Home Forums 2-Cycle Racing 3-disk vs. 2-disk dry clutch

This topic contains 4 replies, has 3 voices, and was last updated by  Walt Gifford 4 years, 6 months ago.

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  • #39340

    Daniel White
    Participant

    I race in Yamaha SR-Y pipe class (360 lb weight minimum), use a Patriot 3-disk dry clutch, and want to know if I should switch to the 2-disk version. What are the disadvantages of my current set-up versus the smaller clutch?

  • #39364

    Walt Gifford
    Participant

    Either one would work but, the Patriot needs X amount of heat to work at optimum. The 3 disk runs cold on the 4 hole and the 2 disk would get hot on the L2 pipe but you’re running something in between so you’re on your own there. Allot depends on the track, do you see allot of clutch slip or hardly any? Do you bog the motor allot? The smaller clutch is less mass to horse around. If you can run it without over heating it you will accelerate and decelerate slightly faster in theory but, it’s more important to have it slip and lock up consistently through the race.

    Hope that helps,
    Gif

    FAA certified jet engine and aircraft technician,
    Nicholson Speedway class champion 2001,
    Yamaha KT100 Service Center,
    41 years karting experience

  • #39392

    Daniel White
    Participant

    Thanks Walt. This helps inasmuch as it confirms how much I need to learn about clutches.

    At first I had a 2-disk Horstman dry, but the gear sheared off from the drum, so I borrowed a competitor’s 3-disk Patriot, liked it immediately, and arranged a trade (had to replace the broken part of my Horstman of course). The Patriot setup worked well for quite a while before I broke a floater. At that point I learned about gap settings (I tell ya I’m an ignoramus), so I measured everything, found out my gap was .097 (the manual says it should be .025-.032), and decided to replace the friction disks and the one broken floater. I bought a set of gap keys and set it correctly, but the kart wouldn’t take off. Found out my stall speed was around 7700, so I just start turning the screws until it felt better.

    I’m frankly mystified that my rebuild didn’t give me the results it was supposed to, and that my kart seemed to run better with the way-off gap.

    I think I should just get a KPV.

  • #39432

    Gary Lawson
    Participant

    A few things seem odd. First I wouldn’t think it would even be possible to get .097 air gap. Was there any friction material even left?

    To address you current issue you needed to have the pressure plate resurfaced so that it is flat like the new floater and disks. Springs could also be fatigued and need replaced. The easy decision wpuld be to send it to comet to be rebuilt next time. Stall speed will always need adjusted after a clutch rebuild. The decrease in air gap will lower your clutch rpm significantly, just spring tension decreased as air gap opens up from wear.

  • #39449

    Walt Gifford
    Participant

    If the clutch was in bad condition like you say the other floaters and plates might be warped which will make it drag and lock early. Also, the spring height is critical. All springs should be adjusted to the same height. Factory starting height is .650″ but check your manual to see where it’s measured because it’s different than a Horstman.

    FAA certified jet engine and aircraft technician,
    Nicholson Speedway class champion 2001,
    Yamaha KT100 Service Center,
    41 years karting experience

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