Lube selection From an engineer pov

[MotorsportsX]

So.. I'm curious.. A trans uses trans fluid, engine uses engine oil, rear end uses 90w..etc...But then you get into a motorcycle and one Lube does two different purposes.... What got sacrificed
What if instead of trans gears there was a ring and pinion plus engine that needed Lube.. What would u use then? Is it a byproduct of the type of gear tooth? The chemical makeup of the oil.. Or. Something else all. Together...

Just looking for general conversation and discussion on this topic

 

[Shannow]

If it goes into a wet clutch application, then friction modifiers go out the window, as they aren't wet clutch compatible.

Motorcycle gearboxes are only slightly helically cut, and have minimal sliding along the tooth face (think hypoid gear for a LOT more sliding), so the additives in engine oils are satisfactory (not necessarily ideal) in those shared applications.

But the gearing tends to cut the oil up pretty badly.

 

[MotorsportsX]

Yeah i probably need some gear study.. The heck is a hypo id gear lol

 

[blupupher]

Depends on the bike.
Some are separate engine and transmission, both requiring specific, different fluids.
Then you have those that are also shaft drive, also requiring a different fluid.

 

[knerml]

I have seen other applications that use motor oil in transmissions.

I had a Honda riding mower, for example.

GM was looking at using motor oil in their H-Body (Monza) manual transmissions in the 1970's, when they where planning on using Wankel rotary engines (before the fuel crises).

 

[A_Harman]

Originally Posted By: MotorsportsX
Yeah i probably need some gear study.. The heck is a hypo id gear lol


Mr. 'Splainer-Man definition:
A hypoid gear set is a type of ring and pinion where the shaft axis of the pinion gear is offset from the axis of the ring gear.

 

[MotorsportsX]

I appreciate the input.. Ive read, and basically found that Im not going to find the answer to my question by my own study. there is just to much and it would take months..

so I guess what I would like to know, is there any sort of ring and pinion setup.. with a gear ratio from 1:1 to 2:1 that is satisfactorily lubricated with motorcycle engine oil (combined engine/trans/clutch type oil)

I was also thinking.. would it matter if the lubrication was not splashed based? (therefore not chopped up as much) and was pressure fed directly to the contact points, from the center of the pinion... then centrifugal force and a windage/stripper plate would direct the oil back to the oil pan... would that matter at all as far as lube choice?

noise and vibration dont matter all that much to me.. neither does gear shape. i can design and mill and profile i need, i just dont know which one to use.




i should also state.. all im trying to do is change the angle of the torque.. the angle of the ring gear is 90 degrees (straight up and down) and the force acting on the pinion is at 70. ..not really sure how to explain it better so that it makes sense.,.


this is the closest picture i can find to what im trying to do.

 

[A_Harman]

I'm thinking that it's not a good idea to design gears that are pressure lubricated from the shaft. Holes would have to be drilled in the root of every tooth, and each of those holes would be a great place for cracks to form right where the tooth bending stress is the greatest. It would be a nightmare from a fatigue standpoint, and expensive to manufacture.

I have read about geartrains that use targeted tubes that spray a fine mist of oil at the gear meshes. The amount of spray has to be carefully calibrated to prevent an excess of oil being trapped between tips and the conjugate roots, thereby causing an excess amount of drag and heating of the oil.

I'm not clear on what physical arrangement you are trying to attain. Is the angle between the pinion axis to ring gear axis still 90 degrees when viewed from the top, but 70 degrees when viewed from the side?

 

[MotorsportsX]

imagine a car drive shaft and pinion cocked 20 degrees to one side.. that angle is what i'm trying to accomplish, but it has to be engine oil fed. so I need a gear profile that will work with engine oil. (motorcycle engine oil)

 

[A_Harman]

That sounds easy. Design the ring and pinion with crown angles of 55 degrees instead of 45.

 

[MotorsportsX]

the mating angles are the design problem.. the correct type of tooth to work with engine oil is. if i use a standard ring/pinion profiles and just change the angles i end up with a ring and pinion that still require 90 weight.

 

[A_Harman]

That's not as bad as you make it sound. Don't be deceived by the standard SAE viscosity numbers.
90 weight gear oil has a viscosity range that includes much of the 40 weight engine oil range.
Example: Redline 75w90 gear oil has a KV100 of 16.1, which is at the high end of the 40-weight engine oil range (12.5-16.3)

 

[MotorsportsX]

there is still a difference between the two lubes, and im forced to use one not used currently. i need to understand why they use gear lube. .what is is about ring and pinions that makes them so they dont use engine oil.. what would make them "live" longer if you were using engine oil.

 

[MotorsportsX]

i found this

http://www.bestlubeusa.com/gearlube.pdf

 

[Silk]

Honda shaft drive v twins have a right angle gear drive and many other bikes too...lubricated by engine oil.

 

[Shannow]

Originally Posted By: MotorsportsX
i found this

http://www.bestlubeusa.com/gearlube.pdf


Look at the (fuzzy) picture, and see if you can grasp the concept that I mentioned of sliding across the gear teeth.

The straight cut, and bevels don't have teeth that "slide" along each other, and thus don't need the additives that form a sacrificial "soap" to stop the sliding surfaces microwelding to themselves.

(The herringbone is same, we've got herringbones at work transmitting 12,000 hp with nothing more complicated than an ISO 32 hydraulic oil).

Here's a better explaination...

http://machinedesign.com/whats-differenc...-and-worm-gears

 

[Number_35]

Many years ago a friend had an Austin Mini - this was the genuine BL one from the 70s, not the newer retro BMW one.

The car was equipped with a small 4-banger (c. 1000 cc?) and a 4-speed manual transmission. Anyway, he said that the sump was large for the engine size - around 5 Imperial quarts - but that it served both the engine and the transaxle. So, the transaxle was lubricated by plain old 10W-30 dino.

 

[Shannow]

Yep, Doug Hillary has posted some really good information on the BMC shared sump/GB.

That's why 20W50 was "invented", and became the go to oil for a lot of the world...shared applications.

 

[Silk]

I never saw any undue wear and tear in a Mini engine or gearbox in many years of working on them. Maybe the oil got chopped up to kerosine, but it didn't wear them out more than the same components in a rear wheel drive car. That is, the Mini used the same engine and gearbox design as say a Morris Minor. And I don't like to hear them called a product of BL, they were BMC.

And not just the Mini, BMC produced the 1100/1300 with the same power plant, and the 1800 with the B block, then onto BL we had the Maxi,Princess, Kimberly and Tasman...and a few others with different badges. A long lived design that got the world onto the fwd path.

Oops, another edit - also produced as automatics....using engine oil again. What was fun with the Mini auto was individual gear selection, drive like a manual. Reinvented decades later as tiptronic.

 

[CR94]

Originally Posted By: Silk
I never saw any undue wear and tear in a Mini engine or gearbox in many years of working on them. Maybe the oil got chopped up to kerosine, but it didn't wear them out more than the same components in a rear wheel drive car. That is, the Mini used the same engine and gearbox design as say a Morris Minor. ...
Did those have hypoid final drive (typical of non-transverse fwd layouts, as well as rwd) lubricated by the shared oil? If not, that would explain why they survived on engine oil. That, and low power and weight.