LC4 shock rebuild parts?

Discussion in 'Thumpers' started by rz35027, Dec 20, 2010.

  1. Luke

    Luke GPoET&P

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    I forgot about the mandrel.... I never used one, I didn't know it was needed. Just press the bushing in from the top with a flat washer and it will end up in the correct place. You need to be careful choosing the socket to hold the bottom of the 'adapter cpl' body as the bushing sticks a mm or so out from it.

    The reservior body doesn't need to be unscrewed- the piston can be forced out with compressed air. However, when I first tried to unscrew the cap I held the shock body instead of the reservoir body and the whole reservoir unscrewed so I had to make the tool to get the cap off.

    If you do this, be very careful not to damage yourself or the piston. I have modified my reservoir pistons so that they can be grabbed from the bottom. This is really helpful in dissasembling the shock and setting the piston height when putting it back together.

    http://www.advrider.com/forums/showpost.php?p=6136196&postcount=27 Shock disassembly.
    http://www.advrider.com/forums/showpost.php?p=6137864&postcount=29
    Reservoir piston mod.



    Here's how I vacuum bleed the shock. http://www.advrider.com/forums/showpost.php?p=6158218&postcount=34 Set up the pump like that, suck the air out and when the bubbles stop then release the vacuum so that fluid gets sucked back in to the shock. Repeat until no bubble come out. Using thicker hose from the shock to the fluid jar makes things much faster.
    #21
  2. rz35027

    rz35027 Been here awhile

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    A picture is worth a thousand words...

    My homemade pin wrench (dirty), ugly but functional...

    Attached Files:

    #22
  3. rz35027

    rz35027 Been here awhile

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    The bracket I used to brace the shock while torquing on it...

    I intend to use air to blow out the resevior piston, by screwing the shock body cap back on, putting a rubber plug (drilled through) in the hole and applying air. Carefully... And will be installing the "set screw" in the resevior piston.

    The stack of shims in my 95 RXC shock has far fewer shims than those discussed in this thread http://www.advrider.com/forums/showthread.php?t=620602

    It will be interesting to compare what is inside the other shocks I'm dealing with...

    Attached Files:

    #23
  4. Tseta

    Tseta Lost

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    This has turned out to be a very great thread indeed. Many thanks to Luke for the answers.

    The shock service procedure is quite clear to me now, maybe a bit fuzzy around the edges. I'm sure it will all make sense once actually doing the service, hands on.

    One additional point that could be clarified more and expanded upon is the piston height setting. Luke's separation piston mod is a good one, and I understand it will be immensely helpful in setting the correct piston height. However, I find the actual height specification and it's measurement confusing. Is the piston height measured relative to the end cap or to the shock body? In other words, if you want to set the piston at 10mm, do you push it down 10mm from the endcap level, or pull it up 10mm from the shock body casting?

    -T
    #24
  5. rz35027

    rz35027 Been here awhile

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    10mm from the shock body. Part of the reason for the gas chamber is to provide room for the fluild displaced by the shock shaft as is goes into the shock body.... Not enough room = hydraulic lock.

    How much vacuum does one of these pumps put on the fluid?

    I've read a plastic pop bottle can be fitted with tubing, a slight vacuum can be created by squeazing the bottle at the appropriate moment....
    #25
  6. Tseta

    Tseta Lost

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    I found a really nice adjustable pin wrench, with interchangeable pins, the Facom 117-B. Some info here.

    For the vacuum bleeding, I bought a similar Mityvac-copy that was shown by Luke in a previous post.

    Soon I'll have all the tools and supplies necessary for doing the shock service myself. How exciting!

    -T
    #26
  7. Desert Silver

    Desert Silver Desert Rat

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    I know this is a very old thread but I'm new to shock rebuilding. I've rebuilt everything else but never tried the shock. The question I have is if you set the resivorior piston higher than 10mm would it give you a more progressive compression dampening like raising the oil level in a set of forks due to a smaller volume to compress? By the way the shock is off of a 1996 ATK 406.
    :ear
    #27
  8. Luke

    Luke GPoET&P

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    Not really. For perspective, it takes about 1500 pounds to compress the shock spring all the way. (6kg/mm, 115mm travel) The shaft has an area of about 1/2 in^2, so for 20% extra force it would take 600 psi of pressure in the shock. That would be a bit rough on the seals.
    #28