Interesting thread. Must be winter.
BSME, MSME here.
'Film strength' is not a lube yield stress or a compressive stress that a lube can be put under in service (tolerable hydrodynamic pressure is much less than purported 'film strength'). Film strength is a calculated number from a very crude (and questionable) Falex Test that drags the lube into a joint where the surfaces have high sliding velocities relative to each other (not a stationary joint, such as for splines). Even the term 'film strength' is a misnomer.
The Falex Test is not applicable for moly paste in a stationary joint, however it provides wonderful hocus pocus data for marketing types to claim a high film strength number. You can find lots of such 'film strength' data by lube manufacturers--it isn't proof and should be taken with a grain of salt.
There is no fitting test that I know about for paste in stationary joints as the effectiveness of the lubrication is highly dependent on the joint itself and not solely on the paste (as long as the paste is present in sufficient quantity). Also of importance in the case of moly paste is the particle size of the moly-disulfide--yet that data isn't reported that I know of for any such moly paste or lube. Moly particles are very hard and dense (more so than the steel of a spline tooth), and if the moly particles are relatively coarse the contact surfaces can wear much quicker.
Regarding the well-beaten subject of spline teeth count that can be expected to be in contact: it approaches 100% of teeth, all of the time, if the parts are built to print and the joint stays lined up. Any slight high point on a tooth wears down very quickly and is actually beneficial so that the load is always spread to all the teeth. I've yet to see a spline (ST1300) where NOT all of the teeth were in contact. But all that is moot.
The moly paste in a spline squeezes out of the contact surface when load is applied (when accelerating the bike for example)--it is squeezed back in when load is reversed and the backside of the tooth is taking the load (when decelerating the bike for example). The more volume there is for the paste to squeeze out (such as for well-worn splines), or the less the paste there was applied, the less lube there is that squeezes back and forth onto the tooth contact area.
Points:
1) The more the spline wears, the faster it wears. So, if you've a worn spline, don't transmit high power through it. Also ensure the 6905 driven spline bearings are good because they are what keeps the spline aligned (and hence why the 6905 bearings easily fail in this application).
2) Use ample paste whenever working the splines (there's reason to not be miserly), making sure every tooth's front-side and back-side are coated, and make sure the O-rings are in good condition so that the moly paste isn't leaked outside of the spline joint during service. The rule of thumb to "don't over-pack grease in bearings; leave 30-50% air space in the raceway" does NOT apply to paste on splines.
3) Use fresh paste every time and clean off any dried paste from the splines--not because the moly-disulfide has lost it's capability, but because the carrier paste is no longer flowable to be squeezed back and forth across the tooth onto the contact surfaces between acceleration and deceleration.
4) Just because there's paste slung on the driven flange outside of the O-rings doesn't mean there's a problem. It can mean the O-ring is damaged, or it can simply show that plenty of paste was used. My ST1300 always had the paste slung on the driven flange because I used the paste amply and some of it inevitably ended up smeared outside the O-ring as I worked to put the wheel and axle back into the bike--there was always still flowable paste on the splines when the wheel was removed for tire changes and that's what matters.
Perhaps I missed it, but I'm still stuck on the premise of the thread. So I ask: "What source shows that Honda officially recommends M77 assembly lube in lieu of M60 paste? Is there a Honda Service bulletin?" Keep in mind that the use of assembly lube has always been a shortcut by shops, even years ago when M60 was easy to acquire. Now, with Honda M60 no longer available, even shops who follow the book have to use something.
