Note: This is the first of three parts dealing with the Mirage Drive. Part II has to do with lubrication points: http://www.hobiecat.com/community/viewtopic.php?t=6320. Part III is about inspecting and adjusting the Drive: http://www.hobiecat.com/community/viewt ... 9602#29602
I decided to test three popular lubes -- the ever popular WD-40
, my favorite Breakfree
, and Rynkster's dealer's favorite silicon
Initial characteristics: WD-40
is a thin, penetrating oil that displaces water. It feels moderately slippery between the fingers. BreakFree
has a little higher viscosity (thicker), comes out in a foam, has friction modifiers and is very popular in the gun world. It feels thicker and slipperier. Silicon
is a dry friction reducer that has a liquid carrier for penetration and distribution, which evaporates in short order. It feels squeaky between the fingers.
This first pic shows each sprayed on a vertical sheet of ABS plastic:
Within five minutes the liquid carrier for the silicon had evaporated. After two hours (below) a portion of the WD-40 had also evaporated.
A gentle stream of water was applied to the plastic sheet, washing away the BreakFree, but not the remaining WD-40 (surprise!):
Talcum powder was distributed on the entire area to detect any remaining oil. This would simulate dirt, mud or debris in the water. After being blown off with an air hose, it stuck almost exclusively to the WD-40 sample (below):
Again, water was applied. The remaining talcum washed off all but the WD-40. It had congealed with water and oil to form a sludge (below):
Results and interpretation: The silicon
has no corrosion protection, is not a particularly great friction reducer, and had little to commend it. The dealer, IMO, is misinformed. Whereas it's essentially useless on the Mirage Drive, it is the best lube (and only one I would use) for the Twist & Stow rudder -- it flushes and frees up the mechanism without any sludging effect or attracting any dirt or grime.
is acceptable. It penetrates, displacing water (as most petroleum based products do) and offers protection against corrosion. It's biggest shortcoming in these tests, is its tendency to retain and accumulate small particulates. This could increase wear.
offers superior penetration into wear points because of its foaming action (doesn't run off so fast). It seals and coats the parts better than WD-40 because of its higher viscosity. It lubes better because it contains friction modifiers. It washes free rather than turn to sludge in water. I have a six year old drive that has been maintained with BreakFree since new. It has been used in salt water as well as fresh water. As you can see below, it still looks excellent and runs like a top:
Or maybe I'm a bit biased. I'm sure there are equally good or better lubes available, but at least among these, you can see what works and what doesn't work, and why.