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Discussion Starter · #1 ·
I’ve had a few 34 SCs come across my desk, including my own 3 times, with leaky FIT4 dampers. I changed the seals on mine about 50h ago and again lost lock-out during my last ride. Last time I THINK it was a leak from the bottom of the bladder, but all parts seemed OK and when I cleaned and re-bled everything the lock-out was back on all forks, some of which have now been run 200+ hours after the oil change and bleed.

Any experiences? Is the new chassis so flexy that on a bigger impact the parts move and leak oil? Have I overfilled the bladder on mine last time? Fox have no 34 SC specific instructions available for consumers so I followed the normal FIT4 guide, which suggests compressing the damper around 75mm before removing the bleed syringe and closing things up.
 

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Discussion Starter · #3 ·
I don’t have a dyno but I’ll try and cycle the damper on the bench to see if it still leaks after an oil change. Using Motul 5Wt Factory, which is maybe a tad thinner than the Fox 5Wt.
The attachment for the bladder on the SC FIT4 seems a bit dumb with no groove for the bottom to seal against. It just sits on top of the damper body and is held in with a circlip and pressure from the lower “lip” inside the bladder.
 

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Usually those suck in air and go slurpy before the main seals leak oil out. Can you do a few hundred bench tests and check for leaks? A dyno would be ideal to stress test it and see where it bleeds.
A FIT damper should be totally silent in operation, right? My CTD is sounding like a Motion Control on bigger hits...
 

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The SC dampers with the floating bladder end use the previous generation design to cut weight. Many of the previous service techniques would apply.

Don't compress it 75mm at the end. That is your mistake. They should be full with the shaft completely extended. When those are under filled, they can draw air into the damper. I'd expect through the topcap u-cup.
 
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