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Xj550s "clutch boss spring"?

Discussion in 'XJ Technical Chat' started by SlammedYammie, Apr 12, 2019.

  1. SlammedYammie

    SlammedYammie New Member

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    Wasnt sure where to post this discussion so decided on techical chat, but wanted to have a meeting of the (xj550) minds about the purpose of the clutch boss spring on the xj550 clutch pack. I was installing new friction plates today and the new aftermarket friction plates i was given (that says for 81-83 xj550s) had 8 plates and not one of them had the larger ID for the boss spring to fit into, so it got me thinking. What the heck is the purpose and reasoning behind this wavy metal oring? I know the European 550s had 2 boss springs and the American 550s had 1. From what i get is the 650s and up do not have this boss spring? Im actually really curious about this and its purpose and why its neccessary for this to be installed in the xj550s and position its in. Can anyone can chime in who can shine a little light on this grey area for my brain. Ive looked it up only to find "not really sure" on some threads unless i missed something which is easy for me to do sometimes haha. Thanks in advance!
     
  2. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    That has been covered in this thread.
    CLUTCHES 101-Part 1: the 400/550/600s with pics

    So the "not really sure" answer is the most correct. Yamaha (and all of the big 4) did a lot of experimentation during the 80's, and did not publicly document the purpose of all of their efforts.
     
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  3. XJ550H

    XJ550H Well-Known Member Premium Member

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  4. SlammedYammie

    SlammedYammie New Member

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    K-moe i followed that thread while i was doing the clutch job and it was exactly what the doctor ordered. Great instructions! But all in all was just racking my brain about the purpose of this part. I was thinking maybe somewhere along the lines of some sort of silencer ring to put pressure on the plates to cut down on a clutch rattle or noise? Best i could come up with
     
  5. Colin 85 700

    Colin 85 700 Active Member

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    Most "wierd" clutch parts or dics were originally intended to allow more oil thru the clutch to keep it cooler and improve clutch pack life, most of these didnt make any signifigant difference, and were replaced with "standard" clutch packs.
     
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  6. Colin 85 700

    Colin 85 700 Active Member

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    A kinda wierd, cool story about experimentation...
    Anyone who has ridden a dirtbike has probably noticed that when you hit powerband and roost the tire, the bike tends to squirrel out to the right side 90% of the time.
    Honda realized that this was due to the direction of rotation of the tire and the fact that the chain drive is on the left, causing slight gyroscopic precession.
    In 1982, Cr250 was introduced with a right side chain and a left hand kicker. (I had one)
    This DID allow the bike to track straighter while spinning, however racers that stalled the bike found it too difficult to restart the bike quickly mid race, and the idea was scrapped after one year. (And Woooeeee, it was a bitch to start left footed! Lol! ) ;)
     
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  7. SlammedYammie

    SlammedYammie New Member

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    I guess ill be experimenting myself since i didnt install the boss spring. Guess ill find out the reason behind it later if something happens haha:D
     
  8. XJ550H

    XJ550H Well-Known Member Premium Member

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    plain ring is to protect the basket from wear as it is built out of aluminim alloy and the plain plate is steel.

    look at how the clutch works friction disc lock into the basket
    the steel plates hook into the clutch hub

    if plain was not there the first friction plate would wear into the base of the basket

    the basket spins freely of hub (primary driven gear)with clutch pulled in.
     
    Last edited: Apr 12, 2019
  9. SlammedYammie

    SlammedYammie New Member

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    I understand the concept of that part of the clutch but im talking about the "boss spring". Its the wavy o-ring thats in the 3rd friction plate from outside in. Not sure about the concept of it
     
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  10. Kickaha

    Kickaha Active Member Premium Member

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    Yamaha IT175/200 models had a right side chain and right side kick start from 1980 through to 1986
     
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  11. XJ550H

    XJ550H Well-Known Member Premium Member

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    maybe the boss spring is used to start the separation of the discs
     
  12. Ryengoth

    Ryengoth Active Member

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    It looks to me like it's part of the starter clutch setup, to allow crank-side slippage at slow revs and not produce too much drag on the starter. Even if the clutch is not compressed there's a ton of friction in that pack when it's together.
     

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