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HO World International - Table and Rules
Thunderjet Division
Special Thanks to Jim Welty for the Track Design and VHORS for the basis of the rules.

HO World International Table

Thunderjet Division

5' X 9'

Scott Dunlap, of SoCal, built this Tomy track replica of the International

Official HO World
International Rulebook

Thunderjet Division




The following rules are being presented as an International set of rules that take advantage of the Aurora Thunderjet chassis, and any other available parts offered to the public by various manufacturers and HOPRO’s, that might improve performance, yet not be cost, time, or skill, prohibitive for the vast majority of people.


The basic idea is to have a chassis that, after being set up, may be used to accommodate formats from the skinny wheels of the original Thunderjet (15/16”), to 1 3/16” track (TuffOne), up to the 1 5/16 track (Fray style races).


We do not suggest any particular race format. These rules, and the suggested International Track design are intended as a universal standard so that cars, tuning, and lap statistics might be more uniform and standardized.


 These rules, like any good document, will be a reflexion of contemporary trends, and will change, not for the sake of change, but to stay viable.




HOPRO: Any Home Production manufacturer of parts who is not a commercially known manufacturer. Thus, availability of said products is not obtainable on the common mass retail market. More so these products are procured direct from the manufacturer themselves or a specialized store or location such as online auction, slot car shows, etc. These are some times referred to as “repro”, or “reproduction”.



“On Market”: In reference to a new product either by a HOPRO or known manufacturer who introduces a new product to the slot car market. For car bodies only: bodies must be from a production run of at least 100 pieces and publicly available for at least 60 days prior to the event. All other items must be publicly available worldwide for at least 60 days prior to the event. 



Manufacturer: Designation for mass production producers of HO slot car related items and accessories.



Handling Pan:  Any metal or plastic piece attached to the bottom of the car to improve handling. This also includes extra molded or attached plastic/resin into a body for the same effect.


Track: The distance from the outside of the front or rear tire, to the outside of the opposite tire.






1. Car weight requirement of fully assembled cars must be from 19.00 to 23.00 grams. Any car, which is over, or under the weight limits, will not be allowed to participate in an official event.






1. Bodies must be of the hard shell variety. (No vacuum formed bodies.)

 2. Bodies must be complete with windows, bumpers, drivers, or roll bars as originally manufactured.

2b.Lexan replacements may be substituted for original windshields, and must have the same shape. They must be one piece. They must follow the rules for the original windshields.


3. Bodies must be originally manufactured with two screw posts specifically for mounting to a Thunder Jet Chassis. (E.g. Aurora, Johnny Lightning, Model Motoring, Bauer, Faller, Playing Mantis, etc.) No modified AFX, Tyco, LifeLike, G-Plus, etc. type bodies will be permitted.


4. HOPRO bodies must meet the defined “On Market” definition requirements.


5. Body must be fastened to chassis using two screws.


6. Bodies may be hollowed out to lighten the weight but cannot be cut through.


7. Interiors may be removed from bodies that have a fully covering roof.


8. Fender wells may be cut only enough to accommodate oversized tires, and may not remove any “horizontal” portion of the car’s body (i.e. any area considered the “top” of the car).


9. Fenders may not be completely removed.


10. Wheel wells may not be cut to allow changes to the original wheelbase of the body.


11. Screw posts may be cut to lower body.


12. Split screw post may be repaired using plastic or aluminum sleeves only. No brass. Sleeve wall must not exceed 1/32” thickness.


13. Screw posts may be replaced with plastic only and must be positioned at original location, and mounted with non-metal adhesive, such as modeling glues and super glue type products. Products like JB weld are not allowed.


14. Body must not exceed original manufactured width.


15. Windshields or windows may be sanded to allow body to sit lower, but glass must fill window opening in the front and rear. Side windows may be removed.


16. Fenders may not be flared unless originally manufactured as such.






1. Chassis must be stock Thunder Jet with all copper components.


2. Bearings and bushings are not permitted


3. Weights and handling pans are not permitted.


4. Chassis cannot be cut, sanded or drilled in any way. The only exception will be rule number 5 below.


5. Gear plate rails may be cut or sanded only to lower the body. No material may be taken from any other part of the gear plate, below the horizontal plane of its top. Patent and mold numbers must be visible


6. Pick up shoes and springs must be stock copper Thunder Jet, or Johnny Lightning silver Thunderjet 500. "Ski" shoes or other pick up shoes where the original contact point has been shortened or lengthened are not permitted.


