Results 1 to 12 of 12
  1. #1
    mtbr member
    Reputation:
    Join Date
    Nov 2005
    Posts
    269

    Lefty "clunk" on rebound - any fixes?

    Hi folks, I really enjoy this forum and hope you can help me out like you help others. Merry Christmas.

    I have a Prophet 2000 (2005) with a Lefty Max Carbon. It has been troublefree and wonderful for the past 2 years, and I ride fast in rocks. So it is durable. I rest bearing migration always, change the oil frequently and refresh the grease and air filter often. But I have now developed a "clunk" on rebound that I can cure. It just started out of the blue - no crash, etc. I've tried everythging, stipping it down and building it back up, to no avail. I finally took it to the local Cannondale shop, and they said it looked "perfect" but didn't know what was causing the clunk either. It is like a topping out feel, noticable with the lefty on or off the bike.

    Any suggested fixes would be most appreciated! The Cannondale dealer said for me to wait until early January, when the traveling factory rep will be at his shop and can look at it. It's been off the bike now for a month and I want to ride!

    Best Regards

  2. #2
    mtbr member
    Reputation:
    Join Date
    Jan 2004
    Posts
    1,010
    Don't have a Lefty or any experience with Leftys.

    Didn't the 2000 come with SPV?

    Ignoring the SPV it sounds like your shock is topping out. Normal fix for this is increasing rebound. If that doesn't fix it then you might need a new rebound cartridge.

    If your shock is SPV then it could be an SPV issue. Try increasing the pressure to see if the noise goes away. If it does than your rebound cartridge needs to be replaced. If it doesn't then the SPV value might be stuck or sticky.

    If you do a search of using the word "devolve" in the shock forum. There are all kinds of dicussion about SPV issues.

  3. #3
    All Lefty's, all the time Moderator
    Reputation: MendonCycleSmith's Avatar
    Join Date
    Feb 2005
    Posts
    12,972
    Does your rebound function fully? I'm thinking possibly a stuck SPV valve on the rebound shaft too. Other than that, it sounds like you're doing everything right, particularly if it's been functional for a good period, after you've worked on it. Maybe it's time to go TPC?
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  4. #4
    widebody
    Reputation:
    Join Date
    Mar 2004
    Posts
    195
    Quote Originally Posted by MendonCycleSmith
    Does your rebound function fully? I'm thinking possibly a stuck SPV valve on the rebound shaft too. Other than that, it sounds like you're doing everything right, particularly if it's been functional for a good period, after you've worked on it. Maybe it's time to go TPC?
    Oh man you didn't have to say that. So a carbon SPV can be changed into a carbon TPC? Now I'm gonna be wanting a carbon lefty Mendon thanks for building me a sweet lefty Stan's Arch front wheel. Been working out awesome over here in Seattle.
    On a side note, any problem hanging a lefty (FFD) fork on the wall by the rear wheel? I am having a very very slight drip/seep from the bleed screw.
    Happy Holidays. John

  5. #5
    All Lefty's, all the time Moderator
    Reputation: MendonCycleSmith's Avatar
    Join Date
    Feb 2005
    Posts
    12,972
    Quote Originally Posted by ssumo
    So a carbon SPV can be changed into a carbon TPC?
    Yep, not cheaply though, as you'll need to replace both dampers, should run a bit over $250 with labor etc. But, you can sell the SPV on ebay and get a chunk of your money back..... As for hanging, you should be bale to do it any way you like. If it's dripping, it's not due to hanging. Chances are, the tiny o ring seal is torn. Easy to fix, no fork opening required, but if you've lost enough oil, may help to re-bleed it too. Glad the wheels rockin for you, happy trails!
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  6. #6
    mtbr member
    Reputation:
    Join Date
    Jan 2004
    Posts
    1,010

    Devolve

    Quote Originally Posted by Mendon CycleSmith
    Yep, not cheaply though, as you'll need to replace both dampers, should run a bit over $250 with labor etc. But, you can sell the SPV on eBay and get a chunk of your money back..... !
    I don't own a lefty so I don't know for sure. Theoritcally you should be able to perform the Devolve fix. Basically disabling the SPV and using the SPV air pressure as bottom out control. You may also need to play with oil weights and adding or removing rebound shims.

