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17,431 Posts
Discussion Starter #1 (Edited)
This is not meant to be comprehensive, but rather a pragmatic approach to how I go through one of these transmissions. I will try to list tool sizes and thread sizes when I remember

These are honestly pretty easy to fix if you follow a few key steps. I will bold areas where you should be careful.

There will be several parts to this, this is just the start. I will add to this thread as I go through the whole process.

Before I get started, please know you do not need to be rough on one of these transmissions to get it apart. If you find you are really having to handle something roughly you need to stop and think. Check for missed bolts, dowels, things slightly out of mis-alignment, etc.

These all don't necessarily need to be in this exact order, but use some common sense.

Step 1
The first thing I do is pickup the transmission using a engine hoist by the bellhousing holes to get ALL the oil out of it. If you pick it up this way and let it drain for 10 minutes there will be only an ounce or two of fluid left.

I had this trans apart a few weeks ago to take the counter shaft oil guide from it for my main trans, and noticed it was very dirty and had water and rust in it. I put 2 quarts of really low mile RP synchromax in it and noticed it came out a LOT dirtier than it went in. More on that later.

These transmissions are heavy, so I use the hoist when possible. Easier on the back.

Step 2

If your trans is really dirty on the outside take it to the local car wash and use the engine clean setting on it, blast off as much dirt and grease as you can. The cleaner it is when you take it apart the less stuff falls in it. Think of an open trans as an open wound. Keep it clean. Put it back together sitting loosely if you have to leave it sit out.

Step 3
Go over any bolts that look questionable. The trans mounts were super tight and my impact really got a workout. Luckily only one pulled the threads out, two I could save. You can see my super trick tap... (used this to cleanup a block thread with the heads still on):

Trans mount bolt holes are 12mm by 1.25 pitch.

Two cleaned up great, one had the threads come out completely.


If you need to repair a t-case hole I STRONGLY suggest using a drill press to be sure the hole is plumb. Very easy to get one in at an angle.

Going over the block to trans holes (also m12 by 1.25)

I did the t-case holes as well, they are m12 by 1.75. I also did the side brace mounts which are m10 by 1.5 and the slave cylinder mount, which is m8 by 1.25. Use lube when tapping. Clean the threads when done. I like to do all the bolt holes before starting because you will know if the case has serious damage and any metal mess when get cleaned up before cracking the trans open.

At this point you want to remove the shifter detents, reverse lockout, and the reverse light switch:

You will need a 24mm wrench for the big can looking thing, which is the reverse lockout. You will need a 13mm socket for the shifter guide above that and you will need a 22mm socket for the shift detent above that.

The reverse switch is 24mm.

All of these parts are set with blue loctite, so they may take some effort to remove. I have seen the threads worn quite a bit on these when removing them sometimes. Work them in and out and use lube if they get stuck. The trans really isn't all that thick there, but I have never broken the case yet.

More continued...

All of my posts and images in this thread are copyright Chris Behnken 2016
17,431 Posts
Discussion Starter #2 (Edited)
once that is out of the way, remove the 4 bolts holding the shift tower in.

Remove the two bolts holding the L-shaped bracket that moves the shifter up and down (side to side in the car, not pictured).

You will need to carefully work the square shifter base off the trans.

It will be rtv'ed if the trans has been apart before or will have the anaerobic sealant on it if its never been opened or someone used the correct stuff last time. It will be tough because there are two dowels, so you can't twist it. I don't advise being too rough on it because there is a spring inside you can damage. You can use a small chisel and work it loose a little at a time on each side. Be careful not to mar anything up. Any high spots will need to be filed down and any low spots are potential leak spots. Small nicks don't cause problems if they are sanded smooth in my experience.

Carefully work this piece up and out:

The spring will usually fall off, mine stayed on because I greased it recently, installing it.

Here is what you have now:

You can see the original anaerobic sealant the last guy to touch this didn't even bother removing before using a bunch of rtv :(

Now we are moving on to the dowels and bolts...

