Showa Fork Rebuild - Dampers doing my head in.....
  • James450xNZ
    Posts: 2
    Joined: Mon Feb 05, 2018 6:59 pm

    Showa Fork Rebuild - Dampers doing my head in.....

    by James450xNZ » Mon Feb 05, 2018 7:17 pm

    Hey there CRFers, new to this so go easy.....

    Working on an 05 450x with Showa 49mm front forks.

    Had an oil leak on the left so purchased requisite seals and parts and stripped the forks down. Main tube and outer all look good, inners and pistons all ok too. Oil was sludgy and smelly, has been in there a while.

    Have cleaned the dampers up, filled with oil(192ml per manual), lifted the piston up and down to bleed and replaced the damper cap according to the manual.

    Tightened to the cap, cycled the piston 3or4 times around 100mm, then cycled the piston full stroke.

    This is where things go pear shaped.

    When cycling the piston I lose around 75ml of oil instead of the 17ml the book tells me I should expect. Continuing to cycle the piston loses me more oil.

    The piston then retracts and stays shut, pull it out and it goes back in - basically the whole thing is running backwards.

    I’ve noticed the spring in the damper cap is lose when on the bench, is this normal? Is there a proper overall length for the damper cap? Can’t find any info on this part for service and specifications.

    Have done both forks and getting the same result. Have watched a bunch of UTube, repeated the process and no change.

    Any ideas?

    TIA.
  • User avatar
    JimDirt
    Posts: 3859
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: Showa Fork Rebuild - Dampers doing my head in.....

    by JimDirt » Tue Feb 06, 2018 9:14 am

    Welcome to the site !! \:D/

    What you have "should" be 47mm forks , not sure on the Euro bikes , but U.S. bikes are 47mm , ..... As for your leak , its the Free Piston Seal , the Free Piston is the aluminum floating part on the Fork Cap Assembly (where the loose spring is) , the seal when it goes bad allows oil to flow from the inner chamber to the outer chamber via the weep drain holes your seeing the oil flow from , the assembly needs to be disassembled and the seal replaced , its a little involved , so if you do not want to tackle it , then you can buy the replacement from Honda (dealer will have to order it) , and just replace the whole Fork Cap Assembly , then insert it as you had into the Inner Chamber and bleed it and go riding , if you do want to try to replace the seal , i can walk you thru it , you will need to make a tool to hold the Base Valve while unscrewing the Compression Needle head , by basically cutting a wrench and drilling a hole and adding a roll pin

    Tool:
    Image

    Tool in use:
    Image

    The Arrow points to the Free Piston on the Fork Cap Assembly , the tool would insert into one of the 2 bleed holes in the Base Valve just to the right of the piston , then you loosen the locknut on the shaft to the left of the piston and remove the Compression Needle assembly with a 32mm socket:
    Image

    To replace the Fork Cap Assembly , you need part # 15:
    http://fiche.worldofpowersports.com/yel ... 0-%20FRONT

    Hope that helped ;)
    2020 CRF450R
    02 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho
  • James450xNZ
    Posts: 2
    Joined: Mon Feb 05, 2018 6:59 pm

    Re: Showa Fork Rebuild - Dampers doing my head in.....

    by James450xNZ » Tue Feb 06, 2018 11:27 pm

    Thanks JimDirt - great info.

    Trying to avoid a complete new unit if possible, this is the damper cap off my fork just for reference, assume when dissembling i'm starting from the left working right? Does the tool shown in your post just allow removal of the center shaft lock nut so you can get the piston off? :-k
    IMG-5602.JPG
    Does the tool locate onto the hole in the center boss where the needle valve is?
    IMG-5603.JPG
    Is it normal for the free piston assembly to have some free play or should the spring hold it down at the very bottom of its allowable travel - mine has around 4mm of play from the bottom seat up to the spring when at rest.
    IMG-5604.JPG
    Once apart, where is the seal located? Assuming this is an oil lip seal inside the bottom of the piston cup onto the center shaft?

    Any idea on where to get the seal from? Parts not listed with Honda, is the seal a standard oil seal I can get from a bearing shop or something special?

    Thanks in advance.
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  • User avatar
    JimDirt
    Posts: 3859
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: Showa Fork Rebuild - Dampers doing my head in.....

    by JimDirt » Wed Feb 07, 2018 12:50 am

    In your picture , you would "try" to take it apart from right to left ,(note the lock nut to the right , it holds the Compression adjuster/fork cap , and take note of the exact amount of total clicks , even if it ends in a position halfway between clicks , when reassembling , you have to adjust the needle assembly and count the clicks to get it back to where it was , so try not to move the locknut far from original position as you will end up with one fork with less or more clicks than the other , try to measure where everything is and return it as close as possible to the position it started , as that will make it easier when reinstalling as it keeps any chance at damaging the new seal to a minimum IF you can remove the Base Valve with the "tool" by holding the fork cap with a 32mm wrench or socket or fork cap tool before loosening the lock nut , then remove it and replace the seal from that side , so you won't have to worry about the adjustment

    And yes the "tool" i pictured holds where you put the arrow in your second picture , your 3rd picture is in fact where the seal rests , note the orientation of the seal when removing and be sure to install it in the same direction , and you should seek Suspension shops or suppliers , such as Race Tech or Factory Connection , etc. , to get the proper seal , you just need to tell them the year/model/make/ (country where the bike was sold if not in the U.S. as some euro parts differ from U.S. models) you did not mention where your from but i am assuming New Zealand by guessing at your user name , and yes the free play of the spring is "normal" , no issue with that

    To remove the seal you must remove the 2 outer bushings , a C-Clip and washer , underneath the washer is the seal , then after everything including the O-Ring is removed , clean the excess oil off the piston , then heat it with a Propane torch at the seal , till the seal starts smoking , then use a screwdriver to pry it out , it will easily come out once its heated , you can hold the piston in a vice if you just gently close the jaws on it or use vice grips to hold it while heating , clean the piston off with cleaner once its cooled , and/or a Scotch Brite pad , then install the seal in the direction it originally faced (without heat , usually a deep socket works well , make sure it goes to the outside edge of the seal not down into the recess , then reinstall the washer and C-Clip and O-Ring and Bushings , and reinstall onto the assembly , and check all your clicker settings , and adjust if necessary , install in cartridge , bleed , and reassemble the fork and your done... Just count clickers and measure stuff before disassembly and write it all down and you should be fine

    EDIT:
    Forgot to mention , to use Teflon Tape over the threads of the shaft where the piston goes , otherwise you will damage the seal as the threads are very sharp .... hopefully you read this before you assemble..... [-oo

    EDIT EDIT: 2/8/2018 - 10:35am
    Forgot to mention #-o when reinstalling the needle assembly , have the needle clicked all the way out (CCW) then click it in 24 clicks , then screw it on till it just touches/bottoms the needle , then tighten the locknut to it , that way you don't have to worry about measuring , check the other side/fork and make sure it has 24 clicks as well , if not adjust the just installed one so it gets the same amount of clicks when it bottoms as the other fork , so they match........AGAIN .... IF you can remove the Base Valve with the "tool" by holding the fork cap with a 32mm wrench or socket or fork cap tool before loosening the lock nut , then remove it and replace the seal from that side , so you won't have to worry about the adjustment , sometimes the base valve sticks on , and that is why i suggested doing it from the needle side....... hopefully you read this before you start ...my bad , been preoccupied with my suspension and getting my bike back together for the weekend and just forgot to mention a few key things that i should have mentioned in the first part of this post ..... :oops:
    2020 CRF450R
    02 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho

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