Fray Rules

Fray in Ferndale Rules
March 2014


These rules are written with the intent of providing a precise specification that will define the cars construction. It is fully expected, and in fact intended, that the racers will adhere to these rules as they design and build their cars. Any breach of these boundaries will result in the car’s disqualification.

The following rules list what can be done to the car.  Anything not listed as allowable, is not allowed.  For example:  No fillers can be placed in the gap between the three com sections because there is no rule allowing it.

To support this principle, the tech committee will gladly answer any of the racers’ questions of the rules prior to tech. Also, please remember when testing your armature, for the Fray in Ferndale, the room temperature is 55F-65F degrees. The voltage for the Fray is 20 volts. This is the Final rules update for the 2014 Fray. Clarifications, if needed, will be dated and posted in Clarifications section below.

Complete Car Regulations:

  1. The complete car must weigh at or between 20.0 grams and 24.0 grams.

  2. The complete car must freely pass through a standard 1.3125 (1 5/16) HO tech block.

Body Regulations:

  1. Body: The body must be a copy of a 1:1 car and concept cars.

  2. Bodies must be manufactured by either the process of casting or injection molding and be made of resin or plastic. No featherlight resin allowed.

  3. Bodies must be originally manufactured with the intention of being mounted with the use of two (2) screws via two (2) bodymounting posts on a/an: Aurora Model Motoring (which includes: Vibrator, Thunder Jet Wild Ones, Tough Ones and Xlerators), Bachmann, Faller, Model Motoring ThunderPlus, Marx, Eldon or Tyco S series HO chassis.

  4. Bodies with castin handling pans or exaggerated details  such as unrealistic or inappropriate hood scoops, oversized windows, side pipes, sloped sides, or snow plow noses  are not allowed.

  5. No Indy style Formula 1 or Formula style openwheel bodies will be allowed.

  6. No ballast or fillers, other than color pigment, are allowed in the plastic or resin.

  7. Maximum overall body width is 1.200. Accordingly, the body must pass through our 1.2 bodytech device.

  8. The maximum thickness of the lower portion of the body, including items such as the front end, rear end, fender flares, and running boards must not exceed 0.125.

  9. With the body mounted securely to the chassis and viewed from above, the body must cover the chassis except through windows and vents. Unrealistic overly large windows and vents are not allowed.

  10. With the body mounted securely to the rolling chassis and when viewed from the side and/or the rear of the body, the upper edge of the top-plate, minus rails, cannot be above the rear window frame as measured at the rear of the topplate. (i.e.horizontal top of the gear plate (base) cannot protrude above the rear window opening).  Put another way : The lower rear window opening must be equal to or higher than the gear plate plane.

  11. Bodies must be fitted with all of the manufacturer’s original or exact-replica bumpers, heads, rollover bars, etc. in their stock locations.

  12. Cracked or broken bodymounting posts may be repaired or with the use of glue and/or a plastic sleeve around the original post or a plastic rod/tube in place of the broken post.

  13. Other than the plastic post reinforcements, stated in Body Rule 12, no additional weight may be added to the body.

  14. The body may be lowered and lightened by removing material through the process of grinding or scraping as long as Body Rule 9 is not violated. Bodies cannot be heated or reshaped from the original cast of the body.

  15. Bodies that have a separate roof and windshield casting/molding, and have moldedin interiors (also known as Hardtops, e.g. Aurora’s ’65 Mustang), may completely remove the interior portion of the body.

  16. Front and rear wheel wells may be opened up for tire wheel well clearance. This opening may be no larger than a 1/8inch drill bit (.125″) around the entire wheel well and tire.

  17. Wheel wells must not be modified in such a way as to allow the use of any other wheelbase than that which was originally intended by the manufacturer of that body.

  18. Any bodymounting screw may be used. Nonmagnetic screws are recommended so that a loose screw will not be picked up by a passing car, thus causing damage to the car and/or the track.

  19. Both front and rear screws must be used and must secure the body to the chassis at all times.

  20. The front windshield must be plastic or resin, clear or painted, may be glued in place or molded in, and must fill the frame. Tape windshields are not allowed. Side and/or rear windows may be removed.

  21. Bodies that violate Body Rules 4 and 9 by having illegal openings such as too large or unrealistic windows, missing engine covers, and open truck beds may be repaired by gluing a 0.025 minimum thickness plastic cover over the opening. The repair must be made so that its thickness can be checked using a micrometer having a diameter anvil.

ThunderJet Rolling Chassis Assembly Regulations:

  1. Only original Aurora ThunderJet chassis assemblies with nonplated copper electrical components are allowed. Commutator brush springs may be bent to alter brush tension. Pickup shoe hanger plates may be bent.

  2. The rolling chassis axle, armature, and drive pinion shaft holes may be opened up slightly for increased clearance.
    (2a) The Truck hole cannot be utilized in any way.

  3. The rolling chassis assembly must not be fitted with bushings.

  4. The chassis may be trimmed slightly (no more than .010) to allow for crown gear tooth clearance.

  5. Only an original Aurora TJet pancake gray armature with two laminations, with its original commutator, and all of its original unmodified windings may be used. The armature may be balanced and trued.

  6. Each armature pole is to be measured across two separate commutator segments. The AVERAGE of all three poles must be 16.0 ohms or greater at 70 degrees. This armature is LEGAL. All measurements are to be taken at the current available room (ambient) air temperature. The warming of either the commutator or the armature is not allowed before/during measuring. (The combined total ohm reading of all three armature poles must equal or exceed 48 ohms.) We have an armature that tests 16.0 on all three poles at 70 degrees. It ohms lower in cooler temperatures and will be the standard for testing arms at the event. The Hall temperature can vary between 60 to 70 degrees depending on time of year.

