Installation Method for Armature

12V Starter, Mitsubishi Vehicles (Professional Universal Version)

1. Application Scope

• Voltage: 12V series starters

• Structure: Armature + Commutator + Core Winding + Bearing / Bushing

• Application: Standard reduction / direct‑drive starters for Mitsubishi cars, SUVs, light trucks, vans

2. Tools & Consumables Preparation

• Socket / screwdriver set, snap‑ring pliers, bearing puller / installation socket

• Dial indicator (runout inspection), feeler gauge (axial clearance check)

• Insulated sandpaper, electrical cleaner, grease (high‑temperature grease for starters)

• Torque wrench, rubber mallet, lint‑free cloth

3. Mandatory Pre‑Installation Inspection (Critical for Service Life)

1) Armature Inspection

• Windings: no burning, no loose solder, no rubbing damage

• Commutator surface: smooth, no burn marks, no excessive ovality; runout < 0.05 mm

• Armature shaft: no bending, no worn grooves, bearing journals smooth and clean

• Insulation test: armature to core – good insulation (infinite resistance)

2) Housing & End Cover Inspection

• Front/rear bearings / bushings: no excessive play, no uneven wear, no burning

• Pole cores: no displacement, no detachment, no rubbing marks

• Housing interior: clean, free of metal chips, oil, and contaminants

3) Brush & Brush Holder Inspection

• Brushes: sufficient length, no sticking, normal spring tension

• Brush holder insulation: intact, no cracks, no short circuits

4. Standard Installation Procedure (Sequence Must NOT Be Altered)

1) Lubrication & Pre‑assembly

• Apply a small amount of high‑temperature starter grease to front and rear armature journals.

• Install front bearing / bushing (dry operation prohibited for bushings).

2) Install Armature into Housing

• Place horizontally and gently; DO NOT strike commutator or windings.

• Insert slowly to avoid contact with pole shoes or jamming.

• Verify armature rotates freely, no rubbing, no abnormal noise.

3) Install Brush Assembly (Critical Step)

• Spread brushes using a brush holder spreading tool.

• Install armature, ensuring brushes contact commutator evenly.

• Release brushes; confirm no sticking or uneven wear.

4) Install Rear End Cover / Bearing Housing

• Align with locating pins / slots; pre‑tighten evenly diagonally.

• Install snap ring, thrust washer, and lock washer.

5) Adjust Axial Clearance (Mitsubishi Standard)

• Axial end play: 0.1 – 0.3 mm

• Too large: add adjusting shims

• Too small: remove shims or replace bearing

6) Check Commutator Runout (Critical)

• Measure outer commutator with dial indicator:

  Maximum allowable runout ≤ 0.05 mm

• If exceeded, refinish or replace armature.

7) Insulation & Short Circuit Check

• Armature winding to housing: good insulation

• Between commutator bars: no short circuit, no open circuit

5. Standard Torque Values (Mitsubishi Universal Specification)

• End cover mounting bolts: 8 – 12 N·m

• Brush holder mounting bolts: 4 – 6 N·m

• Terminal nut: 6 – 10 N·m (DO NOT over‑tighten)

6. Post‑Installation Acceptance Test

• Rotate armature by hand: smooth, no binding, no rubbing

• Axial end play: 0.1 – 0.3 mm

• Brief power test: smooth operation, no excessive sparking, no abnormal noise

• Commutator spark class: ≤ 1.5 (small spots are normal)

Installation Precautions for Armature

12V Starter, Mitsubishi Vehicles

(Concise On‑Site Repair Version)

1. Core Safety & Prohibitions (Strictly Forbidden)

• Do not strike the commutator, armature windings, or shaft journals during disassembly/assembly – prevents wire breakage, insulation damage, and shaft bending.

• Do not use general grease or engine oil for lubrication. Only use high‑temperature, anti‑wear grease for starters to avoid melting, leakage, and seizure.

• Do not assemble with oil, metal chips, or dirt. Clean the housing thoroughly to prevent short circuits, rubbing, and jamming.

• Do not bump or squeeze terminals and insulation parts. Replace damaged insulation washers/sleeves immediately.

2. Armature & Shaft Installation Key Points

• Lubricate the armature shaft, bearings, and bushings before assembly – dry installation is strictly forbidden.

• Insert the armature into the housing horizontally and gently; do not tilt or force it, to avoid scratching poles or windings.

• After assembly, rotate by hand to confirm: smooth, no binding, no rubbing, no abnormal noise.

• Do not install a bent armature shaft, out‑of‑tolerance commutator, or burned/broken windings – repair or replace first.

3. Brushes & Commutator (Directly Affects Spark & Service Life)

• Use a special brush spreading tool to install brushes; do not pry or force, to avoid breakage or brush holder deformation.

• Brushes must contact the commutator evenly – no one‑sided pressure, uneven wear, or sticking.

• Clean or refinish the commutator if burned, ridged, or oily; do not install directly.

• Brush holder insulation must be intact. Short circuits between brush holder, housing, and terminals are strictly forbidden.

4. Clearance & Shims (Critical Control Items)

• Axial end play must be strictly 0.1–0.3 mm.

• Too large → gear jumping, shock loading

• Too small → rubbing, seizure, overheating

• Adjust clearance by adding/removing shims. Do not force‑tighten the end cover.

• Thrust washers, snap rings, and retaining rings must be fully seated to prevent ejection at high speed.

5. End Cover & Bolt Tightening

• Align the end cover with locating pins/slots; do not force misaligned assembly.

• Tighten mounting bolts evenly and diagonally – do not fully tighten one side at a time, to avoid housing deformation and rubbing.

• Follow specified torque values. Do not use impact wrenches or over‑tighten – prevents housing cracking and thread damage.

6. Insulation & Electrical Prohibitions

• Check insulation before and after assembly: armature windings to core/housing must be well insulated. Do not install with short circuits or leakage.

• Terminals, leads, and brush holder wires must not rub on rotating parts or sharp housing edges – secure and protect properly.

• Do not sand or scrape winding insulation – prevents breakdown and short circuits.

7. Mandatory Post‑Installation Checks (Minimum Acceptance Standards)

• Hand rotation: free, no binding, no rubbing, no noise.

• Axial end play: within standard range 0.1–0.3 mm.

• Power test: smooth operation, mild sparking (≤ Class 1.5), no heavy sparking, no odor, no rapid overheating.

• Recheck all bolts, snap rings, shims, and wiring – no looseness, no interference, no rubbing.

References：

Installation Precautions for Armature (12V Starter, Mitsubishi)

Source and Basis of Content

I. Core Original Equipment Technical Basis

(I) Mitsubishi Factory Service Manual (FSM)

(II) Mitsubishi Aftermarket Technical Standards

II. National / Industry Mandatory Standard Basis

(I) QC/T 731‑2005 Specifications for Automotive Starters

(II) GB/T 28673‑2012 Technical Specifications for Remanufactured Automotive Parts – Starters

(III) SAE J2807‑2016 Motor Vehicle Electrical System Service Safety Standard