Jonathan Dietch <<nmerider>>
writes:

The DuPont Teflon Grease that I previously wrote about was only
good for ~95 hours before it needed replacing. I believe that it should have
lasted longer.

http://ozreport.com/20.060#1

Over the past hours of flying my VG rope tension had been increasing and when
I'd release the haul-back and fold in the wings there'd be too much juddering.
All of the pulley sheaves I inspected appeared in good working order and so I'm
not inclined to fault the blocks and pulleys. I removed the crossbar hinge pins
and there was black oxide in the Teflon grease and not much slippery feel left.
I cleaned all the bearing surfaces inside and out with Coleman fuel and
re-lubricated with a clear, red synthetic, extreme pressure grease I had in my
garage.

The grease was a sample I had on hand from my planetary telescope days long ago
and I don't recall the manufacturer or part number.

I flew a strenuous racing task at Crestline against Bruce yesterday. I was on
and off the VG and lot during the flight including hauling in while the sail was
already loaded.

I found the pull need to exceed 4/4 VG was a fraction of what it had been on my
last previous flight and was getting to the end of the rope quickly and without
even realizing it.

Some food for thought: Use a proper synthetic, extreme pressure grease that will
protect from oxidation and is formulated for slow moving sliding surfaces and is
rated for dissimilar metal contact. Grease gone bad over 100's of hours of
flying may result in excessive pull forces on the pulleys and may lead to
premature pulley wear and replacement.

Pilots may wish to become proficient at removing and replacing the crossbar
hinge pins in order to re-lubricate as needed or regular intervals.

I noticed that Bruce's Laminar has what appear to be bronze bushings on the
crossbar hinge pins. I'd be interested to know how well this performs and holds
up over time. I did a quick search online and found something that looks like it
may work well and last a while between re-lube cycles:
https://www.grainger.com/product/MOBIL-Mobilith-SHC-220-Red-Lithium-5ZN11

I called Mobil Oil Industrial Division and spoke with a rep to discuss the issue
and it sounds like the Mobilith® SHC 220 will work very well. It's certainly
affordable at $12/cartridge.

It's hard to believe just how much difference it makes. I hear so many pilots
complaining about the force needed to pull their VG's and how they'd like to
invent an electric VG system.

These are guys with far more musculature than me. I'd hate to try flying their
gliders if that's the case. Even assuming they invented electric VG one they'd
still be fighting against the same resistance that gets incrementally worse from
day 1.

Here's a follow up:

Lucas Oil Products, Inc.

Red “N” Tacky #2?

http://lucasoil.com/products/grease/red-n-tacky-grease

$5 at Home Depot--what's not to like?
Http://www.homedepot.com/p/Lucas-Oil-14-oz-Red-N-Tacky-Grease-10005/202521504

The specs sound good:
http://lucasoil.com/pdf/TDS_Red-Tacky-Grease.pdf (extreme pressures, sliding
surfaces, oxidation inhibitors)

It probably makes little difference that it's not a synthetic since few gliders
ever get the 1,000+ hours that mine has.

Be careful to check whether it stains any exposed Dacron fabric.

Many pilots I've spoken with have told me how their VG rope pull forces
increased noticeably over relatively short intervals from when their gliders
were new.

So I hope this information encourages pilots and dealers to stick their heads
inside their gliders and inspect them more thoroughly. I will be sure to remove
the pins after 100 hours and see how the new grease is doing.

Don't forget I discussed this with an engineer at a major petroleum company. We
are dealing with a non-automotive hinge: Hardened stainless steel against
aircraft aluminum. You won't find a hinge joint like this in any automotive
application that I'm aware of. As a home bicycle mechanic I can tell you there
is a lot of crap grease out there that will migrate out of a sliding surface
hinge like ours and soon be useless.

We need a grease that stays where you put it and that withstands extreme
pressures. We are pulling that VG rope while there's very concentrated pressure
on the pins.

There's a reason I wanted to use the synthetic, extreme pressure grease that
stays put.

Honestly, I would not screw around with this and risk blowing not just one
flight but blowing an entire comp because the VG system is dragging.

Please don't be penny-wise and pound-foolish. Do it right the first time. I'm
sure the Red N Tacky #2 will do a good job.

I think I'll order some Mobilith® SHC 220 in the meantime so I know what I'm
putting in the hinge.