DIY Transmission Re-Build Tips
I just finished changing...
1st,2nd,3rd, and 4th gear synchro's
1-2 and 3-4 hub and slider
2nd gear with clutch teeth
3rd gears (Evo8)
4th gears (Evo8)
4 main bearings
*** Things that are important to note ***
All the snap rings are ground to a specific thickness so that the bearings/gears have little to no play. IIRC the standard clearance between the snap ring and the gear/bearing was .0000" to .0035" My feeler gauge only went down to .002" Basically you dont want ANY clearance between the snap ring and the gear... My thoughts were that if you have play there it allows for axial movement on the shaft when the helical gears are engaged causing movement and loading in the axial direction resulting in poor gear contact and excessive load applied to the case. Mitsubishi sells these snap rings in 3 sizes (depending upon which snap ring your replacing) Mine were ironically all 1.51mm thick snap rings. YOU SHOULD REPLACE ALL OF YOUR SNAP RINGS. Yes this means you'll have to measure their thickness once they are removed and then order them from the dealer. I ordered my snap rings from Russell @ Bruce Titus Automotive (mitsubishiparts.net) Russell knew exactly what I was talking about and got me the right stuff the first time.
*** Modifications***
Double roll pin the shift forks and safety wire the roll pins. That Sh*& will never fail.
Oiling modifications... the only ideas I had were cross drilling and radiusing the openings. All the shops talk about their modifications, but I don't know what they do specifically.
***Observation***
I was examining my used 3rd and 4th gear clutch teeth (teeth that engage with slider and are part of the gear) I was thinking that the incomplete tooth shape was from damage/impact/wear....it turns out the NEW parts had the same incomplete shape. I brought in my transmission expert (10+years of transmission design experience @ New Venture/Process Gear) and he informed me that the teeth were forged on the gear and that they had a void which produced this incomplete shape. Basically, there wasn't enough material present at the time of forging and the shape wasn't compelte (think sand castle) He said the only way to fix this is to buy several of the gears and pick the best one. (Maybe a reason why tranny shops will sell you parts.... they'll sell you the ones they don't want to use?)
*** The FSM is extremely useful***
I had marked all the gears with a paint pen to get their orientation correct....but like always you confuse yourself and you try and remember which way some part went on. The FSM will clear all that up for you. The exploded parts diagram and install/removal procedure helps out.
*** USE A PRESS!!!***
I used a press...it was really easy. We have a lathe with a bunch of scrap steel /aluminum bits and tons of schedule tubing.... so I just had to scrounge around for the right ID/OD tubing to pressure on and remove gears. If you have a lathe... and a bunch of round stock you can make your own tools. It would've been really nice of me in hindsight to list the ID/OD of all of the tubing I used with their lengths for pressing on and removing gears.
*** WARNING ***
if you install the roller tapered bearing on the output shaft BEFORE you start pressing on gears (AS THE FSM STATES IS THE CORRECT ORDER) you will have to support the shaft with a large nut/washer as to not destroy the bearing. The bearing actually sits farther down than the end of the shaft...and if you press on a gear from the other side you'll crush the cage that holds the roller bearings. I had to use a nut the entire reassembly time and be very careful... PUT THE BEARING ON LAST!
***WARNING ****
DO NOT USE REDLINE LIGHTWEIGHT SHOCKPROOF IN YOUR TRANSMISSION!!!!! Regardless of what AMS says or Shep... this will separate into a fluid and a solid. The solid ends up clogging up your oiling passages within your transmission. TRUST ME... I'VE SEEN IT WITH MY OWN EYES. Team Rip Engineering (TRE) has said this before and HE IS RIGHT. I only had the lightweight in for MAYBE 2k miles. It had completely clogged the 5/R oiling passage underneath the sleeve.... not allowing lubrication to 5th gear or Reverse!!!!!!!!!! I'm now using the Redline Cocktail 2qts of MT90 and 1qt of MTL.
***WARNING***
transmission rebuilding n00bs. When you're pressing on a gear that has an unseated synchronizer assembly against the hub you have to make sure that it is seated properly in the gear (four prongs) otherwise you'll crush the synchro! This may not make sense now, but I think you'll get two/three opportunities to screw it up! lol I remember seeing kids in my transmission class do it.... amazing! Don't worry though, the FSM warns about this in the procedure... so if you forget... Mitsubishi has your back.
