🏷️ Basic Information

Make:

Harley-Davidson

Model:

Duo-Glide

Year:

1958

Engine Variant:

74 OHV

Product Identifier:

Harley-Davidson Duo-Glide 74 OHV 1958 Factory Service Repair Manual

👋 Introduction

Target Audience:

Enthusiast owners, home mechanics, and professional motorcycle technicians specializing in vintage Harley-Davidson motorcycles.

Manual Advantage:

Provides factory-authorized procedures and specifications, ensuring accuracy and completeness for servicing this iconic motorcycle model. Essential for preserving originality and ensuring correct operation.

Usefulness:

Essential resource for diagnosing, repairing, and maintaining the Harley-Davidson Duo-Glide, ensuring longevity and optimal performance of a classic machine.

Accessibility:

Designed to be user-friendly for both experienced mechanics and DIY enthusiasts undertaking their own repairs.

📋 Manual Details

Primary Coverage:

Comprehensive repair and maintenance for the 1958 Harley-Davidson Duo-Glide 74 OHV.

Specific Systems Covered:

Engine (OHV V-Twin), Transmission (4-speed), Clutch, Frame, Suspension (Front & Rear), Brakes (Drum), Electrical System (Ignition, Lighting, Charging), Fuel System, Carburetion, Exhaust, Wheels, Tires, Controls, Bodywork, and accessories.

Estimated Pages:

300-400

Type:

Factory Service Repair Manual

Language:

English

Format:

Print (Paperback)

📖 Manual Coverage

Powertrain:

Detailed coverage of the 74 cubic inch (1208cc) OHV V-Twin engine, including disassembly, assembly, inspection, and repair of all internal components (crankshaft, connecting rods, pistons, cylinders, heads, valves, camshafts, lifters, timing gears). Covers clutch operation, maintenance, and adjustment. Includes full transmission overhaul procedures for the 4-speed constant mesh gearbox.

Chassis And Frame:

Comprehensive instructions for frame inspection, repair, and alignment. Detailed procedures for front fork (leading link) disassembly, reassembly, fluid changes, and adjustments. Rear suspension components, shock absorber maintenance, and swingarm bearing service are thoroughly covered.

Brakes And Wheels:

In-depth guidance on front and rear drum brake systems, including brake shoe replacement, drum inspection, linkage adjustment, and brake fluid (if applicable, though typically mechanical linkages) service. Wheel bearing maintenance, spoke tensioning, and tire fitting procedures are included.

Electrical System:

Detailed wiring diagrams for the 1958 model. Covers ignition system (magneto or distributor, points, condenser, spark plugs), lighting circuits (headlight, taillight, stoplight, indicators), battery maintenance, charging system (generator, voltage regulator), horn, and starter motor.

Fuel And Exhaust:

Instructions for fuel tank maintenance, fuel line inspection, and carburetor (likely a Linkert type) disassembly, cleaning, adjustment, and rebuilding. Covers exhaust system inspection, gasket replacement, and mufflers.

Routine Maintenance:

Oil changes, filter replacement (if applicable), spark plug inspection and replacement, battery charging and terminal cleaning, tire pressure checks, chain lubrication and adjustment, lubrication points schedule.

Troubleshooting:

Systematic diagnostic procedures for common problems related to starting, running, electrical issues, braking, and shifting. Fault-finding charts and symptom-based solutions are provided.

Disassembly And Assembly:

Step-by-step instructions for complete vehicle tear-down and reassembly, including engine, transmission, and all major components. Torque specifications for critical fasteners are provided.

Component Rebuilding:

Detailed procedures for rebuilding carburetors, generators, starters, ignition systems, and any other serviceable components.

Adjustments:

Guidance on adjusting clutch, brakes, throttle, idle speed, ignition timing, and suspension.

Depth:

High. Covers everything from basic maintenance and adjustments to complete engine and transmission overhauls, including internal component specifications and tolerances.

📊 Manual Specifications

Format Type:

Physical printed manual

Paper Quality:

Durable paper stock suitable for workshop use.

Print Clarity:

Clear text and legible diagrams/illustrations.

Binding:

Stapled or perfect bound paperback

⚙️ Engine Specifications

Engine Type:

Overhead Valve (OHV) V-Twin

Engine Displacement:

74 cubic inches (1208cc)

Bore X Stroke:

3.4375 in. x 4.25 in. (87.3 mm x 108.0 mm)

Compression Ratio:

Approx. 7.0:1 (varies by sub-model and tuning)

Horsepower:

Approx. 50-55 HP @ ~5000 RPM (estimated, specifications varied)

Torque:

Approx. 65-70 ft-lbs @ ~3500 RPM (estimated)

Carburetor:

Linkert M-series (e.g., M74B, M74C) or similar downdraft carburetor.

Fuel Type:

Leaded gasoline with appropriate octane rating (typically 91-93 RON / 87-89 AKI recommended, manual will specify).

Oil System:

Dry sump lubrication with a separate oil tank.

