Adjustable clutch preload ring

Discussion in 'Trials' started by heffergm, Apr 6, 2018.

  1. heffergm

    heffergm Long timer

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    Anyone have a bike with an adjustable preload ring? Ever set it anywhere other than the first step? End result?
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  2. KevinBB

    KevinBB Trials Addict (I drank the kool-aid)

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    You know I have the Ice Hell with the adjustable Vertigo clutch. Set it to position 3 and was better, smoother than position 1 or 2. But still quick. Have not found a slower, progressive feel like a GG on the Vertigo. However, I'm not clear on how he adjustment on the Vertigo is intended to perform. Manual says 1 thing, Adrian says another!
    #2
  3. motobene

    motobene Motoing for 46 years

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    Adjustments like this are not absolute, so position one, two, or three are interpreted in context, in how something works at whatever setting.

    It's a nice to have, and something to play with. I backed off preload on my 250 Sherco to same as the 125. I like that better. Someone else might go the other way. It would be nice to have that in an adjustment rather than via shim washers or changing the pressure plate.

    On the Shercos they change the preload by changing the spring retailer plate, or rather, the depth of step cut for the spring in the plate.

    Having a 30-hole spring retainer plate with 3 steps for the 10 posts would be a nice accessory. However when riders have a function they believe is working quite well, the motivation to tweak and adjust is low.
    #3
    Frantz100 likes this.
  4. heffergm

    heffergm Long timer

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    I'll answer my own question for posterity. This is on a 2018 bike with the GG adjustable ring and a Xiu clutch:

    - in the stock setting (1) I was finding the clutch bite both a little weak and a little vague. It also wasn't as progressive as I'd like. My prior setup (same clutch with a Xiu ring on step 1) didn't really cause me any of these concerns.

    - moved the adjustment to step 3. I notice a very very small increase in lever effort. But the difference in the clutch bite is huge. Very immediate when it bites, but better progression up to that point. Night and day difference compared to step 1.
    #4
  5. motobene

    motobene Motoing for 46 years

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    A wider slip/engage zone is usually associated with reduced spring preload, and a narrower slip zone with more forceful engagement is associated with more preload. The vague feel at preload position 1 (least adjustable preload) means your particular bike was on the light side of preload at position 1.

    'More progressive' is a subjective term, and associates with less spring preload. 'Vague feel' can result from being too light on preload.

    But positions 1, 2, and 3 don't so accurately compare between bikes, however, because spring preload in an individual clutch results from the sum of parts that influence preload.

    The behaviors may compare more closely when one bike is in position 1, with another in position 2.

    The strongest influencers of individual bike preload variances are the clutch pack thickness (sum of thickness of the 3 fiber-faced metal plates and the 2 metal plates). The other parts are typically vary less due to the nature of the manufacturing processes and part shape.

    Individual springs are often assumed to be the same, but they may not be. Again, due to the nature of the manufacturing process of Belleville springs.

    The spring material thickness tends to be consistent. 1.5mm for Gas Gas and 1.7mm for Sherco-Scorpa. BTW, the GasGas pressure plate contacts the inner spherical radius via a raised ridge on the pressure plate, whereas on Sherco-Scorpa pressure plate contact, via a kind of thrust washer, is on the outer edge of the spring.

    You can roughly compare springs by laying them on a flat surface, larger contact diameter down, then measuring the vertical height to the domed edge of the inner diameter.

    There are more variables that this in the spring if course, but the above measurement usually can determine which spring is stiffer.

    These single springs are very stiff. Small variances in how much space they displace can translate to felt differences at the clutch lever and in slip/engage-zone feel.
    #5
  6. motobene

    motobene Motoing for 46 years

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    Update: For 2019 Sherco has gone to a thinner spring and more preload via a thicker 'precharge' ring. One fellow measured 1.2mm for spring thickness. If that's right the spring is thinner than the 1.5mm GasGas spring and 0.5mm thinner than Sherco 2017- 2018.
    #6