Here in Part 1 we will be disassembling the 2003 Toyota Celica GTS C60 transmission and comparing parts to the common C50 5 speed. The bell housing on the C60 has a different starter orientation and the rear mount attachment is different. We are hoping the 6 speed parts can be installed in the 5 speed case, making it a direct fit. The tools required to disassemble and service these transmissions varies, and gears can break when stressed in the wrong areas. Armed with that information, please proceed with this project at your own risk and consult a transmission specialist if you are not comfortable. Now, Lets get started:
We start by removing the end cap, exposing the 5th and 6th gear components. This is the hardest part of the disassembly, you need to knock out the keepers and use pullers to remove all of these parts. You need the proper tools, penetrating oil, and a torch to complete this part of the job. First you need to remove the shifter rod from the case:
Remove the shift bracket attachment point and the end cap, then just pull the rod out paying attention to it's orientation and springs. Then you want to reach into the case and pry up both the 1-2 and 3-4 shift rods, locking the gears together. Now you can start pulling off the 5th and 6th components:
Once you pull off all of the gears you can then knock the keepers off the shift rods and remove the rear bearing plate. There are snap rings holding the bearings to the case that need to be expanded to remove.
Next you can remove the shift rod detent springs and balls under these covers. Use a small pick and a magnet to remove the parts from the case, then remove the reverse holder screw and case bolts (don't forget the 3 bolts inside the bell housing).
Now we can start comparing things, of course the gears are different but the forks and rods look the same as the C50. The shafts are longer to accommodate the 6th gear, but otherwise the look identical to the Scion xD shafts. Reverse looks identical, no surprise there. Lets keep going, remove the reverse gear and shaft, then the linkage. Remove 1st and 2nd shift rod detent spring and ball then grab both shafts and the rods together and wiggle them up and out of the bell housing. You can then just lift the differential out of the bell housing.
Now is the moment of truth, will all of these fancy 6 speed parts fit in a C50 bell housing and case? I believe they will, I've compared the two cases and the only differences are: 1-C50 has a reverse lockout(removable, no big deal). 2-pinion shaft bearing size in the bell housing(can be changed, no big deal). This is great news, we can keep moving forward with this project! Stay tuned for Part 2 where we will address some issues we found with the 6 speed synchronizers, and thoroughly inspect all the gears and bearings. We are still unsure on what axles we need, but that can be dealt with later.