I'm sorry if this is obvious, but I searched the archives and came up empty handed.

Please: how do the bumper "shocks" or impact absorbers/dampers work?
Are they meant to absorb force and RETURN to their original position?
Or be used ONE TIME?
Is it common for them to rust up so tightly that they do NOTHING but pass impact on to the frame?
Is their a way to TEST them?

It's just that our 1987 745 got rear-ended badly, and I'd like to get it put back together properly. The dampers seem to have been seized... worthless.
Too bad.

Thanks very much!
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Gregg in MN

And then there are the solid ones that just snap when hit. The left side of my rear bumper has this problem from when a fat cow of a woman hit me from behind in her minivan.

-rt

Oil filled compartment: when the shock is struck, the oil bursts a seal and flows through a metered port into another compartment. There is no return, hence they need to be replaced after use.

Thanks, Steve, for your help with the bumper shock.

I see now that it is time for me to cut a few apart and have a look-see, since, not only, as you explained, do "they need to be replaced after use," THIS set needed replacing BEFORE use to have actually done any good. ;-)
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Gregg in MN

Don't cut them apart. At most, you might want to drill a hole into them, but be careful.

Thanks, Steve, and rcsammy, for the cautions.

I thought of Steve (and his bum leg) earlier this week, after I foolishly tried to scuff out a fire near the boathouse. First, I was wearing sandals. Second, it wasn't just some leaves burning, but turned out to be molten plastic (it was in the dark of night, and hidden) under the trash, melted from the portable toilet that had been torched. I don't want to get into the details, but it was 2nd and 3rd degree burns on toes and soles, and pain, and inability to do diddly for many days. Dumb.

So it's NOT my week for screwing around with stuff. :-)

--
Gregg in MN

It is not a good idea to cut them apart. I believe this is imprinted on them. Drilled a hole in some Ford ones and crap came flying out with enough force to take your eye out. Some shady bodymen/mechanics have been known to spread them back out an use them but they are worthless safety wise after the first hit. later rcs

No matter what vehicle they are from, they are intended only to "protect" in slow speed occurances, not impacts where "you get rear-ended badly." They sound like they are bent beyond use, after all they are just a cylinder in a tube not meant to respond to impacts that aren't dead center or flat on to the bumper. Get them when you get a "new" used bumper from a wrecking yard. Alterativly, if the old ones didn't suffer any bending or twisting, they hypothetically could be hammered until the strut part rebounds again, but, for my time/money I'd get the used ones.