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How to Rebuild an 88/89 KM132 Manual Transmission

STEP BY STEP W/PHOTOS

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#21 kev

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Posted 05 August 2015 - 06:31 AM

Take a gear and it appropriate synchronizer ring, mate them together and measure the gap:

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That is hard to see but the gap was 0.042”.   Per the FSM, this can be as low as 0.020”.   So not too bad, but let’s do the same measurement with a new ring:

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So that is 0.055”…in the brand new never installed condition.  That gap may reduce some once assembled.   Regardless, the rings should be replaced in the rebuild and I did replace them on mine even though the gap was within spec on all rings.





#22 kev

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Posted 05 August 2015 - 01:21 PM

Synchronizer Ring Inspection:

I’m just going to show some snap shots of each synch ring to show the minor differences I saw on 1st and reverse compared to the others.  If you buy the rings from manualtransmissionparts.com you will get two larger rings that are identical (for 1st and 2nd) and four smaller identical rings (for 3rd, 4th, 5th, and reverse).  But as stated earlier, I bought 1st and reverse from Mitsubishi to be consistent with the OEM configuration.  

1st:

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Note those indentations on the side.  They aren’t there on 2nd.

2nd:

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3rd, 4th, 5th:

I’ll lump these using 4th as an example…all three are the same.

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Reverse:

Note the different pattern on the inside!  There are larger gaps in the recesses.  I believe this is for ease in shifting into the reverse gear????

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#23 kev

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Posted 05 August 2015 - 01:25 PM

New Parts:

Let’s run thru the new parts quickly.  I don’t want to spend a lot of time on this for you may need more or less depending on the state of your transmission.    I replaced ALL the bearings including the needle roller bearings…well all except one that was NLA no matter how hard I looked.

Pretty easy to see what I bought from Mitsu vs aftermarket places.  Please note:  these P/N’s are for the 88/89 transmission…they may and WILL differ for the earlier models.  Consult your parts manual and take the time to understand it…the parts manual covers ALL KM132 trannies…including the trucks, etc…so you need to make sure you are looking at the right model and year!

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I bought this from manualtransmissionpart.com to use on the assembly of all of the roller bearings and movable parts.  You’ll see a lot of parts with green grease on them from here on out…this is what it is.   The supplier swore by this stuff…similar to an engine assembly lube but this stuff is much more viscous.

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I show a couple more new parts during the assembly phase too.  Specifically the countershaft shims that I bought after taking measurements.

#24 kev

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Posted 05 August 2015 - 01:31 PM

Transmission Assembly:

We are finally ready for assembly.  Everything is nice and clean, everything is organized, all or most of your new parts are acquired.
Let’s start with the synchronizer assemblies that should still be laid out nice and organized like shown earlier.    Use the grease and apply it thoroughly to the keys and reinstall the c-clips..one on each side, with the gaps staggered 120 degrees.   This takes a little thought to get them in sufficiently…see the photos but it is hard to explain until you actually do it:

(I’m showing 3rd/4th synch assembly…first pic is 3rd gear side, second is 4th…a c-clip per side with it center on separate keys)

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Now I lubed all of the outer cogs

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And install the outer ring to your marks.

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If you lost angular orientation, just make sure that you clock it with the large tooth on one of the keys…there won’t be a tooth to the left or right of the large one.  JUST MAKE SURE YOU PUT THE OUTER RING ON CORRECTLY…not only clocking it to the key, but in the correct direction.   The outer ring has chamfers that differ from side to side.  Hopefully you didn’t inadvertently flip it over during handling, etc.  This is why your notes, markings, layout area, method of disassembly/cleaning, etc. is so important.   If you aren’t sure, look over your notes, look over the pictures, etc.   Don’t put it on backwards!!!   Definitely don’t rely on the cartoon pics in the FSM or parts manual to direct you….it won’t be of any help.

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Now lube her up really good and install the new synchronizers.  Make sure you install the right ones…hence why I wrote all over these suckers.

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Do this to all three synchronizer/hub assemblies. I also went ahead and greased all of the needle roller bearings good:

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#25 kev

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Posted 05 August 2015 - 01:35 PM

Let’s now press some bearings on.  Starting with the input shaft.  Make sure you put the bearing on in the right orientation..flange away from 4th gear!  Use a good strong 3 jaw puller for this.

