8-speed cvt automatic transmission planetary gear 1087240049

Key Features & Analysis:

1. Application: ZF 8HP series (likely 8HP45/55/70), supporting 2nd/4th/6th/8th gear ratios.

2. Design: Compound planetary set (Ravigneaux or Lepelletier type) with hardened 18–22 tooth sun gear and 42–46 tooth ring gear.

3. Material: Case-hardened 20MnCr5 steel (core hardness 58–62 HRC, surface >800 HV).

4. Critical Tolerances:

   • Backlash: 0.05–0.12mm (exceeding 0.15mm causes whine)

   • Runout limit: <0.03mm

5. Failure Modes:

   • Pitting/spalling (fatigue due to high torque cycling)

   • Bearing journal wear (if oil debris present)

   • Thermal distortion (if ATF exceeds 140°C)

Note: Requires ZF Lifeguard 8 fluid for proper lubrication. Common in Audi/BMW applications.