Note the dowel pin. I always hammer them out before pulling the case apart. This keeps you from beating on the case and damaging the shift fork rails. The factory did us a favor and gave an access hole:

Tap it out with a punch.

The six speed has a bellhousing bolt INSIDE the bellhousing. if you can't see it the clutch fork is in the way...

17,431 Posts
Discussion Starter #3 (Edited)
The bellhousing bolts are 10mm headed.

Remove the clutch pivot ball because its probably worn out. (17mm IIRC)

If your ball looks like this replace it, they are like $4.00. It will impact your clutch pedal performance.

There is another dowel on the other side:

Remove ALL the bellhousing bolts:

Depending on how much RTV the last guy used it may be hard to get the bellhousing to come off. Tap on the safe spots (they are rectangular spots on a couple ends of the case) until you get it to crack loose. Use a rubber mallet or block. Work your way around evenly. Don't be tempted to put a chisel in there... Do not beat the crap out of it. Try another side if you can't get it loose. Make sure you have ALL the bolts out. Lift it straight up to avoid damaging the input shaft internal seal.

You should be greated with this:

and this:

A filthy bellhousing. Notice the clean line?? That is where the new fluid reached... No one can say synchromax doesn't have enough detergent... that was just sitting still a couple weeks.

I already notice a broken oil tank:

Seems pretty common, I am going to leave it out going forward.

After some work the bellhousing is pretty clean inside and out:

I use mineral spirits and brake cleaner. Try not to get harsh chemicals inside the input shaft bearing. Oil all the races when its cleaned up and the inside of the input shaft bearing. You don't want the input shaft bearing to dry out as it is unavailable now, except the last few NOS ones.

looking much better (note the counter shaft bearing race oil guide is missing, I used it for my other trans, ninja is supposed to be sending one):

Next we will separate the midcase. I probably will have an update in the next 2 days. We will continue after that, getting the end case off, and breaking all the shafts down.
17,431 Posts
Discussion Starter #4 (Edited)
Inspecting the input shaft reveals some pretty bad damage to the area the input bearing rides. I suspect a machines shop could fix this by machining it down and pressing on a sleeve, but I have a spare, so I will use that. I would not use this as is because its going to make a lot of noise and destroy the input bearing. Careful inspection of the input bearing revealed it was okay.

Remove the input shaft plug by either very carefully prying it out or driving a sharp pic through the center and prying it out. The pick method is safer to the transmission case, but if you are very careful sometimes you can save the plug if you pry it out from the edge.

You need to remove the 4 bolts holding the detent plate in now. Don't remove them completely, because once you break the sealant loose springs make it want to pop out.

Carefully pry the plate loose, try not to damage the sealing surface. In cases like this I always want to pry on the top side, because damage to the top is less likely to leak than the bottom.

Place a magnetic tray under the detent plate if you have one to catch things an finish removing the bolts.

Use a magnet to pull out any detent balls that stayed in.

Remove all the 13mm headed bolts (The German heritage of the trans shows through since this does not use Japanese spec bolt heads) Leave the side facing bolt in, that holds the reverse idler bracket in.

Knock out the dowels:

With all the bolts removed, flip the trans so the end case is on the bottom and using a mallet knock it loose from the sealant. I usually try hitting the front diff area as it seems to come apart easily then. Use a RUBBER Mallet.

17,431 Posts
Discussion Starter #5 (Edited)
You now need to slightly twist the mid housing so it clears the 1st gear and then pull up:

The mid housing will come out now, you can see how truly disgusting this trans is inside:

You should now see the input shaft, counter shaft, vcu/center differential assembly, and the end case.

Cleaning the case with a brass brush and solvent:

I hate rtv...

Keep cleaning, use a screwdriver and twist a bit to remove the sealant in the bolt holes:

Getting cleaner:

Clean and installed on the bellhousing to keep it clean:

17,431 Posts
Discussion Starter #6 (Edited)
Engage two shift rails/gears at once so the input shaft can't spin:

You need to use a 12mm allen socket to remove the input shaft bolt. Its 70 ft/lbs and has loctite, so an impact wrench makes it much easier.