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Might as well install the c-clip now:

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Countershaft bearing inner race installation:

Let’s move on to installing the inner races of the countershaft bearings.  First off…mark the inner/outer races properly so you don’t mix them up!   You don’t what to inadvertently swap the outer races from their respective inner races.

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Starting from the harder side, slide the inner bearing down the shaft in the right orientation…cone out.   Note: I missed a pic here, this shows it already installed.   What I did was then slid on the old inner race with the cage removed….I used this as a ‘tool’.

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#26 kev

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Posted 05 August 2015 - 01:38 PM

Then slide a pipe over the shaft and contacted that old inner race.

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And hammer her home

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What will happen is that you will not only seat the new bearing in position, that old bearing race will be pressed in slightly as well…so pull that old race off via your puller

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Flip over and install the other bearing inner race…again cone out.   I used the same old inner race as a tool.  

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Input shaft flange prep:

Press in your input shaft seal (note the orientation)

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#27 kev

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Posted 05 August 2015 - 01:43 PM

Fully installed

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Ok, all of the little stuff is done with exception to the speedo gear and extension housing…we’ll do those later…let’s focus on getting the transmission gear train all back together and clear away some parts from your lay down area before they get mixed up.
Grab your main shaft.   Follow along with the photos…

Starting in reverse order from disassembly..we need to install the 1st/2nd gear assembly prior to putting the shaft in the housing.   Slide the needle roller bearing from the tail side of the shaft all of the way down to the shaft.

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And move on…everything just slides on now.

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Even though I greased the sync good, I still added some oil to the mating surface….probably overkill.

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Snych assembly…make sure you put it on in the right direction!

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Bushing:

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This is as far as you can go until we install the shaft:

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#28 kev

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Posted 05 August 2015 - 01:45 PM

Ok…to prevent this 1st/2nd assembly from moving around, I added a zip tie to keep things where they should be.   We will pull this off later on…just remember it is there!

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Ok now, slide the shaft in….It barely fits but it goes in…Posted Image

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Now to put your countershaft in…play with the angles…it fits, just take your time.

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Lay the housing on its side

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Here is what you will be seeing:

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#29 kev

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Posted 05 August 2015 - 01:48 PM

Now to install 3rd/4th gears:

Reach in thru the input shaft hole and slide on the needle bearing

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Then 3rd gear

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Now the synchro….remember we need to pull the ring.  Note that I labeled the hell out of her:

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Pull the ring

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Slide on the assembly thru the input shaft hole.

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Now work the ring in thru the pan hole, orient and align it correctly. Make sure you indexed it correctly on the key.  

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Note that I pushed the ring all of the way into 3rd gear.  I did this on purpose…to give us more room to get the input shaft in.
Ok, put on your snap ring…thru the input shaft holePosted Image

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#30 kev

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Posted 05 August 2015 - 01:51 PM

Now slide on the small needle roller bearing

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Input shaft installation:

It’s time to install your input shaft.   Note the notches on the side again.

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Now work it in there.

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Pic inside…note I slide the ring of 3rd/4th back to the neutral position.

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Well the work on the inside is done

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#31 kev

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Posted 05 August 2015 - 01:54 PM

Back to the input shaft side.  Install the outer race of the countershaft bearing…it slides right on.  Make sure you install the mating outer race to the inner on the cross shaft..note my markings made prior

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Flip around to the other side and install the other countershaft bearing outer race.  This will now support your countershaft nicely.

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Ok, pick up your input shaft flange cover.  I took a dab of grease used to hole the shim in position for assembly

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Set the shim in position on the grease.

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Now take the front shim for the countershaft…add some grease to it and put it directly against the outer race of the bearing.Posted ImagePosted Image

#32 kev

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Posted 05 August 2015 - 01:57 PM

Now slide on the flange….put a little oil on the input seal!  NO GASKET YET…we need to take some measurements

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If your studs are still in, spin a few nuts on them and snug the assembly down…not too tight.   I just used some bolts for this because I removed my studs to clean that flange better.

