how much damage does a vehicle chassis need to sustain to render it unsafe to function?

Answer 1

Now-a days the chassis is designed as a sacrificial
structure, intended to fail in a controlled manner,
protecting the occupants.
Any deformation compromises this intent, as the
planned progressive energy absorbing failure is already
started and thus not available next time.
'Used to be `if you could beat it back into some semblance
of its original form you were 'good to go` but the good old
days are gone.

Answer 2

only when fatigue is noticeable under careful inspection in the area known as pressure points especially areas close to the wheel axle or suspension, because if that gives it would be a serious problem at high speeds and also check for corrosion and metal density that might weaken the structure if left un-check and if you notice some handling problems better call your mechanic because it may be signs of a weaken structure.

1.in F1 racing terms when small cracks or bends shows up in the scanning instrument then that part gets replace. thats 5% to 10% damage. (that will affect milliseconds of speed and cornering )

2.in demolition-derby terms when the car is immobilize. 70% to 95% damage (car is totally unusable)

3. for normal road car that will be around 40% to 65% damage. (when handling is bad to worse)

Answer 3

Aargh, before I too kto the high seas, The slightest bend, fold, or dent in the 'between the wheels' part of a chassis of a wrecked car would earn it a big NAY from my company.

Answer 4

I think it's something like 95% of its hit points.

Answer 5

If it's cracked at pressure points or it is no longer straight.