you don’t really know what size you will need until you are back in the reassembly phase!
Another source of bearings is motion-industries. Some of the bearings are available thru them but you must have the bearing manuf. part number.
I purchased the high strength roll pins for the shifter forks and the retainer hardware through mcmaster-carr.
Tooling Req'd: This rebuild required a really good set of pullers. Prior to this I invested in a puller kit. It was expensive but it has paid for itself on this project and several others since. Unfortunately you still need to either find the true Mitsu puller with extension rods for removing the center bearing (such as what PQ did on his thread) or make a custom puller (the route I went).
Starting Point: I started with the transmission removed from the car and the following parts previously taken off: pan, rear steel yoke protector (it just pulls off), speedo gear assembly, clutch throughout bearing/fork, and reverse switch (don’t lose the steel ball behind it!).
As seen in the photos, I thoroughly cleaned the outside of the tranny and bell housing area prior to taking anything apart. I don’t like to introduce any un-needed debris into the transmission even during disassembly. For this, I used simple green first and then mineral spirits. I probably went much farther in cleaning than the typical member here because I wanted to paint the components in the process.
Posted 04 August 2015 - 05:48 AM
Remove the bolts for the shifter housing cover
Remove the bolts for the extension housing
Don't forget these two.
Separate the shifter housing cover...note the two dowel pins.
Remove the cover
Remove this spring
Remove the ball bearing under it
Posted 04 August 2015 - 05:52 AM
Remove the springs and plungers.
Mark them accordingly....the plungers are different for each side.
With the tranny in neutral, you have to move the shifter over as far as you can to the right (looking at the trans in the pic below) and then pull it back. This separates the main shifter linkage arm from the three shift arms in the trans. You have to separate this joint in order to get the housing off.
Now tap her off.
Posted 04 August 2015 - 05:56 AM
The one thing that I didn’t fully disassemble on my rebuild was that main shifter linkage shaft. It has a special ‘lock pin’ between the fulcrum and shaft that I really didn’t want to get into. Just inspect everything real good and determine if you need to disassemble it. If you do disassemble this, please take some pics and let me know…I’d be happy to add it to this thread!
Posted 04 August 2015 - 05:58 AM
Ok let’s move on in tearing her down:
Drive out the three spring pins for connecting the shift forks to the linkage rods using a drift punch.
Posted 04 August 2015 - 06:02 AM
Next using a set of vernier calipers or depth gauge, you want to measure the distance from the casing to the top of the set screws. Note: the FSM manual gives values for reinstallation but I like to measure the previous values and set them back to these upon completion of the rebuild. The reason being is that the casting differs a bit from tranny to tranny. So measure all three and RECORD
Now that you have the values recorded, spin out all three set screws.
Then pull out the spring plungers (Note the direction they are installed, they are tapered).
Behind the spring plungers are steel balls…remove all three of them using a magnet.
At this point you can remove the 5th/reverse linkage arm.
In between the linkage arm holes is a spacer. Remove it using the magnet and pick.
Posted 04 August 2015 - 06:06 AM
You can remove the 5th/reverse shift fork now.
Note the orientation! I put a ‘dot’ on the side facing up and laid all parts neatly on some cardboard on a separate bench. It is so important that you record the orientation of EVERY part during disassembly. Do whatever you need to do to maintain your part orientation…pictures, marks, maps, etc. Anticipate worst case and that this tranny might be torn apart for a long time due to potential unforeseen problems…don’t rely on memory, rely on good documentation of the disassembly process!!!!!!!!!!!! I’ll be bringing this up many times in this write-up. Hopefully you read this entire thread prior to starting and understand the importance of this.
Remove the next spacer.
You won’t be able to remove the last linkage arm yet due to this:
OK, it is time to start pulling parts off of the shafts. As stated earlier, clear off a bench or table away from where you are disassembling your tranny. Coat it with some cardboard. Use this bench to store you components. I lay each component facing up the way I removed it from the shaft. I wrote all over the cardboard on what each component was, the direction, etc. Line up the parts in order corresponding to the shaft they were on. Use the cardboard as a tool for you to recall how you took it out…the more info the better. Surprisingly I didn’t snap too many pics of this cardboard layout ‘zone’…although I think you’ll see it in a few photos down the line. I cannot stress this enough. As an alternate you can mark the gears like PQ did in his thread but I found that those markings just rub off and could cause later issues….but you could do both! Use the cardboard and some consistency/diligence and you’ll be good to go.
Moving on: Using external snap ring pliers, remove the outermost snap ring on the output bearing:
Now pull the bearing. I had to use my largest puller to clear the main/output shaft although there are probably many ways to pull this bearing being that it is out there away from other obstructions.