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What you want to do is snug up the fasteners and then back them off to finger tight.   We want to slide in a feeler gauge to check the spacing between the housing and the flange.   That hole for the shifter fork works perfectly for this.Posted Image

What you want is a gap of 0.000 – 0.004”.  Mine was within spec (.002).   If not, you need to buy a thicker or thinner shim…the larger one in front of the input shaft bearing.

Ok, pull off that flange.

If your studs have been removed, reinstall them.  I used some Loctite here. As well as my shifter fork fulcrum

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#33 kev

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Posted 05 August 2015 - 02:00 PM

I’m not too fond of relying on just the gasket, so I used some gasket sealer too.   This looks messy in the photos due to the reflection, but it is really a very thin coating.

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Lube that seal again with oil

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And install…7-9 ft lbs

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Now flip the tranny back over…time to work on the back end.

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First thing is first…get rid of that zip tie we put on earlier

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Now slide the center bearing on the shaft…it will go this far

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#34 kev

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Posted 05 August 2015 - 02:04 PM

So now what I did was used the components of the tranny to stack up and take the gap between the bearing and the threads.  You could use any old spacer if you wanted as well but the actual components work…note I didn’t put on the gears, just the bushings, etc.  We don’t want to load up those synchronizers themselves.    I simply want to use the large nut to install the bearing.

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Now using an old driveshaft to hold the main shaft (covered up to prevent debris from coming down on our nice clean transmission and a crescent wrench…drive it until the bearing is seated.   Take your time and use judgment, you don’t want to screw up the threads on that shaft.   It should install pretty easy though. You’ll feel when it is seated.

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Ok..good thing is the hardest parts are done.  Bad thing is that we need to shim this dang countershaft.   Here is where I made a fundamental error again.  I didn’t catch my error until almost fully assembled and I had to tear back down to address.   So I’ll try to talk you thru this.  

First thing you want to do is measure the ‘gap’ between the top of the outer face of the rear countershaft bearing and the housing.   I used some markings here.

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I added the original shim too.  I can see that it is undersized and fell into the hole….thus knowing I need a thicker shim.   Yours may be the opposite!

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I mounted a dial indicator on the end of the shaft.

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Now I set a flat block (my polishing stone in this case) over the housing and shim.  And measured the slop.  

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This told me the approximate ‘range’ of shim I need.  Basically the measured slop is in addition to the thickness of my old shim…in my case.  You want to shoot for 0.000” but not create a binding situation!   That’s difficult.  But the max slop you can have is 0.002”.  

However, here is where I screwed up!    Remember we just installed new bearings in our countershaft and I didn’t take account any potential compression by torqueing the nut at the end of the shaft.  You need to account for this and it is not easy!    What I did was bought four shims in the approximate range I measured.   Then I selected the one that was perfectly flat with the top of the flange.  I don’t own a depth mic so I had to improvise.

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I checked my slop again…it was negligible…thus I went with it.

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But again I didn’t take in account any compression during torqueing.  When final assembled, I checked my slop again and I was at ~.003” which was out of spec!  

To account for this; you can try to assemble the countershaft with the gear components temporarily and deliver the torque and then re-measure.  This will be difficult because the tranny cannot be locked into gear yet.    What I did was that I knew I was .003” out of spec so I had to select a spacer .003” over what I installed…of which was larger than my largest shim purchased.  So I had to order some more…coming from Japan….5 weeks lead-time!   Dang!   When they came in, I measured them, selected the one closest but not greater than .003 over the last one, tore the hole back end of the tranny back apart, swapped the spacer and reassembled.    I guess another avenue would have been to select a shim in the front side of the countershaft that we assembled earlier that was .003” over the one installed….but in either case, it resulted in rework.   What I’d do if I were you, is find out what thickness shim you need to achieve zero gap in the un-torqued condition and make sure you buy shims that go up to .003-.005” over.    Then assemble the rest of the gear train keeping in mind that you will have to recheck your countershaft slop once the countershaft nut is torqued and that it may result in tearing back down and going with a different shim.  

That is long and drawn out, but I hope you get the point.  You want close to zero slop but not binding!   When it was all said and done, I had ~.0005” slop but it derailed my project for a long time!

#35 kev

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Posted 05 August 2015 - 02:07 PM

Ok moving on.   Let’s install our reverse idler shaft now.  Put the nut on to prevent thread damage.

