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  1. #1
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    Very Strange Problem with 2000 Manitou SX Sport

    Ok, this is weird. After a maybe 3 days of moderate riding my 2000 Manitou SX Sport, full travel ceases to exist with a dull metallic clunk about 1.5" into compression. And there it stops. Removing the spring and damper and pumping the fork for a minute (with the top plunger out) brings it back to full travel and smoothness, with the first pump or two feeling spongy. It will only be a few days, though, before I'm back to the clunk and limited travel. The way the travel and overall plushness go downhill is gradual over several days. I have applied the temp fix probably a dozen times, but I'm really wanting to get to the bottom of this.
    When I first got this fork I broke it down to the major components for a thorough cleaning, after which it got fresh grease (Royal Purple UPG thinned with fork oil) and a new dose of oil (Amsoil Shock Therapy 5w). Everything inside looked sweet, with no wear to speak of and no visible damage, although there was at least a half cup of water locked inside.
    After a couple of weeks, I did notice the oil was too far from the top of the crown, so I added some and pumped the fork for a bit to get rid of the air until I saw no bubble rising from below. Seeing the oil was low made me wonder if there was airl left behind right after the first overhaul...but I did pump the fork for at least 2 minutes and why would there be a clunk feeling if there is air in there?
    I've been working on my own bikes for about 13 years and forks for about 10.
    This has me totally stumped - the only thing that comes to mind is a bad damper? But it looks fine, other than it's made of cheese?

  2. #2
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    I don't know anything about that specific fork model, but what you are describing sounds like an o-ring is letting oil seep into the lowers- when the fork compresses it hits the non-compressable oil and goes 'thunk'. This goes along with your observation of the oil level getting lower over a very short time. Same exact thing happened to my Rock Shox.

  3. #3
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    When I took it apart to pinpoint the prob, I didn't see anything wrong with the seals. Maybe I should take tear it down again (ugghnn.) to see if there is oil in the lower, then check the seals again. Anybody feel like there could be another problem?

  4. #4
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    How much oil did you add total? If you overfilled it, you could be hydrolocking it on compression.

  5. #5
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    Maybe, you should look in spring

  6. #6
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    I didn't measure the overall volume, but went by the top of the oil as measured from the distance from the crown - 5 inches I think. Only thing I can say for sure is that I went by the manual when I filled it with oil. Like I said everthing looked really good inside this fork when I gave it the inspection including all the seals I observed. But the idea that a seal has gone bad and is letting oil seep into the lowers is the only thing that makes sense to me. Must be a seal in a less obvious place not easily seen. I'll have to look at the manual again I guess.
    The spring stack is in perfect shape.

  7. #7
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    From the symptoms, the damper rod seal is leaking oil into your lowers. The seal is located at the bottom of the stanchion, where the damper rod enters the stanchion. I'm not positive, but I'm fairly certain it's a standard o-ring size, but Dougal would know for sure.

  8. #8
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    Quote Originally Posted by bad mechanic View Post
    From the symptoms, the damper rod seal is leaking oil into your lowers. The seal is located at the bottom of the stanchion, where the damper rod enters the stanchion. I'm not positive, but I'm fairly certain it's a standard o-ring size, but Dougal would know for sure.
    We have the damper rod seals here: OE SUSPENSION PARTS

    I kind of doubt the damper rod seal is leaking, though. That's a grease-lubed fork so the main seal where the stanchion enters the lower leg is not really designed to keep oil in. Once any significant amount of oil built up in the lower leg it would be pushed out of the main wiper/seal and you would have lots of oil running down the damper leg.

  9. #9
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    No signs of leakage on the lowers that I saw , I'll double check. But like I said when I do the temp fix in order to bring it back to life for a couple of days, compressing the fork after pulling the spring stack and top plunger, there is a lot of slow, spongy resistance on the downstroke first or second time - after that completely smooth.
    After this, plushness (as plush as an SX sport gets, prolly) for a few days.
    If I keep riding it it will lock out almost completely with only about 1/2 inch travel.

  10. #10
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    I should recommaned you a ROCKSHOX suspension

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