TH350C Input Shaft Wear
Racer
Joined: Jul 2018
Posts: 331
Likes: 123
From: Sandusky, OH
Shows what kind of ill conceived pile the 350 lock up was. Salvage some parts and go to a regular non lock up 350TH. Superior Transmission Products had a conversation kit, IIRC. But you need to swap in enough parts that you should just build a clean 350TH core.
May be time for an overdrive conversion….
Steve O.
May be time for an overdrive conversion….
Steve O.
2nd Gear
Joined: Jul 2024
Posts: 2
Likes: 0
I had this problem on an 81 GMC van. Quite certain it was caused by a shudder in the lock up torque converter, which had gone bad. The sealing ring was also missing from mine, as it is yours. Definitely replace it.
I suggest dealing with the converter issue asap. Some people say new fluid can fix it, or just get a new lock up converter (or retro the whole unit to a non lock-up TH350, which will require a TH350 oil pump, new converter, input shaft, and mods to the valve body).
The vibration may have worn your bushings and/or snapped the input shaft where it mates with the output shaft. You should probably replace the worn shaft anyway. You can buy these shafts with the drum already pressed in on eBay, or without the drum if you’re willing to press the old shaft out and the new shaft in.
I suggest dealing with the converter issue asap. Some people say new fluid can fix it, or just get a new lock up converter (or retro the whole unit to a non lock-up TH350, which will require a TH350 oil pump, new converter, input shaft, and mods to the valve body).
The vibration may have worn your bushings and/or snapped the input shaft where it mates with the output shaft. You should probably replace the worn shaft anyway. You can buy these shafts with the drum already pressed in on eBay, or without the drum if you’re willing to press the old shaft out and the new shaft in.
Last edited by mattdander; Jul 25, 2024 at 02:52 PM.
