Brush Spring

Measure force of brush spring with a spring pressure gauge.
Replace the spring if necessary.
1. Standard force:
  1. 0.71~0.93 lb-ft (3.1~4.1 N.m, 0.32~0.42 kg-m)
  2. Minimum:
  3. 0.36~0.52 lb-ft (1.60~2.4 N.m, 0.16~0.24 kg-m)
NOTE: Read spring pressure with brush tip projecting 0.08 in (2 mm).

Fig 1: Measuring Brush Spring Tension
Courtesy of KIA MOTORS AMERICA, INC.