1.0 Chassis Rules Types  A/B, C, D, S

1.1 Chassis rules are a guideline.  WTC officials may refuse any chassis at their discretion.  WTC inspection is for competition and safety recommendations.  Racing is known to be dangerous, and no chassis is considered to be safe. Individual race vehicle owners, drivers and crew chiefs are responsible for the safety of their race vehicle.

1.1 addendum 3/14/25

• No offset Chassis or Frame components of any type.
  • Main front and rear hoop are to be mounted directly, in an approved manner to the main frame rails.
    • Offsetting the front clip is strictly prohibited.
    • Offsetting the rear clip is strictly prohibited
    • The driveline, front clip, rear clip, main frame rails, and front and rear main hoops must all share the same centerline.

1.2  Chassis Option Type A/B
(NETS Chassis – Metric Chassis – Waterford Based Chassis)

• GM 1978-1987 G Body 108 inch Metric Frame with all suspension points retained to manufacturer specs.  Must be able to pass inspection using Johnson Chassis inspection tools.
• Frame may be fabricated forward of the front spring buckets.
• A/B Replacement of the rear frame from aft side of spring pocket perch allowed with Minimum 2×3 x 0.90
  • Replacement tubing of the rear frame must maintain a minimum of 8 inches ground clearance.
  • Section must maintain width equal or greater than distance between outside of rear spring bucket.
  • Rear frame between rails must use same size tubing.
• C Channel
  • C Channel recommended to be boxed
  • C Channel may be replaced with 0.125 square tubing .
    • Minimum 2 inch X 3 inch allowed
    • 3inch  X 4 inch tubing is preferred.
• Rear Shelf
  • There is no penalty of removing or altering the rear shelf
    Please note: removal of the shelf alters the rear clip strength.
    • A tie in replacement tubing that runs from side to side in place of the shelf is recommended

1.3 Chassis replacement components for A/B, C, D, Seekonk Metric and S

• Johnson Chassis Complete
  • 78-89 GM-METRIC FRAME 4-Link
    OEM 225 lbs 3″ X 4″ x.125 Main Frame Rails
• Front Clip Type A / NETS Chassis/ Type B /D
  •  Johnson Chassis X-Y-G Metric Front Clip
    (Please note: Clips come with various engine mounting specs. Engine mounts must locate Engine so that Forward most spark plug base is 2 inches forward of imaginary Line between center of Ball Joints. 
  • Hamm Replacement for OEM Metric is allowed
  • Howe OEM Replacement
    • Howe tags and logo must be in tact.
    • Team must contact Howe and supply inspection diagram in advance of entering race 
  • Any snout may be submitted for approval. Approval is at the discretion of WTC and may refused without explanation or reason.
  • All snouts must maintain Lower A Frame mounts within metric factory spec in relation to each other.
  • All snouts must maintain metric factory spec as it applies to height of lower control arm mounts in relation to center of C Channel / Main fraim rail.
• Rear Clip
  •  Johnson Rear Replacement Frame allowed
  • Any rear clip design may be pre-submitted for approval.

1.4 Roll Cage / Chassis/ Frame

• Main Cage Tubing
  (Halo, Front and Rear Main Hoop, Ear bar, Door Bar)
  • All welds must be complete
  • Minimum Size
    • 1.50 inch with minimum .120 wall tubing on grandfathered cars. No new chassis will be approved with this specification
    • 1.750 with minimum  .090 tubing
  • Locations (WTC reserves the right to authorize variances)
    • Halo must be within 4 inches of front edge of roof
    • Front Hoop to Ball joint measurement maximum 28 inches
    • Rear Hoop to center of rear axle minimum 32 inches
      • Trucks built after Feb 1 of 2016 must have a continuous diagonal bar extending from the driver’s side top corner of rear main hoop to the base of the rear main hoop on the passenger’s side
        • Anti bow bars must be installed to support the diagonal brace
    • Distance from top of frame to bottom edge of rear hoop minimum 40 inches.
    • Ear bar must be no more than 6 inches forward of rear main hoop (b Post)
    • Right/Passenger side door bars – X method is allowed
    • Drivers Door Requirements
      • Minimum 4
      • Must be plated with minimum .125 thickness steel
      • Minimum height of door bars from frame to top of bars is 22 inches
  • Front down tube
    • minimum wall thickness is .083
    • Must extend forward past front spring buckets
    • Recommended to align with top driver’s door bar
    • No excessive bracing
  • Aft of main hoop
    • Minimum Four back stays
      • Minimum wall thickness .083
      • Recommend two back stays align with top of driver’s door bar and extend to area of rear spring bucket
      • Recommend two back stays run from top of main hoop to frame.
  • Fuel cell protection bar mandatory
  • Bumpers
    • Must contour to body
    • Single tube – front conforming to nose
    • Single tube – rear conforming to bumper cover

