8HP70, 8HP75

38 Splines

The ZF8HP70 is equipped with a 38-spline "E" clutch hub from the OEM. However, some ZF8HP70 applications may have been updated to an OE 48-spline hub and planetary due to a previous failure. Make sure to verify spline count before purchase.

Symptoms:

• Failsafe mode
• Gear ratio codes
• Code P0731
• No 2nd
• No 3rd
• No 4th
• No 6th
• No 8th

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.

Vehicles with ZF8HP70 transmissions utilize an "E" 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.

This Sonnax heavy duty "E" clutch hub 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