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Old 05-27-2010, 06:29 PM   #1
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Default OS SPEED crankshaft pin diameter

anyone know what the diameter is the OS Speed crankshaft pin is supposed to be? trying to mic it to see if its wore or if the rod is wore... slight play between the two... Im hoping its the rod. If anyone knows what the crank pin should mic at, please let me know... THANKS
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Old 05-27-2010, 06:34 PM   #2
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4.94mm or .194" when new. My used ones mic out at between 4.92 and 4.93mm.
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Old 05-27-2010, 06:58 PM   #3
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Not doubting you Koby, but I'm fairly certain OS has a .195" pin. Nova's are .196 and my RB C6 has a .198. Food for discussion? I got that info from Ed Bridges and from measuring my own engines. I could very well be wrong though.
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Old 05-27-2010, 07:09 PM   #4
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Not doubting you Koby, but I'm fairly certain OS has a .195" pin. Nova's are .196 and my RB C6 has a .198. Food for discussion? I got that info from Ed Bridges and from measuring my own engines. I could very well be wrong though.
I'll go with what you and Ed have found. I measured one of my new speed crank pins with a set of good digital calipers and it came out .194. That doesn't mean it is an accurate number though. Anyway, .194 or .195 is what it should be. IMO there is not enough of a difference between the two to actually make much of a difference in real world fit. I'm sure they're not all exactly the same too. As long is it is in that range, you should be fine.
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Old 05-27-2010, 07:32 PM   #5
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Originally Posted by Greenlee37 View Post
anyone know what the diameter is the OS Speed crankshaft pin is supposed to be? trying to mic it to see if its wore or if the rod is wore... slight play between the two... Im hoping its the rod. If anyone knows what the crank pin should mic at, please let me know... THANKS
Is the DLC gone? It only about 6μm.
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Old 05-27-2010, 07:38 PM   #6
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Is the DLC gone? It only about 6μm.
6 what?
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Old 05-27-2010, 07:44 PM   #7
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6 what?
m is 1 micron. Inch conversion is 3.93700787402 10-5 Inches.
So 6μm = 0.000236220472441 Inches.
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Old 05-27-2010, 07:51 PM   #8
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What he said. LOL.

While the DLC coating is very thin, it usually lasts a LONG time, unless you ingest dirt or something. I guess the type of fuel used could have an effect on it too. For the most part the DLC will still be on the crank after pretty much everything else in the engine wears out.
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Old 05-27-2010, 08:26 PM   #9
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THANKS to all who replied... good info... reason I ask: cracked a case last weekend.. took all my internals out and installed in a 9/10 shape older OS case, one that was used in an EB Modded Vspec... says 2007 on one side... only difference in this case and Worlds Edition case is the pinch bolt vs the oring set deep inside the neck. After installing all internals in the other case, everything fit perfect.... but after installing flywheel, I put the head up to my ear, to listen to everything inside while turning the crank... I can hear "slop" somewhere, everything is oiled up with RB Mod oil, bearings feel perfect, but I can hear a click when I rock the flywheel back and forth, only thing I can think it is, is some slight play between rod and crank... I ran a club race with it last night, ran purfect, idle is like music to my ears... but just knowing that slight play is in it, I went ahead and ordered a rod today. will change out next week, a wore rod will wear the crank pin fast also, so I dont wanna leave it in too long. If new rod makes the same sound, then going to just order a new motor.... Have 6 gallons on the 2nd set of P/R/S... 3rd set of bearings, original crank and carb.... I run Byrons 30%, use RB ARO most of the time.. run out fuel after every race.. THANKS AGAIN for your guys input
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