Special Tools
DescriptionPart NumberQty.

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:
To prevent accidental vehicle start-up, which could cause death or serious injury, remove main fuse before proceeding. (00251b)
  1. Disarm security system. Remove main fuse. See Maintenance and Lubrication → Fuses and Relays.
  2. Shift transmission to neutral.
  3. NOTE
    When adjusting a new belt, rotate rear wheel a few revolutions prior to setting the tension.
  4. See Figure 1. Measure belt deflection using BELT TENSION GAUGE (Part Number:HD-35381-A):
    1. Slide O-ring (4) to zero mark (3).
    2. Models equipped with belt deflection window: Fit belt cradle (2) against bottom of drive belt in line with belt deflection window.
    3. All other models: Fit belt cradle (2) against bottom of drive belt halfway between drive pulleys.
    4. Press upward on knob (6) until O-ring slides down to 4.54 kg (10 lb) mark (5) and hold steady.
  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 1.6 mm (1/16 in).
    2. All other models: See Figure 2. Measure amount of deflection (4) while holding gauge steady.
  6. NOTE
    Set to the lower (tightest) specification if the belt has less than 1,600 km (1000 mi).
  7. Compare with specifications. Refer to Table 1. If not within specifications, see a Harley-Davidson dealer.
  8. Install main fuse.
Table 1. Belt Deflection
All models
1Belt tension gauge
2Belt cradle
30 lb (0 kg) mark
510 lb (4.5 kg) mark
Figure 1. Belt Tension Gauge
1Transmission sprocket
2Rear wheel sprocket
310 lb (4.5 kg) of force
4Amount of deflection
Figure 2. Checking Belt Deflection
1Drive belt
2Deflection graduations (Approx: 1.5 mm (1/16-in)
Figure 3. Belt Deflection Window