Zane Laverda. Wive's Tale 1. Oiling Issues.

When I said all bullshit, I was referring to the amount of different theories on big end gap as there does not seem to be a finite consensus on even that! (Which to me is bullshit. With the technology we have in this decade, we should have some finite theories) I was not referring to the other theories re oiling, out of round grinding ect.

I have found that my own cranks have been originally ground at about 55 micron, which, based on all but the FAG theory, is, in my mind, as Piet says, way too much.


The triangulation theory has proved difficult to disprove. Of the 5 cranks I have pushed apart, the 10 webs all show about 0.0001" out of round on the part of the pin that was pressed into the web. I used that area as it is not exposed to wear, but, admittedly, may be subject to compression forces from being pressed into the outer web. I have no idea about that.

On the roller parts of the pins I am getting up to about 0.0005" wear

I took 5 of these webs to an engineering works and asked them to check for triangulation of the pins. I think they set them up in a mill with a 1 micron dial guage, and reported no deflection whatsoever. This does NOT correlate to me. If I can measure 0.0001" variation up to 0.0005", then the dial guage should have registered about 2.5micron variance, up to about 12 micron.

The retired fitter/machinist at the end of my street, of whom I bounce off ideas and checks my measurements, says that there is too much sideways movement in the head of a mill to take such accurate measurements. I think my engineering shop has ripped me :-\

GregT's comments are most interesting.

I have contemplated getting a run of cages made of 6000 aluminium based on pin OD and Nickel Teflon coated. Aluminium is a lot lighter, and I believe has a much higher temperature coefficient of expansion than steel, and should expand away from the pin as temp increases.

I'm getting a bit obsessed with all this. Inzanety is obviously setting in :P

Regards to all

Greg
 
Cam,

Centrifugal force throws the cage around.  Choice of diameters determines if it rubs on the pin or rod.  While it guides the rollers, the rollers cannot guide the cage, otherwise you would end up with a lot of internal friction where the rollers and cage contact, and a difficult/expensive to manufacture cage.  The mass of the cage "attached" to the rollers would also increase the weight of the individual rollers, drastically increasing bearing surface forces.  The rollers rotate at an average speed of 31m/s at 8000rpm (around the crank axis), with lots of centrifugal forces acting on all components.  You have the rollers trying to escape through the rod, the rod pressing on the rollers and the crank generally bending and doing its best to fly apart.

No big deal with Laverda alloy cages.  While the triple cages are almost flat on their OD and rub across their entire width, the twin cages have a little rim next to the roller slots.  The cage contacts the rod only at the rim, at first.  These rods often show grooves worn into the big end.  The grooves can be ignored as long as the bearing surface shows no indications of breaking up at the edges of the grooves.  Usually, the grooves disappear to a great degree when the rods are honed to accomodate new bearings. 

Greg T,

While I appreciate the advantages of a silver-plated steel cage, it is a mod more closely related to enhancing high-speed reliability in scantily-lubed 2-stroke race engines.  The stock copper-plated steel Zane cages are well up to the job, even in stressed competition engines (not that very many are used in anger any more).  We have experienced absolutely zero crank or oiling-related issues with re-worked OCT cranks.  The engines also immediately attain an uncanny level of mechanical quietness, quite scary if you're used to the normal clatter these engines release.

piet
 
You've got it Piet. IMO all cages should have the raised shoulders - or depressed centers...To be rod ID guided.

I know what you mean by shockingly quiet cranks when all is good and true. I built a Z1 race engine for which the owner had secured a "welded and trued from new" crank which came out of a race engine which had never been used.
The history was documented with period invoices etc.
When I fired it up in the bike all the engine noise I could hear was the camchain tensioner rollers....Quietest Z motor I've ever heard.
Red's light cranks are the same standard.
 
Quote from a previous post of mine. "I'm talking about too much oil in the FRONT of the crank rollers. Over oiling, in my mind, can cause a wave in front of the roller, like a car tyre on the road when it hits a patch of water, to skid. Both the roller and the car tyre lose traction. What happens then???"

Quote from Greg T  "Oiling - roller bearings don't need much oil. Irving postulated that if there was an optimum amount of oil, there should also be a "pessimum" amount which would lead to failure. In his experience it was usually too much oil that could be a problem."

Piet also made a comment "I don't think a wave of oil before the big end rollers can be achieved with a low-pressure system such as that used in the Zane engines.  Surplus oil will simply over-flow from the slingers.  But, this surplus may cause drag in other areas of the engine."

So, the question I'm asking, is do we think we have put a final lid on the modification of oiling systems to provide more oil on a "normal", not race, Zane? And that the "Wives Tales oiling issues" has been disproven, as per Piet has been saying?

Regards, Greg
 
It might be different on the 650/668 engines, as they are purely oil/air-cooled and might need different things, but on the 750's, I assume an oil-pressure issue as a fairy tail...
 
ghwallice said:
Quote from a previous post of mine. "I'm talking about too much oil in the FRONT of the crank rollers. Over oiling, in my mind, can cause a wave in front of the roller, like a car tyre on the road when it hits a patch of water, to skid. Both the roller and the car tyre lose traction. What happens then???"

Quote from Greg T  "Oiling - roller bearings don't need much oil. Irving postulated that if there was an optimum amount of oil, there should also be a "pessimum" amount which would lead to failure. In his experience it was usually too much oil that could be a problem."

Piet also made a comment "I don't think a wave of oil before the big end rollers can be achieved with a low-pressure system such as that used in the Zane engines.  Surplus oil will simply over-flow from the slingers.  But, this surplus may cause drag in other areas of the engine."

So, the question I'm asking, is do we think we have put a final lid on the modification of oiling systems to provide more oil on a "normal", not race, Zane? And that the "Wives Tales oiling issues" has been disproven, as per Piet has been saying?

Regards, Greg
Click to expand...

I certainly do. :D

piet
 
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