Description

Send Inquiry

Starter Motor 12417521116: Features, Working Principle & Technical Specifications

Core Features

The 12417521116 (12 41 7 521 116) is an original Bosch/Valeo OEM planetary gear reduction starter exclusively engineered for BMW N52, N54, N55 3.0L inline-six turbo & naturally aspirated gasoline engines, covering 1/3/5/X/Z series platforms.

Compact Planetary Gear Reduction Design

Built-in multi-stage planetary gear set delivers stable 1.1–1.2kW cranking torque, offering powerful cold-start performance for high-compression BMW straight-six engines while keeping a lightweight, space-saving structure for tight engine bays.

Side-Mounted Integrated Solenoid Assembly

The electromagnetic solenoid is fixed on the side of the motor housing. It simultaneously pushes the drive pinion to mesh with the flywheel and controls high-current main circuit switching. Equipped with standard M8 threaded B+ main bolt terminal and dedicated 50-type plug control connector, fully compatible with original BMW wiring harness.

9-Tooth Reinforced Drive Pinion

Hardened floating pinion matched with heavy-duty overrunning clutch, achieving smooth, low-noise meshing and reducing gear abrasion under frequent urban start-stop cycles.

2-Hole Standard Mounting Flange

76mm centering flange with two fixing holes (1 threaded, 1 through hole), supporting rigid direct bolt-on replacement without engine block modification.

Premium Durable Construction

Anti-corrosion black coated motor housing, high-temperature resistant carbon brushes, wear-resistant copper armature windings and cast aluminum gear housing, designed to withstand long-term daily driving and low-temperature environments.

Wide OEM Interchangeability

Interchangeable with multiple BMW OE supersession numbers, abundant new and remanufactured aftermarket alternatives are globally available for repair shops and spare parts traders.

Working Principle

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

Solenoid Excitation

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

Pinion Axial Engagement

The plunger drives the shift fork to slide the 9-tooth pinion outward axially, forming full meshing contact with the engine flywheel ring gear.

Engine Cranking Output

After complete gear meshing, the solenoid closes heavy-duty internal contact points. Hundreds of amps 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 BMW six-cylinder engine for ignition.

Automatic Anti-Reverse Protection

Once the engine ignites and rotates faster than the starter pinion 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 idle position, and motor power supply shuts off automatically.

Complete Technical Parameter Table

Parameter Item	Standard Specification
OEM Part Number	12417521116 / 12 41 7 521 116
Original Manufacturers	Bosch, Valeo
Nominal Operating Voltage	12V DC
Rated Output Power	1.1 kW / 1.2 kW dual versions
Starter Internal Type	Planetary Gear Reduction Starter
Drive Pinion Tooth Count	9 teeth
Rotation Direction (View from Pinion Side)	Clockwise (CW)
Centering Flange Diameter	76 mm
Mounting Holes	2 holes (1 threaded, 1 unthreaded)
Main Power Terminal	M8 threaded B+ bolt terminal
Control Connector	Standard 50 Jet plug-in terminal
Approximate Net Weight	~3.08 kg
Compatible Engines	BMW N52, N54, N55 2.5L / 3.0L Inline-6 Gasoline
Applicable Vehicle Chassis & Models	E82/E88 1 Series; E90/E91/E92/E93 3 Series; E60/E61 5 Series; E70 X5, E83 X3; Z4 E85/E89; 128i, 135i, 325i, 330i, 335i, 525i, 535i
OEM Cross Reference Numbers	12412354701, 12417521122, 12417521123, 12417526236, 12417579155
Aftermarket Equivalent Parts	Bosch 0986021500, Valeo 438272, AS-PL S3163S, WAI 17922N, RIDEX 2S0511

Supplementary Notes

This OEM-spec starter is factory-calibrated exclusively for BMW N52/N54/N55 straight-six gasoline engines, with unified mounting dimensions and electrical interfaces for plug-and-play direct replacement.
The 1.1/1.2kW high torque design delivers reliable cold-start performance even under freezing weather, meeting the frequent startup demand of luxury passenger vehicles.
Full range of new and remanufactured spare parts are stocked worldwide, with complete cross-reference part numbers to simplify procurement for auto repair workshops and cross-border auto parts merchants.

packing customized