MAHOR Car Rules
11) The body must be fitted with the manufacturer's original or exact replica bumpers, roll bars, etc. in their stock locations.

12) Cracked or broken body mounting posts may be repaired or replaced with the use of glue or a plastic sleeve around the original post or a plastic tube in place of the broken post.

13) Other than the plastic post reinforcements stated in body rule #12, no additional weight can 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 #10 is not violated. The body cannot be heated or reshaped from its original casting.

15) Bodies that have a separate roof and/or windshield and have molded-in interiors may have the interior portion completely removed.

16) Front and rear wheel wells may be opened up for tire clearance. This opening may be no larger than 1/8" around entire wheel well.

17) Wheel wells must not be modified in such a way as to allow the use of a wheelbase not originally intended by the body manufacturer.

18) Any body mounting screw may be used. Non-magnetic screws are recommended so a passing car will not pick up a loose screw, thus causing damage to the car and/or track.

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

20) The windshield must be plastic or resin and must fill the window frame. Tape windshields not allowed. Side and/or rear windows may be removed.

Chassis rules:

1) Only original Aurora Thunderjet chassis with non-plated copper electrical components are allowed. Brush springs may be bent to alter brush tension. Pickup shoe hanger plates may be slightly bent.

2) The rolling chassis' axle and armature holes may be slightly opened up for clearance. The front truck axle hole cannot be used.

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) Any original Aurora T-jet two-lamination gray pole armature with original commutator and original unmodified windings may be used. The armature may be balanced and/or trued.

6) Each armature pole is to be measured across two separate commutator segments at the solder lugs. 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 or during measuring. The combined total ohm reading of all three armature poles must equal or exceed 48 ohms.

7) Any original Aurora T-jet / AFX magnets or commercially available stock replacement magnets may be used. The distance between the magnets must be a minimum of .700"; no exaggerated sanding is allowed to close the arm gap.

8) Magnet shims may be used as long as they are made of non-ferrous material. 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.

10) Any stock or commercially available stock replacement 14-tooth brass armature pinion gears are allowed.

11) Any stock or commercially available stock replacement 24-tooth brass idler and driven gears are allowed.

12) Any stock or commercially available stock replacement 9, 12 or 14-tooth brass drive pinion gears allowed.

13) Any stock or commercially available stock replacement 15-tooth crown gears are allowed. The crown gear boss may be trimmed or have a spacer added to adjust for proper gear mesh.

14) Only metal drive gear shafts may be used. The shaft may not exceed .065" diameter.

15) Gear tooth friction surfaces may be deburred by polishing, filing, or sanding.

16) Gears may not be chamfered, lightened, or relieved.

17) Any wheel and axle combination is permitted providing the chassis is centered between the wheels and the assembly does not exceed 1.085" in width. Front tires cannot be smaller than .300 in diameter. Rear tires must be stock width T-jet rubber or slip-on silicone.

18) Front and rear axle shim washers or spacers are allowed. Front axle shim washers or spacers must be on the outside of the frame rails.

19) Any non-plated 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. Replacement shoes may be American Line, BSRT #504, Slottech or Wizzard.

20) Bend 1 of the pickup shoe (below the hanger slot) may not be altered in any way. The step in the pickup shoe must remain intact and be unaltered. Only the first bend in the step (bend 2) may be changed slightly for proper shoe-to-rail contact. No flattening of the step allowed. The area between bend 1 and 2 may flattened for better rail contact. The vertical slotted portion of the shoe above bend 1 may be bent to limit travel. The rear hook portion of the shoe may be bent to limit travel and tension. See diagram below.

21) The pickup shoe spring may be cut, stretched, shimmed, or compressed.

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

23) Guide pins must be plastic and must be of a design essentially similar to the original Aurora black plastic front guide pins. The guide pin may be trimmed or bent. Countersinking the guide pin screw hole is allowed.

24) Glue may be used on the chassis only for the purposes of attaching the gears, guide pin, or axles. Solder may be used to attach gears to shafts.

