1978-1987 John Deere 670A/672A Motor Grader Repair Manual (P/N TM-1188)

• Official 774-page John Deere OEM publication TM-1188 (revised December 1987)
• Covers 1978–1987 John Deere 670A and 672A heavy-duty motor graders
• Details the JD672A front-wheel-drive hydrostatic system alongside standard tandem drive components
• Documents technical baseline specifications for 14 primary sub-systems, including hydraulic cycle times, electrical schematics, and drivetrain torque values
• Features critical 1987 revision updates covering Weather Pack electrical connectors and radial piston pump CTM-7 assemblies

Technical Coverage and System Architecture

Shop mechanics know that exact factory tolerances are non-negotiable. This publication breaks down component layouts, testing parameters, and assembly details specifically for the 1978–1987 JD 670A and 672A graders. You get a direct look into engine auxiliary systems, transmission controls, transfer drive housings, and steering hydraulics. Inspecting the power-shift transmission? The manual delivers in-depth data on planetary gear reduction to speed up component evaluation on the shop floor. It also catalogs frame configurations and operator station setups to help identify unit-specific hardware.

Working around heavy earthmoving drivetrains involves immense crush hazards and high-pressure fluid risks. Always depressurize systems and use proper blocking techniques before applying these factory specifications in a live workshop environment. Please keep in mind this page functions strictly as a contents review to verify manual compatibility for your project. It outlines technical parameters and does not provide step-by-step diagnostic or repair tutorials.

Specifications and Maintenance Data

System diagnosis on heavy equipment relies entirely on accurate baseline numbers. This resource outlines exact capacity limits for the fuel, engine lubrication, and cooling networks. For these specific models, the coolant system holds exactly 7 gallons (26.5 liters), and the standard operating engine speed is rated at 2300 RPM.

You will find detailed hardware torque tables for high-stress structural fasteners, such as the tandem housing and articulation pivot pins. The manual also fully maps out fluid pressure thresholds for the main hydraulic system and hydrostatic charge. Need to verify the differential lock pressure? It sits exactly at 635 psi, and the text explains how to safely adjust that setting using shims in precise 31 psi increments.