Results 1 to 13 of 13
  1. #1
    mtbr member
    Reputation:
    Join Date
    Aug 2006
    Posts
    62

    DD50 cartridge teardown

    Since I was replacing the "spring" in my DD50, why not open up the damper cartridge and change the oil. This was pretty straight forward. Used the Park green spanner to remove the end cap, dumped out the old oil, cycle the piston a couple of times, remove the other cap, inspect all the parts, reassemble, fill with fresh oil, cycle a few times to purge air bubbles, replace end cap, cycle some more and listen for air bubble, none?, good to go!
    Attached Thumbnails Attached Thumbnails DD50 cartridge teardown-dscn0728.jpg  

    DD50 cartridge teardown-dscn0729.jpg  

    DD50 cartridge teardown-dscn0731.jpg  

    DD50 cartridge teardown-dscn0733.jpg  

    DD50 cartridge teardown-dscn0734.jpg  

    DD50 cartridge teardown-dscn0735.jpg  

    DD50 cartridge teardown-dscn0736.jpg  

    DD50 cartridge teardown-dscn0737.jpg  


  2. #2
    All Lefty's, all the time Moderator
    Reputation: MendonCycleSmith's Avatar
    Join Date
    Feb 2005
    Posts
    15,776
    You'll need to pull that brass pin for a proper bleed. If you did it prior to fully tightening the cap, it would've worked better. Now? Loosen the cap, get a sharp edge under the pin to get it up and out. Careful,. it may be under some pressure, and cause oil to exit, abruptly

    Tighten cap with pin out, reinsert pin. Not doing this will create extra pressure inside the cart as the oil heats up. This will cause leaks, lack of proper function, and can even cause some funky feelings like partial lockout, and damping issues.
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  3. #3
    mtbr member
    Reputation:
    Join Date
    Aug 2006
    Posts
    62
    Thanks for the tip. I hesitated to pull the brass pin, in case it would not seal properly after reinsertion. It definitely is under pressure since I topped it up before recapping. Thanks.

  4. #4
    mtbr member
    Reputation:
    Join Date
    Sep 2010
    Posts
    328

    New question here.

    I have a F700 with a P-Bone D that is having a few issues. Is the procedure for that cartridge teardown the same? I stopped at my LBS and they said they doubt Cannondale would have any parts for it.

    The P-Bone sounds kind of like how a half-filled oil-filled shock sounds when you compress it and hear some squishing sounds from the air mixing with the oil. The shock otherwise seems to be working, and the bearings seem good because there is no actual play in anything. Also, when I lock the fork out it will still compress about 3/4" before it stops. Does it sound like attempting to refill the oil cartridge would be at least a partial fix?

    andy b.

  5. #5
    mtbr member
    Reputation:
    Join Date
    Aug 2006
    Posts
    62
    Not familiar with a P-Bone D, but your symtoms sound like low oil (air) in the hydraulic damper unit. I would start with the oil cartridge.
    Good Luck.

  6. #6
    mtbr member
    Reputation:
    Join Date
    Sep 2010
    Posts
    328

    New question here.

    Dale,

    Thanks for the reply! I have a bunch of questions about your photos and procedure. I have never had a headshok apart.

    What part are you showing in your 8th photo and where would the items in the first few photos be located in respect to it?

    In your first photo you show a white cap being removed and a shaft with nothing on the end of it. Then in the fifth photo is a shaft with a white cap as well as what looks like the lockout nut and top silver retaining ring. When I take the black cap off the top of my fork tube, that is what I see. In your first photo, is teat the bottom of that shaft, or did you somehow remove that top nut and silver retainer? How does that entire shaft come out of the fork stem?

    On mine I think I need some type of Cannondale castle nut tool. From what I can see you didn't need this tool, correct?

    And lastly, does the entire fork need to be removed from the bike frame to do this procedure, or did you just remove that cartridge?

    Thanks to anyone for replies!

    andy b.

  7. #7
    All Lefty's, all the time Moderator
    Reputation: MendonCycleSmith's Avatar
    Join Date
    Feb 2005
    Posts
    15,776
    Quote Originally Posted by andy b.
    I have a F700 with a P-Bone D that is having a few issues..
    The D series has no oil at all. Just a friction damper. Biggest issue will be finding elastomers when yours goes south, which it inevitably will......
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  8. #8
    mtbr member
    Reputation:
    Join Date
    Sep 2010
    Posts
    328
    Ahhh, so what you're saying is attempting to take it apart and "refill the damper" ain't gonna happen.
    Oh well, then maybe it is functioning as well as it ever did. Is it normal for one of these forks to compress maybe 1/2" or so when locked out? I checked again and it isn't quite 3/4" like I wrote earlier.

    andy b.

