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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
oil holes in Crank pin?
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<blockquote data-quote="oexing" data-source="post: 172650" data-attributes="member: 1493"><p>There is a good reason to have the TWO oil holes per conrod at 90 degrees past TDC, but I don´t see the idea to have them at 30 degrees, before or after TDC. Anyway, the oil enters the crankpin at the timing side end and when you got one hole each at exactly TDC it will be centrifuged out at the nearest hole, at the t.s. conrod hole. So I say the d.s. conrod bearing will get less oil then. </p><p> Simple correction is to have the holes at 90 degrees past TDC, well, before TDC would work too. But I like the theory that when revving/accelerating the engine up the oil level in the crankpin will shift a bit for the 90 degree past TDC position, so you get another extra cc into the bearings - not so with holes at 90 degrees before TDC. And when having the holes at 90 degrees the bore in the crankpin will fill up at half diameter till it can reach the holes to exit into the bearings. So centrifugal forces will have the oil in the crankpin form a perfect level all along in there and lubrication will be same for both conrods from this effect. </p><p> In my engines I do TWO oil holes per conrod, positioned just outside of roller or needle tracks, left and right. So with a 20 mm bearing you drill them at 9mm from center line, no factor when having holes at 90 degrees past TDC at highest load positions as needle tracks don´t reach holes.</p><p> I did central holes in my crankpins about 14 or 16mm i.d. and finally plugged to hold press fits in the crankshaft assembly , 40 mm pin in high tensile crank webs from 1.6580 30CrNiMo8. I have never found case hardened cranks , only high tensile, and provided all is well you don´t need to add hardened washers at both sides of conrods as basically there is no side load from bearings - well, when all bearing faces are machined perfectly parallel, no taper acceptable here and 0.01mm play within bearings minimum ! </p><p></p><p> Vic</p><p>[ATTACH=full]59495[/ATTACH]</p></blockquote><p></p>
[QUOTE="oexing, post: 172650, member: 1493"] There is a good reason to have the TWO oil holes per conrod at 90 degrees past TDC, but I don´t see the idea to have them at 30 degrees, before or after TDC. Anyway, the oil enters the crankpin at the timing side end and when you got one hole each at exactly TDC it will be centrifuged out at the nearest hole, at the t.s. conrod hole. So I say the d.s. conrod bearing will get less oil then. Simple correction is to have the holes at 90 degrees past TDC, well, before TDC would work too. But I like the theory that when revving/accelerating the engine up the oil level in the crankpin will shift a bit for the 90 degree past TDC position, so you get another extra cc into the bearings - not so with holes at 90 degrees before TDC. And when having the holes at 90 degrees the bore in the crankpin will fill up at half diameter till it can reach the holes to exit into the bearings. So centrifugal forces will have the oil in the crankpin form a perfect level all along in there and lubrication will be same for both conrods from this effect. In my engines I do TWO oil holes per conrod, positioned just outside of roller or needle tracks, left and right. So with a 20 mm bearing you drill them at 9mm from center line, no factor when having holes at 90 degrees past TDC at highest load positions as needle tracks don´t reach holes. I did central holes in my crankpins about 14 or 16mm i.d. and finally plugged to hold press fits in the crankshaft assembly , 40 mm pin in high tensile crank webs from 1.6580 30CrNiMo8. I have never found case hardened cranks , only high tensile, and provided all is well you don´t need to add hardened washers at both sides of conrods as basically there is no side load from bearings - well, when all bearing faces are machined perfectly parallel, no taper acceptable here and 0.01mm play within bearings minimum ! Vic [ATTACH type="full"]59495[/ATTACH] [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
oil holes in Crank pin?
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