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Old January 9th 18, 09:30 PM posted to rec.aviation.soaring
Craig Funston[_3_]
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Default Lubricant for spar pins

On Tuesday, January 9, 2018 at 10:59:07 AM UTC-8, Papa3 wrote:
On Monday, January 8, 2018 at 11:30:06 AM UTC-5, Jim White wrote:
At 14:13 08 January 2018, Papa3 wrote:
On Monday, January 8, 2018 at 7:30:07 AM UTC-5, Jim White wrote:
At 23:35 07 January 2018, john firth wrote:
Wot? nobody pushing good old WD 40?
Seriously, surely the meticulous glider pilot must treat load bearing
pins
=3D
Tell me why? I am presently using WD40 specialist spray grease. Very
slip=
py
and easy to apply.
=20
Jim

I think most folks view WD40 as the "traditional" water displacement
produc=
t in the blue can which is nothing like the WD40 Spray Grease you're
using.=
If anyone really wants to do the work, you can look at some of the key
t=
ests that should be published on the Technical Data Sheets for whatever
pro=
duct you use to see how it performs. Things like ASTM D2266 2596 etc..
def=
ine critical wear prevention properties. =20

P3


Datasheet says:

4-ball Wear Test 0.5 mm (ASTM D-4172) ,
Dropping Point Temperature 118°C (ASTM D566) ,
Corrosion Protection in salt spray test 0 % rust at 72h (ASTM B-117) ,
Temperature (Continuous) -20°C to +115°C as grease, then to +260°C as
liquid

Is that any good?

Jim


If you're going to land out on the beach, then you've only got 72 hours :-)

I haven't played with a test rig for this in over 30 years (college was a while ago), but the 4 ball wear test is for sliding and friction (putting the pins in and taking them out ). There's also a 4 ball welding test that shows how the grease holds up under extreme pressure (e.g. getting smushed by the loading of the wings under bending). The thing that's most obvious to us who fly all year from cold winters to very hot summers is the temperature stability. Looks like the WD40 Grease is probably good enough.

Before anyone complains - yeah this thread has probably gone past its useful life. My sense is that the first step is using SOMETHING religiously to protect against wear and corrosion. Something that's convenient to use and relatively clean probably means you'll be more likely to use it religiously.


It's not usually the spar pins that are critical for lubrication (short of making sure the pin will go in or out). It's the lift pins (fuselage pins that transfer the weight of the fuselage to the root ribs). These pins see small sliding motions under load every time the rudder is engaged. The first course of action is to make sure the shims between the root rib and fuselage bosses minimize any movement although it's impossible to completely eliminate movement and still get the glider assembled. These pins are usually steel on steel with the steel dowel engaging a self aligning ball type socket. I've replaced pins that have shown significant wear so this is a real phenomenon although probably more pronounced on heavier gliders with longer wings. Use a good quality grease that protects against corrosion and provides low friction under high bearing loads.

Cheers,
Craig 7Q