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RockShox SID 06 - technical query on blow-off threshold

beechtreebeechtree Posts: 85
edited June 2010 in MTB workshop & tech
I have a query about how the blow-off threshold actually works.

I have just serviced my 2006 SIDs. Mainly because the lockout (poplock) wasn't working at all and noticed that the blow-off floodgate rarely extends out to the closed position, when i turn the floodgate adjuster knob. AND on the occations when it does extend, a light tap will cause it to retract. So i think the root of the problem, ie reason why it's not locking out is that the blow off is being triggered.

i'm looking at the top of page 8 in the service guide: ]

I've replaced all the o-rings in the compression damper, including the internal ones that are not shown on the service guide, but still get the same issue.

One of the questions i had is what, mechanically, causes the flood gate to extend to the closed position and whether i can remove or by pass the blow-off function, i don't find the blow-off useful, but do find lockout useful.

Thanks in advance and make no appologies for the lack of toilet humour based puns - feel free to add your own (but technical help would be more appreciated.
'97 GT Zaskar Red Annodised
'08 Kona Kula
'09 Specialized Rockhopper
'10 Planet X SL Pro Carbon SRAM Red


  • The RookieThe Rookie Posts: 27,804
    You probably want the blowoff with it locked out, otherwise a big enough hit will damage the forks, a hit the blowoff is designed to protect them against!

    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • nicklousenicklouse Posts: 50,675 Lives Here
    I am not quite sure what is going on here as the floodgate is just a threshold setting.

    when the fork is locked out it allows the fork to become unlocked if a big force is applied (rock/drop/hit) but it should return to the locked situation afterwards.

    the adjuster changes the pressure that the valve opens at, it should then close again or that is the way i have always seen it and how it seems to behave on mine.

    remember the floodgate needs setting with the lockout on. and it does not fully lock the fork out.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • beechtreebeechtree Posts: 85
    Thanks Nick and good point Simon

    I'm not sure what's going on either, the floodgate must have an internal spring somewhere tucked away, because it returns to the open position.

    The only way i can (sometimes) get it to extend to the closed position is by the following sequence:
    i) turning the floodgate adjuster knob all the way counterclockwise to the fully open position
    ii) setting the lockout on, ie turning the hexagonal collar just underneat the floodgate control knob that would be turned when the poplock is set
    iii) turning the floodgate adjuster knob clockwise, sometimes the floodgate extends all the way, sometimes it comes out a little then drops back

    If i dial in any floodgate threshold setting (either min, max or somewhere in between) and then turn the lockout on / off, the floodgate itself stays put in the open position. As i'm reading the way it should work, if i dial in a floodgate threshold of max, the floodgate should stay out as i lock / unlock the lockout. BUT would be pushed in to the open position in a "big hit" situation, thus opening the floodgate.

    Is this right?
    '97 GT Zaskar Red Annodised
    '08 Kona Kula
    '09 Specialized Rockhopper
    '10 Planet X SL Pro Carbon SRAM Red
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