February/March 2019 Interim Rule Changes

Comments noting ambiguities in this announcement, typographical or other errors in the specifications, and problems with changes which may have been overlooked may be addressed to the Rules Committee via e-mail (rules@pcaclubracing.org) or by using the contact form on this page.

Rule Book

Download your copy of the existing rule book (sans the changes summarized here).


Use the links below to jump directly to specific class changes:

Contact the Committee

SPB Shocks

The Bilstein PSS9 shock, which is the spec shock for SPB, is no longer available, and it appears that parts to rebuild this model shock are also NLA.  The SPB rules are amended to add the Motion Control Systems SPB damper, part number SET-1WNR-SPB-01 as an alternate shock for the class.  Additional details on the MCS SPB program can be found here.

The aluminum upper rear spring seat and the tender springs and separators may be aftermarket parts so long as they are substantially similar to the PSS9 part.  Minor trimming of rain gutter sheet metal in the rear trunk above the shock adjuster to improve access is allowed.

The Club Racing Rules Committee would like to offer its special thanks to John Gladwill for his efforts on behalf of the Spec Boxster class.


The 2019 SP1 rules are amended as follows:

  1. Engine
    • Engines with the 9.5:1 pistons may use an offset cam timing key.
    • The fuel lines may be replaced with lines of the same inner diameter as stock, in the same routing location and of the same length.
  1. Transmission / Differential
    • The 1989 ASG/ASH (2.7) transmission is allowed (gear ratios the same as allowed).
  1. Suspension / Wheels / Tires
    • Brake and clutch bleeders are free as long as they do ot change their function.
    • The camber portion of Suspension D is amended to read:
      Camber plates are allowed but must be available at retail to the racing public, bolt to the chassis using existing shock mounting holes and standard hardware, do not involve any modification to the shock tower or the shock, and consist of no more than two plates, one of which bolts to the shock, and one to the chassis. The top of the shock rod must not exceed 1.5″ above the adjacent strut tower lip, and for purposes of limiting caster, must be at least 1 3/8″ forward of the back side of the rear top plate mounting studs
  1. Bodywork C: (Add the following)
    • The KBD urethane 944 front valance may also be used (part# NASA-2096).


The SP911 rules are amended as follows:

  1. Chassis, Body and Interior
    • Add the following
      Removal of front headlights and metal headlight buckets is allowed, as are plastic headlight covers.  Headlight and windshield washer system components may be removed
  1. Engine
    • Amend H. 3.0 liter engine specs to add the following sentence:
      Allowable intake systems are: 40 or 46mm Weber or PMO carbs, CIS intake manifold from any year and with any fuel injection system, Bosch low butterfly MFI from 1969-1973, 3.2 intake manifold with any throttle body and airflow meter, “straight-through” fuel injection systems with individual throttle bodies no larger than 46mm (e.g. TWM, Jenvey, etc.), 3.6 intake manifold from 1989-1995 911 with any throttle body(s), AT Power individual throttle body systems, with individual throttle bodies incorporating throttle plates no larger than 46mm.   Slide valve intakes are prohibited.
  1. Transmission and Clutch
    • CV joins are free.

The weight table is amended to show these weights based on engine size and intake type:

Engine Displacement Induction TypeMin. Race Car Weight
3.0 litersAT Power ITB2425 lbs.
3.0 litersPorsche 3.6 plenum-based(*)2400 lbs.
3.0 litersCarburetors2340 lbs.
3.0 litersPorsche/Bosch CIS2340 lbs.
3.0 litersBosch MFI 2400 lbs.
3.0 liters"Straight-through" Fuel Injection (ITB)2400 lbs.
3.2 liters2340 lbs.


The GTB2 class is abolished.

The 2014-15 981 3.4 liter Cayman S is moved from GTB2 to GTB1 and must meet a minimum weight of 3050 pounds and 125 pounds must be added if the car has a PDK.  If these are not the appropriate weights to compensate for the improved chassis and PDK, they will be adjusted as experience dictates.

GTC6 and GTC7

The spec rear dry tire is the DHD2 compound.

911 Cup

The rules for this series (found here) have added these provisions:

  1. Underdrive pulleys of any belt type are allowed.
  2. All Stock rules not specifically modified by the 911 Cup rules must be followed.