Belt missalignment fix

Discussion in 'Whizzer Motorized Bicycles' started by Kep1a, Jan 25, 2009.

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  1. Kep1a

    Kep1a Guest

    I have found that there is a missalignment of the front and rear belt.

    First what I found was that my pivot bolt was mounted with the bolt entering the from the right side of the engine.

    Simply switching the bolt so the shoulder was entering the arm first (from the left) fixed 60% of the pulley angle when under belt tension issue. It did not however bring the pulleys into parallel alignment.

    I decided that having the bolt pivot in the bushing in the motor and having a tight fit of the pivot bolt on the arm would be desirable. I decided to peen the arm to create a tight fit (see Photo). Peen the entry side of the arm first and then thread the bolt through until the threads are clear before you press or hammer the bolt all the way in, thus protecting the threads. Then turn the arm over and peen the arm around the bolt on the exit side of the arm. You will no longer be able to twist the bolt by hand once done if your starting tolerances are the same or close to what mine were. Note: I lubed the pivot bolts exposed shoulder and used lock tight on the threads for my final assembly. Making sure the arm moved freely on its pivot when done.

    I then did similar to Hals photo and used a long straight edge to allow me to measure the amount of missalignment of the front pulleys. In my case I found it to be .055 on two arms and .080 on the other.

    With the numbers written on the pulley side of each arm it was now time to go to the machine shop and remove that exact amount from the surface that the clutch mounts against. I brought the LH bolt with me to ensure that the machining was exactly parallel. To do this on the pivot end would have added cost and complications due to the stepped profile on the pivot bolt side.

    Once I did the above and installed the assembly the alignment of the front belt to the naked eye looked to be perfect. The above procedure noticeably helped the rear belt alignment as well. With this fix and the AX-27 front belt I expect to see long belt and clutch bearing life (no lateral missalignment pull anymore) and zero belt slippage on either the front or rear belts.

    The other thing I did was relocate the spring attachment hole in the clutch pivot arm a very small amount to make my spring have a little more tension. The reason I did this is because I have the 70mm clutch and found that once the rear belt was tight it seemed to loosen the front belt slightly. This additional tension fixed that issue nicely in my case.

    It should be noted that the LH threaded clutch mounting bolt should be only snug (no more than 50 inch pounds) or just snug. The threads should have lock tight and dry fully before use. You will need to have the belt on before the cluch assembly is mounted to the pivot arm or it will not clear the pivot bolt for rear belt installation. This is the only negative I can see, is that the clutch will have to be removed any time the rear belt needs to be replaced.

    I should get time to finish my repairs soon and will report on my tires ASAP.


    Note:I copied the missalignment example from Hal's post on the same belt missalignment issue.

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    Last edited by a moderator: Jan 25, 2009