Now this is how I like to press the input shaft out of the bearing in the end case. I use a fairly large puller. Loose the bolt a few turns. Press it loose, then loosen it more turns and press it all the way. not having the bolt all the way loose at first will help prevent damaging the threads in the input shaft. I have never found one of these super tight. If you have a big enough press you could do that, but I like this way because nothing is trying to fall out.

You can see the bolt removed now and the input shaft is pressed all the way through:

You will now find the shift rails are bound up, keeping the case on. Wiggle the case off the shift rails.

Pull the case off.

Hopefully your trans is not this gross.

17,431 Posts
Discussion Starter #7 (Edited)

You can press synchro rings against the gear cones and measure the wear. if there's no gap, like this 2nd gear then its worn out:

3rd is also gone (on the input shaft)

What the forks look like cleaned and set in the case for safe keeping.

The bearing races in the end case look pretty bad. The circular discoloration doesn't bother me too much, but the horizontal pit type marks do. I have spares I will use.

Using a bearing race puller is the easiest way to pull races.

Grime and the counter shaft oil guide.

Guide removed, yummy.

17,431 Posts
Discussion Starter #8
Pulling the other race. don't be afraid to tighten the pulling tool with a wrench, this one is hard to pull because there were no shims under it.

A couple sharp wacks usually removes it.

The input shaft bearing feels AWFUL. Growls just spinning by hand, feels very rough. To remove it you have to remove the reverse idler and its two bolts.

Once you remove the two bolts the idler bracket comes out easily.

Lift the idler out.

You have to remove the bearing retainer at this point. 5 4mm bolts, sounds simple? Well they are counter sunk allen bolts, with loctite, made from cheese. You will almost always strip some. Instead of a 4mm hex I drive a T27 torx in right away, hard.

Heat around the bolt heads can help. Don't melt the plastic seal on the bearing if you are trying to save it.

Once you get them out remove the retainer.

Flip the end case over, use a 24mm socket or similar to knock out the bearing. It is not a tight press fit.

17,431 Posts
Discussion Starter #9 (Edited)

Driving the races back in.

I use a sealing and bearing driving kit from harbor freight. The races often want to go in crooked pay attention. You can damage the case. It should not take the hammer of Thor to install these. If it gets crooked, straighten it by tapping on the high side. Once it is straight it will go in fairly easily. Keep driving it until you hear the tone change, then you know its all the way in.

Don't forget to install the original shims. You can use the solder procedure in the manual to verify the end case input bearing preload at this point if you want. I am of the school of thought that the shims are designed to make up for production tolerance in the aluminum castings, the bearings and races are made to such a close tolerance they should not affect pre-load.

I don't think re-shimming is important unless you change the counter shaft or one of the case thirds. Its up to you. Follow the manual if you want to.
17,431 Posts
Discussion Starter #10 (Edited)
Really nice old end case input bearing. I used a pic to remove the plastic seals. By design sealed bearings are supposed to let transmission oil in and keep dirt out.

You should have felt it. Was like a grinding stone inside. Would've not been good at 7000 RPM.

You may be thinking, hey forest you destroyed those end case bearing retainer bolts using a T27 torx! What can I do now?

The bolts are actually not hard to get all at.

6mm by 1.0 thread. Counter sunk/flat top allen. 20mm long. Grade 10.9

$0.65 at the local ace hardware. Replace them all, even if you save the originals.

17,431 Posts
Discussion Starter #11
Putting the new screws in and the bearing retainer.

You need an inch pound torque wrench for this because the bolts are only 7 ft/lbs. 84 inch pounds. If you use a wrench that starts at 5 ft/lbs it is not very accurate at 7.

Use loctite 242 "blue" on the bolts.

Set the idler back in. oil the needle bearings.

There are 2 different length bolts for the idler. The longer one goes through the side.
Blue loctite and 18 ft/lbs.

