D3 2008   Retro Pro   Regulations

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D3 2007 1/24 Retro Pro racing class rules (version V4, 06-15-08)

1. Intent: The intention of this class is to provide a class of scratch-built slot cars reflecting the spirit of the early 1970's racing era at low cost, to attract more experienced racers and builders.

2. Dimensional Specifications

2a. Maximum Overall Chassis Width: 3.125" (measured across any part of the chassis)
2b. Maximum Rear Tire width: 0.800"
2c. Minimum Rear Tire diameter: 0.8125" (13/16")
2d. Minimum Front Tire width: 0.090". O-ring tires allowed.
2e. Minimum Front Tire diameter: 5/8"
2f. Minimum Clearance: 0.050" (measured under rear axle excluding gear) and 0.015" (measured under front axle). Both clearances measured with car standing on a flat tech board on its wheels, without guide.

3. Chassis construction

3a. Chassis type: Any personally-built or commercially-available scratchbuilt chassis conforming to these specifications and to the spirit of the intent statement is allowed.
3b. Chassis Materials: Brass sheet, rod, and tube; steel wire, pin tubing, and guide tongues are allowed. Other than guide tongues, stamped steel parts and EDM or laser-cut parts of any material are not allowed unless submitted for approval.
3c. Drive type: open to the imagination.
3d. Other than a drop arm, all hinged movements must be oriented in only one direction (i.e. either side pan hinges OR a plumber hinge, NOT BOTH, meaning that a "loose" hinge may not provide movement in more than one direction). Centerline hinges (Flexi hinges) are not allowed. No chassis movement, dynamic or induced, may extend the overall chassis width to more than 3.125".
3e. Front axle: A single straight, one-piece front axle is required, carrying both front wheels. The axle may be fixed or in a tube. No visual obstruction of any kind across either front or rear wheels must be seen when viewing the car from its sides. Small flats can be ground only for set screw location. NO hinged front wheel movements are allowed (i.e. no "L" arms). Front wheels may rotate independently.
3f. Guide: One guide flag centered on the longitudinal axis of the chassis (i.e. no sideways "free float" or offset) is allowed.

4. Motor rule

4a. Motor type: Pro Slot PS4002C motor can/end bell combo set with PS-4010 armature but retaining stock magnets. A gauss meter may be used at tech inspection to verify magnet strength. Magnets may not be moved or modified in any way other than by re-zapping in the can. The following motor parts are legal for RetroPro EURO Mk1 motors and parts The suggested motor for RetroPro is the PS-4002C Euro Mk1 motor with American-made BD (Big Dog) armature While referred to by Pro-SLot as the Big Dog motor this is the base motor for RetroPro as of January, 2008. PS-4008 Replacement balanced armature for the PS-4002 (commutator trued and rebalanced) PS-4009 (Puppy Dog) American-made replacement armature (required modified end bell PS-4011 for commutator clearance) The suggested replacement armature for RetroPro is thePS-4010 BD (Big Dog) American-made replacement armature (required PS-4011 for commutator clearance). PS-4011 Replacement end bell modified for commutator clearance with American-made armatures. $5.99 Technical notes: The PS-4011 replacement end bell modified for commutator clearance with American-made armatures comes standard on Pro Slot motors with the American arm but will be needed to convert cans that originally had the Chinese armature. Can and end bell bushings may be replaced with any commercially-available bushing. Shunt wire and spring insulation are only legal in Big Dog.

Big Dog motors may run ball bearings in the can and/or end bell. All armatures may be balanced and re-trued. RetroPro Big Dog For Big Dog, any available over-the-counter unmodified armature is legal but the PS-4012 X12 armature with 38° timing American-made replacement (requires modified end bell PS-4011 for commutator clearance) is the recommended armature. Modifications to shorten or move the commutator shall be deemed no longer legal after June 1, 2008. In practical terms a Cobalt 12 would be legal; a shortened International 15 would not. The Pro Slot PS-4012 X12 should outperform and run cooler than the Cobalt 12. Motor changing during or after qualifying will only be allowed if the motor fails. We do not intend for this class to be a motor-changing class. Expect to use one motor only except in very rare situations. Do not expect to be able to abuse this rule. Any over-the-counter spring or brush is legal. Shunt wire and spring insulation are legal Racers are also welcome to run D3-legal FK type motors Other Pro Slot Mk1 current motors are legal and they include: Available Double Security Sealed PS-4000 Euro Mk1 Motor PS-4001 Euro Mk1 Motor PS-4002B Euro Mk1 Motor - with American-made PD (Puppy Dog) armature as used in retro Can-Am racing The PS-4002 Euro Mk1 Motor PS-4002-12 Euro Mk1 Motor with American-made X12 armature 38° is only legal for RetroPro Big Dog

5. Body rules

5a. Body style: Bodies must be originals or exact reproductions of 1966 to 1973 Pro-Racing bodies by Russkit, MAC, Lancer, Associated, Dynamic etc. No "flattened" or "aerodynamically improved" bodies allowed (i.e. no molded-in spoilers, wings etc that were not on the original full-size car or original mold). Front wheel arches must be cut out. Rear wheel arches may be left closed if the original full-size car ran with closed wheel arches. Bodies must be presentably painted and carry at least three racing numbers, one on each side, and one on the front. Bodies with molded-in cockpits are not allowed. No part of the chassis or tires may be seen when looking on the car from its top.

5b. No air-control devices may be added to the one-piece bodies.

Example of car for this class:





Approved bodies listing:

MAC-V10 Porsche 917PA
MAC-V02 Ti22
MAC-V04 Lola T290
MAC-V05 Ferrari 612
MAC-V06 Ferrari 512M
MAC-V07 Gulf-Mirage
MAC-V08 Porsche 917-30
MAC-V09 McLaren M20
TrueScale Porsche 917

Other bodies must be submitted to The Division III Committee members for approval.
Bodies must be molded from material with a minimum thickness of 10 thousands of an inch.

5c. Cockpit: Cockpits must be fully opened following the natural line of the windscreen and body. A separate 3-D driver figure painted in at least 2 colors must be fitted.

Any matter regarding this class must be submitted in writing to Division III Committee member Mike Boemker.

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