1g Transmission internals swapped into a 2g case by Tim Zimmer (twicks69) 11/22/19
This article was originally posted by @twicks69 on 11/22/19 and he was kind enough to allow us to add it to the Tech Article Section for a useful tool to others.
Thank you Tim!
To start out, this swap is not as short and simple as just swapping a bellhousing.
The transmissions need to be completely torn down.
You will need to use the 2G DSM transmission case (the bellhousing, gear cluster case section, bearing plate (only interchangeable part), and 5th gear set cover (the early 5th covers are different than the 1991.5-1999 covers so that is why I am saying you need a matching set; it will be obvious when disassembled and there is a different style 5th gear set in the 1G transmission; if they are the same gear set dimensionally, then you can use either 5th gear cover).
Now, it is also going to depend on the internal components installed in either one as for parts interchangeability. The reverse idler gear and shaft is specific to the 2g transmission case and you will need to use that. The reverse idler gear lever should be the same.
The shift selector assembly (not the external lever; the internal shift selector tab and cage that actuates the shift rails) has two variations; a 1989-1991.5 version with a longer protruding tab from the cage, than the 1991.6-1999 style shorter tab. The cages are the same; the selector tab length was long on early stuff (weaker shift rails) and shorter length on later stuff (stronger shift rails).
Now, the shift rails are numerous variations. IF the shift selector is different length, you will need to use the matching rails to the selector -- BUT, there is a catch.... The 2g 3-hole 3rd/4th shift fork is different than the 1990-1992.5 2-hole 3rd/4th shift fork; which also has a different roll pin orientation and the shift forks are not interchangeable on the 1989-1991.5 (weak rail ends 2-hole shift fork) and 1991.6-1992.5 (strong rail ends 2-hole shift fork) vs. the 1992.6-1997 (strong rail ends 3-hole shift fork and 5th/rev shift fork pin orientation faces into gear) and 1997-1999 (strong rail ends 3-hole shift fork and 5th/rev shift fork pin orientation faces away from gear). So, if the built 1G transmission has the same shift selector length as the 2g transmission, then you can swap over the 1/2 and 3/4 shift rails, but you will need to confirm orientation of the 5th/reverse shift fork roll pin location before you just swap over the 5th/rev rail as you will need to use the matching shift fork otherwise.
The shift lever assembly on the outside of the transmission, you will need to continue using the 2g style "L" shift cable bracket that bolts onto the transmission, and the "L" style shift lever that goes in to the transmission that actuates the shift selector internally. There are numerous lever variations, and you NEED to use the matching "L" style levers on a 2g DSM with the matching shift cable bracket.
Internally, you will need to use the 2G DSM final drive, as it is supposed to be a W5M33-2-MUZT transmission which has a 57-tooth final drive ring gear and matching pinion gear shaft (they are a matched set). You will not be able to use the 1G front diff ring gear and output pinion shaft unless you do 2 things which are change your speed sensor to a 95-96 style (to get your cars speedo correct) and the transfer case final drive is 1.090 on 1991-1996.5 vehicles and the 97-99 are 1.074 ratio -- you would have to change tcases to match the final drive if you are using the 1G DSM 58-tooth ring and pinion gearset in your trans.
The gearset will need to be swapped over as a matched set of input shaft, intermediate shaft and center differential assemblies -- the gear tooth profiles need to match up. You will need to use the matching shift fork and shift rail for 3rd/4th to the swapped gearset (again, referring to above, you will need to confirm the shift selector length and shift rail end dimensions -- early style will not work, you will need to purchase the correct shift fork then for a 1991.6-1992.5 or an Evo 3 3rd/4th shift rail and grind it down to fit). The 5th gearset again needs to use matching gears, hub and slider assembly (2 variations -- small and large synchro diameter), and shift fork (4 variations; but the big thing is if the 1g has an early gearset it will have an aluminum shift fork and the rail will be an early style with the roll pin facing the gear for the 5/R fork; vs. the later 1991.5-1999 style gearsets use the large diameter hub and slider and steel 5/R fork); making sure that again, you confirm the orientation of the roll pin vs. the shift rail used and use a matched set.
The 5th gear cover needs to match the gearset. The 5th gear covers again have 2 variations, one that only fits a small diameter hub and slider assembly, and one that only fits a large diameter hub and slider assembly. You need to use the matching cover. AS WELL, the black case plastic oil guide....You CAN use either the 2g oil guide or the 1g oil guide (only if it is a 1991.5-1992.5 with the later version 5th gearset and cover -- the 1990 oil guide does not work with the later year 5th gear covers) in your 2g transmission case.
The output shaft and needle bearing, you should be using a 23-spline output shaft. I would suspect that most rebuilt transmissions do not have a 22-spline output shaft installed, but you can tell the spline count by counting, or by simply seeing the spline cut profile at the portion that is exposed to the transfer case. The 23-spline and 22-spline have a different profile on how they are cut as a quick reference.
You will need to swap over the bearing races to match the bearings used, then you will need to check the bearing preload / endplay values before swapping in shims. You will use 0.062" solder for the input shaft, intermediate shaft and front differential and 3/32" solder for the center differential and output pinion shaft (without the shims in place -- use the solder in place of the shims for this testing to get the zero value to determine bearing preload and end play values to select the proper shim).
Well, i think that this should help any of you through most of it. Be sure that any shop you are dealing with are not retards, because there are plenty of places that can't handle this. I know this stuff with my eyes closed.
Good luck on the projects!
Tim Zimmer
TMZ Performance
[email protected]
Tim Zimmer
1999 Mitsubishi Eclipse GSX
www.tmzperformance.com
Drag Race Build 7K 12 1 76
1999 Mitsubishi Eclipse GSX
9.499 @ 155.00 · 2G DSM
This article was originally posted by @twicks69 on 11/22/19 and he was kind enough to allow us to add it to the Tech Article Section for a useful tool to others.
