1998 GMC Forward Control 7.4 BFACTORY OEM SERVICE PROCEDURE

Commutator End Frame & Bearing

Replace armature assembly if commutator outer diameter is less than 1.378" (36 mm) or if undercut depth is less than .008" (.2 mm). DO NOTΒ  undercut insulation. Ensure commutator end bearing has not spun in frame. If bearing has spun, replace frame and bearing. DO NOTΒ  lubricate bearing. If bearing is dry or damaged, replace bearing. Measure original bearing depth and install new bearing to same depth.

Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.