Seekonk Metric Chassis dimensions

A- Centerline hole, Forward placement of snout will use two holes for measurements. OEM – 26.5″.
Johnson/Hamm – 27.125″. +/- ½”. Snout MUST be centered to FRAME and REAR CLIP, NO tolerance.
B- Frame rail lengths, from snout centerline hole to end of rail – 75″ Maximum.
C- Chassis frame rails width outside to outside Max 54.0″ +/- ½”.
D- Rear clip outside to outside 42.0″. Mounted centered to front snout.
E- Wheelbase length 102.0″ minimum. No tolerance.
F- Rear clip length 66.0″. +/- ½”.
G- Roll cage length, measured outside of main posts – 44.5″. +/- ½”.
H- Roll cage height: top of cage to bottom of chassis – 47.0″. +/- ½”. The cage must stand at 90 degrees
to the chassis and not go further back than frame rails allow at 74.5″. Refer to (B)
I- Roll cage halo 44.0″ length / 29.5″ width. +/- 1.0″.
J- Down bars from main cage – top 38.0″ outside to outside +/- 1.0″. Bottom attaches to end of chassis piece (N). Bars may intersect with other bars before connection to chassis.
K- Roll cage A-post leg and foot bar maybe moved 3.0″ to outside of main frame rail. 2” x 4” tubing .120″
wall, must be used under the repositioned bars welded off main frame rail or in front of kickout. This is
the only portion of the cage allowed to be repositioned, giving more leg room to the driver.
Rear clip consists of 5-pieces L thru P using 2″ x 3″ .083″ steel box tubing. All angles are with 36-degree
cuts. Listed are the lengths of each piece before angle cuts are made. Don’t forget to factor in blade widths of saw when measuring.
L- 18″
M- 18″
N- 19″
O- 10″
P- 25″
Q- Length between L to O rear clip 41″

C Type Chassis Specific Rules 

• FRAME: 1965-2015 American production full frame cars -wheelbase between 108 and 112 inches.
  • Alteration to obtain 112″ wheelbase allowed
    ( must be within 12 inches of the rear mount points of the rear trailing arms.)
  • Frames may be interchanged from one manufacturer’s line or make to another
• Front and rear snouts must remain stock for make of frame.
  • subject to verification by officials for year, make and model
  • May be refused without reason at sole discretion of series officials
  • Cross member
    • cannot be moved from original location , altered  or out of tolerance
• No sub-frames / No Offset Frames
• Rear frame section must be stock configuration with reinforcement permitted after rear of mount points of rear trailing arms.
• Altered rear kick-up permitted for axle clearance.
• Frame rails
  • Must remain hollow. No added bracing, tubing permitted inside the frame rail.
  • No holes may be cut in the frame rails to lighten frame.
  • will be measured and verified by officials for year, make and model.
  • Two inch by four-inch steel tubing is permitted from the center of the rear axle to the rear bumper.
  • Two inch by four-inch steel tubing may be used in front of the steering box and A-frame mounts.
• 1.4 Roll Cage / Chassis/ Frame
  • Main Cage Tubing (Halo, Front and Rear Main Hoop, Ear bar, Door Bar)
    • 1 and 1/2 with minimum .120 wall tubing
    • 1/3/4 with minimum  .090 tubing
  • Halo must be within 4 inches of front edge of roof
  • Front Hoop to Ball joint measurement maximum 28 inches
  • Rear Hoop to center of rear axle minimum 32 inches
  • Distance from top of frame to bottom edge of rear hoop minimum 40 inches.
  • Ear bar must be no more than 6 inches forward of rear main hoop (b Post)
  • All welds must be complete
  • X method for Right/Passenger side door bars is allowed
  • Drivers Door Requirements
    • Minimum 4
    • Must be plated with minimum .125 thickness steel
    • Minimum height of door bars from frame to top of bars, 22 inches
    • Padded with proper resilient padding
  • Trucks built after Feb 1 of 2016 must have
    • Continuous diagonal bar extending from drivers side top corner of rear main hoop to the base of the rear rear main hoop on the passengers side.
    • Anti bow bars must be installed to support the diagonal brace.
  • Front down tube minimum wall thickness is .083
    • Must extend forward past front spring buckets
    • Recommended to align with top driver’s door bar
    • No excessive bracing
  • Aft of main hoop
    • Minimum 4 back stays
    • Minimum wall thickness .083
    • Recommend 2 back stays align with top drivers door bar and extend to area of rear spring bucket
    • Recommend to back stays run from top of main hoop to frame.
    • Fuel cell protection bar mandatory
  • Bumpers
    • Single tube – front conforming to nose
    • Single tube – rear conforming to bumper cover
    • Must contour to body

