The best replacement for torque converter is clutch.

The best alternatives to torque converter are rated as following:
★★★★★  clutch
★★★★  transmission
★★★★  stall converter
★★★★  centrifugal clutch
★★  fluid coupling
★  dual clutch
★  catalytic converter
★  bad transmission
  non lock up
  cvt
  wet clutch
  clutch go kart
  dsg
  hydraulic coupling
  c4 torque converter

Your alternative for torque converter is not listed? Suggest!
Speaking about torque converter, one probably shouldn't forget about manual transmission.

Other search terms related to torque converter and their ratings are:
★★★★★ manual transmission
You have in mind a companion for torque converter and it is not yet here? Propose!



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torque converter
clutch
transmission