Oil Capacity:

Approx. 4 US Quarts (3.8 Liters), including oil tank and crankcase.

Oil Type:

Viscosity grade HD 30 or 50 based on ambient temperature (refer to manual for specific recommendations, often straight-weight oils like SAE 50 were used).

Ignition System:

Battery-coil ignition with distributor or magneto ignition system (depending on specific build/options).

Spark Plug Type:

Champion, Bosch, or equivalent (specific part number in manual, e.g., Champion H10 or H12).

🔧 Transmission

Transmission Type:

4-speed, constant mesh, foot-shift

Gear Ratios:

Specific ratios available in manual, typically: 1st: ~9.0:1, 2nd: ~6.5:1, 3rd: ~4.8:1, 4th: ~3.5:1 (approximate values)

Transmission Fluid Type:

Gear oil (e.g., SAE 80W-90 GL-4) or specialized transmission fluid (manual will specify).

Clutch Type:

Wet multi-plate clutch, operated by foot pedal and hand lever.

Clutch Fluid:

Typically no hydraulic fluid; mechanical actuation. Clutch adjustment is crucial.

📐 Dimensions

Wheelbase:

Approx. 59.0 inches (1500 mm)

Length:

Approx. 88.0 inches (2235 mm)

Seat Height:

Approx. 29.0 inches (737 mm) (unladen)

Dry Weight:

Approx. 500-550 lbs (227-250 kg) (depending on accessories and options)

Gross Vehicle Weight Rating:

Not typically specified in the same manner as modern vehicles, but safe operating load should be considered.

🛡️ Safety Features

Crash Test Ratings:

Not applicable for this era of motorcycle; safety focus is on rider control and machine integrity.

Braking System:

Dual drum brakes (front and rear). Effective use requires proper adjustment and maintenance.

Lighting:

Halogen headlight, taillight, stoplight, and often front/rear turn signals (optional on some models).

Frame Construction:

Robust steel frame designed for stability and durability.

Suspension:

Telescopic front fork (leading link design) and dual rear shock absorbers provide ride comfort and handling.

💡 Technology Features

Audio System:

None. This era focused on mechanical and rider experience, not integrated electronics.

Electronic Aids:

No electronic rider aids (ABS, traction control, etc.) were available. All control is mechanical and rider input.

Connectivity Features:

No connectivity features (Bluetooth, USB, app integration).

🔧 Maintenance

Oil Change Interval:

Every 1,000-2,000 miles or annually, whichever comes first (refer to manual for specific mileage).

Engine Tune Up:

Recommended annually or every 3,000-5,000 miles, including ignition timing, carburetor adjustment, and valve lash check.

Chain Adjustment:

Check and adjust every 500-1,000 miles.

Fork Oil Change:

Annually or as needed based on riding conditions.

Engine Oil:

SAE 50 (or HD 30/50 depending on temperature). Specific brand recommendations in manual are often for Harley-Davidson branded oils or equivalent API classifications.

Transmission Oil:

SAE 80W-90 gear oil or equivalent (manual will specify GL rating).

Primary Chaincase Oil:

Often shared with the transmission, or a specific lighter oil may be used. Manual is critical here.

Oil Leaks:

Common on vintage Harleys due to aging seals, gaskets, and case joints. Manual provides procedures for locating and rectifying leaks.

Carburetor Issues:

Linkert carburetors can be prone to wear and require precise adjustment for optimal performance. Gumming from old fuel is frequent.

Electrical Gremlins:

Aging wiring harnesses, connections, and primitive electrical components can lead to intermittent issues. Manual's wiring diagrams are essential.

Drum Brake Performance:

Drum brakes require frequent adjustment and maintenance for adequate stopping power, especially compared to modern disc brakes.

Clutch Adjustment:

Needs regular adjustment to ensure proper engagement and disengagement. Manual details the correct procedure.

📚 Vehicle History

Founding:

Harley-Davidson Motor Company was founded in 1903.

Legacy:

Renowned for producing iconic American motorcycles, particularly large-displacement V-twins.

Duo Glide Introduction:

The Duo-Glide name signified the introduction of rear suspension for Harley-Davidson Big Twins, replacing the rigid frame of previous models like the Hydra-Glide.

Predecessors:

Evolved from the Panhead engine era, succeeding the Hydra-Glide. The 'Duo-Glide' designation accurately described its dual suspension capabilities.

Successors:

The Duo-Glide was succeeded by the Shovelhead engine models starting in 1966, which featured updated styling and engineering.

Production Years:

The Duo-Glide model range was produced from 1958 to 1964.

Engine Era:

The 74 OHV (Panhead) engine was used in Harley-Davidson Big Twins from 1948 to 1965.

🏆 Awards & Recognition

Historical Significance:

The Duo-Glide represents a significant step in Harley-Davidson's evolution, bringing rider comfort and improved handling to their large-displacement motorcycles, cementing their reputation in the touring and cruiser segments.

Enthusiast Appreciation:

Highly regarded by collectors and vintage motorcycle enthusiasts for its classic styling, raw V-twin power, and historical significance.