TypeD Type Chassis Specific Rules   (Street Stock Conversion)

• Any American made production chassis with a minimum stock wheelbase of 101- 110″ inches, from 1972 to current date.
  • Chassis may not be altered from stock appearance
  • No alteration/moving of chassis suspension mounting points or spring locations
  • Cross-member may be only altered for engine clearance.
  • Reconstruction of chassis permitted from steering box forward .
  • Reconstruction of chassis permitted from center of rear wheels back.
    • Replacement tubing of the rear frame must maintain a minimum of 8 inches ground clearance.
    • Construction must resemble stock placement.
    • Minimum 2″ X 3″ steel box tubing .090 thickness may be used.
    • No bars may travel under rear end housing.
    • Section must maintain width equal or greater than distance between outsides of rear spring buckets. Rear frame between rails must use same size tubing.
  • Wheel base must be altered to 108 inches with 1” tolerance.
  • The use of X-Y-G Mandrel bend Johnson chassis with no modifications is permitted.
  • Front mandrel bend clip assemblies from Johnson
  • Uni-body chassis must use sub-frame connectors.
     
  • C Channel may be boxed.
    • C Channel may be replaced with 0.125 square tubing .
      •  Minimum 2 inch X 3 inch allowed .
      • 3inch  X 4 inch  tubing is preferred.
         
  • Chassis is eligibility is based on EXISTING street stock being converted.  Cage must be constructed by guidelines of original rules for the street stock being converted and also conform with the rules below.  WTC officials may refuse any chassis at their discretion.
    • Main Cage Tubing (Halo, Front and Rear Main Hoop, Ear bar, Door Bar)
      • 1and 3/4 with minimum .090 wall tubing
      • 1 and 1/2 with minimum .120 wall tubing
         
    • Ear bar must be no more than 6 inches forward of rear main hoop (b Post)
    • All welds must be complete
    • X method for Right/Passenger side door bars is allowed
    • Drivers Door Requirements
      • Minimum 4
      • Must be plated with minimum .125 thickness steel
      • Minimum height of door bars from frame to top of bars, 22 inches
      • Padded with proper resilient padding
         
    • Front down tube minimum wall thickness is .083
      • Must extend forward past front spring buckets
      • Recommended to align with top driver’s door bar
      • No excessive bracing
         
    • Aft of main hoop
      • Minimum 4 back stays
      • Minimum wall thickness .083
      • Recommend 2 back stays align with top drivers door bar and extend to area of rear spring bucket
      • Recommend to back stays run from top of main hoop to frame.
      • Fuel cell protection bar mandatory
    • Bumpers
      • Single tube – front conforming to nose
      • Single tube – rear conforming to bumper cover
      • Must contour to body

Seekonk-Sport Type Chassis Specific Rules (Does not apply to new Seekonk Metric)

• Main Cage Tubing (Halo, Front and Rear Main Hoop, Ear bar, Door Bar)
  • 1and 3/4 with minimum .090 wall tubing
  • 1 and 1/2 with minimum .120 wall tubing
• Ear bar must be no more than 6 inches forward of rear main hoop (b Post)
• All welds must be complete
• X method for Right/Passenger side door bars is allowed
• Drivers Door Requirements
  • Minimum 4
  • Must be plated with minimum .125 thickness steel
  • Minimum height of door bars from frame to top of bars, 22 inches
  • Padded with proper resilient padding
     
• Front down tube minimum wall thickness is .083
  • Must extend forward past front spring buckets
  • Recommended to align with top driver’s door bar
  • No excessive bracing
     
• Aft of main hoop
  • Minimum 4 back stays
  • Minimum wall thirstiness .083
  • Recommend 2 back stays align with top drivers door bar and extend to area of rear spring bucket
  • Recommend to back stays run from top of main hoop to frame.
  • Fuel cell protection bar mandatory
     
• Bumpers
  • Single tube – front conforming to nose
  • Single tube – rear conforming to bumper cover
  • Must contour to body
• Chassis Weight -All trucks must be specified minimum weights and percentage at all times
                            .
  • Automatic`/ Standard Transmission 2900 lbs
  • Weight Tolerances:  None
     
• Maximum left side weight percentage 56%
   
• Wheel base 102 inches
  • Add 10 lbs for every inch / 5 lbs per 1/4 inch under 108
     
• Ground Clearance
  • All components / body parts must maintain a minimum of 4 inches ground clearance.
  • Chassis 4 inches
  • Fuel Cell 7 inches
  • Exhaust 4 inches
     
• Crankshaft height / placement
  • 12 inches
  • Centered between frame rails
     
• Engine location
  • Forward most spark plug must be even or forward of an imaginary line between ball joints.