Remove the lower snap ring
Now we want to relax the crimps in both locking nuts (the main/output shaft and the countershaft). I had to grind down a chisel to fit in the slots and simply hammered out the crimps.
Posted 04 August 2015 - 06:11 AM
Engaging in reverse:
Engaging in 2nd
Note: looking back at my pics, I think I mistakenly engaged it in 3rd instead of 2nd. Oh well, it worked. Locking it up in both directions is what you want to relax the torque in the locking nuts.
Ok, now to relax the torque. I used a piece of angle iron bolted to the pan mounts as a brace to relax the torque on the nuts.
Main shaft nut:
Spin them off
Now let’s focus on the countershaft. We need to pull that rear most bearing. Using a standard 3 jaw puller, I went right for the gear for better grip. Pull the gear and bearing as an assembly:
With this bearing off, you can pull out the gear along with that last shaft that had the notch in it. Remember to lay out your parts in order with the top side facing up on your cardboard laydown area.
Looks like I didn’t pull off that lower gear at this stage…you could if you wanted to..well you should (try not to jump from shaft to shaft..remove all parts in order until you get to the point where you cannot remove anything else…this keeps your parts in order). Looks like I moved to the reverse idler shaft next.
Pull out the cotter pin and untorque the nut
Posted 04 August 2015 - 06:17 AM
Back to the reverse idler shaft: Pull these in order and lay them out, top facing up on your cardboard. Looks like I jumped around again with my photos…so let me put them in better order. Stay on the reverse idler shaft until you removed all of the parts that you can.
Now to the main shaft. I was just learning at this stage and made a few errors…1st being that I jumped between the two shafts…not a big deal but leaves more chance of mixing things up. 2nd error was I started to disassemble the synchronizer assemblies piece by piece. Don’t do this! Pull the sync assembly in one piece (gear, both synchs, and outer ring)…like I did later on with the 1st-2nd and 3rd-4th sync assemblies. If you do separate them, just mark them really good so you know how to put them back together as a unit (take advantage of that cardboard again). Make sure you record which direction the outer ring goes…they have different chamfers on each side…and cannot be flipped during assembly!
I pulled the outer ring of the reverse-5th syncro assembly. Don’t do this, pull it as an assembly. BTW: you can take it out of reverse now that we have the nuts off.
Posted 04 August 2015 - 06:21 AM
Ok, now pry up a little bit on the bottom gear to free up the assembly.
Now start pulling parts off one by one and laying them on your cardboard face up in a line in the order of removal.
Note: I should have pulled that lower sync with this part as an assembly! Not the worst thing I could do, just would have been better if I did. Once it was off, I put the outer ring back on it.
That last spacer on the main shaft wouldn’t come off easy for me…No big deal, we’ll get it when we pull the center bearing. Here is what you will see now. Almost have the full back of the transmission apart…getting ready for the hard part.
Posted 04 August 2015 - 06:24 AM
Remove the retainer
Before we pull that reverse idler shaft, lets get rid of those shift forks just bobbing around down below:
Mark your orientation…although the forks are pretty easy to figure out later on if you mix them up.
Ok let’s pull the reverse idler. Manual says to drive it out from underneath. Tried that for a few blows but didn’t want to hit the aluminum casing…so I took advantage of my slide hammer puller and using the castle nut, I drove out the reverse idler. Naturally you can do it the way the manual states just be careful not to mess anything up. This sucker is pressed in there good.
Ok, last thing I missed is the shim over the countershaft bearing. This is the shim that I mentioned early on that we may need to replace with a different size during reassembly.
After the shim, go ahead and pull the outer race of the rear countershaft bearing.
Posted 05 August 2015 - 05:53 AM
Undo the nuts:
I had trouble pulling the housing due to some idiot going nuts on gasket sealer during a former replacement of the input shaft seal….ie that idiot was me, haha. So I removed the fulcrum for the shift fork and put in a bolt to pry the housing out. This left an indention in the aluminum but I later remedied that. You shouldn’t have an issue removing this as I did.
Take a look at the gasket sealant and the makeshift gasket that I did a few years prior…that was stupid of me…too lazy to buy the right gasket I guess. Don’t lose that shim there!
I went ahead and removed the external snap ring at this stage.
Then remove the shim and outer race of the front countershaft bearing:
Ok, here is where I messed up…on multiple counts. First off, I lost my photos from this stage forward of the disassembly! I really could use some help from a member to fill in the gap here. I will do my best to explain in words on how to finish the teardown plus the reassembly photos should help as well…just follow them in reverse.
