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clutch spring length

Discussion in 'XJ Technical Chat' started by bensalf, Apr 4, 2018.

  1. bensalf

    bensalf Well-Known Member

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    so , whilst renovating my spare engine, I measured the old clutch spring length.
    Haynes manual states
    clutch spring free length-
    standard---------------42.8mm,,,,,(1.69 in)
    minimum--------------41.8mm,,,,,,,(1.65 in)
    old springs measured
    from 40.3mm to 40.78mm
    so out of spec
    ordered new clutch springs from ebay.... EBC ones
    new ones measured
    from 41.89mm to 42.06---------- WTF.
    ok so they're above minimum but not up to standard length---- sheesh, i'm going to use them anyway
    maybe Haynes is slightly wrong.
    stu
     
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  2. cds1984

    cds1984 Active Member

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    The interesting thing about clutch springs is that the longer and stiffer they are the less likely your clutch will slip... so...

    If you look at the engineering behind it, it seems to be based on what can the bolts/hub can handle without stripping and/or snapping and then how much the clutch cable/lever/operator can actually handle to pull that sucker out and let the clutch slip when shifting...
    .
    .. what was I talking about again... oh yeah... don't get too bent out of shape about the minute size differences of the springs, keep an eye on the plates, thats where the magic is at.
     
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  3. bensalf

    bensalf Well-Known Member

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    yeh , thanks. plates are within spec. I guess that's why most modern bikes have hydraulic operated clutches.
    stu
     
  4. Toomanybikes

    Toomanybikes Well-Known Member

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    EBC ones may have a higher spring rate than oem ones so I would not panic.
     
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  5. Ketchup

    Ketchup Member

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    Hello Bensalf,

    Ordered some EBC springs a while back and wondered the same thing.

    This EBC spring kit was for an XJ550, part number CSK14. The shortest spring of this kit was discarded and not used. They were about ~25% stiffer than the stock clutch springs - give or take.

    Spring Min: 40.89mm
    Spring Max: 41.73mm
    Spring Avg: 41.245mm ((sum of length of six springs) / number springs)

    Torque to proper inch pounds, and make sure all of the plates are aligned properly.

    No observable or measurable issues/problems with the EBC clutch springs VS stock 35yr old clutch springs. Clutch lever only slightly more difficult to pull - 3-5%? However, I've replaced the clutch cable and it basically glides like butter blowing all of the above referenced percentages clear out of the water. Very, very easy now.

    Skol,
     

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    Last edited: Apr 10, 2018
  6. bensalf

    bensalf Well-Known Member

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    yeh, thanks lads,
    it is a fairly new cable , so I don't think there will be any problem.
    strange how they send the springs for my specific bike , but theres 6 springs in the pack , my bike only takes 5.
    same a few years ago , when I did my café racer, ive one left over from that set also.
    thanks stu
     
  7. Polock

    Polock Well-Known Member

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    extra one is in case one is short :)
     

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