Cub Cadet Tractor 72/104/105/124/125 1967–1969 Service Manual (P/N GSS-1398)

• Factory publication and coverage: International Harvester Blue Ribbon Service Manual GSS-1398, dated September 1969, for Cub Cadet models 72, 104, 105, 124, and 125. The 121-page PDF also contains the IH equipment sections described below.
• Engine coverage is matched to the tractor: K-161S electric-start and K-161T retractable-start engines for the 72, K-241AS for the 104 and 105, and K-301AS for the 124 and 125. The manual keeps their starting, ignition, governor, valve, and adjustment differences separate where required.
• Engine repair procedures cover removal, teardown, inspection, cylinder reboring, crankshaft and connecting-rod service, pistons and rings, valves and guides, camshaft and Automatic Compression Release service, crankshaft seals, cylinder head, breather, carburetor, and final reassembly.
• Gear-drive coverage for the 72, 104, and 124 details tractor splitting and recoupling, clutch service, reduction drive, the three-speed transmission and differential, rear axles, brake, optional creeper drive, and front and rear PTO work. Inspection procedures address bearing preload and tooth contact, followed by the required operating adjustments.
• Hydrostatic coverage for the 105 and 125 explains system operation and addresses both charge-pump types, relief and check valves, hydro unit removal and installation, pump and motor disassembly, differential service, neutral and speed-control linkage adjustment, brake adjustment, and fault isolation.
• Chassis and electrical work includes steering-gear overhaul and adjustment, front wheels and axle, magneto and battery ignition, the motor-generator, cut-out relay and current-voltage regulator, ignition timing, and recoil starter repair, backed by model-specific wiring information.
• IH equipment service covers mower removal, spindle teardown, inspection, blade sharpening, reassembly, belt setting, and deck leveling. Snow thrower coverage is limited to its gearbox; the rotary tiller material covers tine timing and gearbox service.

International Harvester wrote this manual for its dealers and factory-trained servicemen. Its overhaul depth, measuring procedures, presses, pullers, and special-tool references make it best suited to experienced mechanics equipped for shop-level repair rather than first-time maintenance work.

Engine, Fuel, and Electrical Detail

The engine chapters provide inspection limits for the cylinder, crankshaft, rod, piston, rings, valve train, bearings, and camshaft, along with component-specific torque and clearance tables. The K-161 valve procedure calls for correcting clearance at the valve stem, while the K-241 and K-301 use adjustable tappets. Automatic Compression Release engines also receive their own compression-check method, avoiding the misleading results produced by an ordinary low-speed test.

Fuel-system coverage distinguishes the Model 72 carburetor and governor arrangement from the setup used on the larger tractors. Carburetor disassembly, cleaning, float setting, mixture adjustment, governor reset, and throttle linkage work are all addressed. The electrical chapter provides test and adjustment information for breaker points, condenser, coil, starter-generator, relay, regulator, and timing—not just a wiring overview.

Drivetrain, Hydrostatic, and Reference Detail

On gear-drive tractors, the manual follows the repair path from tractor separation through reduction-drive and transmission teardown. It documents gear and spacer order, differential bearing preload, bevel-gear backlash, and tooth-bearing pattern checks. Rear-axle construction is also differentiated: the 72 uses a carrier bushing, while the 104, 105, 124, and 125 use a needle bearing.

Hydrostatic service is treated as internal repair work, not merely linkage adjustment. The section explains the variable-displacement pump and fixed-displacement motor, shows both charge-pump assemblies, and covers polished rotor, piston, slipper, valve-plate, swash-plate, center-section, and bearing inspection. Factory data tables supply charge pressure, spring tests, wear limits, special torques, lubricant requirements, and adjustment specifications.

The illustrations include the schematic wiring diagram of magneto ignition, electric lighting wiring diagram, electric starting wiring diagram, exploded steering assembly, exploded hydrostatic transmission, and the foldout Hydrostatic Transmission oil-flow and control schematic.

Three listed special tools are identified by number: FES 54-4 rear seal protector, FES 54-5 front seal protector, and FES 54-6 seal driver. The procedures also show the OTC-950 puller, a dimensioned hydrostatic holding fixture, and the adjusting gauge supplied with the front clutch disc repair kit.

The repair notes warn that installing the engine-breather plate with its drilled hole out of position, or putting the reed on the wrong side, causes oil leakage. In the hydrostatic unit, the two-notch pump valve plate and four-notch motor valve plate must remain correctly identified and protected from drops or scratches, since damage to these precision faces reduces pump efficiency.

Tractor splitting, hydrostatic repair, and PTO or clutch work involve heavy assemblies, rotating components, and hydraulic oil. The manual calls for battery isolation, blocking, lifting support, and careful cleanliness before service begins.