2021 NSR GT3

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Series Manager: Mark L/Spyder #21
Period: 2Q-2021; April – June

Final Rules as of Feb 26

GT3 is an exciting IMSA-governed racing class that allows “production” cars to be raced on world-class international circuits.  The base cars must be offered to the public for sale, although many of them are above the budget of the average car enthusiast.  These cars have extraordinary power (500 to 600bhp) and handling in stock form, thus IMSA limits modifications to the engine and suspension, while allowing most of the interior and “consumer” components to be removed to reduce weight, clutter and flammable material.  Allowed race equipment includes racecar management electronics, traction-control systems and air-jacks.  In person the cars are impressively beautiful, loud and fast!  During it’s relatively short history (ca. 2005) approximately 52 cars have been proposed for consideration, with a mouth-watering list of marques such as Aston Martin, Maserati, Porsche, Ferrari, Lamborghini, Lotus, Audi, McLaren, BMW, Mercedes, Bentley and many other brands known for high performance and luxury.  America is represented by Vipers, Corvettes, Cadillacs, Mustangs, and Camaros.  In 2021 cars legal for the Deutsche Tourenwagen Masters (DTM) series will move to GT3 rules.

ASCC’s 2021 series is based on GT3 coupes offered in the current and vintage NSR catalog, with limited modifications to make the cars more race-worthy, while taking advantage of their ready-to-race performance (typical of NSR), and limiting the required investment of team owners.

Entry Fee  $5 Premium members; $10 Standard; $15 Guest



  • Required: OEM hard glass & cockpit (no Lexan). At the start of each weekly-round & all Heats; major body parts (esp. windows, lights, wings) must be intact. Wings must be re-attached for each heat. Permitted: Wings can be reinforced with ShoeGoo, styrene or rubber (e.g. Thunderslot donut holes cut to parallelogram shape).
  • Permitted: Small Vulnerable Parts: antennas, mirrors, wipers, tow-hooks do Not have to be replaced after race damage. Driver’s legs/feet can be trimmed to prevent contact with motor shaft, axle, ballast or underside of body.
  • Permitted: Smoothing the various bumps on the light-buckets *if* front tires are contacting them. Thin washers on the front body post to solve tire contact, etc.
  • Options: White Kits must be painted or decaled; Required: three race numbers (both doors plus either -Hood, -Trunk, -Roof, or -Windshield)
    **Duplicate Pre-Decorated Liveries must be made unique – either with Different Race Numbers, painted wings or body panels, or decals.
  • Prohibited: Tires visible past 0.5mm from skirt/fender/wheel-well (when inspected from above)


  • Options: *Recommended* Extra-Hard-Green or Hard-White chassis/pan; OEM Black-Medium hard
    Example:  ASV WH1459, GR1488; C7 WH1492, GR1494; R8 WH1475, GR1486; Z4 WH1463, GR1489 etc.
  • Required: Drop Arm – Red/Hard (NSR-1234)  Permitted:  Arm may be screw-fixed, floppy, or spring-loaded.
  • Permitted: Flash may be sanded; and molding nipples removed. Ballast for tuning weight-distribution on chassis or motor pod.
  • Open Choice: OEM or Brass 4-40 axle adjustment screws.
  • Options: *Recommended* NSR Guides -Wood (deep/long) screw mount (NSR-4859); OEM snap-in (NSR-4841) *good to add shims under pan to remove slop and extend the depth of the keel/blade.
  • Open-Choice: Motor Lead Wires, Grommets, Pick-up braid (i.e not required to be NSR brand)
  • Open-Choice: Body (and motor pod) Screws (i.e. may be smooth shank brass screws from Slot.IT or NSR)
  • Prohibited: Magnets; ballast below the pan; gaps with body and chassis (or pod) exceeding 1mm (credit card thickness)


  • Options: (OEM) Shark-25-EVO (NSR-3043; 25K 180GM); Shark-21.5 (NSR-3041; 21.9K 164gm); vintage Shark-22 (NSR-3001; 22.4K 168gm)
  • Permitted: If the ‘rapper comes off (dawg!), if the “can tattoo” for Model/RPM is Viewable the motor can pass. Tattoos resist lubes and VooDoo juice.
  • Permitted: Trimming Endbell Side Shaft for tire clearance. Shaving the can, on the drive side, near the Spur gear bushing for clearance.
  • Prohibited: ANGLEWINDERS AND INLINES ESP. LONG-CANS Changes to the armature, brushes, bushings, magnets.

Motor Pod

  • Options: *Recommended* Sidewinder OEM Red/Hard (NSR-1264); Black/Medium (NSR-1262) Triangular
  • Permitted: Gluing motor to the pod. No screw holes are in the OEM pod.
  • Prohibited: Pod protruding below the chassis more than 0.5mm;  IW AND SW


  • *Recommended* OEM Pinion: 6.45mm-DIA 11z  NSR-6911A (NSR does not have any other 6.45 pinions)
  • *Recommended* Sidewinder Spurs OEM 17.5mm-DIA 32z NSR-6032;  6030, 6031 – 6037
  • Open-Choice: Any NSR pinion and spur sizes (some older NSR GT cars may not use the 6.45Pin-17.5Spur combo)
  • Open-Choice: Gear-Ratios (OEM: 32/11 = 2.91 therefore rear wheel RPM 7,875 = (25,000 * 11v/12v) / 2.91)
    Examples: HOT 31/11 = 2.82 ~ rear wheel RPM 8,127    SMOKING 30/11 = 2.73 ~ 8,395


  • Required: OEM factory wheels  FRONT: (NSR-5003) 17dx8w  REAR: (NSR-5004) 17.25dx10w
  • Options: Porsche REAR (NSR-5003 17dx8w)
  • Permitted: Filling the Air-System-Gap with Thunderslot Foam Donuts THRMRFM001
  • Required: NSR brand wheel inserts; Open-Choice: Type and Style


  • Required: NSR brand solid axles; Bushings
  • Open-Choice: Stop collars, Spacers/washers
  • Prohibited: Independent rotating front axles.


  • Options: FRONT: No-Friction/Zero-Grips (NSR-5226) 18dx8w -or- (NSR-5201) 17dx8w
  • Options: REAR: (NSR-5230) 20dx11w Supergrip  -or- (NSR-5231) 20dx11w Ultragrip
  • Options: Porsche REAR (NSR-5206; 19dx10w Supergrip; Porsche)
  • Permitted: Tires may be glued. ShoeGoo is recommended rather than CA (superglue) which may split both Supergrips and Ultragrips.
    *Recommended* Truing camphered tyres (shoulders rounded).
  • Prohibited: Traction Compounds (bite, goop, glue)