***NOTE***
I think HI-RES pictures of new parts will be helpful for people to realize how damaged their parts actually are. These mitsu parts aren't perfect.
*** NEXT TIME I WOULD...***
have my gears shot peened and have my Hubs REM treated. The factory hubs still had machining burs on them and the gears didn't look to be that well post processed. Poor Q/C IMO. I also would've ordered all of the snap rings before hand...and just bought all three sizes. They are about a dollar a piece and would cost a total of 20 bucks to order all of them and use what you need. Dan Bushur told me to just "reuse" what was on the shaft before because they are precision ground fit. IMO... that's just wrong. Order a new snap ring.
I also think that TRE has a lot of good modifications that they do to the gears that the pictures hint to. I think that I need to pick Jon's brain.
I was going to post all the pictures, but it's SOOO redundant of the FSM that it's really unnecessary.
1st,2nd,3rd, and 4th gear synchro's
1-2 and 3-4 hub and slider
2nd gear with clutch teeth
3rd gears (Evo8)
4th gears (Evo8)
4 main bearings
*** Things that are important to note ***
All the snap rings are ground to a specific thickness so that the bearings/gears have little to no play. IIRC the standard clearance between the snap ring and the gear/bearing was .0000" to .0035" My feeler gauge only went down to .002" Basically you dont want ANY clearance between the snap ring and the gear... My thoughts were that if you have play there it allows for axial movement on the shaft when the helical gears are engaged causing movement and loading in the axial direction resulting in poor gear contact and excessive load applied to the case. Mitsubishi sells these snap rings in 3 sizes (depending upon which snap ring your replacing) Mine were ironically all 1.51mm thick snap rings. YOU SHOULD REPLACE ALL OF YOUR SNAP RINGS. Yes this means you'll have to measure their thickness once they are removed and then order them from the dealer. I ordered my snap rings from Russell @ Bruce Titus Automotive (mitsubishiparts.net) Russell knew exactly what I was talking about and got me the right stuff the first time.
*** Modifications***
Double roll pin the shift forks and safety wire the roll pins. That Sh*& will never fail.
Oiling modifications... the only ideas I had were cross drilling and radiusing the openings. All the shops talk about their modifications, but I don't know what they do specifically.
***Observation***
I was examining my used 3rd and 4th gear clutch teeth (teeth that engage with slider and are part of the gear) I was thinking that the incomplete tooth shape was from damage/impact/wear....it turns out the NEW parts had the same incomplete shape. I brought in my transmission expert (10+years of transmission design experience @ New Venture/Process Gear) and he informed me that the teeth were forged on the gear and that they had a void which produced this incomplete shape. Basically, there wasn't enough material present at the time of forging and the shape wasn't compelte (think sand castle) He said the only way to fix this is to buy several of the gears and pick the best one. (Maybe a reason why tranny shops will sell you parts.... they'll sell you the ones they don't want to use?)
*** The FSM is extremely useful***
I had marked all the gears with a paint pen to get their orientation correct....but like always you confuse yourself and you try and remember which way some part went on. The FSM will clear all that up for you. The exploded parts diagram and install/removal procedure helps out.
*** USE A PRESS!!!***
I used a press...it was really easy. We have a lathe with a bunch of scrap steel /aluminum bits and tons of schedule tubing.... so I just had to scrounge around for the right ID/OD tubing to pressure on and remove gears. If you have a lathe... and a bunch of round stock you can make your own tools. It would've been really nice of me in hindsight to list the ID/OD of all of the tubing I used with their lengths for pressing on and removing gears.
*** WARNING ***
if you install the roller tapered bearing on the output shaft BEFORE you start pressing on gears (AS THE FSM STATES IS THE CORRECT ORDER) you will have to support the shaft with a large nut/washer as to not destroy the bearing. The bearing actually sits farther down than the end of the shaft...and if you press on a gear from the other side you'll crush the cage that holds the roller bearings. I had to use a nut the entire reassembly time and be very careful... PUT THE BEARING ON LAST!
