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Starter Motor 02B911023BX: Features, Working Principle & Technical Specifications

02B911023BX Starter

VAG Reduction Starter

Core Features

The 02B911023BX is a genuine Bosch OEM planetary gear-reduction starter exclusively for Volkswagen Transporter T4 (1999–2003) petrol vehicles under the VAG Group.

Compact Planetary Gear Reduction Design

Equipped with integrated multi-stage planetary gears, it outputs stable 1.1kW cranking torque with compact dimensions, perfectly matching the narrow engine bay of VW T4 vans.

Top-Mounted Integrated Solenoid Unit

The electromagnetic solenoid is installed on the upper housing, which simultaneously drives pinion axial movement and controls heavy-current main circuit switching. It comes with a standard M8 threaded B+ main terminal and a dedicated 50-type plug control connector, fully compatible with original VW wiring harness.

10-Tooth Reinforced Drive Pinion

Hardened floating pinion matched with a heavy-duty overrunning clutch, delivering low-noise, low-wear meshing with the flywheel ring gear during frequent cold startups.

3-Hole Standard Mounting Flange

76mm centering flange with three threaded mounting holes, enabling rigid direct bolt-on replacement without engine block modification.

Heavy-Duty Durable Construction

Anti-corrosion coated black motor housing, high-temperature resistant carbon brushes, wear-resistant copper armature windings and cast aluminum gear housing, engineered to withstand daily commercial vehicle start-stop cycles.

Full OEM Interchangeability

Interchangeable with supersession part numbers including 02B911023B, 02B911023F, 02B911023FX for universal aftermarket replacement.

Working Principle

This starter converts 12V DC electrical energy from the vehicle battery into mechanical cranking torque through four sequential working stages:

Solenoid Excitation

When the ignition switch is turned to the START position, low-current control power energizes the solenoid coil, generating magnetic force to pull the internal metal plunger forward.

Pinion Axial Engagement

The plunger pushes the shift fork to slide the 10-tooth pinion outward axially, achieving full meshing contact with the engine flywheel ring gear.

Engine Cranking Output

After complete gear meshing, the solenoid closes heavy-duty internal contact points. High current flows into the DC armature motor; high-speed rotation torque is amplified by the planetary reduction gear train to drive the flywheel and crank the petrol engine for ignition.

Automatic Anti-Reverse Protection

Once the engine ignites and runs faster than the pinion rotation speed, the built-in overrunning clutch slips to prevent reverse rotation damage to the starter assembly. The solenoid cuts power, a return spring retracts the pinion back to its idle position, and the motor power supply shuts off automatically.

Complete Technical Parameter Table

Parameter Item	Standard Specification
OEM Part Number	02B911023BX
Original Manufacturer	Bosch (VW Genuine OEM Supplier)
Nominal Operating Voltage	12V DC
Rated Output Power	1.1 kW
Starter Structure Type	Planetary Gear Reduction Starter
Drive Pinion Tooth Count	10 teeth
Rotation Direction (View from Pinion Side)	Counter-Clockwise (CCW) / Anticlockwise
Centering Flange Diameter	76 mm
Mounting Holes	3 threaded fixing holes
Main Power Terminal	M8 threaded B+ bolt terminal
Control Connector	Standard 50 Jet plug-in terminal
Approximate Net Weight	~3.3 kg
Compatible Engines	VW 2.0L petrol engines for Transporter T4
Applicable Vehicle Models	Volkswagen Transporter T4 Bus / Van (1999–2003)
OEM Cross Reference Numbers	02B911023B, 02B911023F, 02B911023FX, Bosch OE: 0001107088
Aftermarket Equivalent Parts	RIDEX 2S0960, AS-PL S0066, HC-Cargo 112611, ELSTOCK 25-1260

Supplementary Notes

This Bosch OEM starter is factory-calibrated exclusively for VW T4 commercial petrol vans, with unified mounting dimensions and electrical interfaces for plug-and-play direct replacement.
The 1.1kW power output delivers consistent stable cold-cranking torque under low-temperature environments, meeting the frequent startup demand of delivery vehicles.
Mass stock of new and remanufactured aftermarket alternatives are available globally, with complete cross-reference part numbers to simplify spare parts procurement for repair shops and cross-border auto spare traders.

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