All back together. Spin the reverse idler to be sure its smooth.

Sit the end case on the midcase, carefully over the rails and put two bolts in. This just keeps dirt out and now I have a complete, clean, transmission case assembly. That's why I clean the cases first, now I have a clean workspace, and can focus on the shafts.

The shafts will be next.
17,431 Posts
Discussion Starter #12 (Edited)
OK, I promised some updates. Here is the disassembly of reverse from the counter shaft. I am also showing how to modify your press to be wide enough to accept the gear set. If you have a bunch of really good press plates or a bigger press you may not need to do this. I do not accept any liability for anyone modifying their press or shop equipment. If I were to press something with a heavy press fit I take my spacers out and make the press table stock width. Keep in mind the wider you make your press table the more stress there is on the press pins. I have used this successfully on a harbor freight 12 an 20 ton press, but make no guarantee this will work for you or be safe. To avoid that I am not going to explain any further.

Drill two holes of approx 5/8" for your long 5/8" bolts. Bolt it together and THEN cut the supports. This assures your bolt holes line up.

Hopefully you do better than me and make up spacers from better than random junk I had laying around. I have included the level to show the gap that can be achieved. Assemble the table on a flat surface, you don't want it warped.

17,431 Posts
Discussion Starter #13 (Edited)
To do this job properly or at least use the techniques that I show you will need a bearing splitter of approximately 8" or larger size.

I am blessed to have a OTC 952 that I have used and abused for years. It is very thin towards the center and this is great for pulling gears by their engagement/dog teeth. It also makes it easy to pull bearings off by their inner race in a lot of situations and be able to re-use them. Never pull or press a bearing by its cage, only use the inner race.

Here is basically how you set it on the press table, I normally put it on top of the press plates.

I also include pillow under the press in case something gets away from me it may not be damaged.
17,431 Posts
Discussion Starter #14 (Edited)
Now, we want to put the counter shaft, reverse side up into the bearing splitter. I am pressing it by the bottom of the hub:

Be VERY careful to not be touching any other gear teeth or they can quickly be ruined. We are also not trying to grip it by the slider (synchronizer sleeve), by the hub.

A view from the top:

You can just pull the gear and bearing off first if you want, but it just makes it harder. The synchronizer balls and springs want to fly out then and you still need to press the hub off. When I do this stuff I usually press as many things off at once as I can, but press one thing back at a time when I re-assemble.

My press arbor will fit through the counter shaft, but I like to use a seal driver between it and the shaft because the soft aluminum will not damage things if it gets a little mis-aligned at first.

You need to be pressing on the shaft itself, INSIDE the diameter of the bearing inner race. If you catch any of the bearing race you will destroy something.

It will take a mild effort to break the press fit at first. You can see the shaft splines pressing out of the hub below. If anything starts to get harder after the first crack loose then back off and make sure everything is re-aligned. It should get easier as you go.

Continue to press, be mindful that the counter shaft will fall out at some point. Keep your hand under it and press slightly upward, it is a little heavy. When it falls through you can grab the hub/synchro assembly, gear and bearing:

Do not use RTV, especially not like the last guy that had this apart. How long do you think this needle bearing would last with the oil hole 100% plugged?

That's all RTV I pulled out of the shaft!

All the reverse parts:

Reverse is beat up, but still usable. If it is ground down so far that there is no back taper to the engagement teeth it may fall out of gear. This one in a perfect world would have the gear and synchronizer hub/sleeve replaced, but that is about $600-700. If this was a 1-6 speed gear it should be replaced. They get like this when the reverse lockout stops working and people grab reverse instead of sixth. There should be an extra "hump" you have to get over to go past 6th and get reverse.

It is hard to do and photograph at the same time, but you need to press the synchro ring against the gear and measure with a feeler gauge.

This gear to synchro blocker ring measurement is .041 inches, which is acceptable. If it was under .025 to .030 I would replace it. You also want to inspect the synchronizer friction cone surface on the gear for any discoloration or grooving. Place the synchro on the gear, try to push them together and turn the synchro independent of the gear. It should lock together and hurt you if you try to turn it. If it slips something is worn.

