May 19, 2024

Indy Car Rules

ECHORR Indy CLASS RULES – Effective – 08/03/20

Cars – General

1.     Each racer may have only one car pre-inspected for the entire ECHORR Indy Class event. After a car has been inspected for an event, there shall be no substitutions or replacements. The only exception to the substitution/replacement Rule is where, in the judgment of the Rules Committee or Tech Committee member(s) present at the time, extreme circumstances are present, such as where a car becomes physically unfit for participation. Such a decision lies within the sound discretion of the Committee member(s) and is final.
2.     There is no weight limit for the fully assembled ECHORR Indy Class car.
3.     Cars should pass freely through the Official Tech Block: 1 5/16″ (1.3125” )width.
4.     Every component on the car shall meet the “On Market” requirement.


1.     Bodies shall be injection molded plastic when using original Aurora, Atlas, Tyco, etc. or resin cast (no feather light resin allowed) based on original Indy or GP 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 windows, drivers, roll bars and other accessories which accompanied the car as originally manufactured.
4.     Bodies must contain the original two screw posts. The original position of screw posts must remain intact and shall not be relocated to suit a different setup or wheelbase. Further, the posts shall be included and designed as part of the body specifically for mounting to an Aurora Thunder Jet Chassis.
5.     Body must be fastened securely to the chassis using two screws.
6.     There shall be no substitute materials for original injection molded plastic windows used by Aurora, Atlas, Tyco, etc. Resin cast bodies must have glass comparable in thickness to original bodies.
7.     Drivers are required in all cars.


1.     Chassis shall be stock Aurora Thunder Jet with all copper components. Silver colored rivets on solid rivet chassis are allowed. Re-rivoting of chassis allowed.
2.     Brush springs shall not be modified in any way. They may be adjusted only in their original configuration to change the tension on the brushes.
3.     Guide pins shall be original design, must use a full guide pin, guide pin hole may be countersunk for body screw.
4.      They shall not be metal.
5.     Guide pins may be glued to chassis.
6.     Guide pins may be shortened in length to accommodate different tracks.
7.     Two mounting screws shall be used to hold the body securely on the chassis.
8.     The gear plate clamp may be bent (but not cut or otherwise altered) to improve fitment.
9.     The gear plate rail shall not be cut or altered.
10.  Squishing of the Idler gear post is permitted.

11. All chassis holes may be peened

Pickup shoes and springs 

1.     Pick up shoes and springs shall be solid copper and manufactured by Aurora, Model Motoring or American Line, BSRT (model 504 only) Slot Tech, Dash or Wizzard. Dr. Oogan, Wizzard, Champ and BSRT t-jet springs are legal.
2.     Pick up shoe springs may be cut (coils removed) to desired length.
3.     Pick up shoe springs may be stretched to desired length.
4.     The pickup shoe may be bent, but only for the purposes of adjusting the original contact area to accommodate different rail heights of the various tracks.
5.     Pick up shoe travel may only be adjusted by 1) bending the front “window” portion of the shoe that hooks to the front of the chassis, 2) bending the rear hook which attaches to the chassis’ copper hardware, or 3) bending the hangers on the chassis into which the rear hook of the shoe connects. 4) By using tape or heat shrink tubing on the front window of the shoe.
6.     The window of the shoe cannot be part of the contact patch. We understand that some of the new DASH PU shoes are bent so that the window slightly becomes part of the contact patch, these will be evaluated on a case by case basis.


1.     Magnets shall be manufactured by Aurora and originally supplied with the Thunder Jet chassis. No tough ones or AFX magnets allowed.
2.     Magnet combinations allowed are green/white, green/orange, black/black and black/ black with white stripe, No tough one or AFX magnets allowed.
3.     Magnets may be shimmed using non-ferrous materials only.
4.     Magnets may be matched.
5.     All paint on magnets shall have original factory paint.  In the event of paint shortage on the magnets, they will be compared to magnets in the official tech kit and if still in question they will be measured for strength against like magnets by the designated measuring tool for the event.
6.      Painting of magnets shall not be allowed.
7.     No “reversed zapped” magnets.
8.     Magnets shall not be sanded at all in this class.



1.     Only original, stock, with gray tips shall be allowed.
2.     Armatures shall measure an average of 16 ohms or greater across the poles.
3.     Armatures may be balanced but not trued. The use of glue between comm plate gaps is not allowed in this class.
4.     Shims between the armature and top plate are not allowed.
5.      No Hand Wound or rewound or de-wound armatures allowed. The tech committee will have privy to comparative arms and other hand wound detecting tools to make an intelligent decision on a case by case basis.
Commutator Brushes

1.     Commutator brushes shall be manufactured of a copper/carbon compound.
2.     Both the top and bottom surfaces shall remain flat.
3.     Brushes may be lightly scored to keep from rotating.
4.     Replacement brushes must meet ECHORR “On Market” definition requirements.
5.     No “dimpling” of the brush tensioners allowed.


1.  The armature pinion, idler gear and driven gear shall be brass. T
2,. The armature pinion gear shall have 14 teeth.
3.  The idler gear shall have 24 teeth.
4.  The driven gear shall have 24 teeth.
5.  The final pinion shall have 9 teeth.
6.   Minimum top plate gear thickness shall be .046.
7.  The Crown gear shall have 15 teeth, 4 gear specialty chassis crown gears are not allowed.
8.   The Crown gear shall not be metal.
9.  The Crown gear shall not be shimmed.
10. The Crown gear minimum diameter will be no less than .300
11. Gears may be lapped and/or polished. They shall not be beveled.
12. Shims between the gears and top plate are not allowed.
13. Plastic top plate gears are not allowed.
14.Hollow cluster shafts are not allowed.

  1. Lightened gears are not allowed.


1. Fronts can be any slip on tire or O-ring, 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″

1a. Independent front ends are allowed in this class. Must be readily available and not one of’s…
2. Truck axle hole will be used for front axle.
3. Tires may be made of silicone.
4. Tire width shall be no wider than .175 (AJ’s Width)
5. Tires may be glued to the hubs.
6. Re-coating of tires is not allowed and will be looked at carefully in pre-tech.
7. Only four dimple chrome hubs, yellow wheel truck hub, or after market replacements are allowed; i.e. HO Reproduction s, ZoominMotorsports, JW, etc.
8. Double Flange Wheels are allowed.
9. All wheels must be plastic, no metal wheels of any kind.
10. Spacers or springs shall be kept on the outer side of the chassis.
11. Spacers shall be made only of plastic, copper, aluminum, brass, or steel. The diameter of the spacers  must not exceed 0.125″.
12. No wheel weights of any kind allowed.
13. Axles shall not exceed 1 and 5/16th inch in length. Any axle may be used.
14. All four tires shall simultaneously touch the test track in the static position.
15. Lateral movement of the front tire/axle assembly shall not exceed 1/32″ (.03″)

NO “one of “parts allowed on the cars.