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Rear Drive Belt

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One For The Road

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Hi,
I have a question concerning the rear drive belt on a 2005 Ultra Classic. I just changed the rear tire so I needed to set the belt tension. I don't have a Harley belt tension gauge so I used a fish scale to apply 10 pounds and measured the deflection with the rear wheel in the air. I set the deflection at just over 1/4 inch. I heard it was better to have it a bit on the loose side.

When I went for a ride I noticed a bit of whine coming from I think the rear of the bike. It only seems to occur when slowing down under 40 mph. I checked the tension when I got home. It was much less then when it was cold.. Is it normal for the belt to get considerably tighter when warm.

Thanks for you reply,

Steve
 
If you checked the tension post ride with the wheel on the ground, it's normal to be tighter. The swingarm moves in an arc, and is a tiny bit farther away when laden. The whine, I can't diagnose, I seem to notice some different sound every time I work on my bike.
 
Recheck the belt tension with the wheels on the ground.
If the belt is too tight than it will whine, if it is tight enough to whine than it is going to also make heat, heat leads to deteration.
If it was my bike I would readjust a little to eliminate the whine. If it is the belt.
 
Take a look here, also take a look in the self help section under Drive belt adjustment.
  1. Rear Belt Drive Adjustment

    Performance and Technical information on the rear belt drive for Harley-Davidson motorcycles.
    Belt Drive Adjustment for Big Twins

    Set belt tension a the tightest rotational point on the sprockets.
    The adjustments should be done when the bike is cold.
    The adjustments should be made with the weight of a rider on the bike.

    1. At the lower strand, position "A", mid-way between transmission sprocket and rear wheel sprocket, apply 10 Ibs. of upward force on lower span of rear belt. Harley-Davidson has a BELT TENSION GAUGE (Part No. HD-35381) to help.

    2. Measure belt deflection "B" several times, each time with belt moved (by rotating rear wheel) to a different position on sprockets. With sprockets rotated to tightest belt position, belt deflection "B" (measured at position "A") should be 5/16-3/8 in. Check your manual to be sure of the measurements, the newer models have changed.

    ADJUSTMENT

    1. Loosen rear axle nuts.

    2. Measure each side from the flat to the end of the swingarm, to be sure rear axle is correctly located.

    3. Turn axle adjuster nuts (metric) on each side of swing-arm to adjust belt deflection.

    a. Turn clockwise to decrease deflection (increase tension).
    b. Turn counterclockwise to increase belt deflection (decrease tension).

    Turn each adjuster nut exactly the same number of turns to maintain rear wheel alignment.

    5. Tighten axle nut to 60-65 ft-lbs.

    CAUTION

    Keep dirt, grease, oil, and debris off the belt and sprockets. Clean the belt with a rag which is slightly damp with light cleaning agent.

    All belts must be handled carefully to prevent bending stress. The belt must never be formed into a loop smaller than 5 inches in diameter and never be bent back wards. Sharp bending can weaken the belt and lead to premature failure. Old belts that are taken off a bike during repairs must be reinstalled so they rotate the same direction.

    Tricks of the trade
    With a high horsepower engine, it is better to have the belt a little tight rather than loose. A loose belt will break much more readily than a tight one. Most people do not tighten the belt to its proper tension. If you plan on "racing" or hot rodding your bike, invest in a Harley-Davidson BELT TENSION GAUGER (Part No. HUD-35381).

    glider., Jul 9, 2007Report
    #1Like+ QuoteReply

 
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If belt is too tight it will whine when the bike is in use friction will cause the pulleys to warm up and they will expand and tighten the belt, tension should be checked with a rider on the bike
I have tried to do it by the book but belt always whined so I loosen off till it stops whining now I do it by hand and feel for the tension I would have used on a chain drive bike

Brian
 
Thanks for the replies. I loosened it up just a little and the whine is gone. The belt seems plenty tight after a ride so I will leave it as is. As usual the brain trust here is great. Thanks again.

Steve
 
check the drive belt tension in about four differsnt places around the belt there will be normaly tighter sopts find the tighter spot and adjust it from that spot .... g..hill
 
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