Child Seat Tethers

[C M Smith <cmsmith@domain.elided>]

A steel parcel shelf will be plenty strong enough for a car seat tether, 
especially one with the large steel washer backing  the mount. The newer 
cars built since the tether mount became required in Canada have a much 
smaller washer and an obvious pre threaded strongpoint in the parcel shelf 
steel. The older tether mounts were designed to be used in the normal steel 
of the parcel shelf, imagine the force required to pull that washer through 
steel of any gauge, let alone the gauge used in car bodies and you'll get 
the idea. Just don't think for a minute that the forces on that point in a 
collision are light, or that the tether mount is "optional" it's essential 
unless the car seat was designed without one, I don't think there are any 
of those manufactured anymore.

The "parcel" shelf steel will be an integral part of the rear bulkhead 
which stiffens the body of a sedan. The fact that this is missing in cars 
with hatches or fold down seats is a serious challenge to the body 
engineers to provide adequate stiffness with this bulkhead missing, in 
newer cars the pass through behind the fold down seats is noticeably 
smaller than in past years as the side impact rules require as much 
stiffness there as can be achieved. Note that roll cages for racing sedans 
usually have stiffeners across this bulkhead area as well as over the roof, 
it stiffens the body significantly, which leads to improved handling as 
well as rollover and intrusion protection.



Michael Smith
Calgary, Alberta
Canada
91 Alfa 164L, White, original owner

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