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Now the retainer

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Using some new bolts…don’t have to but I did, add some Loctite and install…11-15 ft-lbs

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Take off that nut

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Back to the main shaft.  Note that I used my spacer as part of the system to press in that center bearing….in doing so, it pressed onto the shaft in addition to the bearing…no big deal at all, so I left it there.   Install the roller bearing over it

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Next is the reverse gear

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Lube it up…..i didn’t show this on every photo prior but I did lube every mating surface

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#36 kev

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Posted 05 August 2015 - 02:10 PM

Synch assembly installed correctly

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And now 5th gear.

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There will be a lot of slop between the ID of 5th gear and the shaft…that is coming next

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This is for 88/89’s only.  There is this custom spacer with a split needle roller bearing around it.  I believe the earlier ones don’t have this custom spacer and it resulted in a loss of preload from the main nut causing failure.  This was a mod in 88/89.  

Install the two piece needle roller bearing on the spacer

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Stop here on this shaft until you get that countershaft torqued up and check your slop. I didn’t; so you may see the thick c-clip and main nut installed in later pics…ignore them!

Let’s move on to the reverse idler

Put on both needle roller bearings

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#37 kev

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Posted 05 August 2015 - 02:13 PM

And the gear

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Washer

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Nut…don’t torque it yet

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Back to the countershaft

Install the spacer

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Gear

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I put a little oil in here due to the splines

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Ok before you go further…remember that we need to install that one shift rod in combination with the big gear at the end of the countershaft!!!

#38 kev

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Posted 05 August 2015 - 02:16 PM

So, grab your 1st/2nd and 3rd/4th forks….lube them up and install them in the appropriate grooves in the synch outer rings.

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Might as well lock her in reverse and 2nd now.  Slide the 5th/reverse collar down to engage reverse

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And 1st/2nd down to engage 2nd

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Now…lube the lower shift arm hole closest to you in the tranny pan

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Put the first spacer in between the shift rods now that you have easy access…Lube it!

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#39 kev

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Posted 05 August 2015 - 02:19 PM

Lube the upper hole good

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Lube the appropriate shaft…it’s 1st/2nd .   It’s the one with the notch in it!

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Start it down the hole closest to the bottom of the pan

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Now slide on the gear of the countershaft

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And slide down the rod until it enters the holes closest to you in the forks

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Wiggle them down

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Ok, install your new countershaft rear ball bearing.

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Install your countershaft nut….I used a new one…still available from Mitsubishi.   Torquing the nut will install the bearing!

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#40 kev

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Posted 05 August 2015 - 02:23 PM

Tighten the nut down…see how it seated the bearing

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Now torque her down…the tranny is locked from earlier but you’ll need your restraint bar to hold the tranny.  116-137 ft-lbs

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Now before you go any further…re-measure your countershaft end play!   Make sure it is .000-.002”…preferably on the minimum side.   You might have to disassemble back down to that shim and install a different one!!!!   I don’t have pics of this but it is the same as before with the dial indicator.   I used a small crow bar under the large gear of the countershaft in the pan area to ‘flex’ the shaft to measure the end play.
Only when you are comfortable that you achieved end play within spec, should you move on to torqueing the other two nuts.   First the reverse idler;  15-43 ft-lbs

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Naturally it is a castle nut so you need to align a notch to a hole…while still in your torque range!

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Put in a new cotter pin…just like this so it doesn’t hit anything

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Back to the main shaft.   Install your large c-clip.    Note the manual tells you to measure this and select a c-clip of the proper thickness…unfortunately Mitsu has discontinued all of these suckers!   So I just had to reuse my original.  I honestly needed one a mil or so thicker but what could I do?  I didn’t want to try to fabricate one of these…may lead to more problems than reusing the original.

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You should have pretty much no slop in your gear train now.  Even though I measured a mil or so gap prior to installing the clip, I didn’t notice any slop after installing it…that is a good thing.    Remember that the nut goes on next and is added security.  I felt it was low risk by not having the exact right thickness c-clip.

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Now for the nut.   Mitsu discontinued it as well.  I bought an aftermarket one thru manualtransmissionpart.com, but it wasn’t the right one!  Note the lack of crimp collar.   So I didn’t use it, and reused the original.   If you were looking closely earlier, I used the new nut as a tool to seat that countershaft bearing!

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