  7. Only Johnny Lighting, Auto World, or Dash Motorsports Magnets  may be used. The magnets may be sanded to fit the chassis. The distance between the magnets must be a minimum of .700″; no exaggerated sanding is allowed to close the armature gap. This will be teched using our custom designed, specially fabricated Plug.

  8. Nonferrous magnet shims may be used. No shims are allowed either under or on top of the magnets.

  9. Any flat top and bottom carbon/copper motor brushes are allowed. Brushes may be scored with one score line or an X. No exaggerated deep cuts or crevices allowed; this will be checked for at tech.

  10. All brass gears must be minimum thickness of .048

  11. Only stock TJet or commercially available stock replacement 14 tooth brass armature pinion gears are allowed.

  12. Only stock TJet or commercially available stock replacement 24 tooth brass idler and driven gears are allowed.

  13. Only stock TJet or commercially available stock replacement 9 tooth brass drive pinion gears are allowed.

  14. Only stock TJet or commercially available stock replacement 15 tooth crown gears are allowed. The crown gear must equal or exceed .300″. In reducing the crown gears to .300″, the crown gear must maintain the 90 degree angle to the back of the gear’s top and bottom. The gear cannot be angled, tapered, rounded, beveled, thinned, sliced, diced, drilled, etc. The idea is to allow the stock crown gears to be the same diameter as the aftermarket crown gears. This will be looked at VERY closely. The crown gear boss may be trimmed, spacer(s) may be added to adjust for proper gear mesh within the crown gear box.  You can add a small delrin retainer to the driver’s side rear axle for the purpose of adjusting crown gear mesh with the 9T rear pinion. The diameter of the delrin retainer must not exceed 0.125″  with a thickness not to exceed 0.070″. The new Wizzard crown gear #RGT 15 is approved for use.

  15. Only metal drivengear shafts may be used. The drivengear shaft must not exceed .065″ in diameter.

  16. Geartooth friction surfaces can only be deburred by polishing, filing, or sanding.

  17. Gears must not be chamfered, lightened, or relieved.

  18. Only commercially available front wheel, tire, and axle assemblies including Wizzard, Zoomin Motorsports, JW, and RTHO may be used with two exceptions. The front and rear axle diameter must not exceed .065″ and the front tire diameter must equal or exceed .300″. Front axle washers (small spacers) are allowed. All spacers/washers must be located outside the chassis or chassis frame rail, with the exception to the above rolling chassis rule #13. Maximum lateral movement in the front wheel assembly is 0.031 (1/32).  All unmodified commercially available front wheel, tire, and axles parts may be mixed and matched.   Note: The approved offset weight front ends that are legal for the Fray are:  Zoomin Motorsports # FE01 and RTHO # RT230.

  19. Rear wheels may not be made of Brass or solid Delrin. No axle weights, wheel weights or hub caps allowed on rear axle or inside the wheels. Note: A small delrin retainer will be allowed on the driver’s side rear axle for the purpose of adjusting crown gear mesh with the 9T rear pinion. The diameter of the retainer must not exceed 0.125″ with a thickness not to exceed 0.0700″ (See Rule #13).

  20. Any stock or stock replacement pickup shoe may be used. These shoes must have a factory formed step and the step must be unaltered  except to allow flat pickup shoe contact with the track rail. American Line #313, BSRT #504, Slottech, and Dash 504
    #1440, Wizzard #E82 and stock Aurora ThunderJet shoes are allowed. Ski shoes are not allowed.

  21. The “step” in the pickup shoe must remain intact, unaltered and a minimum height of .010 from the top of bend #2 to the bottom of bend #3.  The first bend in the step, (Bend #2), may be changed slightly so that proper “pickup shoe” to “rail” contact can be achieved. No attempts to “flatten” the “step” are allowed. The area between Bend #1 and Bend #2 may be “flattened” to achieve better contact with the “rails”, however Bend #1 must remain as stock. The front vertical slotted portion of the pickup shoe may be bent to limit shoe travel. The rear hook portion of the pickup shoe may be bent to limit shoe travel and adjust shoe tension. The chassis’ copper pickup retainer may be bent slightly to improve electrical contact.

  22. Pickup shoe springs may be cut, stretched, shimmed, or compressed.

  23. Any amount of the vertical gearplate rails above the upper horizontal plane may be removed. No amount of material may be removed from the gearplate at or below the upper horizontal plane. The serial/patent numbers and letters must also remain intact.

  24. Commercially available guide pins must be plastic and must be of a design essentially similar to the original Aurora black plastic front guide pins. They may be cut, trimmed, or bent. Countersinking of the guide pin screw hole is permitted.

  25. Glue may be used on a rolling chassis assembly only for the purposes of attaching gears to shaft, guide pins to chassis, and front wheel axle retainers to the end of front axle. Solder may be used to attach metal gears to their metal shafts.

  26. The axle and gear shaft holes may be enlarged or decreased slightly to adjust for proper fit without the use of fillers.

  27. The Chassis may be oiled to maximize performance.

  28. The Fray promoters reserve the right to clarify and interpret the rules as they arise for the best interest of the event.

These rules are an enumeration of what can be done.  Doing something not listed as allowed is not allowed.