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  1. #1
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    New question here. Lefty Max FFD - clunking noise

    I have problem with my Lefty Max Fluid Flow from 2005 Prophet 600.

    Every time it compresses (especially during fast compression on square-edged bumps) it makes annoying clunking noise.

    Some clues:
    - preload rings are tightened rather well (first I thought it could be loose spring);
    - bottom part is filled fully with oil (leaks through air bleed hole while tightening);
    - oil is Motorex 5W (I know it should be rather about 2,5W, but culd it make such difference?)
    - I've done bearing reset well;
    - rebound setting barely changes anything.

    Any ideas how to fix it? Considered pro rebuild by the dealer, but the wait is about two weeks, so...


    PS. I've found similar threads but only about SPV version.
    PS2. First post here, so hello
    Last edited by wooyek; 03-31-2008 at 05:29 AM.

  2. #2
    All Lefty's, all the time Moderator
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    A few thoughts. Pull the spring, grease the living snot out of it. If it's still noisy, try this. Starting position at 12 oclock, rotate the spring on the rebound shaft, to three, check for noise, then six, then nine, see if that helps. A lot of springs have one spot that seems to make them happy. You say the rebound has little or no effect, regardless of position? Turn it fully to stop clockwise, from there you only have about a turn or so, to fully open. If you still have no effect, sounds as though your push rod is frozen. That'll keep you busy for a few minutes
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



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  3. #3
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    Thank you for your reply!

    I've tried your ideas but only found out that I was wrong about rebound adjuster - it does have influence on the noise. When rebound is closed (from fully clockwise to 1/4 turn out), noise stops.

    But riding in such setting is nonsense - rebound is veeery sluggish (probably because of 5W oil too, but on rebound fully open damping works ok).

    So I guess it's something about rebound push rod (what do you think?)? When I took it out today, it was dry - should it be greased somewhere? What should I do with it?

  4. #4
    All Lefty's, all the time Moderator
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    Quote Originally Posted by wooyek
    Thank you for your reply!

    I've tried your ideas but only found out that I was wrong about rebound adjuster - it does have influence on the noise. When rebound is closed (from fully clockwise to 1/4 turn out), noise stops.

    But riding in such setting is nonsense - rebound is veeery sluggish (probably because of 5W oil too, but on rebound fully open damping works ok).

    So I guess it's something about rebound push rod (what do you think?)? When I took it out today, it was dry - should it be greased somewhere? What should I do with it?
    Sounds like you have some air bubbles on the top side, above your valving. If your rebound is working, your pushrod is fine. Sounds like it's bleeding/oil change time.
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  5. #5
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    Mine was doing that and I had to send it in for a complete rebuild.

  6. #6
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    Quote Originally Posted by MendonCycleSmith
    Sounds like you have some air bubbles on the top side, above your valving. If your rebound is working, your pushrod is fine. Sounds like it's bleeding/oil change time.
    Could you please describe an air bleeding procedure? Manual says about changing oil but nothing about bleeding. I've changed oil lately but I guess I did it wrong...


    lou_b_83 => and did it solve the problem?

  7. #7
    hithard
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    Yea it fixed it. It is like it is new again.

  8. #8
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    OK, so here is the problem (I'm doing nearly complete rebuild right now):

    Clunking was most probably caused by insufficient oil volume. BUT when oil volume is right (about 150 ml, bled while moving without spring inside, with overflow when putting damper in - I've found this method on this forum) Lefty... doesn't work.

    I mean, compression is blocked somehow - oil pressure allows only about 5 mm of compression.

    I have problems with unscrewing damper bolt (19 mm, inside upper leg), so I have no access to the part in the bottom of upper leg. I guess the problem sits there - or am I wrong?

    Please, help - Lefty is waiting in by bathroom

  9. #9
    All Lefty's, all the time Moderator
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    Quote Originally Posted by wooyek
    Please, help - Lefty is waiting in by bathroom
    You have hydraulic lock. I could explain it, but it's rather confusing, as well as pointless. The foam sheet that is wrapped around the compression assembly, is saturated with oil. It needs to be replaced. Annoying? You bet. Unrideable till you do? You bet. If you can't get one from an LBS, you'll have to improvise, you need 1/4" foam, with a soft, rubbery feel. Others may work, but that's how it started life. Sorry, good luck!
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  10. #10
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    Quote Originally Posted by MendonCycleSmith
    You have hydraulic lock. I could explain it, but it's rather confusing, as well as pointless. The foam sheet that is wrapped around the compression assembly, is saturated with oil. It needs to be replaced. Annoying? You bet. Unrideable till you do? You bet. If you can't get one from an LBS, you'll have to improvise, you need 1/4" foam, with a soft, rubbery feel. Others may work, but that's how it started life. Sorry, good luck!
    Thanks for reply - now at least we know what the real problem is...

    So you say that it's caused by this piece of foam:
    https://www.wooyek.pl/a/ffd.jpg ?

    Could you please spend some time to write a thing or two about why is this happening? Such damper construction is new to me and I would be pleased to know, what is what in my bike (partially because I'm technical univerity student ).

  11. #11
    All Lefty's, all the time Moderator
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    Quote Originally Posted by wooyek
    So you say that it's caused by this piece of foam).
    It's not caused BY the foam, but the fact that the foam is saturated with oil, which occurs over time. It's a compression compensator, in a closed system, without something to absorb the momentary oil pressure created during the change from rebound, to compression, or resting, to compression, the compression locks out. Sorry, busy busy busy....
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  12. #12
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    Ok, now I get what you are talking about And now I know that this "rubbery feel" is vital here (to not saturate with oil too quickly).

    Buying new foam from distributor would be good idea, but in Poland it is not so easy as it seems (probably I will have to wait till they get this part...)

    But thank you very much for your help! Cheers.

  13. #13
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    this clunk happened to me during hard compressions and was fixed by a complete rebuild by my LBS

  14. #14
    hithard
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    Did you fix it? What was the problem?

  15. #15
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    Mendon was right, obviously!

    Problem was caused by worn foam on compression damper, which caused hydraulic lock, explained by our Lefty-Guru When I bought my Lefty it had too low oil volume, which allowed it to compress, but caused clunking.

    To replace original foam (distributor don't have any and should call me when they get one for me...) I used 5mm foam used as underlay for... aquarium. It's has closed porosity and is made probably of polythene (so it should be strong enough to keep those pores closed for a while). It's significantly harder than original, but it works flawless.

    Now compression is smooth and quiet, just as it should be.

    Thank you Mendon!

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