MAXIMUM VELOCITY! ®
4071
4070-BSA Pinewood Derby Ultralight Matched Speed Wheels &
5094-BSA Speed Axles
2.1 Gram Wheels By DerbyWorx
BSA wheels are well designed, but unfortunately the wheels vary considerably from mold to mold. Most of the wheels are not perfectly round and the tread surface is not even.
Our Ultralight Speed Wheels are official BSA wheels which are sorted by mold number, and then precision machined with a CNC (computerized) lathe for maximum performance. To provide you with an awesome set of wheels, we perform the following operations:
- The wheels are sorted by mold number, and any defective wheels are discarded.
- Inner and outer hub faces are squared to ensure accurate mounting on the CNC lathe.
- Wheel bores are reamed and bored perfectly round and smooth.
- The wheel tread is lathed with True Track to achieve a perfectly round wheel, a flat tread surface, and a slight radius on the edges to replicate the look of a stock BSA wheel.
- The inside edge of the wheel is trued, and a small radius is formed on the edge.
- The weight of the wheel is reduced by removing plastic from the underside of the wheel tread, and the backside of the wheel face.
- The inside wheel hub is lightly beveled to reduce contact with the car body.
If you would like to order wheels with a particular mold number, Click Here.
Benefits
- Round and smooth wheels roll faster than standard wheels.
- Matched mold numbers ensures that the bore diameter and other wheel measurements are identical, maximizing performance.
- The molding mark on the tread is virtually removed, eliminating the 'bump'.
- The weight reduction provides a faster start, and improves the balance of the wheel for a smoother ride.
- The beveled hub reduces the braking that occurs when the wheel hub contacts the car body.
Usage
The Ultralight Matched Speed Wheels are used without any additional preparation. Just lubricate and race!
Important Note
The lathing operation removes a small amount of tread surface. The serrated edge is intact. The tread reduction is barely visible to the eye, but is measurable with a caliper. If your race restricts the use of lathed wheels, consider using our specialty tools and supplies to prepare a set of raw wheels.
Comparison Chart and Photos of Matched Speed Wheel Types
| Model | Trued
Tread | Coned
Hub | Trimmed
Edge | Reamed
Bore | Weight
Reduced |
| 4090/4091 |
Yes |
No |
No |
No |
No |
| 4080/4081 |
Yes |
Yes |
Yes |
Yes |
No |
| 4070/4071 |
Yes |
Yes |
Yes |
Yes |
Yes |
| 4060/4061 |
Yes |
Yes |
Yes |
Yes |
Yes |
Technical Information for 4070/4071 Wheels
- Wheel Diameter: 1.170 ± 0.001 (Raw Wheels: 1.184 to 1.199)
- Wheel Bore ID: 0.098 minimum
- Wheel Weight: 2.1 grams per wheel (Raw Wheels: 3.6 grams/wheel)
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