Losing sleep over a fork damper
  • Drone6667
    Posts: 3
    Joined: Mon Jul 09, 2018 11:41 am

    Losing sleep over a fork damper

    by Drone6667 » Mon Jul 09, 2018 12:35 pm

    Hello fellow dirt lovers, new to this site or any site for that matter. Quick question...I’ve just gotten my hand on a 2005 Crf250r that needs a ground up rebuild, at the moment I’m at the fork rebuild stage and ran into an issue. The left fork damper push rod refuses to extend fully, it’ll only do so about 50% of the way. After a 5th attempt to bleed it I figured I neede help, I also have Honda’s official shop manual on hand and it’ll only having bleed it again and again you get the point :D do I need to replace the unit? Any info on the matter is greatly appreciated... thanks
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    JimDirt
    Posts: 3016
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: Losing sleep over a fork damper

    by JimDirt » Mon Jul 09, 2018 7:37 pm

    Welcome to the site !! \:D/

    What it sounds like is the "Free Piston Seal" is leaking , it is inside the cartridge where the small Pressure Spring is and your valving , the seal is located on the inside of the Free Piston , you can order a new seal from Race Tech or Factory Connection for about $10.00 , when/if you get the seal i can guide you thru installing it , as you will need to disassemble the Fork Cap Assembly

    Seal is located here:
    Image

    Or you can buy the whole assembly from Honda for about $106.00
    (Part # 14) http://fiche.worldofpowersports.com/yel ... 0-%20FRONT
    02 CRF450R
    06 CRF450X
    Image
    Weiser , Idaho
  • Drone6667
    Posts: 3
    Joined: Mon Jul 09, 2018 11:41 am

    Re: Losing sleep over a fork damper

    by Drone6667 » Wed Jul 11, 2018 1:44 pm

    JD, You rule... i’ve already purchased an entire rebuild kit with bushings and seals and installed them. I also used a pick tool to maneuver that lower seal onto the cartridge, without disassembling the unit...so there is a possibility I might have damage :roll: the O-ring seal. Fortunately I have an additional seal, any assistance you can provide with the disassembly and assembly of the cartridge would be appreciated. Thanks
  • User avatar
    JimDirt
    Posts: 3016
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: Losing sleep over a fork damper

    by JimDirt » Wed Jul 11, 2018 3:55 pm

    JD, You rule... i’ve already purchased an entire rebuild kit with bushings and seals and installed them. I also used a pick tool to maneuver that lower seal onto the cartridge, without disassembling the unit...so there is a possibility I might have damage :roll: the O-ring seal. Fortunately I have an additional seal, any assistance you can provide with the disassembly and assembly of the cartridge would be appreciated. Thanks
    It won't be the outside visible "O-Ring" that is bad , its a actual seal located on the inside of that Free Piston in the picture with the arrow , its where that Piston rides on the shaft , it will require disassembly of the Fork Cap Assembly , the seal will not be part of any "rebuild" kit and has to be purchased from a suspension company or supplier like Suspension Direct , or Race Tech or Factory Connection , its called a Free Piston Seal , the "rebuild kit" will have everything else you need , except that seal , and (if it goes bad) the Cartridge Seal where the rebound rod comes out of the cartridge (do not remove the rebound rod without taping the threads or you will ruin that seal , and its a different process than what i describe below to replace it), ....... there are a few ways you can replace the Free Piston Seal , you can file down a 13mm open end wrench and then take a 32mm 6 point socket and remove the compression adjuster and needle
    , or , make another "custom" wrench by grinding and cutting a box wrench and drilling a hole and putting a Split Pin in the hole that fits either of the 2 opposing holes in the Base Valve (i believe its 1/8") , and holding the cap assembly with a 32mm socket (or the special Fork Cap holding tool) and undo the base valve

    Once the base valve or compression adjuster is off , you can remove the piston (if you remove the adjuster , then you need to measure the locknut distance from the end of the threads closer to the piston , so when you remove it you know where to put it back as it makes the adjustment different if you don't get it back in the exact location it was , you also need to count the total clicks from stop to stop , which would be around 23-26 depending , and write that down , as you will need to check as your tightening everything down to make sure its the exact same as it was , if it stops at halfway between clicks you need to note that as well)

    Once the Piston is off you will remove the O-Rings , Bushings (2 of them they are the teflon flat split rings on the outside of the piston just above where the arrow is in the picture i posted) , on the underside there will be a snap-ring (C shaped) and a flat washer , once all that is removed , put the piston (gently) in a vice or in vice grips , and take a Propane torch and heat the seal , as soon as it starts smoking , then take a small flat blade screwdriver and pry the seal out

    Let everything cool , then clean off the parts , and install the seal , note the orientation of the seal when your pulling it out , put the new one in , facing in the same direction , then install the washer and snap-ring , then the bushings and O-Ring , oil everything with fresh fork oil , then take white Teflon/Plumbers Tape and wrap the threads on the shaft of the fork cap assembly , you want at least 4-5 wraps , so the threads are covered good , ad the threads are very sharp and will tear the new seal if you don't cover them , install the piston , Pressure Spring and either Base Valve assembly or Compression Adjuster depending on which one you took apart (note that you do not have to worry about measurement of the locknut or clicks on the compression adjuster if you remove it from the Base Valve side)

    Here are what the tool look like
    Cut Box Wrench with Pin:
    Image
    Image

    The thinned down wrench is just a 13mm that is ground down on a grinder to make it physically thinner on the open end side , so it fits between the Pressure Spring

    If you get stuck doing anything , or don't follow what i said , just ask and i will try to walk you thru it , once you do it , you will be able to do it again easily , and you will have to replace them both from time to time , as the seals do go bad , the usual sign is not being able to bleed the Fork Cap Assembly , as you noticed ;)
    02 CRF450R
    06 CRF450X
    Image
    Weiser , Idaho
  • Drone6667
    Posts: 3
    Joined: Mon Jul 09, 2018 11:41 am

    Re: Losing sleep over a fork damper

    by Drone6667 » Fri Jul 13, 2018 12:30 am

    Talk about needle in a haystack, JD I’m beyond grateful for your detailed instructions, and intel, I’ll place an order for parts and began fabrication of tools as instructed. I’ll also keep you updated on progress...your an asset to this site, thanks Drone6667

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