So, about to take my 959 off the road for a bit to do the 15k Desmo service. Looking at the workshop manual and owners service book it specifies checking and greasing as necessary the steering head/stem bearings and to check wheel bearings but no further info. So, a few questions: No grease is specified for head bearings, i'm assuming Moly B? No greasing of wheel bearings is suggested, so I assume they're sealed and maintenence free and just to be replaced when they start feeling rough? No mention of swinging arm or rear shock rocker pivots, so again, just to be ignored till they're toast?
Yep, all wheel bearings on the 899/959 are sealed. Haven’t done the steering head bearings yet but have done the rear shock rocker. The manual states 60Nm for those two torn taper head bolts. They’re nowhere near that as only made of alloy. A good mod here is to use an M14 Ti bolt all the way through and a nyloc nut on the back.
"No grease is specified for head bearings, i'm assuming Moly B?" this will flush a few posters out.. - moly is not suitable here as too slippery/over adequate for this application (moo). Here's a quote that out-eloquences anything I might have attempted this morning:- "Greases containing moly are recommended for roller bearings subjected to very heavy loads and shock loading, especially in slow or oscillating motion such as found in universal joints and CV joints. If such greases are used in high-speed bearings, problems can be experienced with roller “skidding” where the bearing roller fails to rotate through the full 360 degrees due to reduced friction. As a result, the roller develops flat spots, and its service life is reduced."
Hi Chris, factory spec is for a multi purpose molybdenum disulphide grease with a high solid content (to stay where it is put) equivalent to Castrol Moly or MS3 in old money, the first sentence from your quote explains it. It is the multi purpose one referred to as Grease B in the manuals
sorry Andy, not sure what you are saying, - all molybdenum disulphide greases that i'm aware of would cause problems in above environment due to their abilty to "skid" at times not to mention the possibility of encouraging corrosion in that already possibly damp environment. It's totally up to the owner but the confirming text is there in many locations.
...but steering-head bearing are definitely a slow-speed application. Must be the slowest-rotating bearings on the bike!
I said it would get a lot of posts, and that's why I quoted someone else rather than wade in with my own thoughts, think of me as the messenger here.. it's more about the pressure involved and how well it stays on surfaces. As I tried to say earlier, go and research it for yourselves all you Intelligent Richards, and by all means try using Moly on headstock bearings and see what happens after extended use, the problems discovered don't happen overnight.
that bit is contained in the quote, so although I know what they mean, I can pass that flack on. It's certainly a high enough speed, with a small enough load, for "skidding" to occur, more on the upper race than the lower. https://www.machinerylubrication.com/Read/28632/use-right-grease https://www.ccjdigital.com/maintenance/article/15114002/the-fundamentals-of-truck-and-trailer-grease-application#:~:text=Greases containing molybdenum disulfide shouldn,move at a rapid pace. https://www.mrsilicone.co.in/2021/08/10/moly-grease-and-its-functions/
Thanks to all, good info re bolt tork at the top from Bettes, will be careful there. About the grease, the expected moly/no moly grease-guns a dawn response! Thanks for all the input. Having done a little reading around this disagreement seems universal. My thought is that head bearings are slow speed and so moly is going to be fine and the links from Chris seem to be aimed at wheel bearings and high speed rollers. When I get access to 'em I suppose its really just a case of having a look at the existing, if it's black I'll use moly! Anyone any thoughts on swinging arm pivot bearing maintenence? Workshop manual doesn't specify any inspection or maintenance schedule at all, seems a bit odd.
unfortunately you've missed the point, get talking to a proper lubricant engineer if in doubt, definitely not suitable long term.
