Symptoms:
Code P0731
No 2nd
No 3rd
No 4th
No 6th
No 8th
Failsafe mode
Gear ratio codes
Cause:
The lock splines on the "E" clutch hub have broken/sheared off and/or the clutch splines are heavily worn.
Correction:
Restore normal operation and avoid comebacks by installing upgraded Sonnax heavy duty "E" clutch hub.
850RE, ZF8HP51, ZF8HP55
Heavy Duty "E" Clutch Hub
Part No. 35572-62T
62 Splines
Vehicles with ZF8HP55 and Chrysler 850RE transmissions utilize an "E" clutch hub that is made from weak, cast A380 aluminum. This material is no match for the high torque generated in these applications. The lock splines of the hub are prone to shearing or breaking, resulting in failsafe, ratio codes and loss of movement. In addition, the steel clutch plates dig into the splines on the drum, causing the plates to hang up and burn. This can happen in as few as 20,000 miles.

Sonnax heavy duty "E" clutch hub 35572-62T is crafted from forged 4000-series aluminum, the same material used for high performance engine pistons. The Sonnax billet hub features a far superior yield strength versus the OE hub so you can rest easy knowing it will stand the test of time — no more worrying about comebacks due to a failed OE hub.

High-strength, forged hub eliminates spline failure
Improved material significantly increases "E" clutch durability
Note
For 53 spline hub, use 35572-53T.