This entire reverse set once cleaned is okay to re-use.

This is why if I am rebuilding a trans I break down all the gears, even if they look ok. Had I not seen that huge blob of RTV the reverse needle would've burned up and wrecked the trans. Reverse spins constantly in our transmissions.

Be wary if someone says they just had 2nd or another single gear replaced in a transmission. You can't tell the condition of a transmission without fully breaking it down.

I am certain I will find my gears blocked up like that.

The next thing I like to do is fully clean all the pieces and bag them, so they are ready for assembly later. Next we will pull 1st and 2nd off the shaft.
17,431 Posts
Discussion Starter #15 (Edited)
Two of my friends, a little oil can for oiling new parts, and mineral spirits for cleaning parts. You can hit them with brake cleaner as well if you are anal.

Loading the springs and balls back in:

You need to be sure to get the spring inside the little dimple drilled in the hubs. Then place the ball on top the spring. Then use a small flat blade screw driver and push down and in until it snaps in.

Once you get all three balls and springs in, sit the synchro on top to help keep things together. Oil everything with your favorite transmission fluid (using redline d4 myself at the moment believe it or not, GL4 rated, nice and thin for cold temps).

Sit the gear on right away, reverse tries to jump apart:

The opposite side where you can see the snap ring that prevents shifting the wrong direction out of reverse:

Now reverse is clean and ready to press back on later.

1994 Mit 3000gt VR4 6spd
1,298 Posts
extra reserve for you chris....just in case theres extra extra extra extra to add.

One fix at a time
7,839 Posts
This is a really well thought out guide. I had a friend show me quite a few things on rebuilding our transmissions. Some things were by mouth and others he showed me so it's good to review it all step by step. I have a few transmissions to go through and assess the damage or part out so this is good. We're losing quite a few good transmission builders.
17,431 Posts
Discussion Starter #19 (Edited)
You can press 1st gear, 1st bearing sleeve, 2nd gear, 1/2 synchronizer assembly, hub and slider, and the counter shaft bellhousing side bearing all off in one shot:

Put your bearing splitter just under 2nd gear. Be SURE you can still rotate the shaft slightly. You don't want your bearing splitter touching the gear teeth that is part of the counter shaft when you press or you will scar them. Once again I use an aluminum seal driver to protect the shaft.

It will take a bit more pressure to press all this at once, but it shouldn't be insane amounts. Here you can see it starting to come apart:

The press arbor easily goes inside the bearing:

This will press quite a distance before the counter shaft comes out. Be sure to catch it.

Now the counter shaft will be free. Notice the oiling holes are plugged on this as well:

Unplugged, but still filthy:

All the parts pressed out of the shaft:

Not looking good, lol:

First gear, shows some wear, but as we don't usually abuse 1st too much it should be okay to re-use with a good cleaning and new synchro components.

1st Synchro is about half worn out and very dirty. I will replace it.:

Hub springs are broken. I have broken down three of these six speeds and every one had broken hub springs. When they break you have basically no synchronization. I think they break from people shifting too hard and powering through grinds:

17,431 Posts
Discussion Starter #20 (Edited)
the 2nd gear side of things isn't looking much better. Notice the bits of springs:

Whoah, not looking good:

Worst synchro I have ever seen:

Synchro sleeve is blunted pretty bad, I have a better spare:

Here is the synchro on top of 2nd gear. Notice zero gap between the teeth on the outer synchro and the gear. This means the synchro is toast. Also notice the engagement teeth on 2nd are really bad.

Piece on the right is a pretty burned up inner synchro from 2nd. The left one is a better spare I have and will use.

Time for some new parts. Toyota part number for a mark 4 supra v160 trans that is the same as our 1/2 friction rings.

What a new friction ring should look like:

A better 2nd gear. It has taken some hits over its life, tomorrow I will deburr it and post some cleaned up pics.

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