counterbalance pistons Archives - Transmission Digest
Solenoid Control in the TF60-SN (09G/09K/09M)

Starting with a few four-speed automatic transmissions, increasing with the five-speeds and more so with units having six or more speeds, it is interesting to see the use of counterbalance pistons in clutch drums that drive the planetary system. Since drive-style clutches are rotational, there is a tendency for centrifugal force to creep the clutch on when it is not in use, which could cause premature damage to the frictions.