DS1k Variable Valve Timing

[alibaba]

I repaired a Triumph whose handlebars could barely move side to side.  The steering head bearings were packed with white Lithium grease  It has solidified to the point that it was almost crumbly.  It was hard to believe my eyes.  And this bike was ridden fairly regularly.  I don't know how the owner coped with it for so long.

Since then I have confirmed this problem with others several times.
Never again white lithium grease for me.

 

[WTSDS]

Yep, know zactly what you are saying but steering head bearings are highly likely to get exposed to water and, more importantly they don't roll very far when the bars go from lock to lock.

I reckon I'll get at least another 40,000 km from my idlers now that they have been re-charged, and it's so damm easy to take off the inspection covers to check how they feel, which I do now and then when I have a peep at how my white-lettered non-Ducati Gates belts are faring - they're now 3 years old, looked mighty fine when I had them off a few weeks ago.

Far as I'm concerned anything is better than waiting for my idlers to fall apart like the pics from Speeddog's OP, ouch that could have been a disaster......

[Airborne]

Do you know what are the part numbers for the idler and tensioner belt pullies. I think I need to replace mine as the belt on my horizontal cylinder keeps shreding/rubbing up against the belt cover. I retensioned the belts (put a new one on) and still have that problem on that cylinder. I'm thinking one of them is cockeyed. Any other suggestions. If I put a new belt on it will just shred again over time.

[Speeddog]

You can get the parts catalogue from ducati.com: http://www.ducati.com/services/maintenance/index.do
Go to 'Spare Parts Catalogs" middle of page, right side.

Where is the belt rubbing on the cover?

Pic?

[aaronb]

White Lithium Grease, water insoluble, from Plews - must be good, made in USA :-)

if you don't know what grease came in the roller from the factory, you may want to pick the seals off and clean the rollers then reapply a proper bearing grease.  not all greases are compatible and mixing may cause undesirable results.  

http://www.machinerylubrication.com/Read/1865/grease-compatibility

also, why white lithium when there are so many good synthetic bearing greases available?  without measuring anything, i bet that bearing spins at 1-2x engine speed.  this is no time to just guess.    

edit, not to be picking on you, but i have to mention, max operating temperature, 248F. 
http://www.plews-edelmann.com/brochure.cfm?brochure=12158&location_id=18562

[Langanobob]

aaronb,

Something else that you didn't mention directly is that ball bearing manufacturers do not completely fill their sealed bearings with grease at the factory for a reason.  They usually recommend that only one-fourth to one-third of the internal bearing volume be filled with grease.  As an extreme example, the bearings in my surface grinder are only supposed to be 11% filled with grease.   According to the bearing maufacturers, overfilling with grease can cause overheating and premature bearing failure.

Bob 

[WTSDS]

>>  why white lithium when there are so many good synthetic bearing greases available?

Not in my shed that day, it was either that or two tins of 20 year old chassis greases.

Sheesh, beginning to feel a little guilty here....... only injected a little squirt, 1/2 a ml. in each, didn't inhale,

Not hard to check how they're travelling and if hot grease spews onto my belts I'll use something else next time.





   

[duc_fan]

aaronb,

Something else that you didn't mention directly is that ball bearing manufacturers do not completely fill their sealed bearings with grease at the factory for a reason.  They usually recommend that only one-fourth to one-third of the internal bearing volume be filled with grease.  As an extreme example, the bearings in my surface grinder are only supposed to be 11% filled with grease.   According to the bearing maufacturers, overfilling with grease can cause overheating and premature bearing failure.

Bob 

Not trying to be insulting, I'm just hugely inquisitive:

If overfilling can lead to overheating, why do shop manuals and manufacturers recommend you "pack" wheel bearings with grease?  While they're often not "sealed", there are cases where folks use those spring-loaded pressure caps for marine wheel bearings that go so far as to maintain the grease at a slightly positive pressure (to keep water out).

Sincerely, I don't mean to be obnoxious, I'm just trying to understand this so I don't ruin the next set of bearings I go to inspect and service.  Up 'til now every serviceable bearing I've messed with I have packed to the brim with grease, so much that it comes squirting out the edges of the cap when I put it all back together.  Granted, I've never mucked with the internals of any "sealed" cartridge bearings, I've just installed them per the manual's recommendations and check them occasionally for roughness or slop.

[Speeddog]

These belt tensioner rollers turn about 1.25 x crank rpm.
At that speed, they're better off not being packed full of grease.

A wheel bearing is only turning 800-900 rpm on the freeway (regular size moto or car tire).

[Howie]

Not trying to be insulting, I'm just hugely inquisitive:

If overfilling can lead to overheating, why do shop manuals and manufacturers recommend you "pack" wheel bearings with grease?  While they're often not "sealed", there are cases where folks use those spring-loaded pressure caps for marine wheel bearings that go so far as to maintain the grease at a slightly positive pressure (to keep water out).

Sincerely, I don't mean to be obnoxious, I'm just trying to understand this so I don't ruin the next set of bearings I go to inspect and service.  Up 'til now every serviceable bearing I've messed with I have packed to the brim with grease, so much that it comes squirting out the edges of the cap when I put it all back together.  Granted, I've never mucked with the internals of any "sealed" cartridge bearings, I've just installed them per the manual's recommendations and check them occasionally for roughness or slop.

When you "pack" an open bearing there is room for expansion between the bearings and seals.  Also, packing means forcing grease between the rollers and the cagen not filling the whole cavity with grease.

As far as marine goes, I have no expertize, but would guess those bearings either are low speed or have a weep hole.

[duc_fan]

Thanks for the info.

Didn't think about the fact that wheel bearings are turning significantly slower than most sealed cartridge bearings on the motor.  Timing belt tensioners, accessory belt tensioners, etc... they all turn at relatively high speed compared to wheel bearings, which are only 800-900 rpm @60 mph for average car-sized tires (as pointed out by Speeddog above).  Big difference in heat generated that must be dissipated.

I'll continue my practice of packing wheel bearings as full as I can with high-quality synthetic wheel bearing grease, because I've had many miles of success with that (and decades of experience by my father before that).  Sealed cartridge bearings I will continue to not tamper with... simply install per factory/mfr recommendations, inspect regularly, and replace as needed.