Holding 2.5L six-cylinder engine torque, the BMW 323i 323is 1998-1999 automatic transmission 4-speed 4L30E remanufactured unit provides reinforced brake bands and upgraded clutch packs for classic E36 models. The higher torque of the M52 six-cylinder engine accelerates wear on standard four-cylinder 4L30E second-gear bands, causing slipping 1-2 shifts and burnt transmission fluid. This remanufactured transmission incorporates a heavy-duty six-cylinder spec brake band, reinforced clutch drums, new shift solenoids, and a rebuilt torque converter.

Technicians dismantle both the main transmission pan and the forward adapter pan, replacing all paper gaskets and molded rubber lip seals with high-temperature elastomer materials. The front oil pump housing receives precision line-boring and a new bronze drive bushing, preventing converter hub galling and front pump seal leaks. Every unit runs on automated load dynos through multiple warm-up cycles, confirming that fluid pressure and shift timing match factory BMW six-cylinder shift maps.

Technical Specifications of BMW 4L30E (6-Cylinder Spec)

- Four-Speed Dual-Pan GM Architecture: Features main oil pan and forward overdrive adapter pan calibrated for the 2.5L M52 engine.
- Heavy-Duty Six-Cylinder Brake Band: High-friction composite lining prevents 1-2 shift slip and drum scoring under acceleration.
- Re-Machined Front Oil Pump Housing: New bronze drive bushing and Viton seal eliminate front torque converter fluid leaks.
- New Shift and PWM Lockup Solenoids: Replaces tired electrical solenoids to restore crisp shift transitions between all four gears.
- Rebuilt Balanced Torque Converter: New damper springs and internal lockup clutch stop highway cruising vibration.
- Complete Gasket and O-Ring Overhaul: High-temperature seals prevent external fluid weeping and internal pressure loss.
- High-Energy Multi-Plate Clutch Packs: New OEM friction discs throughout all forward gear assemblies prevent slippage.

Brake Band Upgrades & Six-Cylinder Calibration

Designed for E36 coupes and sedans, this heavy-duty 4-speed automatic transmission delivers factory-quiet operation and smooth shifts.

- Six-cylinder brake band upgrade withstands 2.5L engine torque, preventing band glazing and intermediate shaft slip.
- New shift solenoids and PWM lockup valves eliminate delayed gear engagement when shifting into Drive or Reverse.
- Dual-pan sealing overhaul stops fluid leaks between the main transmission case and forward overdrive extension housing.

Vehicle Fitment & Cooler Line Flushing Requirements

Built for 1998 to 1999 BMW 323i and 323is models with the 2.5L M52 engine, this rear-wheel-drive unit bolts to factory engine blocks and subframes.

Warranty Protection & Fluid Filling Protocol

- Independent service centers receive 3-Year or 100,000-mile parts warranty coverage covering internal gears, clutches, and casing components.
- Core return requires an intact, drained 4L30E six-cylinder core and matching torque converter inside the original crate.

Thoroughly flush the radiator cooler circuit, install a new transmission oil pan filter, and fill with approved synthetic Dexron III fluid. Check fluid level through the pan check plug with the engine idling in Park. Order the BMW 323i 323is 1998-1999 automatic transmission 4-speed 4L30E remanufactured unit from Mulmotor.com for guaranteed factory-fresh units, complete manufacturer warranty coverage, and dedicated commercial equipment support.