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rear wheel alignment and belt alignment

  • micathia
    micathia
    3 years ago
    Hi
    My dyna, it seems I can't get both wheel and belt aligned at the same time. My wheel is at least I believe its perfect aligned. The bike track straight perfectly. but the sprocket is scratching the belt. if I reverse, let the belt and sprocket aligned, the wheel won't be aligned. 

    What could be wrong with it? 

    thx 
  • FXDF08
    FXDF08
    3 years ago
    Sadly the machining of our swingarms is not within very close tolerances. One side will be longer than the other. This means it looks like the wheel is aligned, but isn’t. Use a straightened coat hanger and bend it At one end for the hole (they should be east lengths) then measure to centre of axle/nut on either side to get exact.
    This is the case for my Dyna at least. Good luck
  • Hoodeng
    Hoodeng
    3 years ago
    Do a wheel alignment first, bike vertical with center roll up lifter, front wheel on ground, with two straight edges [angle or RHS] and with the belt loose, then adjust the belt side to spec tension while following on the other side with the same amount of flats. When the tension is set re do the alignment, it will only need a minor tweak on the off belt side.

    Cheers.
  • micathia
    micathia
    3 years ago
    Quoting FXDF08 on 01 Aug 2020 10:56 PM

    Sadly the machining of our swingarms is not within very close tolerances. One side will be longer than the other. This means it looks like the wheel is aligned, but isn’t. Use a straightened coat hanger and bend it At one end for the hole (they should be east lengths) then measure to centre of axle/nut on either side to get exact.

    This is the case for my Dyna at least. Good luck

    Hi, 
    I have that simple tool to measure the axle. But that's not how I align my wheel. The tool can only fix an unaligned wheel to "almost aligned" but not really offering high accuracy. 

    This is what I did, feel free to point out where I did/understood wrong. 

    1. standing behind the bike, say if the rear wheel is slightly turned towards left (11 clock), as a result, when I ride the bike, the triple tree will look slightly turn left too, to make the two wheels parallel; on the other hand, if the rear wheel slightly turns towards to right (1 clock), the triple tree will look slightly turn right to make the two-wheel parallel. 
    2. what I did, was, fine-tune the "axle adjuster" bolt to make sure while riding, the triple tree goes straight. the bike was able to track really straight at that point. but sprocket was scratching the belt. 
    3. then if I use a laser belt alignment tool to align the belt and sprocket, the result makes the rear wheel unaligned again that the triple tree turned to slightly left (11 clock) again. 


    any idea? 
  • Hoodeng
    Hoodeng
    3 years ago
    Look up 'wheel alignment' section 2 in an early 80's service manual, this method uses straight edges along both front and rear wheels to correct a chassis' true.
  • DarKasH69
    DarKasH69
    3 years ago
    I do an alignment by running a string line from rear of back wheel.. down one side to front wheel below axle. 
    Have someone to watch the string move in toward the front of rear wheel, when it touches ... measure how far away the string is to front rim below axle. Will be around 5mm ( this with a 180 rear 130 front tyre)

    Then do same to other side of tyre to front rim. Measurements should be same distance from rim. If it 1-2 mm difference... your alignment is basically as perfect as can be. 
    With practice it’s possible to get same measurement both sides. 

    Just like using a straight edge, but doing it over the length of the bike. 
  • micathia
    micathia
    3 years ago
    Quoting DarKasH69 on 03 Aug 2020 11:37 AM

    I do an alignment by running a string line from rear of back wheel.. down one side to front wheel below axle. 

    Have someone to watch the string move in toward the front of rear wheel, when it touches ... measure how far away the string is to front rim below axle. Will be around 5mm ( this with a 180 rear 130 front tyre)

    Then do same to other side of tyre to front rim. Measurements should be same distance from rim. If it 1-2 mm difference... your alignment is basically as perfect as can be. 
    With practice it’s possible to get same measurement both sides. 

    Just like using a straight edge, but doing it over the length of the bike. 

    I am afraid this is only on paper, not in reality (for dyna). There are some flaws on this method, not to mention it lack of accuracy. 
    1. Your 180 mm back tyre may not be 180mm. It varies noticeably depending on your rim size. Thinner rim narrows the tyre width. 
    2. In case of dyna, this method assumes the engine is fully aligned, if the engine is not aligned, this method won't get your two tyres to stay true. This is is the same using the L shape tool method. Because swing arm is mounted on engine basically, not the frame. 

    That's why the service manual talks about "vehicle alignment", which has two tasks, to align the engine with the frame, and to align back wheel with engine/swingarm. Even this "vehicle alignment" assumes the front and rear rubber mount are in perfect shape, so loosing the upper stabilizer and shake the engine at idle for 15 second will let the engine back to perfect position itself. 

    That's all I know so far, but I am still learning, things I don't understand is, how the upper stabilizer will affect engine alignment. 


  • DarKasH69
    DarKasH69
    3 years ago
    Quoting DarKasH69 on 03 Aug 2020 11:37 AM

    I do an alignment by running a string line from rear of back wheel.. down one side to front wheel below axle. 

    Have someone to watch the string move in toward the front of rear wheel, when it touches ... measure how far away the string is to front rim below axle. Will be around 5mm ( this with a 180 rear 130 front tyre)

    Then do same to other side of tyre to front rim. Measurements should be same distance from rim. If it 1-2 mm difference... your alignment is basically as perfect as can be. 
    With practice it’s possible to get same measurement both sides. 

    Just like using a straight edge, but doing it over the length of the bike. 

    Quoting micathia on 04 Aug 2020 12:49 PM

    I am afraid this is only on paper, not in reality (for dyna). There are some flaws on this method, not to mention it lack of accuracy. 

    1. Your 180 mm back tyre may not be 180mm. It varies noticeably depending on your rim size. Thinner rim narrows the tyre width. 
    2. In case of dyna, this method assumes the engine is fully aligned, if the engine is not aligned, this method won't get your two tyres to stay true. This is is the same using the L shape tool method. Because swing arm is mounted on engine basically, not the frame. 

    That's why the service manual talks about "vehicle alignment", which has two tasks, to align the engine with the frame, and to align back wheel with engine/swingarm. Even this "vehicle alignment" assumes the front and rear rubber mount are in perfect shape, so loosing the upper stabilizer and shake the engine at idle for 15 second will let the engine back to perfect position itself. 

    That's all I know so far, but I am still learning, things I don't understand is, how the upper stabilizer will affect engine alignment. 


    Well the only reason I gave my tyre width was to associate it with the 5mm measurement as an example. . It really doesn’t matter what size ya tyres are. The point is the string line runs from rear of back tyre down to front. When moving string line in toward the front watch the sting touch the front edge of the back tyre. 
    Take measurement and do same to other side. 
    And obviously if engine isn’t aligned then wheels won’t align. 
    I’ve been doing this way of alignment for past 14years, over 400thou kms worth. 
    So I’d say it’s fairly accurate in my eyes. 

  • micathia
    micathia
    3 years ago
    my bad. 
    I think my problem is drive train alignment,  not with wheel alignment. so now researching about engine mount. 


  • DarKasH69
    DarKasH69
    3 years ago
    Quoting micathia on 05 Aug 2020 11:57 PM

    my bad. 

    I think my problem is drive train alignment,  not with wheel alignment. so now researching about engine mount. 


    Depending on how many Km ya bikes done, check swing arm bearing also. With rear off the ground see if you can rock the swingarm back and forth sideways. Shouldn’t be any movement. This will put engine/frame alignment out also. 
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