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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 as shown in figure  1.  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.

Figure 1

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

 

Wheel Hub Squaring

In order to make precise adjustments to the wheel, one must ensure that the wheel can be mounted on the mandrel correctly.  The Pro-Hub Tool will square the hub to the centerline of the wheel which allows for the most accurate tread face finishing.

(The Pro-Hub Tool as shown in figures 2 and 3 , has a square end to improve wheel hub accuracy and a coned end to reduce hub friction). 

 

 Figure 2                                                Figure 3

                To square the wheel hub, which should be done before any other wheel preparation step, perform the following procedure:

1)       Remove the protective cap from the square end of the Pro-Hub Tool, pierce  a piece of 400 grit sandpaper (grit facing outwards) and slide the sandpaper until it contacts the body of the tool as shown in figure  4. To minimize the risk of a hand injury, leave the protective cap on the coned end of the tool.

Figure 4

2)       Place a wheel onto the square end of the tool, hub side first as shown in figure  5.

Figure 5

3)       With one hand hold the tool and the sandpaper, and with the other hand press the wheel against the sandpaper. Rotate the wheel back and forth for about 10 seconds.

4)       Repeat steps 2-4 for the other wheels. Use a new area of the sandpaper for each wheel.

5)       If the hubs will not be coned, repeat steps 2 to 4 with successively higher grit sandpaper (600, 1000 and 1500).

 

Coning and Sanding the Wheel Hub

As you can see, the wheel hub is now true to the wheel itself, but still presents a significant friction point by rubbing against the car body.  We can increase the overall speed of the car by reducing the hub surface area and polishing the remaining portion of the wheel hub.  We will reduce the area by tapering, or coning, the wheel hub.  This process can be performed with the coned end of the Pro-Hub Tool as shown in figure 6, and sandpaper in the following grits: 200, 400, 600, 800, 1200, 1500.

Figure 6

                With the Pro-Hub Tool, perform the following steps:

1.        Pierce a small piece of 200 grit sandpaper (grit facing outwards) with the coned end of the Pro-Hub Tool as shown in figure 7 and slide the sandpaper until it contacts the tool.  Leave the protected cap on the other end of the tool to reduce the risk of injury.

Figure 7

2.        Place a wheel onto the Pro-Hub Tool with the wheel hub facing the sandpaper as shown in figure  8.  With one hand, hold the tool and sandpaper and rotate the wheel with the other hand firmly against the sandpaper back and forth for about 10 seconds.

Figure 8

3.        Perform step 2 with the remaining wheels, moving the sandpaper on the tool as needed once an area has been worn.  The wheel hub should look similar to the one shown in figure 9 when the initial coning has been completed.

Figure 9

4.        Once you have completed the initial coning procedure and then applied the finishing steps as described in the pinewood derby speed tips manual, the hub should look similar to the one shown in figure 10. 

     

        Figure 10

 

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