Special Tools
DescriptionPart NumberQty.
BELT TENSION GAUGE
HD-35381-A
1

NOTE
Always use BELT TENSION GAUGE (Part Number:HD-35381-A) to measure belt deflection. Failure to use tension gauge may cause under-tensioned belts. Loose belts can fail due to "ratcheting" (jumping a tooth) which causes tensile cord crimping and breakage.
Check deflection:
WARNING
To prevent accidental vehicle start-up, which could cause death or serious injury, remove main fuse before proceeding. (00251b)
  1. Disarm security system and remove main fuse. See Maintenance and Lubrication → Fuses.
  2. NOTE
    Customers may purchase gauge from an authorized Harley-Davidson dealer.
  3. To use the belt tension gauge:
    1. Slide O-ring (4) to 0 kg (0 lb) mark (3).
    2. Models equipped with belt deflection window: Fit belt cradle (2) against bottom of drive belt inline with belt deflection window.
    3. All other models: Fit belt cradle (2) against bottom of drive belt half-way between drive pulleys.
    4. Press upward on knob (6) until O-ring slides down to 4.5 kg (10 lb) mark (5) and hold steady.
  4. NOTE
    Measure belt deflection on a motorcycle that is upright or on jiffy stand with rear wheel on the ground and unladen.
  5. Measure belt deflection:
    1. Models equipped with belt deflection window: See Figure 3. Measure belt deflection as viewed through belt deflection viewing window while holding gauge steady. Each deflection graduation is approximately 1.59 mm (1/16 in).
    2. All other models: See Figure 2. Measure belt deflection (4) while holding gauge steady.
  6. Compare with specifications listed in Table 1. Adjust as necessary.
  7. Install main fuse.
Table 1. Drive Belt Deflection
PROCEDURE
SPECIFICATION
Upright or on jiffy stand without rider or luggage
6.4–7.9 mm (¼–5/16 in)
1Belt tension gauge
2Belt cradle
30 lbs (0 kg) mark
4O-ring
510 lbs (4.5 kg) mark
6Knob
Figure 1. Belt Tension Gauge
1Transmission sprocket
2Rear wheel sprocket
310 lbs (4.5 kg) of force
4Amount of deflection
Figure 2. Checking Belt Deflection
1Drive belt
2Deflection graduations (Approx. 1/16th each)
Figure 3. Belt Deflection Window