If the stall speed is 600 rpm or more lower than specification, which problem is most likely?

If the stall speed is 600 rpm or more lower than specification, which problem is most likely?

• A. A freewheeling stator
• B. A torque converter that is not full of fluid
• C. A stuck stator
• D. A transmission that has a seized clutch

Answer: (A)

Stall speed in a torque converter reflects how much torque multiplication the stator provides at low pump speeds. The stator’s job is to redirect circulating fluid to multiply engine torque delivered to the transmission. If the stator is freewheeling, it cannot provide that multiplication, so the system delivers far less torque at a given engine speed. With less torque available to overcome the load, the drivetrain reaches the stalling point at a much lower engine rpm, which explains a stall speed noticeably lower than specification (such as 600 rpm lower). The other issues either don’t remove the torque multiplication or cause different symptoms not tied to a dramatic, specific drop in stall speed.

Stall speed in a torque converter reflects how much torque multiplication the stator provides at low pump speeds. The stator’s job is to redirect circulating fluid to multiply engine torque delivered to the transmission. If the stator is freewheeling, it cannot provide that multiplication, so the system delivers far less torque at a given engine speed. With less torque available to overcome the load, the drivetrain reaches the stalling point at a much lower engine rpm, which explains a stall speed noticeably lower than specification (such as 600 rpm lower). The other issues either don’t remove the torque multiplication or cause different symptoms not tied to a dramatic, specific drop in stall speed.