U151F Automatic Transmission Planetary Gear Assembly 3572028070

Function: Torque multiplication unit for Toyota/Lexus 8-speed transmissions (e.g., Aisin AWF8G30), enabling gear ratio changes via selective clutch engagement.

Key Components:

• Lepelletier Design: 1 Ravigneaux + 1 simple planetary set for compact 8-speed ratios

• Hardened Gears: Case-hardened steel (HRC 60+) with ground tooth profiles

• Needle Bearings: Low-friction support for planetary pinions

Failure Modes:

• Sun Gear Spline Wear: Causes 3-5-7 gear slippage (P2714 codes)

• Pinion Bearing Failure: Results in gear whine (check endplay <0.15mm)

• Carrier Cracks: Fatigue near thrust washers (metal debris in pan)

Critical Specs:

1. Sun gear axial play: 0.10-0.25mm

2. Pinion gear backlash: 0.05-0.12mm

Pro Tip: Always replace planetary thrust washers during rebuilds – worn washers alter gear alignment.