Technical Cheap $5 junkyard part could save your life.

I’ve had one on our Landspeed car since required. I used a 15 psi oil switch with a bypass before electric ones were mandatory.

 

Good tip! Howdy neighbor, from Hiram GA.

 

Girlfriend back in the day was an alcoholic. Driving home drunk from the train one night she had a wreck in her '72 MGB. Damn near wound up in the canal. Only the telephone poles set up at the bulkhead stopped her. Wreck tripped the inertia switch. Took me WEEKS to figure out why the damn thing wouldn't run. Passenger side firewall tucked in way high under the dash. Damn near impossible to get your hand up there to reset it. I moved on shortly after that.
Andy

 

I've seen them get tripped accidentally (I mean, without an accident, to be clear). On a late 90s Explorer, a passenger with large feet bumped the kick panel area as they went across a speed bump in spirited fashion. Thing died right there on the spot, until I was called out to the parking lot to find out why it wouldn't run. Thankfully they're easy to get going again.

It was fortunate I knew where they were, just by chance. The month prior I had used one to create a kill switch of sorts for a Ranger following a divorce, where there was concern regarding the custody of the Ranger being disputed.

 

I installed one from the get-go when I did the wiring. I used a $5 junk yard part from a T-Bird. 81,000 miles, and it's never tripped. A few times over the years I've hit some hellacious drainage dips in the road, one time losing my power steering and brakes from a Tee fitting that got wiped out when the car bottomed out. The inertia switch never tripped. Mine is installed in the trunk. They are easy to check while your still at the junk yard. Push the button in, then slap the unit with your hand. It should pop the button.
I have also installed a roll-over valve on my gas tank vent tube. It keeps the gas from leaking out the vent line in case of a roll-over.

 

You can buy those in the aftermarket with an easier to adapt plug. I do Ford efi conversions and always keep them. It is wise to remember that safety items are for when we aren't thinking, not when we are.