New
2005 Car Specifications for the
San Diego 500.
Afew
corrections and updates to the 4-lane track design
You
can buy aluminum track plating directly from Beta Crafts. Its cheaper and they're
the folks that designed it.
In November-December 1998 The BSA supply system began to ship different pinewood derby kits to its distribution network..
After years of good quality kits coming from Beta Crafts in New Jersey there seems to be something different being delivered this year. For those that have been around a few years you'll remember prior to '92 there was good reason to have rules that permitted the sanding of the plastic wheels that came the box kits. Those wheels were 'out of round', had a molding seam around the center outside portion of the tread and had various plastic debris still hanging off the wheel. While the new wheels aren't really bad, many are not consistent. The worse part is that the axle holes in the wheels are not the same size between kits. Some folks are buying several kits to find what they regard as a "good" set of wheels. It isn't clear that there is a big difference in the wheel's performance but you don't want to mix them up on the same car. The racing officials need to be aware that there are differences in the kits, the racers aren't cheating.
Another problem is the wood block. The axle cuts across the bottom of the block are sometimes out-of-square and the blocks are not always uniform in length, width or height. This means that the car can not track straight without bending the axles. For those units that prohibit the moving of the wheel location this can be a problem for the racer. Correcting the problem by re-cutting the same slot will make it too large for reliable wheel alignment and the axle must be cemented into place. The following table lists typical physical characteristics for the some of the recent BSA Grand Prix Derby wheels. Please understand that while these measurements were taken with very accurate equipment the molding production techniques and various molds used to produce the plastic wheels generate slightly different wheels. You can tell which mold cavity your wheel came from by reading the casting impression on the inside of most wheels. These mold cavities are not identical and neither are the wheels that come from them.
While there are variations on the wheels produced these four groups represent the wheels that have been produced in the greatest volumes.![]()
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| Wheel Characteristics |
Older Wheel C.M.I. |
'98 Wheel Style 14-spoke |
'99 Raised Letter 12-spoke |
'99-02 Smooth
Sided 12-spoke |
| Wheel Diameter | 1.183"-1.187" | 1.187"-1.189" | 1.190"-1.197" | 1.185"-1.194" |
| Skirt Thickness (At Mid-Tread) |
0.118" | 0.090" | 0.087" | 0.091" |
| Tread Width | 0.290" | 0.285" | 0.284" | 0.275" |
| Axle Opening
ID |
0.100" #39 Wire Size |
0.099" #39 Wire Size |
0.089" #43 Wire Size |
0.092" Between #42-#43 |
| Inside Axle Hub OD | 0.246" | 0.250" | 0.272" | 0.275" |
| Axle Barrel Length | 0.298" | 0.272" | 0.361" | 0.353" |
| Wheel Mass (grams) | 3.782 g | 3.273 g | 3.531 g | 3.590 g |
| Supplied Axle OD | 0.090" | 0.089"-0.090" | 0.089" | 0.092" |
| Wheel Thickness (Hub to side-wall) |
0.415" | 0.420" | 0.435" | 0.428" |
| Comments | This wheel type required more work to make competitive |
Very clean molding that required little work to roll smoothly |
Larger axle contact area, more "out-of-round" |
Tread surface
is tapered from inside to outside |