Originally Posted By: TucsonDon
Originally Posted By: G-MAN
Interesting theory. And it would be totally plausible except in the Big Twin oil circuit, the filter is the LAST thing to get the oil before it goes back to the tank. This is the exact opposite of an automotive oil circuit where the oil gets filtered just before it goes to the main bearings.
In theory the placement of the filter in the circuit shouldn't really matter, should it? I mean, if the filter does its job, then in the case of the H-D design the oil tank itself will have the filtered oil. From there it goes -- filtered -- to the main bearings.
Were the filter the first thing then presumably the oil in the tank would be unfiltered. It would get filtered just before going to the main bearings.
In either case, main bearings receive filtered oil?
But if memory serves me correctly, the cams are the FIRST thing to get the oil, which means any shedding from the cam tensioners goes through the engine before it gets filtered out.
Also, remember that except for the plain cam bearings used on the TC96, NONE of the bearings inside a Harley v-twin (not counting the V-Rod) use hydrodynamic wedge lubrication. They are roller bearings, and as such, are virtually impervious to microscopic debris in the oil. Remember, this engine design originally started with a total loss oil system where the oil didn't even recirculate. When an oil pump and recirculation was first incorporated, no oil filter of any kind was part of the set up. That came decades later.
But anyway, the whole 5 micron filter thing is all marketing. Harley does not, in fact, spec a 5 micron nominal filter for the TC engines. I've verified that through Champion, the maker of the Harley filters for the TC engines. What Harley does specify for the TC is an ADBV. That is the real distinguishing feature of the TC filters vs the filters for the EVO engines.