Dyna HD manual belt adjustment

Discussion in 'Dyna Models' started by R_W_B, Dec 2, 2010.

  1. R_W_B

    R_W_B Senior Member

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    2007 HD Dyna Repair Manual
    In section 1.14 on page 1-31, under Inspection of rear belt deflection.
    and using the belt tension gauge it states:

    As part of pre-ride inspection
    ............etc
    When checking belt deflection
    Set belt tension at tightest point in belt
    "Measure belt deflection with motorcycle cold and the approximate weight of the owner on motorcycle".
    ............etc
    then on page 1-32 (the very next page)
    it states in Table 1-6 Rear Belt Deflection
    two different measurements needed to comply
    1. "With motorcycle on Jiffy stand without rider or luggage" FXDB 1/4" - 5/16" deflection
    2. "Vehicle upright with rear wheel in air" FXDB 5/16" - 3/8" deflection
    ......
    What happened to "the approximate weight of the owner on motorcycle" ??
    Obviously I'm missing some concept here ?
     
  2. Hoople

    Hoople Account Removed

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    Yes it is strange that rider weight is not considered. I am no longer in agreement with the MoCo when it comes to belt tension and don't go by the book. Using their numbers and procedure I feel the belt tension is just way too tight. In the beginning I used the 1/4"- 5/16" deflection with 10 PSI when cold and had noise issues along with unnecessary pulley wear and bearing preload. After the bike was hot, the tension was just beyond what I thought it should be. Been doing it my way (feel only) for a year and the bike is so much Happier and I see no reason to go back.
     
  3. R_W_B

    R_W_B Senior Member

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    So I did not miss something they just -left it out ? Or forgot to finish the new edit ? I mean I'm reading about one thing that just drops off and then a new description pops up ?
    Also you would not happen to have a cold measurement on your "feel" would you (wheel hanging or on jiffy). At this point I kinda would rather trust your feel than this botched up area of the manual.
    My last bike (years ago) had a chain so I am unfamilar with belts.
     
  4. Hoople

    Hoople Account Removed

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    You did not miss anything and there was nothing left out of the procedure. When I followed the procedure to the "T", after the bike got Hot, the belt was just too tight in my opinion. How I feel about the the topic of belt tension only applies to my Dyna since that is the only HD I have ever owned. I went round and round with belt tension and then just decided to do what makes sense instead of just following a few steps in a manual thinking it "must be correct" because it says so.

    Point #1.. When downward weight is applied to my Dyna, the rear swing arm follows an arc which increases the distance between the two belt pulleys. Therefore as you said earlier, the weight of the rider does increase belt tension. I have no proof but I would bet that the rear downward travel of my bike is "capped off" or limited to some degree by the belt tension going higher. By that I mean belt tension itself will end up supporting some of the bikes weight when going over say a speed bump for example. That was something I really did not want.

    Point #2..My belt tracking is perfect. My belt does NOT hug either lip of the rear pulley which is something I also agree with. Yes, everything has to be perfect for a belt not to hug a pulley lip, but it also should not be DRIVEN against a lip with high rotational force. A slight DRIFT to a lip is normal but the belt should not PULL HARD or be Driven HARD to an edge or lip of the pulley. High belt tension will drive a belt harder to a pulley edge or lip because the belt is trying to relieve some of the tension on it's own.

    Point #3... For a belt to jump cogs, you would have to have 2" of belt play. Your going to Break a belt before you jump cogs. In all the years I have been around belts & pulleys, I have never seen a need for belt tension to be that high. These belts do not stretch so to be honest I don't know why the MoCo wants the tension that high.

    I was amazed how much more "relaxed" the bike felt once I adjusted the belt by feel rather than by the book. My drive belt no longer has any creaking noises also. Maybe there is a member who's career is understanding drive belt technology and will point out to me why I am wrong. In the mean time if something goes wrong with my procedure or my belt happens to throw a cog, I will be the first to post my mistake, but until then I am adjusting it my way.
     
  5. Brutal FXDX

    Brutal FXDX Active Member

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    You're right the manual does not give you a spec for deflection with rider weight on mc. I totally agree w/ hoople. Especially with these new touring bikes. The company has a new bulletin that came out in aug 9 2010 M-1264 for 09 later touring belt adj. If you set tension at what the book says and after a good ride check it hot. Feels too tight to me.And like hoople said is not good for bulley/belt wear and bearing load. So i usually run them a lil looser than spec maybe a 1/16- 1/8'.
     
  6. R_W_B

    R_W_B Senior Member

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    Yea it's like why even leave that part in there if you are just going to drop it off without giving a spec for that scenario. I'm not sure that could be classified as a typo, it's more like...
    to bake a cake in a "pan", put the cake in a "bowl" at 400 degrees for one hour.
    But thanks to all of you for your input. I will decipher what to do with all of it.
     
  7. R_W_B

    R_W_B Senior Member

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    Checked out your album. Impressive bike. You obviously beefed your setup.
    That windbreaker (or whatever it's called) looks nice.
    Does it deflect much wind ?
    How much do they run and who sells it ?
     
  8. Jack Klarich

    Jack Klarich Expert Member

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    I just got done re reading this thread, I agree with Hoople, the swing arm does move with the rider on there fore the belt would also move, remember the chain adjustments were done with the weight of the rider, why should a belt not be the same?
     
  9. Brutal FXDX

    Brutal FXDX Active Member

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    Its a Harley Davidson Quarter fairing. Does not block wind much, but does keep bugs off the face. You can find it on pg763 of H-D P&A catalog. 269.95 primed. You also need docking hardware 58164-96a which is standard windshield detach hardware for xl/fxd
     
  10. northernrider

    northernrider Member

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    I have been running belts on loser then book states my main reason I ride alot on gravel roads and have rocks get in final drive worried about the belt breaking.

    The belt on my bike has about 80000 miles on it now so far no real issues