Author Topic: Drive Belt Tension  (Read 503 times)

0 Members and 1 Guest are viewing this topic.

Offline Die Hard

  • Full Member
  • Posts: 134
  • Country: us
  • 2015 SG 124"
Drive Belt Tension
« on: April 15, 2018, 01:50:40 PM »
The service manual that covers my 2015 Street Glide Special says the following for drive belt deflection tension:

FLHX/S, FLTRX/S and low models (low profile shock absorbers)   1/4" - 7/16"

All except FLHX/S, FLTRX/S and low models (standard shock absorbers)   3/8" - 9/16"

Factory shocks that came on my bike were 12" low profile - I replaced them with 13" Ohlins 772's. Which spec would you use if you wanted to stay on the snug side?
Life is too short to hang out with a-holes

Offline harley_cruiser

  • Site Supporter
  • Full Member
  • *****
  • Posts: 1996
  • Country: us
    • Rocker Lockers
Re: Drive Belt Tension
« Reply #1 on: April 15, 2018, 02:15:32 PM »
You don't want them too snug, that is hard on everything, but that is not the question that You ask. I would set it at 3/8 and check it in several places.

Offline 88b

  • Full Member
  • Posts: 4137
  • Country: england
Re: Drive Belt Tension
« Reply #2 on: April 16, 2018, 02:11:29 PM »
Are you checking it on the jiffy stand or with the wheel hanging ?

Offline Die Hard

  • Full Member
  • Posts: 134
  • Country: us
  • 2015 SG 124"
Re: Drive Belt Tension
« Reply #3 on: April 16, 2018, 02:49:30 PM »
On the jiffy stand with the wheel on the ground - just like the service manual says.
Life is too short to hang out with a-holes

Offline 04 SE DEUCE

  • Site Supporter
  • Full Member
  • *****
  • Posts: 5936
Re: Drive Belt Tension
« Reply #4 on: April 16, 2018, 04:06:06 PM »
If you're setting the 13" HD772 at a proper laden sag/ride height of 1" - 1.25" you will want to up your measurement as sitting static the swingarm with be farther from the tightest spot in the arch with the longer shocks. 

Offline Die Hard

  • Full Member
  • Posts: 134
  • Country: us
  • 2015 SG 124"
Re: Drive Belt Tension
« Reply #5 on: April 16, 2018, 07:40:30 PM »
If you're setting the 13" HD772 at a proper laden sag/ride height of 1" - 1.25" you will want to up your measurement as sitting static the swingarm with be farther from the tightest spot in the arch with the longer shocks.

Run that by me again please
Life is too short to hang out with a-holes

Offline 88b

  • Full Member
  • Posts: 4137
  • Country: england
Re: Drive Belt Tension
« Reply #6 on: April 17, 2018, 05:25:23 AM »
.

Offline 04 SE DEUCE

  • Site Supporter
  • Full Member
  • *****
  • Posts: 5936
Re: Drive Belt Tension
« Reply #7 on: April 17, 2018, 10:15:39 AM »
If you're setting the 13" HD772 at a proper laden sag/ride height of 1" - 1.25" you will want to up your measurement as sitting static the swingarm with be farther from the tightest spot in the arch with the longer shocks.

Run that by me again please

Simple answer,  adjust the belt per Harley specs for a model that comes with standard 13" shocks.  I don't see what model 88b has referenced so don't know if that is for 13" or 12" shocks.

Primary objective of belt adjustment is to get the tension correct at the point in suspension travel that the belt is the tightest...normally this is where the pulleys and swingarm pivot are in a straight line.  Installing longer shocks raises the rear of the bike (given that shock preload is set similar) and reduces tension on the belt (when measuring tension with wheel in air or bike on jiffy stand) as the swingarm is farther from being in-line with pulleys and swingarm pivot...tightest position for belt.

If 2 bikes have the same measured belt tension with the swingarm/rear suspension positioned at the tightest spot for belt tension,  the bike that relaxes/raises the rear suspension from that position the most will then have more slack in the belt.  In other words a bike with longer shocks that sits higher in the rear will have more belt deflection than a bike with shorter shocks when measured either with wheel in air or bike on sidestand given both bikes have the same belt tension when measured at the tightest point in suspension travel. 

Not worth considering is the slight change in how much the rear suspension relaxes when adding longer shocks to a bike and using the same jiffy stand...bike now leans over farther and places more weight on the jiffy stand and slightly less weight on rear wheel.

Offline Die Hard

  • Full Member
  • Posts: 134
  • Country: us
  • 2015 SG 124"
Re: Drive Belt Tension
« Reply #8 on: April 17, 2018, 08:02:57 PM »
Got it. Thank you.
Life is too short to hang out with a-holes