The 101 Association, Inc.
For the preservation and enjoyment of 1928 to 1931 Indian Scout Motocycles
"You can't wear out an Indian Scout"

Front brake effectiveness - offset cam

  • 05 Mar 2020 4:27 AM
    Message # 8798325

    I have an ongoing quest to improve the effectiveness of my front brake.  Looking at it last night, something glaringly obvious struck me – the shoe cam plates are not centred around the cam, with the trailing shoe being moved by the toe of the cam, the leading by the cam flank.  This leads to differential lift and therefore one shoe doing the work, the other just dragging.  The contact faces of both linings agree with this.  Measuring at shoe contact, I have 2.6mm lift on the leading shoe, 3.8 on the trailing.  The cam is 30mm in length.

    Is this normal? Or do I have the wrong cam?

    What dimension should the cam be?

    If it is, has anyone modified this setup effectively?

    Shortening the cam to 20mm would ensure both shoes lifted evenly, but I have a lot of lever travel with the current setup, so am a bit worried about increasing this by taking this direction.  Any advice gratefully received.

    1 file
    Last modified: 05 Mar 2020 6:02 AM | Stuart Morgan
  • 08 Mar 2020 1:52 PM
    Reply # 8809052 on 8798325


    I still have yet to find my 101 Scout, so no parts comparison here. However, I do know a little bit about drum brake theory and here's what I know:

    The leading shoe tends to be self-actuating, meaning that when it is pushed into the brake drum the friction and direction of wheel rotation tend to pull the shoe on to the drum even harder. The trailing shoe is the opposite, and I suspect that is why the trailing shoe gets more lift.

    Basically, the leading shoe does all the work and the trailing shoe is just along for the ride. That's why twin-leading-shoe drum brakes are so much more effective.

    Has nobody ever cobbled up a TLS brake plate for the 101 Scout?

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