Seatbelts

Owned by Filip Tomic
Jun 21, 2020
3 min read

Key Regulations:

  • Must use 5 or 6 point harness (we picked 5 point)

  • Must attach to the structural chassis

  • Shoulder straps must always be below the horizontal and higher than 30 degrees below the horizontal

  • Shoulder straps must travel inwards half as far as the travel backwards

  • Lap belt must point downwards and rearwards and be between 60 and 80 degrees of the horizontal

  • Anti-submarine belt must be approx. 10 degrees forwards of the plane of the shoulder belts

 

Our Design

  • Lap belts fall always fall between 60 and 80 degrees for all sizes of passenger

  • All lap tabs are identical, they all allow the belts to be from 60 and 80 degrees for all passengers

    • Not totally necessary to have it be able to fit completely form 60-80, just for peace of mind

 

  • Anti-submarine tab is in the right place I forgot to show the sketch :)

  • Anti-submarine tab is at an angle such that the force of the seat belt is parallel to the face of the tab

    • Want to avoid to have the belt pulling up/down on the tab

 

  • For tallest passenger seat belts will be at 27 degrees and at 9 degrees for smallest passenger

  • Rear seat passengers shoulder seat belts are right at the limits

  • For largest passenger the belt will be 28 degrees and for the smallest it is essentially horizontal

  • Initially I had not seen the regulation about the belt being above 30 degrees so another chassis tube needed to be added to the back of the car so that it could be met

  • Rear tabs also ensure that the belt will always travel inwards half as far as it travels backwards

 

  • Front and back shoulder mounts are identical since they all travel inwards and backwards the same amount (tabs need to be same size)

  • Both front and back tabs need to placed “backwards” beacause otherwise they would be going through the seat into the person’s back (ouchie)

  • Shoulder tabs look essentially identical to lap tabs, just slightly different sizes

 

Changes from initial design

  • The anti-submarine tab initially would have been stuck to the bottom panel with adhesive. However, due to the concern that this mounting would not be strong enough in case of a crash it was decided to install tubes across the floor of the car so that the anti-sub tabs can have something to weld to. Initially only thought that anti-sub was used for when the car rolls over but turns out its actually very important in all crashes (stops passenger from sliding underneath the seat belt) so it takes more force than initially thought

     

     

  • As touched on before in order to meet regulations for shoulder mounts of rear passengers a tube on each side needed to be added. This allows all passengers to fall within regulations