Special Tools

Description	Part Number	Qty.
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:

As part of pre-ride inspection.
At every scheduled service interval.
With transmission in neutral.
With motorcycle at ambient temperature.
With motorcycle upright or on jiffy stand with rear wheel on the ground.
With the vehicle unladen: no rider, passenger or cargo.

WARNING

To prevent accidental vehicle start-up, which could cause death or serious injury, remove main fuse before proceeding. (00251b)

Disarm security system. Remove main fuse. See Maintenance and Lubrication → Fuses.
See Figure 1. Measure belt deflection using BELT TENSION GAUGE (Part Number:HD-35381-A):
1. Slide O-ring (4) to 0 kg (0 lb) mark (3).
2. Fit belt cradle against bottom of drive belt halfway between drive pulleys (1).
3. Press upward on knob until O-ring slides down to 4.5 kg (10 lb) mark (5) and hold steady.
Measure belt deflection (2) while holding gauge steady.
If the measurement is not within specification, see a Harley-Davidson dealer for service. Refer to Table 1.
Install main fuse.

1	Belt tension gauge
2	Belt cradle
3	0 lb (0 kg) mark
4	O-ring
5	10 lb (4.5 kg) mark
6	Knob

Figure 1. Belt Tension Gauge

Table 1. Drive Belt Deflection

MODEL	DEFLECTION
MODEL	in	mm
FLS, FLSS, FLSTFB, FLSTFBS**, FLSTN, FXSB	1/4-5/16	6.4-7.9
FLSTC, FLSTF	9/16-5/8	14.3-15.9
* FLS (AUS/APC configurations) uses FLSTC, FLSTF specification. FLSS (AUS/ configuration) uses FLSTC, FLSTF specification. * FLSTFB (BRZ/HDI/IND/ENG configurations) uses FLSTC, FLSTF specification. **** FLSTFBS (HDI/ENG configurations) uses FLSTC, FLSTF specification. To determine configuration from VIN, refer to Identification → Vehicle Identification Number (VIN) → Harley-Davidson VIN Breakdown: 2017 Softail Models.