Adjusting the drive belt
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Seasoned HDF Member
Joined: Nov 2015
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From: Marion NC / Lake Norman NC / Panama City Fla
Adjusting the drive belt
I had new Dunflops American Elites installed on my 96 Fatboy installed by a local indy shop yesterday. Among other things that were subpar, they didn't properly adjust my drive belt it is much looser than it was before.Right now the lower belt has about and inch and half play. Rather then going through the hassle of taking my bike back and risking them screwing something else up I will adjust it myself. I have a service manual, tools and decent mechanical ability. What advice do you geniuses have on this proceedure.
ps I have a fish scale to give it the 10# pull as the service manual recommends for proper adjustment.
ps I have a fish scale to give it the 10# pull as the service manual recommends for proper adjustment.
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Joined: Jun 2014
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From: 90210
sounds like you got everything needed to do it right. to measure the belt deflection per the service manual I prefer to use the spec with the bike up on a center stand with weight off the rear tire.
I will then take a medium sized tape measure and extend it about 8 inches, lock it in place. from under the bike where the belt exits the primary, sort of at the end of the primary but before the swingarm I will stand the tape measure upright on the ground with the 8" sticking upwards past the front of belt.
Adjust the tape measure up or down until it sits at a number like 2" lined up with bottom edge of belt. then push upward or downward on the belt with 10lbs and it's easy to see your amount of deflection alongside the vertical tape measure.
tighten or loosen pulley side adjuster to set belt deflection to spec, then do the brake side adjuster to align the wheel.
I use a dial caliper in the swingarm slot between the edge of outside axle washer and the rear edge of slot. if both sides are within 1mm of each other you're good to go. I know that the book says to adjust off the swingarm pivots but I've done both methods and both methods always come out right.
I will then take a medium sized tape measure and extend it about 8 inches, lock it in place. from under the bike where the belt exits the primary, sort of at the end of the primary but before the swingarm I will stand the tape measure upright on the ground with the 8" sticking upwards past the front of belt.
Adjust the tape measure up or down until it sits at a number like 2" lined up with bottom edge of belt. then push upward or downward on the belt with 10lbs and it's easy to see your amount of deflection alongside the vertical tape measure.
tighten or loosen pulley side adjuster to set belt deflection to spec, then do the brake side adjuster to align the wheel.
I use a dial caliper in the swingarm slot between the edge of outside axle washer and the rear edge of slot. if both sides are within 1mm of each other you're good to go. I know that the book says to adjust off the swingarm pivots but I've done both methods and both methods always come out right.
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Seasoned HDF Member
Joined: Nov 2015
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From: Marion NC / Lake Norman NC / Panama City Fla
Thanks. I am concerned about lining the rear wheel properly but the method you described was about how I was going to go about it.
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Joined: Jun 2014
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From: 90210
good luck- you should be fine. another low tech method you can use is once you have your belt tightness adjusted, find something that just barely passes through the swingarm slot on the pulley side, between the edge of outer axle washer and rear of slot- like a 7/16" socket or metric socket. once you find something that is a tight fit, then adjust other side until you get that same tight fit with the same piece inserted into the slot. it's low tech but accurate. just be sure you have the outer washers on both sides pushed forward on the axle, they are slightly larger than the diameter of axle.
oh and double check your rear brake inner pad that the lower tang of the pad is seated into the bottom caliper slot. it's easy to mess that one up if not paying attention during reassembly.
oh and double check your rear brake inner pad that the lower tang of the pad is seated into the bottom caliper slot. it's easy to mess that one up if not paying attention during reassembly.
Last edited by LA_Dog; Feb 17, 2016 at 07:56 PM.
Road Master
Joined: Sep 2015
Posts: 795
Likes: 75
From: Kane County IL
sounds like you got everything needed to do it right. to measure the belt deflection per the service manual I prefer to use the spec with the bike up on a center stand with weight off the rear tire.
I will then take a medium sized tape measure and extend it about 8 inches, lock it in place. from under the bike where the belt exits the primary, sort of at the end of the primary but before the swingarm I will stand the tape measure upright on the ground with the 8" sticking upwards past the front of belt.
Adjust the tape measure up or down until it sits at a number like 2" lined up with bottom edge of belt. then push upward or downward on the belt with 10lbs and it's easy to see your amount of deflection alongside the vertical tape measure.
tighten or loosen pulley side adjuster to set belt deflection to spec, then do the brake side adjuster to align the wheel.
I use a dial caliper in the swingarm slot between the edge of outside axle washer and the rear edge of slot. if both sides are within 1mm of each other you're good to go. I know that the book says to adjust off the swingarm pivots but I've done both methods and both methods always come out right.
I will then take a medium sized tape measure and extend it about 8 inches, lock it in place. from under the bike where the belt exits the primary, sort of at the end of the primary but before the swingarm I will stand the tape measure upright on the ground with the 8" sticking upwards past the front of belt.
Adjust the tape measure up or down until it sits at a number like 2" lined up with bottom edge of belt. then push upward or downward on the belt with 10lbs and it's easy to see your amount of deflection alongside the vertical tape measure.
tighten or loosen pulley side adjuster to set belt deflection to spec, then do the brake side adjuster to align the wheel.
I use a dial caliper in the swingarm slot between the edge of outside axle washer and the rear edge of slot. if both sides are within 1mm of each other you're good to go. I know that the book says to adjust off the swingarm pivots but I've done both methods and both methods always come out right.
Thread Starter
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Seasoned HDF Member
Joined: Nov 2015
Posts: 11,772
Likes: 41,407
From: Marion NC / Lake Norman NC / Panama City Fla
Road Master
Joined: Sep 2015
Posts: 795
Likes: 75
From: Kane County IL
Yeah tough to do sitting on the bike. Strange they would say to check it with the rider on board? Does the rider need to be present then when someone chooses to have the service department preform this task?
Maybe I should clarify then, the HD 2015 Softail Service Manual specs doing as I posted.
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Outstanding HDF Member
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From: 90210
thanks 1004ron- the various softail service manuals i have are same as yours. there could be some model exceptions, but as yours shows above those are the two typical methods. For home DIY I find the in the air method is easiest to acheive proper alignment / belt tension for someone who does not do this all the time or have all the exact proper tools. the rear wheel only needs to be a hair off the ground.
Road Warrior
Joined: Jun 2013
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From: Louisville, KY
thanks 1004ron- the various softail service manuals i have are same as yours. there could be some model exceptions, but as yours shows above those are the two typical methods. For home DIY I find the in the air method is easiest to acheive proper alignment / belt tension for someone who does not do this all the time or have all the exact proper tools. the rear wheel only needs to be a hair off the ground.
These measurements are based on an "average" rider weight, so it would be a good idea if you're on the heavy side to get someone to check the belt while you're sitting on it, just to be sure that the belt isn't being pulled too tight.