Sprockets Custom Made Sprocket Adapter

Discussion in 'Transmission / Drivetrain' started by Scootmeister, Jun 12, 2012.

  1. Scootmeister

    Scootmeister Member

    Sometimes you can't find exactly what you need for your MB and you just have to make it yourself. With a few basic tools and a little time thinking things through, you can make a component that meets your needs as well as a vendor supplied item. In my case, I needed to be able to easily swap sprockets on my jackshaft to change gear ratios. I had a standard 17 tooth sprocket with 5/8" bore that resulted in gearing that was too low for cruising. So, I purchased a keyed 5/8" steel collar with set screw and 1 1/8" reset ($4), a 3 1/4" diameter steel washer with 1 1/8" bore ($.89), five 5mm x .80mm hex head bolts (on hand), and a 24 tooth bolt on sprocket from Sick Bike Parts($5.95). Replacement sprockets are available from SBP up to 48 tooth. The first step was to dress the washer bore to a true 1 1/8" since the galvanized coating reduced it slightly. The second step was to carefully mark the 5 mounting holes on the washer. I used a chart in the Craftsman manual shown in the photo to determine that a 11/64 drill is appropriate for a 5mm x .80mm tap. Once the holes were drilled and tapped I removed the galvanized coating from the back of the washer and spot welded the washer to the collar. Locktite could be used to secure the mounting screws, but I will use locking nuts instead. This $11.00 adapter works great and gives me the flexibility I need. DSCN2968.jpg DSCN2969.jpg DSCN2967.JPG DSCN2970.JPG
     
    MotorBicycleRacing likes this.

  2. perilous

    perilous Member

    Good job!, it's not that easy to mark and drill holes so accurately with basic tools. I did something similar on my bike although not for the same reason, it never occurred to me you could buy a huge washer like that, I turned mine myself.
     
  3. Scootmeister

    Scootmeister Member

    Thanks, Perilous. Now you've made me envious, being able to turn things with a lathe! You can find these large washers with either a zinc coating or a galvanized one. The zinc ones are better for this type of application because they have a more uniform surface, but I try to use what I have lying around in my junk bins. My washer is 1/4" thick so there are plenty of threads to hold the mounting screws.
     
  4. Scootmeister

    Scootmeister Member

    DSCN2971.JPG DSCN2972.JPG DSCN2973.JPG Here are photos of the adapter installed on the jackshaft.
     
  5. perilous

    perilous Member

    Sweet looking bike (just found your photo album), Never seen a motorised bike done like that before, very cool.
     
  6. Scootmeister

    Scootmeister Member

    Thanks Perilous. I started out with kits and that was great, but I started experimenting and one thing led to another.
     
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