Pinewood Derby Car Design and Speed Tips

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Outer Hub Shaver

 

New Pinewood Derby Wheels

The 2009 pinewood derby season has brought us a new official BSA pinewood derby wheel as shown on the right below compared to the "old" wheel on the left. 

The wheel is lighter, has a much better outside tread surface and has an unusual outer hub design.  It actually has a step or ledge in the outer hub (new wheel on the right) which presents no obvious speed advantages but does have some potential disadvantages.  It creates a second contact point on a beveled axle head and would contact it further to the outside of the axle head, meaning more surface contact area.  With no obvious speed advantage to the step, the predominant speed tip for the new wheel is to get rid of the step altogether.  The Pro Outer Hub Tool seen below was initially created to clean up the outer hub for the old wheel but is nearly perfect for the elimination of the step on the new pinewood derby wheel.  The outer hub tool needs to be sharpened first and that can be easily performed with a file which we will show you after we discuss reaming the wheel bores with the Pro Hub Tool.    

Wheel Bore Reaming

The wheel bore, simply put, is the inside of the wheel where the axle goes.  Molded Pinewood Derby car wheel hubs can vary in size by as much as .01" and you must resolve this situation to have the smoothest fit of the axle into the wheel.  The Pro-Hub Tool allows you to ream the wheel bore to the same size or to at least select wheels from your assortment that have a similarly sized bore radius.  This is a very important alignment tip as it allows the car to sit evenly on all 4 wheels with equal distances from the axle and wheel hub to the track.  You will need the Pro-Hub Tool to complete this speed tip. To perform this procedure:

1)       Test fit each wheel by sliding it onto the tool pin of the Pro-Hub Tool (flat side) as shown below.  If the wheel bore is too small for the tool, use steady hand pressure and a twisting motion to work the wheel on to the tool.  Remove the wheel and repeat 3 times.

Pro Hub Tool (Flat End)

2)       Once completed, choose another wheel and repeat step 1.

 

 Pro Outer Hub Shaver

(Note: The Pro Hub Tool is required for use with the Pro Outer Hub Shaver)

The Pro Outer Hub Shaver will surely become one of the most popular tools for the 2009/2010 pinewood derby season for the following uses:

  •    Ensures accurate rotation of the wheel by squaring the outer wheel hub to the wheel bore for proper mounting of the wheel on the Pro Wheel Mandrel

  •    Reduces friction between the axle head and the outer wheel hub by eliminating flaws on the outer wheel hub and, most importantly

  •    Removes the step in the outer wheel hub on the new wheels which are a potential double friction contact point with the axle head.

Please note that the Pro Outer Hub Shaver is intended for use on BSA wheels only.  It is not recommended for use on wheels made by any other manufacturer.

Sharpen the edge of the Pro Outer Hub Shaver

If you are removing the step in the outer hub on the "new" wheels, you will first need to sharpen the cutting edge on the outer hub shaver.  To accomplish this step, merely file the back side of the cutting edge with a flat file until you have created a small angle to the back of the cutting edge.  A picture of the outer hub shaver with the edge sharpened is shown below on the left compared to a regular cutting edge on the right.  The specific angle is not important.  You do not need to sharpen the cutting edge of the outer hub shaver if you are performing modifications to the "old" wheels.

Note: The Pro Outer Hub Shaver is available as a fully modified tool which includes not only the above filing but a shaping of the edge such that the outer hub is not only shaved but domed as well.  This doming effect reduces the friction between the wheel and the axle head even further.

Instructions for Using the Pro Outer Hub shaver

  •    Remove the protective cap from the square or flat end of the Pro Hub shaver and ream the wheel bores of each wheel per the directions above.

  •    Slide the Pro Outer Hub Shaver onto the pin of the Pro Hub Tool with the cutting edge outwards.  To minimize the risk of injury, leave the protective cap on the coned end of the Pro Hub Tool.

  •    Place a wheel onto the pin of the Pro Hub Tool, spoke side first.

  •    With one hand holding both the Pro Hub Tool and the Pro Outer Hub Shaver, press the wheel against the outer hub shaver's cutting edge with the other hand. Rotate the wheel three complete revolutions.

  •    Check the outer hub to view your progress.  If you are modifying the "old" wheels, you will not need to make too many revolutions with the outer hub tool to complete the process.  If you are removing the step in the "new" wheels, it will take quite a few more revolutions to get the outer edge of the hub even with the inner edge of the hub and completely remove the outer step.  Continue to check your progress after a few revolutions to make sure that you do not remove any excess material past the removal of the step.  The finished product in either case of the "old" or the "new" wheels should look like the wheels shown below. The modified "old" wheel is on the left and a modified "new" wheel is on the right.

Note: The Pro Outer Hub Shaver is available as a fully modified tool as well if the above modifications appear too difficult

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