2nd screw up was a technical one…of which I’m still kicking myself over a year later from doing this rebuild. Not that my mistake hurt the tranny, it just caused me extra work and cash. For the 87 and earlier transmissions, the 4th gear prevents the input shaft from being removed from the transmission without first removing the bearing. For the 88/89 transmissions, they notched the fourth gear, allowing the input shaft to be removed as an assembly with the bearing on it. I was following along with my 87 manual and completely missed this and focused on removing the bearing from the shaft while still in the bell housing. What I did was made a custom clam shell puller to pull the bearing from the shaft while still in the tranny…complete waste of effort. On the 88/89 trannies, the 4th gear has these notches (using a pic from my reassembly phase to show them):
So all you need to do is turn the shaft until the notches line up with one of the gears from the countershaft permitting it to be pulled directly out of the transmission. Your countershaft should be pretty loose now because you removed both other races of its bearings. Just get that input shaft out of there.
I really wish I had pics from here on out, but staying on with the input shaft, you just need to remove the input shaft bearing. Use a shop press or a large 3 jaw puller. Note: this sucker is pressed on there really good! Here is a photo from assembly showing how I used the 3 jaw puller to install the bearing….just flip the puller around for removal:
Posted 05 August 2015 - 05:59 AM
First: reach in thru the hole where the input shaft was and pull out the needle roller bearing (the one with the green grease on it in the photo:
Now reach in with external snap ring pliers and remove the snap ring holding the 3rd-4th synchronizer assembly on the shaft.
Now here is where I defy my own words again…you cannot pull the full 3rd-4th synchronizer assembly as one unit..you must first remove the outer ring…hard to see in this photo, but you have to pull it outwards and work it out thru the tranny. Don’t lose its orientation…make sure you know which way it was installed and record (photo, scratch-paper, marking the ring, etc)!!!!!!
Now you can pull the rest of the sync assembly out thru the front hole
Put that assembly back together immediately and mark the heck out of it!
Next pull 3rd gear out thru the front hole:
Last, pull out the needle roller bearing under 3rd gear
Ok we literally pulled everything possible off of the tranny that we can with the shafts still inside it…with one exception….the center bearing. This is going to be somewhat hard to explain without photos. Flip over the tranny to look at the bearing. Here is a photo from my reassembly. Note this photo was taken prior to pressing the new bearing on. What you will actually see now is the bearing flange flat against the tranny.
If you grab the main shaft and pull up, it will lift up a bit giving you ~.050” between the bearing flange and the aluminum housing. What you need to do is construct a puller to grab the bearing in this gap! Not an easy task but not the worst thing in the world. What I did was measured the flange OD, bearing OD, & gap and worked with a local machine shop (close friend of mine) to make a clam shell puller that would slide in this gap and provide adequate contact area to pull the bearing. So hard to explain with no photos…..argh
I drilled and tapped a hole in each clam shell for ½-13 all thread. I used all thread rods long enough to clear the end of the main shaft and used a standard gear puller spanner bar to pull this bearing.
Of course another alternative is to find the Mitsu tool with extension rods shown in the manual. The cheapest I could find this was $400. I made my tool with $10 all thread and some sweet talking to my machinist friend and the cost of the plate material….but it took a month!!!
Once this bearing is pressed free, pull it front the main shaft. What you are left with is the main shaft and counter shaft kind of floating in the tranny. There is still the 1st/2nd gear assembly on the main shaft but you cannot pull them until you get the shaft out of the housing. Here is a tricky part. You need to wiggle the two shafts just enough to permit removal of the countershaft. Here is a photo from assembly but it shows what you need to do (only difference is yours will be all full of gear oil):
See the little notch in the housing…this is literally there to permit removal/assembly of the countershaft.
Once the countershaft is out, the main shaft comes out with ease.
Posted 05 August 2015 - 06:03 AM
Remove 1st gear
Remove the needle roller bearing
Remove the bushing
Full sync as an assembly:
Remove 2nd gear
And last the needle roller bearing
And you are finally left with a shaft
There you have it. You should be fully torn down with all of your parts neatly laid out and labeled. I’m sure you will have gear oil all over the place and a mess on your bench but the important part is that you have all of the gear train in order and lay out so you remember the exact orientation to reinstall. Can I stress this enough???? Use your head and don’t just follow along verbatim from my photos. You are the one that has to be sure you reassemble this sucker in the right way. If you get one of those synchronizer assemblies installed backwards, you’ll be pissed!
