Generator Service and Rebuild

Complete disassembly, inspection, cleaning, testing, and rebuild of the 1966 Corvette 327 V8 Delco-Remy generator including brush replacement, bearing service, armature testing, and regulator adjustment.

Warnings

Tools required

Parts

• Generator brush set (carbon brushes) × 1 — Delco-Remy 1100695 or equivalent
• Generator drive end bearing × 1 — Use OEM specification
• Generator commutator end bearing × 1 — Use OEM specification
• Generator brush spring set × 1 — Use OEM specification
• Through-bolt fiber washers × 2 — Use OEM specification
• Field coil insulation kit × 1 — Use OEM specification as needed
• Generator pulley nut × 1 — Use OEM specification if damaged
• Armature shaft key × 1 — Use OEM specification if damaged
• Generator mounting bushing set × 1 — Use OEM specification if worn
• Electrical contact cleaner spray × 1 — CRC or equivalent
• Dielectric grease × 1 — Use OEM specification
• High-temperature bearing grease × 1 — Use OEM specification

Preparation

1. Disconnect battery negative cable and secure away from battery post
2. Allow engine to cool completely if recently operated
3. Clean external generator housing and surrounding engine bay area to prevent contamination during disassembly
4. Photograph or diagram all wire connections at generator for reference during reassembly
5. Prepare clean workbench with adequate lighting for detailed inspection work
6. Gather all testing equipment and verify multimeter functionality with known good circuit

Procedure

1. 1

   Remove Generator from Vehicle
   Disconnect the two wire terminals from the generator rear housing (BAT and FLD terminals). Remove the generator adjustment bracket bolt at the generator. Loosen the lower generator pivot bolt but do not remove. Push generator toward engine block to release belt tension and remove drive belt from pulley. Remove lower pivot bolt and withdraw generator from engine compartment. Place generator on clean workbench.
2. 2

   Disassemble Generator Housing
   Scribe alignment marks across the drive end frame, field frame, and commutator end frame for correct reassembly orientation. Remove the two through-bolts that secure the housing halves together. Carefully separate the commutator end frame from the field frame assembly, being careful not to damage brushes or brush holders. Remove the fiber washers from the through-bolt locations and set aside for inspection.
3. 3

   Remove Armature Assembly
   With commutator end frame removed, carefully withdraw the armature assembly from the drive end frame and field frame. Support the armature shaft to prevent dropping. Note the position of any spacers or shims on the armature shaft. Set armature on clean protected surface. Remove the pulley retaining nut from the front of the armature shaft using appropriate socket while holding pulley with strap wrench. Remove pulley, fan, and any spacers. Note the woodruff key position in armature shaft.
4. 4

   Remove and Inspect Brushes
   Remove the brush holder assembly from the commutator end frame by removing the two mounting screws. Disconnect brush lead wires by unsoldering at field coil connections or at brush holder terminals. Measure brush length with ruler; brushes should be at least 1/2 inch long. Measure brush spring tension with spring scale; tension should be 35-53 ounces. Inspect brush holders for wear, cracks, or carbon buildup. Clean brush holder tunnels with electrical contact cleaner and compressed air.
5. 5

   Inspect and Test Armature
   Clean commutator surface with fine emery cloth, rotating armature while holding cloth stationary. Do not use sandpaper. Inspect commutator for scoring, burning, or out-of-round condition. Measure commutator diameter with micrometer; minimum diameter is 1.230 inches. Check commutator runout; maximum allowable is 0.002 inches. Test for shorts between commutator segments using growler and steel strip; vibration indicates shorted windings. Test for opens by connecting ohmmeter between adjacent commutator bars; all readings should be similar (typically 0.1-0.3 ohms). Test for grounds by connecting ohmmeter between commutator and armature shaft; reading should be infinite (open circuit). If commutator is worn or damaged but within diameter limits, turn on lathe to true surface.
6. 6

   Undercut Commutator Mica
   Inspect mica insulation between commutator segments. Mica should be undercut to 0.020-0.030 inches below copper segment surface. If mica is flush or high, undercut using proper undercutting tool or modified hacksaw blade. Work carefully to avoid damaging copper segments. Clean all copper and mica dust from commutator slots using compressed air and electrical contact cleaner. Final clean commutator with clean lint-free cloth.
7. 7

   Inspect and Test Field Coils
   Visually inspect all field coil windings for signs of overheating, damaged insulation, or broken wires. Test field coils for continuity by connecting ohmmeter between field terminal and ground; typical reading is 1.5-2.5 ohms for a good field circuit. Test for grounds by connecting ohmmeter between field terminal and frame; reading should be infinite. If field coils test bad, replacement requires specialized equipment and is best performed by rebuilding shop. If field coils test good, clean field frame interior with electrical contact cleaner and compressed air.
8. 8

   Remove and Inspect Bearings
   Press or drive the drive end bearing from the drive end frame using appropriate bearing puller or press. Press or drive the commutator end bearing from the commutator end frame. Inspect bearing races in frames for scoring or damage. Clean bearing pockets thoroughly. Inspect armature shaft journals for scoring or wear using micrometer; typical journal diameter is 0.6690-0.6695 inches. Check shaft for bend by rolling on V-blocks or flat surface plate; maximum runout is 0.002 inches.
9. 9

   Install New Bearings
   Pack new bearings with high-temperature bearing grease until grease appears at opposite side. Install new drive end bearing into drive end frame using bearing driver and press or hammer, applying pressure only to outer race. Ensure bearing is fully seated against shoulder. Install new commutator end bearing into commutator end frame using same method. Verify bearings rotate smoothly without binding. Install several drops of light machine oil into bearing oil wicks if equipped.
10. 10

    Install New Brushes and Springs
    Install new brush springs into brush holders. Install new brushes into holders, ensuring correct orientation (beveled edge faces away from holder in rotation direction). Solder brush leads to field coil terminals or brush holder terminals using rosin core solder and hot soldering iron. Ensure solid electrical connection with no cold solder joints. Test brush movement in holders; brushes should slide freely without binding. Measure installed spring tension; should be 35-53 ounces when brush is seated.
11. 11

    Reassemble Armature into Drive End Frame
    Install woodruff key into armature shaft keyway if removed. Lubricate drive end bearing with several drops of light machine oil. Carefully insert armature shaft through drive end bearing, supporting armature to prevent bearing damage. Install any spacers or shims in original positions. Install fan and pulley onto armature shaft. Install pulley retaining nut and torque to manufacturer specification (verify exact value; do not rely on an unverified guess). Verify armature rotates freely in bearing without binding or excessive end play.
12. 12

    Reassemble Generator Housing
    Install new fiber washers onto through-bolt locations in drive end frame if originals are compressed or damaged. Hold drive end frame with armature assembly vertical, commutator end up. Slide field frame over armature and align with drive end frame using scribe marks made during disassembly. Hold brushes away from commutator using brush holder springs or wire hooks. Carefully slide commutator end frame over armature commutator, guiding it into field frame while maintaining alignment marks. Release brushes to contact commutator surface. Install through-bolts and tighten evenly in cross pattern. Verify armature rotates freely by hand.
13. 13

    Bench Test Generator Output
    Connect generator to test bench or use battery and jumper cables for field testing. Connect positive battery terminal to generator ARM or BAT terminal. Connect negative battery terminal to generator frame (ground). Energize field by momentarily touching field terminal to positive. Using drill motor with appropriate socket, spin generator pulley clockwise (viewed from pulley end) at approximately 1500-2000 RPM. Connect voltmeter between ARM terminal and ground. Generator should produce voltage that rises with speed (unregulated bench output may exceed 14 volts without a regulator connected). Test output amperage by connecting ammeter in series with ARM terminal; typical output at 2000 RPM is 25-35 amps depending on generator model. If output is low or zero, recheck all connections and brush contact.
14. 14

    Install Generator and Adjust Belt Tension
    Position generator into mounting bracket on engine. Install lower pivot bolt finger tight. Install upper adjustment bracket bolt finger tight. Place drive belt over generator pulley and crankshaft pulley. Using pry bar against generator frame (not housing seam), apply tension to belt while tightening adjustment bracket bolt. Proper belt tension allows 1/2 inch deflection at center of longest belt span with moderate thumb pressure. Tighten pivot bolt to secure generator position. Reconnect BAT terminal wire to generator BAT terminal. Reconnect FLD terminal wire to generator FLD terminal.
15. 15

    Polarize Generator and Verify Charging
    Generator must be polarized to match vehicle electrical system polarity before operation. For the negative ground system (standard 1966 Corvette), polarize at the regulator: momentarily touch a jumper wire from the regulator BAT terminal to the regulator GEN (ARM) terminal for an instant (a small spark is normal). This flashes the field coils with correct polarity. Reconnect battery negative cable. Start engine and verify charging system operation. With engine at fast idle (1500 RPM), battery voltage should read 13.8-14.5 volts. Ammeter should show charging current. If generator charges in reverse (discharge) or does not charge, recheck all wiring connections and repeat polarization procedure.

Reassembly

1. Torque all fasteners to specification when torque values become available in database
2. Verify all electrical connections are clean and tight before operation
3. Recheck belt tension after first 50 miles of operation as belt seats into pulleys
4. Monitor charging system voltage for first few drives to ensure proper generator output

Verification

• Start engine and verify ammeter shows charging (positive current flow) at idle
• Increase engine speed to 1500 RPM and verify battery voltage is 13.8-14.5 volts DC
• Turn on electrical loads (headlights, heater blower) and verify generator continues to charge
• Listen for abnormal bearing noise from generator during operation
• Check generator housing temperature after 20 minutes of operation; should be warm but not too hot to touch
• Verify belt is not slipping or squealing under load
• After test drive, recheck belt tension and all electrical connections for tightness

More procedures for this vehicle