xanthrum wrote:In plain english a properly prepped oil wheel will out perform a graphite prep all day long -- but an oil prepped wheel - will not spin anything like a properly prepped graphite wheel. I am trying to relay on the notion that a spin test does not equate to speed. There are so many other factors that are so much more critical to a cars performance - begining with proper set up - if the rules allow rail-riding - placement of weight - the prep process and all the attention to a million other contributor factors that make a car fast.... Additionally a grooved axle will outperform in application... maybe not in theory but in application.
Lest newcomers to DerbyTalk misunderstand, Bob Barga's tests (2003-4) and Randy's tests (2008) were "loaded spin tests" in which the axle carried a weight comparable to that experience by the rear wheel of 5 ounce PWD car, and the total rotational energy of the weighted wheel was comparable to that wheel's share of a 5 ounce car's linear energy. Further, Bob Barga's tests of Nyoil II vs Hob-E-Lube indicated a substantial advantage for oil under all conditions that I reviewed.
These tests eliminate the effects observed when just finger spinning a wheel on an axle under almost no load. Under such low load, differences such as varying viscosity play substantial role. In Barga's and Randy's tests, the effect of viscosity is comparable to what a wheel experiences when rolling a car down a track!
Most have found that lower viscosity Krytox 100 oil is at least as good as Nyoil II AND is (a lot) easier to apply correctly. So, current opinions regarding comparative quality of graphite vs oil and grooved vs non-grooved are consistent with the results produced by Bob and Randy!
What I would like to do, but have not yet accomplished, is to translate the loaded spin data into coefficient of friction comparisons. My motivation is that we can be confident that, all else being equal, the wheel-axle combination with the lowest coefficient of friction wins. I know the equipment changes necessary, but still need to implement those changes and to understand the math/physics of the conversion.