***WARNING ****
DO NOT USE REDLINE LIGHTWEIGHT SHOCKPROOF IN YOUR TRANSMISSION!!!!! Regardless of what AMS says or Shep... this will separate into a fluid and a solid. The solid ends up clogging up your oiling passages within your transmission. TRUST ME... I'VE SEEN IT WITH MY OWN EYES. Team Rip Engineering (TRE) has said this before and HE IS RIGHT. I only had the lightweight in for MAYBE 2k miles. It had completely clogged the 5/R oiling passage underneath the sleeve.... not allowing lubrication to 5th gear or Reverse!!!!!!!!!! I'm now using the Redline Cocktail 2qts of MT90 and 1qt of MTL.
***WARNING***
transmission rebuilding n00bs. When you're pressing on a gear that has an unseated synchronizer assembly against the hub you have to make sure that it is seated properly in the gear (four prongs) otherwise you'll crush the synchro! This may not make sense now, but I think you'll get two/three opportunities to screw it up! lol I remember seeing kids in my transmission class do it.... amazing! Don't worry though, the FSM warns about this in the procedure... so if you forget... Mitsubishi has your back.
***NOTE***
I think HI-RES pictures of new parts will be helpful for people to realize how damaged their parts actually are. These mitsu parts aren't perfect.
*** NEXT TIME I WOULD...***
have my gears shot peened and have my Hubs REM treated. The factory hubs still had machining burs on them and the gears didn't look to be that well post processed. Poor Q/C IMO. I also would've ordered all of the snap rings before hand...and just bought all three sizes. They are about a dollar a piece and would cost a total of 20 bucks to order all of them and use what you need. Dan Bushur told me to just "reuse" what was on the shaft before because they are precision ground fit. IMO... that's just wrong. Order a new snap ring.
I also think that TRE has a lot of good modifications that they do to the gears that the pictures hint to. I think that I need to pick Jon's brain.
I was going to post all the pictures, but it's SOOO redundant of the FSM that it's really unnecessary.
Nasty,
The solder in the case is no different than using plastigauge on a main/rod bearing right? you put the solder on the end of the bearing and assemble the case. measure the crushed solder thickness and shim accordingly. I haven't done this yet, so I'm asking you if this is correct.
Also how did you quantitatively determine that the input shaft bearing was wasted?
The solder in the case is no different than using plastigauge on a main/rod bearing right? you put the solder on the end of the bearing and assemble the case. measure the crushed solder thickness and shim accordingly. I haven't done this yet, so I'm asking you if this is correct.
Also how did you quantitatively determine that the input shaft bearing was wasted?
Very good stuff here. Anyone have the FSM that they can email or fax me? I am wanting to start on my tranny and transfer case this weekend. Again, thank you all for helping make this article so amazingly insightful. This will need to be a sticky I think once it gets some more info and specs/part numbers. I don't have a problem hosting the files on my site in order to post it here and keep it alive for everyone to make use of.
I am going to be pulling my 6sp trans in the next week. I am having trouble with 3/4gear. I just picked up a donor 6sp trans. The teeth are sheered off on 4th gear. Was told it was 1000 bucks just for that part. If anyone has any thing as far as detailed pics or a service manual that could help me out. Please PM me. Thanks.
When I called about mine i was told that entire shaft had to be ordered so that was 1000 bucks for the part alone. So estimate with parts and labor just for the rebuild was over 2 grand. I was NOT HAPPY
Evolving Member
Joined: Mar 2009
Posts: 182
Likes: 8
From: Seattle
Concur with doubling the roll pins in the shift forks, have seen these things back out on a 5 speed. You just get the smaller size that fits inside the existing pin. Keep in mind it's a metric size.
If it's just a small single chip in a gear like the OP you can take a carbide die grinder and knock the sharp edges off the chip and it will make the ticking noise go away. You can save a gear like this if there's minimal initial damage.
like this picture if it was just the smaller chip it would probably be okay
If it's just a small single chip in a gear like the OP you can take a carbide die grinder and knock the sharp edges off the chip and it will make the ticking noise go away. You can save a gear like this if there's minimal initial damage.
like this picture if it was just the smaller chip it would probably be okay
Wow, I wouldn't be happy either. My reverse idle pulley fell out and screwed up my input shaft, so I'm wondering if that carbide die grinder mentioned by NWM_Tech would help me save it. Damn...
Just waiting on the pdf file so I can tear into this bad boy 
jerry@tripscustoms.com
jerry@tripscustoms.com