fixerupper
Well-known Member
Helped my friend try to figure out why an old military vehicle won't go into 2-3 and 4-5 gears. It's an old WW2 tracked landing craft that you can drive a jeep into the back of and is powered by a 7 cylinder Continental radial engine. It hasn't been driven for 15 years and the previous owner didn't mention any tranny troubles but????
Granny and reverse are in a separate case behind the transmission case and they do shift and work. 2-3&4-5 are inside the tranny case and we can't get them to shift into gear. The gear shift lever just won't move.In this tranny the top shaft is the input and bottom is output. There are two syncronizers on the bottom shaft, according to the parts book. One for for 2-3 and the other one is for 4-5. The shift lever is on the outside of the tranny and the three shifting rods come out of the end of the tranny about 5" and that is where the shift lever engages them. The rods for those two gear selections move freely just a bit and then they act like they hit something hard. I even tapped on the end of one with a hammer while trying to shift it in with the shift lever and it feels like it hits something rock hard. We have the drive shaft off between the engine and tranny and can turn the tranny with the nut inside the input yoke with a socket. If we try to move the shift lever into a gear the input shaft starts turning hard so evidently the syncros are moving just enough to make a little friction, but they won't engage beyond that. Like I said, when moving the shift lever it feels like the shift fork hits something rock hard. I don't know much about syncros, but can they sieze up and prevent the collar from engaging the gear? I have no idea what the make and model is. It's old, it's military and it's not a common gearbox, that's all I know about it.
The engine is not running but he has a spare engine that will be going in. Jim
Granny and reverse are in a separate case behind the transmission case and they do shift and work. 2-3&4-5 are inside the tranny case and we can't get them to shift into gear. The gear shift lever just won't move.In this tranny the top shaft is the input and bottom is output. There are two syncronizers on the bottom shaft, according to the parts book. One for for 2-3 and the other one is for 4-5. The shift lever is on the outside of the tranny and the three shifting rods come out of the end of the tranny about 5" and that is where the shift lever engages them. The rods for those two gear selections move freely just a bit and then they act like they hit something hard. I even tapped on the end of one with a hammer while trying to shift it in with the shift lever and it feels like it hits something rock hard. We have the drive shaft off between the engine and tranny and can turn the tranny with the nut inside the input yoke with a socket. If we try to move the shift lever into a gear the input shaft starts turning hard so evidently the syncros are moving just enough to make a little friction, but they won't engage beyond that. Like I said, when moving the shift lever it feels like the shift fork hits something rock hard. I don't know much about syncros, but can they sieze up and prevent the collar from engaging the gear? I have no idea what the make and model is. It's old, it's military and it's not a common gearbox, that's all I know about it.
The engine is not running but he has a spare engine that will be going in. Jim