    I performed this fix on my Sherman when I started to use the Gemini for Dhing. The SPV was great when I used the Gemini for freeriding slow technical terrain but lacked high speed sensitivity.

    Cost is some new oil and my labor time to make the changes.

    SPV Devolve

  7. #7
    Ridin' dirty!
    Reputation: cdalemaniac's Avatar
    Join Date
    Jun 2007
    Posts
    1,903
    I think if you're "NOT SURE" you shouldn't mess with it or have someone pay you for your "Expertise"
    Sending the fork to Mendon would be the best bet since I only heard good things about him here.
    (And you also get an invoice and a warranty if you have a shop do it).
    Nothing personal but I'd rather be safe than sorry....
    "Common sense isn't always that common!"
    Custom Prophet and Custom Delta V

  8. #8
    oof
    Reputation:
    Join Date
    Jul 2006
    Posts
    22
    I don't think that zero meant he would do it, he meant his own fix cost him his own time
    stay calm

  9. #9
    widebody
    Reputation:
    Join Date
    Mar 2004
    Posts
    195
    Quote Originally Posted by MendonCycleSmith
    Chances are, the tiny o ring seal is torn.
    Mendon, got any of those tiny o ring seals? Or is this a diy Home Depot project? Thanks John

  10. #10
    All Lefty's, all the time Moderator
    Reputation: MendonCycleSmith's Avatar
    Join Date
    Feb 2005
    Posts
    12,972
    Quote Originally Posted by ssumo
    Mendon, got any of those tiny o ring seals? Or is this a diy Home Depot project? Thanks John
    Yep, got 'em. That said though, it would be most likely quicker to go to your local Home center, or hardware store. Actually, call first, and ask if they have o rings ~3mm OD. If not, I've got your back.
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  11. #11
    mtbr member
    Reputation: prophet_1000's Avatar
    Join Date
    Nov 2007
    Posts
    241
    Quote Originally Posted by Dirtvet
    Hi folks, I really enjoy this forum and hope you can help me out like you help others. Merry Christmas.

    I have a Prophet 2000 (2005) with a Lefty Max Carbon. It has been troublefree and wonderful for the past 2 years, and I ride fast in rocks. So it is durable. I rest bearing migration always, change the oil frequently and refresh the grease and air filter often. But I have now developed a "clunk" on rebound that I can cure. It just started out of the blue - no crash, etc. I've tried everythging, stipping it down and building it back up, to no avail. I finally took it to the local Cannondale shop, and they said it looked "perfect" but didn't know what was causing the clunk either. It is like a topping out feel, noticable with the lefty on or off the bike.

    Any suggested fixes would be most appreciated! The Cannondale dealer said for me to wait until early January, when the traveling factory rep will be at his shop and can look at it. It's been off the bike now for a month and I want to ride!

    Best Regards
    Hi I always ran my rebound pretty much the same speed (mid to fast) since I had the bike 2005 prophet 1000, then after watching a tuning video I thought I would set up the rebound a little quicker to see if it would be better, but I must have had it unscrewed too much and over very rough terrain with lots of jumps etc it came unscrewed even more.

    The fork was clunking much as you describe as the fork topped out quickly, I thought that the fork was knackered and set about stripping it down once back home, it turned out to be the rebound had come adrift from the rebound adjusting knob/rod, I screwed it down until it felt like it was engaged again and reset the rebound to how I used to have it and it has been fine ever since. Just thought i'd mention this, although it sounds like you know what you're doing as you have stripped it and also you're dealer has looked to no avail?

    http://www.27gears.com

  12. #12
    mtbr member
    Reputation:
    Join Date
    Jan 2004
    Posts
    1,010
    Quote Originally Posted by GrahamB
    I don't think that zero meant he would do it, he meant his own fix cost him his own time
    Yeah, I won't work on other riders bike unless it's my GF. I work 60 to 70 hours a week and I charge by the hour for my real job. So taking time to work on my bike cost me money.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •