Improving My Sawtooth Rally Clock

Next weekend I will be competing in the 2017 Penn-York Rally that will be held in Beach Lake, Pennsylvania.  This is a time-speed rally that is held under the auspices of the Northeast Rally Club.  This rally is run according to rules that are very similar to the Great Race.  The rules permit only one analogue time-of-day clock be in the car.  Digital time-of-day clocks are not allowed.  Many competitors will use the large diameter Sawtooth Clocks that were made with this rally application in mind.  I too have used this clock in the past for these rallies and I am planning on using it again in the 2017 Penn-York Rally.  My original Sawtooth Clock is shown below.

The Standard Sawtooth Time-Of-Day Clock

The Sawtooth Clock has a sufficiently large diameter such that it is relatively easy to read the seconds.  The clock also has a continuous sweep second-hand movement rather than a step-wise movement.  My Sawtooth Clock will lose about 1.0 to 1.2 seconds per 24-hour day, so during a 9-hour rally day, the time is sufficiently accurate as the time is read to the second.  I just have to set the clock each day of the rally.  And that is where I have a problem with this clock.

With the Sawtooth Clock the clock movement can only be stopped and started by removing the single battery that is located in the movement on the back of the clock.  This can be clumsy and difficult to get right.  I have been using plastic film to make this easier, but problems remain.   As a result of this, I have found a way to add a stop/start switch to my Sawtooth Clock to make setting the clock much easier and therefore more accurate.  My Sawtooth Clock now looks as shown below.

My Revised Sawtooth Clock Fitted With An On/Off Switch

The on/off switch is shown in the two o’clock position on the perimeter of the clock frame.  I was able to add the stop/start switch by using a remote single AA battery pack that came with a slide on/off switch. This is shown a little more clearly in the photo below.

Closer View Of The On/Off Power Switch On The Single AA Battery Pack

The photo below shows how I was able to replace the single AA battery that normally fits in the Sawtooth Clock movement with the remote battery pack with the on/off switch. I replaced the battery with a non-conducting wooden dowel with screws set at each end of the dowel to connect to the positive and negative wires from the single AA battery pack.

Sawtooth Clock ON/Off Power Switch Wiring

As a rally navigator, I am always looking for ways to do my craft in better ways.  Sometimes these are individually only small improvements, but if you make small improvements a number of times, then significant improvements can result.

If you have any comments are questions about this post, then please leave a comment below or you can send me a private email message at the following address: shanna12 at comcast dot net

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4 Responses to Improving My Sawtooth Rally Clock

  1. Mary Lynn and Terry Riggs says:


    We were at the rally last weekend. Wish I had picked your brain. Darned! We had a great time.

    Looking to purchase a clock ASAP for GREAT RACE. Can you direct us to vender?? Thxxxx for modification tips. Mary Lynn Riggs

  2. Rockwell Rookey says:

    I like it. Have been pondering a similar mod. Will let u know what I come up with. Good to c u and Harold at meet David Thai past weekend. Live is good
    Rock Rookey

    • Hi Rock,
      This modification made life a lot easier when setting the clock. It was great to meet up with you and Larry again. Well done on your good finish! Harald and I will have to step our game up at the Great Race to keep up with you folks.
      Steve McKelvie

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