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Thread: What is the clutch I found in box of stuff?

  1. #1
    4 Cycle Advanced User
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    What is the clutch I found in box of stuff?

    I was searching in my old clutch box for Horstman clutch discs and came across a nice looking clutch that I don't recall the brand or model. It is a disc clutch but the pressure actuator is ball bearings trapped under a spring steel plate. The drum is very smooth, pewter colored and the gear can be inserted into the drum just like a Bully. This clutch would be from the middle 1990's era. Any information would be appreciated. I recall running it once or twice, but don't think I cared for it compared to the Horstmans of the same period (I raced flatheads exclusively during this time) Thanks, CMac

  2. #2
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    That is the original SMC clutch.

    Nice piece, but hard for the average karter to set-up.

    I have several used and new ones in my collection.

  3. #3
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    Michael:

    Thanks for the info. I thought it was an SMC, but I couldn't find any photos on the internet to verify this. What was the general trick to setting it up? Will this clutch take a Bully sprocket or is the machined area a different dimension? I was thinking about running a road race with LO206 and wondered if this would perform well--my initial homework suggests WKA road racing rules allow any dry clutch vs. the typical drum style only clutch rule. Thanks, CMac

  4. #4
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    The SMC pattern is what is now considered the industry standard "Small Pattern" so a Bully brand sprocket will work just fine.

    SMC sold a tool that held the center section and had a dial indicator at the proper angle so that you could set the pre-load on the "Springs" by tweaking the tension. You could usually get close by just installing a new set of springs and hope they were close.

    If I recall, they offered three different thicknesses of springs to raise or lower stall. Last I checked, Comet still had some on their webstore. I do not know if SMC has any inventory left.

    There was also a hex shaped shim that helped adjust air gap, which would alter slip duration as well.

    When this clutch dropped in popularity, I had a fixture set up in one of my mills to add 4 more slots and reduce drum height and racers were using them as a "Jammer" style drum. I dreaded opening up the boxes after a while because it was very boring to sit down and modify 15 to 30 drums at a time on a manual mill.

    Since the lining is still readily available, I would not hesitate to run it, especially if you like to tinker.

  5. #5
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    Quote Originally Posted by cmac View Post
    I was thinking about running a road race with LO206 and wondered if this would perform well--my initial homework suggests WKA road racing rules allow any dry clutch vs. the typical drum style only clutch rule.
    If the LO206 race you want to run is following the official LO206 rule set, you wont be able to run a disc clutch.

  6. #6
    4 Cycle Advanced User
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    You can in WKA LO206 sprint, just not CIK

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