7. Pick up shoe contact point may be flattened to allow better surface contact with the rails but must remain stepped. The step point must remain at its original location and must match the original step height of the original pickup shoe. The length of the contact point must match the original contact point length, when compared to an original pick up shoe.


8. Pick up shoes cannot be weighted.


9. The amount of travel of the pickup shoe may be restricted by bending the shoe hanger at the front of the chassis. No bending of the chassis pick up shoe hanger is allowed.


 10. Shunt wires, "tiger tails" or other soldering on the bottom of the chassis is not permitted.


11. Guide pins must be original design, plastic. No rear, swivel, or metal, guide pins are permitted.


 12. Guide pins may be glued to chassis but two mounting screws still must be used to hold the body on the chassis.


 13. Gear plate clamp may be bent or dimpled but may not be cut.




1. Magnets must be stock Thunder Jet or Johnny lightning, as originally manufactured. Original color combinations such as green/orange, green/white, and black/black (1 magnet has a small white stripe).


 2. Magnets may be shimmed (no magnetic material may be used). Tape, paper, plastic, or brass may be used.


3. Chassis cannot be cut to allow repositioning of magnets.


4. Magnets may be sanded on the flat ends of the arc (the poles), but may not be cut.


5. Magnets may be matched.


6. No traction magnets are permitted.




1. Armatures must be stock Thunder Jet, or Johnny Lightning Thunderjet 500. Thunder Jet armatures are typically painted gray and have green, red or gold windings, or a combination of all three colors.


2. Armatures must measure 14 ohms or higher when measured from pole to pole.


3. Armatures may be balanced. Balancing may be accomplished by removing material or by adding epoxy type material. Any ferrous material is not allowed.


4. Armatures may not be re-wound or de-wound.




Commutator Brushes


1. Commutator brushes must be manufactured of a copper/carbon compound.


2. Brushes must be flat surfaced on top and bottom, grooved or crowned brushes are not permitted.


3. Replacement brushes are acceptable as long as they are of the copper/carbon compound material, they are the same style and shape as the original stock T-Jet brushes, and they meet “On Market” definition requirements.


4) Other than cleaning them, brushes must remain unmodified from their original condition.




1. The armature pinion, idler gear and driven gear must be stock brass Thunder Jet type.


2. The armature pinion gear must have 14 teeth.


3. The idler gear and driven gear must have 24 teeth.


4. The final pinion gear must be brass.


5. The final pinion gear must be 9 tooth.


6. Crown gear must have 15 teeth and be of original Aurora type material.


7. Crown gear “boss” may be sanded, shimmed or trimmed.


8. Gears may be soldered or glued to their respective shafts.


9. Gears may be lapped and polished.


10. Gears may not be drilled or lightened in any form.


11. Gears may not be beveled.



12. Replacement gears from other manufacturers must be of the same materials as described above.



13. Replacement gears must meet the “On Market” requirements.






1. Any tire/hub combination is permitted.


2. Axle nuts, spacers or springs must be kept on the outer side of the chassis.


3. Spacers must be made of plastic, aluminum, brass, or steel, no lead is permitted.


4. Overall width of wheel/axle combination is to be determined by the specific format in use for that race and must pass freely through a tech block. The wheel track may not exceed the following widths for these 3 classes:
1. Thunderjet = 15/16”,
2. Tuff-One = 1-3/16
3. Fray = 1-5/16”)


5. All four wheels must touch the track.


6. "Hub caps" or other wheel inserts are acceptable provided they fit entirely within the rim and must comply with the “On Market” requirements.


7. Front tire/axle may be allowed to float from side to side. Lateral movement may not exceed 1/32" (.03").


8. Replacement tires, rims, and axles must meet the “On Market” requirements.






1. Any type of non-adjustable or adjustable (OHM value only) single wound resistor controller is permitted.


2. Any type of electronic controller without a single wound resistor is not permitted.


3. Additional electronics on controllers for changing OHM value is permitted.


4. Additional electronics or hardware on controllers for changing any type of output power to the car other than OHM value is not permitted.


5. Additional electronics or hardware on controllers for changing any type of brake adjustment is not permitted.


6. Additional electronics or hardware on controllers enabling "coast" or "auto-pilot" features where power is supplied to the car when the trigger is fully released by the operator is not permitted.


7. Brakes are not allowed.


8. Any controller or replacement parts must meet the "On Market" requirements.