  9. #9
    PMK
    PMK is offline
    mtbr member
    Reputation: PMK's Avatar
    Join Date
    Oct 2004
    Posts
    2,569
    It may have also been upgraded over the years to a DD series.

    But as Mendon said, a proper bleed and for any longevity you need to bleed with the brass pin removed. These cartridges do not like any internal static pressure at all.

    Also, do not tighten the nylon sealheads, snug is fine. I have seen them distort and destroy the shafts.

    If you want to hot rod the DD cartridge slightly, use one chevron seal next to the oil and replace chevron #2 with a quad ring.

    Don't bother going with double quads the seal drag goes up and it doesn't gain any better sealing. Also, you can not easily replace the seals in the upped sealhead since everything is pressed and loctited together.

    I believe the last DD50 I worked on was in 1996, still have some of the stuff in a box, maybe even entire forks. A newer 1999 or later Headshok is greatly improved, no where near perfect but much better. Better damper, more travel smoother action and lighter.

    PK

  10. #10
    All Lefty's, all the time Moderator
    Reputation: MendonCycleSmith's Avatar
    Join Date
    Feb 2005
    Posts
    15,776
    Quote Originally Posted by andy b.
    Ahhh, so what you're saying is attempting to take it apart and "refill the damper" ain't gonna happen.
    Oh well, then maybe it is functioning as well as it ever did. Is it normal for one of these forks to compress maybe 1/2" or so when locked out? I checked again and it isn't quite 3/4" like I wrote earlier.

    andy b.
    Hold on, I think I mis-spoke. You have lockout? If so, you have oil. Movement during lockout implies a leak. The noise you hear is air and oil mixing, yes. Sorry for the confusion....
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  11. #11
    mtbr member
    Reputation:
    Join Date
    Sep 2010
    Posts
    328
    MCS,

    Yes, it has a lockout knob. I think I'll attempt the oil refill trick then and see what happens.


    PK,

    Thanks for the tip on the seals and nylon cups. I figure I have nothing to lose by attempting a repair. Since I have never had one of these apart, do I have to take out the entire center shaft as Dale shows in his photos, or does everything come apart enough to refill the oil without doing so? I don't have the "bullet tool", but I guess I should probably get one anyway.

    andy b.

  12. #12
    PMK
    PMK is offline
    mtbr member
    Reputation: PMK's Avatar
    Join Date
    Oct 2004
    Posts
    2,569
    First you need to remove the damper from the fork. This requires a Castle tool and Green pin spanner.

    After that use a red pin spanner to unscrew the upper sealhead.

    On a DD series you do not need a bullet tool, just carefully fit the shaft through the seals. Look at the second photo above and you can see the bevel on the shafts end.

    If this was anything but a DD, you should use a shaft bullet and there are several versions.

    One caution is to properly use the castle tool, first back off the preload to nil, then do everything in your power not to scratch the shaft, if you do it will leak and is pretty much scrap since it's made from aluminum that's anodized.

    On an air sprung fork, the damper shaft should be bottomed on the castle tool to prevent damage. A DD has some form of spring so this can't be done.

    PK

  13. #13
    mtbr member
    Reputation:
    Join Date
    Apr 2012
    Posts
    1

    DD 50 Uphill Creaking Noise

    It was good to find this article and photos as there is very little out there on the DD 50.

    The head shock on my F600 (1996 model) locks properly and flexes up and down without issue. After water hosing the bike off last week and riding yesterday I did notice a creaking noise coming form the fork but only on uphill riding and about every 10 to 15 seconds (not constant). Now that the bike is at home I can't seem to reproduce the noise but it was apparent on the uphill ride (fire road) the entire time. I believe there is a way to grease or lubricate the boot but can't find anything on this topic. I've got Allen keys 4mm, 5mm but not the Fly Wheel tool FR-1 or the Park Tool SPA-1. With respect to the Castle tool there's a YT video showing a Cannondale F600 and the tech uses 90 degree plyers which worked but as you say don't scratch that shaft. I'm not sure I need to do all that.

    Any thoughts, suggestions, pointers, etc would be most helpful - thanks to all in advance.

    Rev

Members who have read this thread: 2

Posting Permissions

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

THE SITE

ABOUT MTBR

VISIT US AT

© Copyright 2019 VerticalScope Inc. All rights reserved.