Thank you Tim!
To start out, this swap is not as short and simple as just swapping a bellhousing.
The transmissions need to be completely torn down.
You will need to use the 2G DSM transmission case (the bellhousing, gear cluster case section, bearing plate (only interchangeable part), and 5th gear set cover (the early 5th covers are different than the 1991.5-1999 covers so that is why I am saying you need a matching set; it will be obvious when disassembled and there is a different style 5th gear set in the 1G transmission; if they are the same gear set dimensionally, then you can use either 5th gear cover).
Now, it is also going to depend on the internal components installed in either one as for parts interchangeability. The reverse idler gear and shaft is specific to the 2g transmission case and you will need to use that. The reverse idler gear lever should be the same.
The shift selector assembly (not the external lever; the internal shift selector tab and cage that actuates the shift rails) has two variations; a 1989-1991.5 version with a longer protruding tab from the cage, than the 1991.6-1999 style shorter tab. The cages are the same; the selector tab length was long on early stuff (weaker shift rails) and shorter length on later stuff (stronger shift rails).
Now, the shift rails are numerous variations. IF the shift selector is different length, you will need to use the matching rails to the selector -- BUT, there is a catch.... The 2g 3-hole 3rd/4th shift fork is different than the 1990-1992.5 2-hole 3rd/4th shift fork; which also has a different roll pin orientation and the shift forks are not interchangeable on the 1989-1991.5 (weak rail ends 2-hole shift fork) and 1991.6-1992.5 (strong rail ends 2-hole shift fork) vs. the 1992.6-1997 (strong rail ends 3-hole shift fork and 5th/rev shift fork pin orientation faces into gear) and 1997-1999 (strong rail ends 3-hole shift fork and 5th/rev shift fork pin orientation faces away from gear). So, if the built 1G transmission has the same shift selector length as the 2g transmission, then you can swap over the 1/2 and 3/4 shift rails, but you will need to confirm orientation of the 5th/reverse shift fork roll pin location before you just swap over the 5th/rev rail as you will need to use the matching shift fork otherwise.
The shift lever assembly on the outside of the transmission, you will need to continue using the 2g style "L" shift cable bracket that bolts onto the transmission, and the "L" style shift lever that goes in to the transmission that actuates the shift selector internally. There are numerous lever variations, and you NEED to use the matching "L" style levers on a 2g DSM with the matching shift cable bracket.
Internally, you will need to use the 2G DSM final drive, as it is supposed to be a W5M33-2-MUZT transmission which has a 57-tooth final drive ring gear and matching pinion gear shaft (they are a matched set). You will not be able to use the 1G front diff ring gear and output pinion shaft unless you do 2 things which are change your speed sensor to a 95-96 style (to get your cars speedo correct) and the transfer case final drive is 1.090 on 1991-1996.5 vehicles and the 97-99 are 1.074 ratio -- you would have to change tcases to match the final drive if you are using the 1G DSM 58-tooth ring and pinion gearset in your trans.
The gearset will need to be swapped over as a matched set of input shaft, intermediate shaft and center differential assemblies -- the gear tooth profiles need to match up. You will need to use the matching shift fork and shift rail for 3rd/4th to the swapped gearset (again, referring to above, you will need to confirm the shift selector length and shift rail end dimensions -- early style will not work, you will need to purchase the correct shift fork then for a 1991.6-1992.5 or an Evo 3 3rd/4th shift rail and grind it down to fit). The 5th gearset again needs to use matching gears, hub and slider assembly (2 variations -- small and large synchro diameter), and shift fork (4 variations; but the big thing is if the 1g has an early gearset it will have an aluminum shift fork and the rail will be an early style with the roll pin facing the gear for the 5/R fork; vs. the later 1991.5-1999 style gearsets use the large diameter hub and slider and steel 5/R fork); making sure that again, you confirm the orientation of the roll pin vs. the shift rail used and use a matched set.
The 5th gear cover needs to match the gearset. The 5th gear covers again have 2 variations, one that only fits a small diameter hub and slider assembly, and one that only fits a large diameter hub and slider assembly. You need to use the matching cover. AS WELL, the black case plastic oil guide....You CAN use either the 2g oil guide or the 1g oil guide (only if it is a 1991.5-1992.5 with the later version 5th gearset and cover -- the 1990 oil guide does not work with the later year 5th gear covers) in your 2g transmission case.
The output shaft and needle bearing, you should be using a 23-spline output shaft. I would suspect that most rebuilt transmissions do not have a 22-spline output shaft installed, but you can tell the spline count by counting, or by simply seeing the spline cut profile at the portion that is exposed to the transfer case. The 23-spline and 22-spline have a different profile on how they are cut as a quick reference.
You will need to swap over the bearing races to match the bearings used, then you will need to check the bearing preload / endplay values before swapping in shims. You will use 0.062" solder for the input shaft, intermediate shaft and front differential and 3/32" solder for the center differential and output pinion shaft (without the shims in place -- use the solder in place of the shims for this testing to get the zero value to determine bearing preload and end play values to select the proper shim).
Well, i think that this should help any of you through most of it. Be sure that any shop you are dealing with are not retards, because there are plenty of places that can't handle this. I know this stuff with my eyes closed.
Good luck on the projects!
Tim Zimmer
TMZ Performance
[email protected]
Tim Zimmer
1999 Mitsubishi Eclipse GSX
www.tmzperformance.com
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Drag Race Build 7K 12 1 76
1999 Mitsubishi Eclipse GSX
9.499 @ 155.00 · 2G DSM
