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Lusus Naturae
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Discussion Starter · #1 ·
Folks,
My Stumpjumper FSR Comp with the Fox Float 120 RL started losing air in Downieville a couple weeks ago. Got home and it was at around 20 psi. Pumped her up to 80 but now, two weeks later, its pretty much bottoming out easily once again.

Just the other day after a nice ride, I noticed something looked unusual. Check out these pics.

First two are the left side (bad fork, no singletrack!) and the third pic is the right side (aka no problem). You can tell the difference. Something be wrong. :nono:

https://www.gandarva.com/mtb/badfork1.jpg
https://www.gandarva.com/mtb/badfork2.jpg

https://www.gandarva.com/mtb/goodfork.jpg

So what is the suggestion? Is it easy to push that seal/cover back down and keep an eye on it? Should I take it to the LBS and have them send it to Fox? :madman:

At this point, is it possible some dirt or other crap got "inside" and it should be re-assembled either way?

I was thinking of having the 10mm spacer removed to make it a 130mm fork, so maybe its time. Unfortunately the Downieville XC race is a week away and I can't have delays here! :mad:

OK thanks for any advice! :D
 

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Read the 'seal popped up' thread on here as well as this is the exact same issue.

For both of you guys, the 'seal' that you see is nothing more than a dust wiper. It is designed to keep dust out of the fork only and is not designed to keep anything inside of the fork. A fork designed to keep pressures/oil inside (Marz or RS) would have an oil seal underneath that dust wiper, usually held in place with some kind of snap ring.

The wiper can and should be pushed back into place, carefully with something that CANNOT scratch the stantion if/when you slip. A large PVC pipe section works very well, but you will have to remove the uppers ot use this method.

Now for the cause...
These are both air forks, and as such they use contained air under pressure to provide a spring. Remember, that wiper is NOT designed to hold anything inside the fork..ie there should NOT be any pressure inside the fork lowers exerted on that wiper. Both of these forks use a sealed internal cartrage/chamber to hold the pressurized air and provide the spring rate. This chamber is sealed with some combo of lip seals and or o-rings. In BOTH cases, one or more of these chamber seals has begun to fail, allowing air to escape into the fork lowers, and in turn...putting pressure on the wiper (bad).

So pushing the wiper back into its seat will prevent contamination of the lubrication oil, but it will do NOTHING to fix the problem, and the seal WILL pop back up again and again until the cartrage leak is addressed.

Fox has a GREAT tech section on their web site that shows step by step how-toos for all work on their fork models (YEA Fox)..not sure about the Manituo.

For future reference, every 'feature' of a fork will add complexity, which will in turn add to the possibility of failure. Air forks are, and always will be more prone to issues and need more maintainance. Travel adj, lock down, weird platform damping (spv etc), remote adjusters, etc all add to the chance of failure,and the complexity of repair.
 

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Lusus Naturae
Joined
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2,874 Posts
Discussion Starter · #3 ·
Thanks Davep - Fox pretty much said the same thing in their email response to me - pretty quick response actually. Here it is:

Please call us at 1-800-369-7469 ex 6550 to set up an RA to have your fork come in under warranty. The cause of the dust wiper popping up is that air is going past the u-cup seal under compression and forcing the dust wiper out of its place. The turn around time for warranty work is about 5 business days.


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