Re: [DML] Open Invitational Door Strut Test

["Walter Coe" <Whalt@xxxx>]

> Non-vendors, email me if you want me to run this test.

</sarcasm on> Do I want you to do a Consumer Reports style test of various
door struts at no expense to me and publish the results? Uh, let me think
about this a while.</sarcasm off> Yes!

I have disassembled a door strut that came off a friend's car. I don't know
what brand it was or which vendor it came from. The tube had been
amateurishly spray painted black, so I scraped it off to see if they were
hiding anything. Apparently they were. Whoever did it also sanded off the
numbers to keep their source anonymous.

This strut was substantially similar in construction to smaller struts that
I have disassembled from various junk cars. All struts contain oil to a
height of around 2 to 4 cm measured from one end. One strut used automatic
transmission fluid. I could recognize it by the smell & color. Most struts
use a light (say 20W) oil. It is obvious that all struts should be operated
in the "shaft-down" position to keep the seals from leaking the nitrogen
charge.

Why I'm up on this is because I'm thinking about (in maybe 80 years from now
at the rate I get things done) making some custom struts that would be
rechargeable, dampening & temperature compensated. The dampening is
simple -- just put a spring in the end. Temperature compensation is another
issue. I'm thinking maybe a needle valve or shutter hooked to a bi-metallic
strip. The size of the orifice is very small to begin with, and it would be
difficult to make any temperature compensation reliable. Maybe someone can
come up with a gas mixture that gets thinner with cold temperatures? Fat
chance.

Why I was asking about strut pressures earlier is because I was (note past
tense) thinking about TIG welding a Schrader valve to one end where I could
replace the oil and charge it. But 1400 PSI? Uh, if they are really
charged that much, I'm surprised they don't explode. I've seen Scuba tanks
that have exploded. They are typically filled to around 2500 to 3000 PSI
and are made of tempered metal. In proportion, the struts are made of
sheet metal that apparently is not tempered. It seems dangerous. Does
anyone know what kind of valve would be appropriate to use? I don't think
any Schrader can take that much pressure.

I'm curious to learn anything you find out.

Walt Tampa, FL