lc4 clutch hub grooves

Discussion in 'Thumpers' started by todd83-900t, Sep 17, 2006.

  1. todd83-900t

    todd83-900t Been here awhile

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    May 14, 2006
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    SLC, UT
    After disassembling the clutch I discovered that some of the outer clutch basket fingers have "grooves", see below.

    [​IMG]

    Closeup of a finger.

    [​IMG]

    This looks suspicious and I'm hoping that it's the cause of the clutch dragging. I have no idea if this is considered normal wear. Do I purchase a new clutch hub or try to clean it up? Are there any tricks to cleaning it up from those that have traveled down this dark alley It seems to me that you have to remove the same amount of material on all the fingers.

    Todd ('95 RXC 400)
    #1
  2. urameatball

    urameatball n00b

    Joined:
    Aug 28, 2006
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    8
    pics aren't working but judging from the sound of my bike idling in neutral, there's grooves in my basket too.

    I'm interested to hear whether this is normal on the LC4 and/or whether there's solutions to this.
    #2
  3. dagwood

    dagwood Banned

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    the Lc4 clutch is a notorious rattle box. if you pull in the clutch lever does the sounds lesson? thats just normal. try another oil if you want. sometimes it helps. I found the longer (more miles) on it the better it gets. after 20k miles it's settled down quite a bit but still a rattlebox.
    #3
  4. dagwood

    dagwood Banned

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    PS todd.
    just debure them and don't sweat it. looks normal for a mid/higher mile bike.
    normal wear and tear non issue.
    #4
  5. tcate

    tcate old enough to know better

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    I don't know beans about an LC4, but I sure recognize a worn clutch basket. Yes, it'll make your clutch drag and, yes, it'll get worse if you don't fix it. You can file down the basket fingers and get a little more life out of it. I've always replaced the stock aluminum ones with hardened baskets (like Hinson). If you do that you'll never replace a basket again.

    TC
    #5
  6. todd83-900t

    todd83-900t Been here awhile

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    Dagwood,

    I've decided to send the basket off and have a new one riveted on. I prefer riding to gambling and losing, (conservation of free time, damn little of that). I measured all the clutch disks and the thinnest one was 2.95mm (spec. = 3.0mm), which is pretty darn good. Thinest steel disk measured 1.83mm (spec = 2.0mm). I'll probably replace a couple of them. I still need to measure the springs.

    I'm hope you misspoke (sp?) with the "mid/higher mile" comment. My bike (mistress) has 10K on it now and I'd like to get at least 50K miles out of it.

    Todd
    #6
  7. bmwktmbill

    bmwktmbill Traveler

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    +1 for Dagwood.
    Over the years and back in the day we always filed them flat and raced or rode on....
    Bill.
    #7
  8. dagwood

    dagwood Banned

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    :dunno
    I just see that much wear either. file em smooth repac with new discs if they're worn that much and ride.
    actually at 10k miles the discs shoudn't be worn that much...:dunno

    get Creeper or Dirtrider to chime in. they're the go to Lc4 peeps.
    #8
  9. todd83-900t

    todd83-900t Been here awhile

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    Hi Dagwood,

    I think the real cause for the clutch drag is warped disks, not the basket grooves as I previously thought. Using a thick piece of glass as a base and a cheap-o dial indicator I measured the "warpage" of the steel & clutch disks.

    [​IMG]

    I found 3 steel & 2 clutch disks had a deflection > 0.01" One of the disks had a deflection of 0.4" (huge)! Clearly, this isn't helping my cause.

    I haven't sent the clutch basket off yet (it's sitting in my car) and your voice of experience/reason has me reconsidering.

    Todd
    #9
  10. dagwood

    dagwood Banned

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    Got hot? like Real REAL hot?
    Can't see a problem with .010 thou but .400? thats almost half an inch in real world lingo./.. or .200 TIR lateral. thats huge.
    somethin else is an issue.
    is it draggin? allot a stop and go traffic? feather the clutch allot?
    :scratch
    keep the basket and replace the plates and disc's but check free play in the cable and adjust on the loose side.
    something is funky at those specks.

    Pagiing Creeper. Cereeper to the white courtisy phone. :ears
    #10
  11. todd83-900t

    todd83-900t Been here awhile

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    Dagwood,

    Fat finger alert!!! I meant 0.04" *not* 0.4" sorry for typo. That's still relatively large compared with the rest of the disks. I've ordered the replacement disks.

    Heat obviously caused the disks to warp but what causes the basket grooves? I suspect that lugging the engine, dropping the clutch and acting like your 10ft tall and bulletproof while you ride. Anything else?

    Thanks for your replies.
    #11
  12. todd83-900t

    todd83-900t Been here awhile

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    Closure:

    I replaced all of the warped disks (> .01") and had the grooved basket inspected by one of the main online KTM parts dealers. The inspector said that the grooves were considered normal. I reassembled the clutch and now everything works as it should! It was the warped disks, not the basket as I originally thought.

    Here's one metric for clutch drag. With the bike idling (1st gear & warm) and the clutch depressed push the bike backwards with your feet while you're sitting on it. Repeat the experiment with the engine off. The forces should be approximately equal.

    force (idling) ~= force (off)

    Todd '95 RXC 400
    #12
  13. getagripgreg

    getagripgreg Been here awhile

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    My clutch in an '01 Duke 2 dragged horribly for a while until I found that the culprit was a worn pivot shaft. Water had leaked past the seal and corroded the bearings, so there was huge slop and the clutch wasn't releasing all the way.

    With that replaced, it was vastly improved. The plates had all measured in spec, but I probably have some warpage from the time I spent with the clutch dragging. It still drags like a bitch when cold.

    FWIW, my basket also had some wear grooves, though not as bad as yours. I ignored it.

    Here's a picture of what happens when water gets into your clutch pivot (for you cable operated clutchies)...

    Attached Files:

    #13
  14. taco250

    taco250 wannabe adventurer

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    Todd,

    If you would just go faster on the trail you wouldn't have time to feel whether the clutch was dragging or not! You'd be too busy watching out for trees, boulders, other riders and so on.:doh
    #14