Positioning:
The 1960 Duo Glide represents a pivotal model in Harley-Davidson's evolution, bridging the gap between earlier rigid frames and more modern designs. This manual targets owners and mechanics seeking to maintain or restore these classic motorcycles.
Comparison To Contemporaries:
Competed with models from British marques like Triumph and BSA, and American counterparts from Indian Motorcycle (though in decline). The Duo Glide offered robust V-twin power and the iconic Harley-Davidson riding experience.
Distinguishing Features:
Introduction of the Duo Glide name signified the adoption of hydraulic rear suspension (swingarm), a significant upgrade for ride comfort over previous rigid or sprung-seat models. It also continued the evolution of the Panhead engine.
Engine:
Full engine disassembly, assembly, repair, and tuning for the Panhead engine.
Transmission:
Gearbox disassembly, assembly, maintenance, and repair.
Frame And Suspension:
Front fork (leading link or telescopic depending on exact spec), rear suspension (swingarm), frame integrity, and related components.
Brakes:
Drum brake systems, including adjustment, relining, and troubleshooting.
Electrical System:
Ignition system (magneto or distributor), lighting, charging system (generator), and wiring diagrams.
Fuel System:
Carburetor service and adjustment (e.g., Linkert), fuel tank, and fuel lines.
Clutch:
Clutch operation, adjustment, and component replacement.
Controls:
Throttle, clutch, and brake lever controls, as well as foot controls.
Bodywork And Trim:
Fenders, fuel tank, seat, and other cosmetic components.
Maintenance:
Routine service checks, lubrication, filter changes, and tune-ups.
Disassembly And Assembly:
Step-by-step instructions for component removal and reinstallation.
Repair:
Detailed repair procedures for worn or damaged components.
Troubleshooting:
Diagnostic charts and symptom-based troubleshooting guides.
Adjustment:
Precise adjustments for ignition timing, carburetor mixture, clutch, and brakes.
Depth:
Comprehensive, covering everything from basic maintenance to full engine and transmission overhauls, suitable for professional mechanics and experienced DIY enthusiasts.
Digital Format Details:
If digital (PDF), expect searchable text, high-resolution diagrams, and easy navigation.
Print Quality Description:
Factory manuals typically feature clear, durable paper with high-quality printing for diagrams and text.
Binding Description:
Original factory manuals were often hardbound or spiral-bound for durability in a workshop environment.
Paper Type Description:
Durable, often semi-gloss paper stock designed for repeated use in workshop conditions.
Engine Type:
Air-cooled, 45-degree V-twin, OHV (Overhead Valve)
Displacement:
74 cubic inches (1208 cc) - FL model
Bore X Stroke:
3.4375 in x 4.25 in (87.3 mm x 108 mm) (for 74 CI)
Compression Ratio:
Approximately 7.0:1 (varies slightly by specific variant)
Horsepower Estimated:
Approx. 50-55 HP at 5,000 RPM (estimated for stock configuration)
Torque Estimated:
Approx. 70-80 lb-ft at 3,000 RPM (estimated for stock configuration)
Carburetor:
Typically a Linkert M-series carburetor (e.g., M-74B or similar).
Fuel Type:
Gasoline (typically leaded premium, octane rating suitable for the era).
Ignition Type:
Battery and Coil with Distributor or Magneto (depending on specific variant and region).
Oil Change Interval:
Typically every 1,000 - 1,500 miles, or more frequently under severe use. Consult manual for specific intervals.
Transmission Oil Change:
As per manual, often concurrent with engine oil changes or every 2,000-3,000 miles.
Spark Plug Replacement:
Typically at 5,000 - 10,000 mile intervals, depending on plug type and condition.
Ignition Timing Check:
Recommended at regular service intervals or if performance issues arise.
Engine Oil Type:
Primarily designed for single-weight mineral oils, such as SAE 50 or SAE 60. Use of modern multi-viscosity oils may require careful consideration. Consult manual for recommended oil specs.
Engine Oil Capacity:
Approximately 3 quarts (2.8 liters) for the 74 CI engine, including oil filter. Check dipstick for exact level.
Primary Chaincase Oil:
Separate oil for the primary drive, often a specific Harley-Davidson primary lubricant or SAE 50/60 gear oil.
Fork Oil Type:
Specific hydraulic fork oil, viscosity documented in the manual.
Oil Leaks:
Common in vintage Harley-Davidsons due to aging seals, gaskets, and case materials. Manual provides guidance on sealing.
Carburetor Issues:
Linkert carburetors can be finicky and require precise adjustment. Gumming and wear are common.
Generator Charging System:
Generators can require rebuilding or adjustment; voltage regulator (if applicable) is a common failure point.
Panhead Rocker Boxes:
Potential for oil leaks from rocker box gaskets, requiring proper torque and sealing.
Heritage Summary:
Harley-Davidson, founded in 1903, is one of the oldest motorcycle manufacturers in the world, renowned for its V-twin engines and American V-twin culture.
Predecessor:
The Duo Glide evolved from earlier models like the Hydra-Glide, which featured telescopic front forks but often retained a rigid or sprung rear end.
Successor:
The Duo Glide was succeeded by the Electra Glide, which introduced full electric start and further refinements.
Production Period For Duo Glide:
The Duo Glide designation was used roughly from 1958 to 1964, before the Electra Glide name took over.
Manufacturing Location:
Milwaukee, Wisconsin, USA.