Pro-stock class
(All rules for Stock class apply to Pro-stock class with the following additions)

1) Any front tire/wheel/axle combination and any rear axle may be used.  Rear tires must be slip-on rubber or silicone mounted to plastic wheels.  Tires may be be ground down/trued or chamfered/radiused.  Additional material in and/or around the rear wheels is not permitted (wheel inserts/hubcaps, axle disks etc.). 

2) Maximum lateral movement in the front wheel assembly is 0.031".

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 1-5/16" HO tech block.

Super-stock class
(All rules for Pro-stock class apply to Super-stock class with the following additions)

1) Any front & rear tire/wheel/axle combination may be used.

Indy class

Body rules:

1)  Bodies shall be based on an Indy or Gran Prix car.

2)  Bodies may be lightened but must meet the minimum weight requirement with 2 screws of 3.0 grams.

3)  Bodies must be complete with full original windows, drivers, roll bars and other accessories which accompanied the car as originally manufactured.

Chassis rules:

Magnets shall be manufactured by Aurora and originally supplied with the Thunderjet chassis. No "Tuff Ones" or AFX magnets allowed.  Magnet color combinations allowed are green/white, green/orange, black/black and black/ black with white stripe, No "Tuff Ones" or AFX magnets allowed.

2)  All paint on magnets shall have original factory paint.  There shall be no substantial removal of paint.

3)  No "reversed zapped" magnets.

4)  Armatures may be balanced but not have the poles trued.

5) Only stock or commercially available stock replacement 9-tooth brass drive pinion gears allowed.

6)  Front tires can be any slip-on tire which is stock width or thinner and no smaller than .420". Rears can be any slip-on tire which is stock width and no smaller than .460".  Tire width shall be no wider than .175".  Tires may be glued to the hubs.

7)  Truck axle hole will be used for front axle.  Any front or rear axle may be used

8)  Only four-dimple chrome hubs, yellow wheel truck hub, or after market replacements are allowed; i.e. HO Reproductions, Zoomin Motorsports, JW, etc.  Double-flange wheels are allowed.  All wheels must be plastic.  No wheel weights of any kind allowed.

9)  Spacers or springs shall be kept on the outer side of the chassis.  Spacers shall be made only of plastic, copper, aluminum, brass, or steel. The diameter of the spacers must not exceed 0.125" +/- .005".

10)  Lateral movement of the front tire/axle assembly shall not exceed 1/32" (.03")

11)  The complete car must freely pass through a standard 1-5/16" HO tech block.
Unlimited class

The following restrictions apply:

1) Car must pass freely through an 1-5/16" tech block.

2) Car must have a body (no restrictions).

3) Car must use an Aurora Thunderjet chassis and gear plate.

4) Chassis must use a pancake arm.

5) Chassis may have motor magnets only. No additional magnets.

NOTE: All car rules are subject to tech committee interpretation. If you are unsure if a car is legal, check with the tech committee prior to the race. Any other modifications will be considered illegal unless cleared by the tech committee.                                                                                                           

Stock class

Body rules:

1) The body must be a copy of a 1:1 car and/or concept car.

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

3) Bodies with cast-in 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.

4) Bodies must be originally manufactured with the intention of being mounted with the use of 2 screws via 2 body mounting posts on an Aurora Model Motoring (Vibrator, Thunderjet, Wild Ones, Tough Ones, and Xlerators), Bachmann, Faller, Model Motoring Thunderplus, Marx, Eldon or Tyco S series HO chassis.

5) No Indy, Formula 1 or Formula style open wheel bodies allowed.

6) No ballast or fillers other than color pigment allowed.

7) Maximum overall body width is 1.200".

8) The maximum thickness of the sides of the body (including fender flares and running boards) is .125".

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

10) With the body mounted to the chassis and viewed from the side, the top rear edge of the gear plate (minus rail) cannot be above the body profile (see diagram below).

©Copyright 2016 John M. Habernal. All rights reserved. No unauthorized reproduction.