IM2128 Starter Armature 12V 2.0KW 9 Segments 109 Series
Applicable models:For 109 Series starters used on Audi A8, BMW and Fiat Ducato
Reference part number: IM2128, 5020-3184, 139704, 50203184, 1004011090, 1004011224, 1004011319, 333412, SAB9704BA, SAB9704CL, SAB9704EX, SAB9704RW, 059911311D, 62-27691-W, 318N10075Z.
| Rated output : | 12v 2.0kw |
| Pulley : | 9pcs |
| Size : | |
| Weight : | net weight：1KG |
| Packaging : | Neutral kraft paper packaging |
| Spot/Pre sale : | Spot goods |
| Warranty : | 1 year |
| Product number : |
| Type : | STARTER ARMATURE |
| Specification : | 12V 2.0KW |
| Pulley : | 9PCS |
| Brand : | NUOJIN |
| Number : | IM2128 109-9-24V |
| Quality : | NEW |
| Delivery time : | 10 day |
Product Overview
The IM2128 starter armature (OE IM2128, 5020-3184, 50203184) is a new, OE-spec replacement rotor built for 109 Series starters used on Audi A8, BMW and Fiat Ducato applications. Rated at 12V 2.0KW with a 9-segment commutator, this armature is a core internal component of the starter motor that converts electrical energy into the mechanical torque required to crank the engine.
This aftermarket armature matches the original starting-system requirements of the 109 Series starter family. As a service part, it is intended for use by qualified starter rebuild shops when rewinding and restoring a complete starter. The unit is stocked in-house, backed by a 1-year warranty with a 10-day dispatch lead time.
Key physical spec: net weight 1 kg, supplied in a neutral kraft inner carton.
109 Series 12V Starting System
109 Series starters rely on a correct 12V armature match so the engine starts reliably under normal electrical load and in cold conditions. This armature is engineered to suit the winding and commutator layout of the matching starter, delivering dependable cranking performance after a professional rebuild.
Technical Specifications
| Parameter | Specification |
|---|---|
| OE numbers | IM2128, 5020-3184, 139704, 50203184, 1004011090, 1004011224, 1004011319, 333412, SAB9704BA, SAB9704CL, SAB9704EX, SAB9704RW, 059911311D, 62-27691-W, 318N10075Z |
| Series code | 109 Series |
| Voltage | 12V |
| Power | 2.0KW |
| Commutator segments | 9 |
| Application | Audi A8, BMW, Fiat Ducato (109 Series) |
| Quality | New |
| Warranty | 1 year |
| Net weight | 1 kg |
| Packaging | Neutral kraft box |
| Lead time | 10 days, in stock |
Engine Compatibility and Cross Reference
This starter armature fits 109 Series starter applications (Audi A8, BMW, Fiat Ducato). Do not rely solely on the starter series for fitment validation; always verify the old-armature OE number, voltage, power rating and commutator segment count stamped on your original armature.
| Equipment | Application | Typical Vehicles |
|---|---|---|
| Audi | Passenger car | A8 |
| BMW | Passenger car | Related models |
| Fiat | Van | Ducato |
Multiple OE numbers exist across different production batches and market specifications for this same starter armature family. If your original armature carries any one of the listed part numbers, the IM2128-series unit is a direct service replacement.
What to Look for in a Replacement
Follow these five verification steps before placing your order to avoid wrong-part returns:
1. Check the data on your old armature: confirm the rated power is 2.0KW @12V. Different voltage or power ratings are not interchangeable.
2. Count the commutator segments: this unit uses 9 segments. The wrong count gives poor brush contact and sparking.
3. Confirm your starter is a 109 Series unit used on Audi A8, BMW or Fiat Ducato. Other starter series use different armature assemblies.
4. Match the OE / reference part numbers stamped on your original armature shaft.
5. Weight cross-check: a genuine matching unit weighs about 1 kg net; a significant weight difference indicates the wrong rotor or low-grade build quality.
Application Scenarios
Independent starter and alternator rebuild shops rebuilding 109 Series starters.
