Raising the car off the jack stands to put the front wheels back on.
Heard a Ka-***** sound.
Found these two plates connected with a thin rubber/foam/adhesive backing, lying on the garage floor where there was nothing before.

Approximate location of floor impact: 3-4 inches forward of left strut and about a foot inboard.

At first they appeared to be ceramic, but you can pick them up with a magnet.

I went through the 85RX7 Body FSM, and the 84-85 Body Index, but did not find anything from that location that matched.

I'm curious if they belong on the car and where, or was this something my father installed for me to find later as a practical joke.

 

Wheel balancing weights, perhaps?

 

wheel weights...

 

Yup.

 

If you're lucky, you should find a clean spot on the inside of the wheel that exactly matches the shape of the weights you found. Get some double-sided tape, clean both areas really, REALLY good and then stick it back where it belongs.

Also, the typical reason why these come un-glued is due to either a brake caliper leaking which allows brake fluid to reach the inside of the wheel, or washing your car too vigorously or frequently! Good luck,

 

Well that explains why I could not find a place on the car body.
The wheels were off at the time.

Thanks to all.

 

Thanks again.
I found the spot. Cleaned & scrubbed. A little epoxy, and done.

 

Someday in the future a tire guy somewhere is going to curse you!

 

I bet it slung off and stuck to the frame rail.

 

 

Maybe it'll be the same tire guy that didn't bother to scrub the inside of the wheel down to metal before sticking on the wheel weights!

 

That's what I was going to say, serves him right.

Besides, a smart tire guy, if there is such a thing, would know that a well placed whack with a screwdriver and hammer will pop that epoxy patch right off.

But you might want to take care of that yourself Tim before going in for your next tire balance, to avoid the $20 service charge.

 

How are the ones that fell off different than the weights on the outer rim?

And yes, the weights had grim embedded in the backing.