Quantcast

Weird RC4 clunk/topout?

Discussion in 'Downhill & Freeride' started by 6thElement, Jul 22, 2014.

  1. 6thElement

    6thElement Schrodinger's Immigrant

    Rep/Likes:
    87 / 1,681
    Joined:
    Jul 29, 2008
    Messages:
    3,815
    5 or 6 days of riding after coming back from service my RC4 seems to have developed a clunk when rebounding. It happens before full extension, so not fully topped out. It almost seems to happen as soon as the shock starts to rebound. The "noise" can be felt through the frame and makes a lot of noise when riding. So much so that I cut my last day short out of concern for the noise my bike was making until I'd tracked the issue down.

    Nothing is immediately wrong with the shock, anyone else heard of similar?
     

    Please register to disable this ad.

  2. canadmos

    canadmos Cake Tease

    Rep/Likes:
    246 / 4,727
    Joined:
    May 29, 2011
    Messages:
    9,214
    Location:
    Canaderp
    Does it do it when you remove the shock from the bike?
     
  3. 6thElement

    6thElement Schrodinger's Immigrant

    Rep/Likes:
    87 / 1,681
    Joined:
    Jul 29, 2008
    Messages:
    3,815
    Nope, cycling just the frame doesn't seen to exhibit the issue.
     
  4. StiHacka

    StiHacka Compensating for something

    Rep/Likes:
    330 / 3,642
    Joined:
    Jan 4, 2013
    Messages:
    11,126
    Location:
    i͓̽t͓̽ i͓̽s͓̽ fu͓̽l͓̽l͓̽ o͓̽f s͓̽t͓̽a͓̽r͓̽s͓̽
    IFP is known to be garbage in Fox shocks. I would not be surprised if yours bit the dust (like mine did in DHX5).
     
  5. Bikerpunk241

    Bikerpunk241 Monkey

    Rep/Likes:
    4 / 0
    Joined:
    Sep 28, 2001
    Messages:
    766
    I would guess one of two options.
    1. the IFP was set to the wrong depth and is bottoming out before the shock reaches full extension
    2. the bushing in the seal head is not to spec and so doesn't shut down the oil flow enough for the hydraulic top-out to work

    The latter seems less likely since it's clunking before full extension is reached. Either way, both options require the shock being cracked open again.
     
  6. 6thElement

    6thElement Schrodinger's Immigrant

    Rep/Likes:
    87 / 1,681
    Joined:
    Jul 29, 2008
    Messages:
    3,815
    Took another quick look before posting it back for warranty service this morning. The very first couple of cm seems have a quick rebound before the pause then rebound damping seems to kick in.

    Thanks for the suggestions, I'll see what they say.
     
    #6 -   Jul 23, 2014
    Last edited: Jul 23, 2014
  7. blindboxx2334

    blindboxx2334 Turbo Monkey

    Rep/Likes:
    11 / 100
    Joined:
    Mar 19, 2013
    Messages:
    1,347
    Location:
    Wets Coast
    who serviced it?
     
  8. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

    Rep/Likes:
    94 / 791
    Joined:
    Mar 14, 2005
    Messages:
    4,713
    Sounds like an incorrect IFP depth setting to me as Bikerpunk suggested.

    Not the case with RC4. New design and hard anodized, haven't seen any failures personally.
    The DHX5 was developed in 2004, it was pretty reliable compared to the alternatives at that time.
     
  9. StiHacka

    StiHacka Compensating for something

    Rep/Likes:
    330 / 3,642
    Joined:
    Jan 4, 2013
    Messages:
    11,126
    Location:
    i͓̽t͓̽ i͓̽s͓̽ fu͓̽l͓̽l͓̽ o͓̽f s͓̽t͓̽a͓̽r͓̽s͓̽
    OK, thank you for the correction Udi.