Harley-Davidson Duo-Glide FL/FLH 1958–1959 Service Manual (P/N 99482-59)

Harley-Davidson’s factory Service Manual, P/N 99482-59, covers the 1959 Duo-Glide 74 OHV directly, with applicability to the 1958 model except for minor differences. It includes FL and FLH specifications and repair information for solo and sidecar configurations.

PDF Search, Diagram Detail and Page Count

Search and wiring detail: PDF text search and embedded bookmarks are not available. Small terminal numbers and wire-color codes in the wiring diagram are readable when enlarged.

The ZIP download contains one printable English PDF with 140 pages, including three cover/title pages, six section-divider pages, the foreword and the contents page.

Engine Overhaul, Chassis Repair and Electrical Diagnosis

These selected repair highlights are not a complete contents list; additional topics include handlebar-control servicing and seat-post springing.

• Wheels and frame: Wheel removal, hub-bearing and shim service, spoking, rim centering, wheel truing, and frame-alignment checks.

• Forks and rear suspension: Damper diagnosis, fork disassembly, bushing replacement and reaming, tube and bracket alignment, rear-shock inspection, and rear-fork bearing service.

• Brake repair: Mechanical front-brake and hydraulic rear/sidecar brake service, shoe adjustment, wheel-cylinder repair, master-cylinder work, and system bleeding.

• Engine overhaul: Step-by-step cylinder-head and cylinder repair, crankcase disassembly, oil-pump service, hydraulic-tappet checks, timing-gear installation, and flywheel truing.

• Clutch and gearbox: Foot- and hand-clutch adjustment, clutch and kick-starter teardown, main-drive-gear seal replacement, shifter timing, fork gauging, and gearbox overhaul.

• Electrical diagnosis: A 110-item troubleshooting checklist, standard and radio-special wiring, Model 58 and 58R generator tests, regulator checks, and ignition timing.

Harley-Davidson addresses basic maintenance and repair to the general reader and major repair methods to professional mechanics; the overhaul work suits technicians and experienced restorers equipped for precision measurement, pressing, reaming, and bearing fitting.

Model Application and Parts Selection

For earlier 61 and 74 OHV machines, the factory directs readers to the model-specific parts catalog when determining how the procedures apply. Shared sections identify limited Servi-Car, Sportster, 165, and Hummer applications; they do not provide full service coverage for those models.

The configuration details help match procedures and parts to the machine before disassembly. The non-adjustable fork is for solo use, while the adjustable fork changes trail for solo or sidecar operation. The optional three-speed/reverse gearbox is hand-shift only and cannot be assembled in a four-speed case.

Forks, Wheel Hubs and Hydraulic Brakes

The Adjustable Fork - Exploded View supports the separate fork configurations. Detailed work extends to slider oil seals, steering-head bearings, damper valves, and rear-shock spring settings.

Rear-shock disassembly covers the spring, cover, cams, and related parts. The hydraulic damper units themselves are not repairable; faulty units must be replaced.

Wheel-hub bearings and adjusting shims are factory matched. Mixing parts between hubs can produce an incorrect bearing fit, while excess grease can contaminate the brakes. Brake coverage also includes master-cylinder piston and cup inspection and rear-pedal adjustment.

Cylinder Heads, Crankshaft and Fuel System

The Engine Cutaway, Oil Feed Pressure System, and Oil Scavenger System illustrate the engine’s construction and lubrication paths. The repair sections distinguish top-end work with the engine in the chassis from lower-end overhaul requiring engine removal.

Cylinder-head work includes valve-guide replacement, valve-face and seat grinding, lapping, rocker-arm bearing repair, and tappet adjustment. FL and FLH valve-spring, valve-key, and stem-pad arrangements are distinguished. For valve-seat insert replacement, the manual directs cylinder heads to the factory through an authorized dealer.

Cylinder and crankshaft work covers bore measurement and refinishing, piston-ring fitting, rod-bushing replacement, connecting-rod alignment, race lapping, and crankshaft-bearing selection. Named tools include the Valve Spring Compressor P/N 96600-36, Valve Guide Reamer P/N 94830-47, Flywheel Truing Device P/N 96650-30, and Pinion Gear Puller and Installer P/N 96830-51.

Fuel-system material covers carburetor adjustment and overhaul, float and needle inspection, air-cleaner servicing, fuel-strainer care, and fuel shut-off fitting alignment.

Gearbox Service and 6-Volt Electrical Tests

The transmission sections distinguish foot- and hand-shift mechanisms and both clutch-control arrangements. Clutch, kick-starter, and main-drive-gear oil-seal work can be performed without removing the transmission; internal gearbox repair adds bearing fits, shaft end play, and shifter-clutch clearance checks using Fork Shifter Gauge P/N 96384-39.

A vented shifter-cover screw must return to its designated hole. Incorrect placement can allow gearbox pressure to force oil into the clutch.

The Wiring Diagram and its key identify standard circuits and radio-special connections. Generator coverage includes output and field-coil tests, growler tests for the armature, commutator repair, and polarization for the standard Model 58 and fan-cooled Model 58R.

Two-unit and three-unit regulator diagnosis is supported by a test-specification table. Breaker-point service and timing checks use factory marks and a test lamp, with the Ignition Timing - Schematic showing the model-specific references. Other sections cover lamps, the bulb chart, battery care, horn service, and the speedometer drive.

Examples of Fork-Oil and Piston-Ring Specifications

The fork section distinguishes 6-1/2 oz. of oil per tube for a routine oil change from 7 oz. after the fork has been disassembled and washed.

For piston-ring fitting, the cylinder section specifies a standard compression-ring end gap of .010–.020 in. These examples accompany broader reference data covering component clearances, wear limits, spring-test loads, bearing fits, lubrication, gearing, and electrical test values.

Support the motorcycle securely before wheel, fork, engine, or transmission work, and follow proper precautions around fuel, compressed springs, hydraulic brakes, batteries, and electrical testing.