bad fork seals--how to tell
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  1. #1
    Senior Member dganey's Avatar
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    What symptoms would bad/blown fork seals produce?

  2. #2
    Senior Member lizrdbrth's Avatar
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    Quote Originally Posted by dustyg View Post
    What symptoms would bad/blown fork seals produce?


    What symptoms do you have?



    Blown seals usally leak. If you lift your fork boots up from the bottom and compress your suspension by holding the front brake and moving the forks up and down with the bars you should see oil on the chrome if they're going. Piles of oil running down the fork leg if they're totally shot.



    If neither is happening and the fork is mushy you could just have old, contaminated oil, you could just be low on oil, you could have wasted fork seals AND be low on oil. If you or someone else just serviced the forks and they're leaking they could have been overfilled.



    Need more info.



    I can explain it to you, but I can't understand it for you.

    Powdercoated '87 frame, extended swingarm, YZ fork legs, ATV tire, 14/55, XT350 tank, spliced quick-release seat, disc brake conversion, beeg headlight, beeger rack, Lizrdcooler, Lizrdventz and bunch of other stuff all covered in invisible ink.

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  3. #3
    Senior Member dganey's Avatar
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    Quote Originally Posted by lizrdbrth View Post
    What symptoms do you have?



    Blown seals usally leak. If you lift your fork boots up from the bottom and compress your suspension by holding the front brake and moving the forks up and down with the bars you should see oil on the chrome if they're going. Piles of oil running down the fork leg if they're totally shot.



    If neither is happening and the fork is mushy you could just have old, contaminated oil, you could just be low on oil, you could have wasted fork seals AND be low on oil. If you or someone else just serviced the forks and they're leaking they could have been overfilled.



    Need more info.




    Have not looked under the fork boots yet, but I will tomorrow. New Hyperpro progressive rate springs, old oil shiponed and replaced with dex/merc after flushing at 131 miles. Filled (by volume)to the low end of the spec in the manual. Consistantly hearing loud clunking sound from fork legs over larger bumps. Shocks seem to beworking fine. I am certain that all parts were installed correctly. I only put about two miles on the bike prior to the new springs, so I have no reference in terms of shock noise.



    Dusty

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  5. #4
    Senior Member TW_in_BC's Avatar
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    Quote Originally Posted by dustyg View Post
    Have not looked under the fork boots yet, but I will tomorrow. New Hyperpro progressive rate springs, old oil shiponed and replaced with dex/merc after flushing at 131 miles. Filled (by volume)to the low end of the spec in the manual. Consistantly hearing loud clunking sound from fork legs over larger bumps. Shocks seem to beworking fine. I am certain that all parts were installed correctly. I only put about two miles on the bike prior to the new springs, so I have no reference in terms of shock noise.



    Dusty


    Are you sure the "clunking" is coming from the shocks? I have an annoying clunk in the front somewhere, and I suspect it is some of the stuff behind the headlight, rattling around.

    It's been doing this for over 5 years now!
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  6. #5
    Senior Member atleastbehandy's Avatar
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    I also have an annoying clunk coming from the front. Happens every time the front shocks are compressed beyond 50% of full travel. Drives me nuts in stop-and-go traffic from all the braking...



    Sounds like it is coming from the left fork or perhaps from the steering column.



    I tried re-tightening all fasteners (including the brake caliper) - no luck.



    EDIT: I have trace amounts of oil on the chrome.
    2005 TW200, 2" PowerMadd bar riser, Tusk D-Flex Hand Guards, PowerMadd Hand Muffs, Kick-Start, Valco Cup Holder, Givi E45N Top Case, Inline fuel filter, Storage Tube with MSR bottle, 45 Tooth sprocket, Stebel Low Tone horn, #130 Main Jet / no needle shims / 1.5 turns out on idle, Jimbo Shield, DID O-Ring chain, Clarke XT250 4.1 Gal tank, Custom Cycleracks

  7. #6
    Senior Member lizrdbrth's Avatar
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    Quote Originally Posted by dustyg View Post
    Have not looked under the fork boots yet, but I will tomorrow. New Hyperpro progressive rate springs, old oil shiponed and replaced with dex/merc after flushing at 131 miles. Filled (by volume)to the low end of the spec in the manual. Consistantly hearing loud clunking sound from fork legs over larger bumps. Shocks seem to beworking fine. I am certain that all parts were installed correctly. I only put about two miles on the bike prior to the new springs, so I have no reference in terms of shock noise.



    Dusty


    Since this is the internet and we can't hear the "clunk" here are a few possibilties.



    First of all you should ignore the volume measurement and use the actual oil height, set with the springs removed and the forks compressed. You should also manually cycle the forks few times before you install the springs and caps and check the oil height again. If you didn't do this and you've only ridden a couple of miles your forks could be cavitating (air instead of fluid in the space between the fork tube and the fork leg).



    Typically aftermarket springs are longer than stock. If no spacers were provided and you've used the stock TW spacers you could be in coil bind. Also, if they aren't perfectly centered in the fork tube or if you put the upper washer upside down they could be banging the inside of the fork tubes. You may want to seek some advice on spacer length from someone who's using them. I think there are a couple of posters running the Hyperpro springs.



    Could also be your upper triple is loose above the top bearing, or that the steering bearings themselves are loose.



    Another really remote possibilty is that (if the springs are progressive) there are far fewer coils on one end than the other. These coils would take up less oil volume than the tighter windings, leaving an excessive air gap. If it were my bike I'd put the tighter (closer together) coils in the oil (down) so that the oil level would be closer to correct once the springs are installed.



    The other really ugly possibilty is that the bore of your lower legs is worn out. This will require complete disassembly to check, so look into the other causes first. ATF is cheap. Start with the oil level, steering bearings and check the upper tree.



    I can explain it to you, but I can't understand it for you.

    Powdercoated '87 frame, extended swingarm, YZ fork legs, ATV tire, 14/55, XT350 tank, spliced quick-release seat, disc brake conversion, beeg headlight, beeger rack, Lizrdcooler, Lizrdventz and bunch of other stuff all covered in invisible ink.

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  8. #7
    Senior Member operose's Avatar
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    Just some food for thought: some of my steering bearings had "flat sides"



    This was a well-beaten 1991 model, though
    ITCB

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