ZF 5 HP-24A Teardown: Step 15: Sprag Clutch and F Clutch

After removing the bearing from the rear of the transmission, the rearmost sub-assembly inside the transmission can be loosened and moved forward and out the front of the transmission.

This rearmost sub-assembly is the sprag clutch and F clutch. Together, they form a unit that is removed and installed as a set.

The sprag clutch is also called the freewheel; it is a high-speed one-direction-only ratchet, so that in first gear, when the driver’s foot is removed from the accelerator pedal, the car doesn’t lurch forward due to engine compression braking, but instead coasts along smoothly.

If the sprag clutch fails in one way, and now it always locks up, then this feature no longer works, and the car could lurch forward in first gear.

If the sprag clutch fails in the opposite way, and now it never locks up, then the car would not move forward in any forward gear, though reverse would work just fine.

 

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