Auto-electric workshops servicing Audi A8, BMW and Fiat Ducato vehicles across Europe, Asia, Africa, the Middle East and Latin America.
Parts counters and jobbers stocking 12V starter-armature service components.
Fleet operators and repair facilities servicing Audi, BMW and Fiat vehicle fleets.
Maintenance teams restoring starters to factory-standard condition.
Armature Rebuild and Testing Steps
Starter armature replacement must be carried out by a qualified starter repair shop. The following is a standardized armature rebuild workflow, including pre-inspection, cleanliness control, assembly and no-load bench testing, to ensure the rebuilt starter operates stably.
Pre-Inspection and Disassembly
Confirm the starter housing, field windings and brush gear are intact before committing to a rebuild.
Disassemble the starter in a clean workstation and record the original winding pattern, commutator segment count and bearing positions.
Workstation Cleanliness Control
Work on a clean bench and keep copper dust, oil and metal chips away from the armature to avoid contaminating the commutator surface and winding insulation.
Assembly of the Armature
Fit the new armature into the starter housing, confirm the shaft engages freely with the drive gear and the commutator aligns with the brush gear. Torque the mounting bolts to the manufacturer specification.
No-Load Bench Test
After assembly, run a no-load bench test: apply rated 12V and confirm smooth rotation without abnormal sparking or noise. Verify free-run current and that brushes seat correctly on the new commutator.
FAQ
Q: Does this armature fit my 109 Series starter?
A: This IM2128-series armature is built for 109 Series starter applications (Audi A8, BMW, Fiat Ducato). Always confirm your old-armature OE number before ordering.
Q: My old armature shows OE number 5020-3184 or 50203184 or 139704. Will IM2128 work?
A: Yes. These OE numbers belong to the same 109 Series starter-armature family, differing only by production revision and market specification, so the IM2128-series unit serves as a direct service replacement.
Q: Is this a new or remanufactured armature?
A: This unit is a new armature, quality-tested to original specifications and backed by a 1-year warranty.
Q: Can I install this armature myself?
A: Armature replacement is an internal starter service that requires winding, brush alignment and bench-testing skills. We strongly recommend a qualified starter repair shop carries out the rebuild.
Q: What is your warranty and lead time?
A: Goods are in stock with a 10-day dispatch lead time. A 1-year warranty applies from installation date; it excludes damage caused by mis-installation, forced fitting or operating outside rated voltage.
In Practice
For technicians rebuilding 109 Series starters: before fitting the new armature, inspect the housing bearings, brush gear and field windings. A worn bearing or damaged brush gear will quickly destroy the new commutator. Confirm the no-load free-run current and smooth rotation on the bench before returning the rebuilt starter to service.
Record the winding connection pattern and commutator orientation during disassembly to avoid mis-wiring during reassembly. Test the rebuilt starter on the bench with rated 12V before installation, and verify it produces the expected cranking torque when finally mounted.
References
The armature rebuild method and related precautions are standardized content summarized and integrated based on the universal rebuild specifications of 12V starter systems, industry service standards for starter armatures of the same specification, and practical experience in the automotive repair field. Equipment applications are compiled from original-equipment fitment data for the IM2128-series starter armature family covering 109 Series applications.
About the Author
This article was written by the senior auto-electric technician team at Nuojin Auto Parts, with over 15 years of hands-on experience in automotive charging and starting systems.
Our engineers specialise in Japanese, European, Korean, American and Chinese vehicle charging-system diagnostics, aftermarket alternator and starter-motor cross-referencing, and factory-spec electrical-system restoration for global markets. Every product listing on this site is backed by real bench-tested fitment data and first-hand repair experience, not just copied from manufacturer manuals.
If you have any question about this starter armature or your starting system, contact our technical team and we will help you confirm the correct part for your application.
Nuojin Auto Parts is a professional starter and alternator supplier based in Hejian, Hebei, China, running factory-grade bench testing on every production batch. We support distributors, wholesalers and repair shops worldwide with correct-fit sourcing, a 1-year warranty and responsive after-sales technical assistance.