Now I realize why I couldn’t find any photos of my cardboard layout area…they are part of the missing photos from my disassembly process….can you tell I’m upset about this? Haha. I guess it still worked out using the assembly photos but I wish I at least had pics of that custom puller that I used. Ok, well the good thing is that I have pics from this stage forward!
I did find this one example but I know I took better ones looking straight down on my markings:
There are one or two minor things left though. You need to pull the inner countershaft bearings from the countershaft. This is pretty easy using a puller set. Note: the one bearing is really close to a gear on the shaft and I couldn’t get my puller between the gear and race. So I cut off the cage, removed the bearings and pulled it from the upper lip of the race. Pretty self-explanatory when you get to that stage…even with my lack of photos.
Posted 05 August 2015 - 06:08 AM
Pull the output seal from the extension housing:
Speedo Gear Disassembly:
During the rebuild process, I also rebuilt my speedo gear assembly. I haven’t had one of these leak internally in the 25 years that I’ve owned conquests…but I know these cause issues on other cars…300ZX’s come to mind. So let’s tear her down as well.
Note: the red paint was from a former fresh-up.
Here are your parts:
Take off the three Philips screws
There is a black geared like ring in there…have no clue the proper term. It came out with the end in this case but sometimes it stays in the housing.
Here is what you will see
Flip it around…you’ll see two roll pins..one in the housing and one in the gear…remove them using a drift punch (3/32” is what I used).
Posted 05 August 2015 - 06:12 AM
Look inside, there is the inner o-ring that is usually susceptible to leaking…causing tranny fluid to be pumped up into the interior via the speedo cable. Like I said, never had this happen to a conquest but have experienced it in a 300zx.
And remove the outer o-ring
All of your parts
Cleaning and Inspection:
Ok one by one, clean your parts. I used mineral spirits in my parts washer for all of the gears, etc. Clean it one item at a time from your laydown area. Note your orientation…once clean, make sure you set it back down on the cardboard facing the same direction.
Hold off on cleaning your syncrho assemblies at this point…they are the most critical to hold orientation with….do them last…I’ll show some pics in a few minutes.
Take a look at this…shifter fulcrum material jammed up in an oil hole for one of the gears…scary!
Posted 05 August 2015 - 06:19 AM
Now clean out your tranny housing and extension housing. I first used mineral spirits to get what I could and then I went for my deep sink with dishwater detergent and a tooth brush….it cleaned all of the grime off of that aluminum!
Now I went one step further and scuffed, primed, and painted my tranny. Of course that is out of scope of this thread but it is why the outside surfaces look the way they do from this stage forward.
Since we are on our housings, I used a fine grade sharpening stone to clean up all of the mating flanges. It works like a charm on aluminum:
Now run a tap thru all of your bolt holes. Note: I removed my studs here to clean up that flange good.
Note the condition of my layout bench during all of this…covered to keep everything clean:
Clean off everything…blow gun works good to clear any minor dust, etc from the blocking and tapping.
Posted 05 August 2015 - 06:22 AM
Now the main shaft. I just polished it up using some really fine emery cloth and lubricant
Same with input shaft and countershaft
Posted 05 August 2015 - 06:25 AM
Inspect this good. This sucker takes a beating in our transmissions…especially on the pre 88 models. Mine wasn’t too bad. It had a little ridge in it:
So I used the same stone and made her smooth. If yours is bad, buy a new one! What you want is a nice flat smooth surface. This sucker is pretty much all that holds our main shaft in place and also maintains the slop in your countershaft. It’s the ‘life’ of the transmission..not as susceptible to tranny damage as a bad pilot bearing in the flywheel but it is probably the next most important piece.
Here are my old forks (bottom) and replacements (top).
Let’s zero in on the 3rd/4th fork:
Some noticeable wear…lets measure it…0.162” both sides:
Posted 05 August 2015 - 06:29 AM
I had the same pattern with the other two forks.
The FSM has us measuring these like I did but I cannot remember the limiting value..for this is one of the pages missing from the online 88/89 FSM and I don’t have my hardcopy in front of me as I’m writing it. Look it up and make the assessment on whether or not you want to replace the forks.
Ok, now go for your synchronizers. Clean them as an assembly first. Wipe them down and dry. Now mark the heck out of it. I tried to disassemble/reassemble them exactly the way they came out. But as long as you clock the outer ring, it can be reinstalled in three different positions 120 degrees a part.
Now take her a part carefully. There are two c clip springs holding those three little keys in.
Now clean each piece one by one and lay back in the pattern shown in the pics above. Do this for all three synchronizer assemblies. Honestly I think these are called ‘hubs’ in the manual but I call them synchro assemblies.
Now I’d advise replacing all of the synchronizers during your rebuild, but let’s inspect them:
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