fox dhx 5.0 setup

Discussion in 'Downhill & Freeride' started by djamgils, Dec 24, 2007.

  1. djamgils

    djamgils Monkey

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    I tried the search function but I couldn't find an answer.

    I have a DHX5.0 and I would like to know what all the adjustments are.
    I am not a techno noob(I am in a tech university in the netherlands) it just is that the fox manual is full of crap.

    What I am interested in is the Air pressure and the pro pedal.
    According to the manual: ProPedal damping affects the first part of the compression stroke and is designed to control pedal-induced suspension bob.
    So, untill how far in the stroke does this adjustmant have effect? and what is the effect, does it crank up the LSC?

    The air pressure for the boost valve, according to manual:The Boost Valve creates a position-sensitive damping scheme that allows for a seamless transition from efficient ProPedal to square-edge bump absorption to a bottomless end-of-stroke feel. The Boost Valve is not adjusted directly. Instead, its behavior and performance characteristics are influenced by the air pressure.
    So, what happens, more LSC, more HSC, both?

    My own observations, I took out the shock and removed to spring so I could compress it.
    With the boost valve at 75psi and no pro pedal I could easily compress it. With max pro pedal and 75psi, compressing became harder but I couldn't feel a point where it got less.(where the propedal should stop working)
    With max propedal and 200psi I couldn't compress it any more.
    With 200 psi and no propedal it was somewhere in between. Not really scientifical but still representative I hope.
    My guess is that the pro pedal alters the low speed compression over the entire stroke and that the air chamber increases the low and high speed compression.

    can somebody clearify this for me.

    If the tuning range isn't enough for me I am going to try it with shims or oil weight. I have found some info on RM but I still have a question concerning oil change/no air inside the system.
    Should I completely submerge the shock while reasembling? or how can I guarantee that there is no air inside?
     

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  2. NY_Star

    NY_Star Turbo Monkey

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    the easy thing to do is to send it to a professional who knows what they are doing. this way you don't get **** in your shock while you are tearing it down in your basement.
     
  3. djamgils

    djamgils Monkey

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    well the "easy" way costs 180dollar(send it to push) I dont think that that is worth it. Because then I still have the same shock with the same (****ty) adjustability. So I would rather learn it myself or buy a double barrel.
     
  4. General Lee

    General Lee Turbo Monkey

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    and exactly how does one get sh*t in their shock by removing the spring?


    sending it to someone accomplishes nothing. you'll spend a bunch of money to get a retuned shock that you still don't understand or know how to adjust.

    other than that your advice is spot on:clapping:


    djamgils, what bike are you riding, how do you ride it, how much to you weigh. and what do you want your suspension to feel like?
     
  5. djamgils

    djamgils Monkey

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    I ride a Intense Socom.

    I weigh 75kg(165pounds) with gear on.

    My riding style?, hmmm, I would rather pick a technical line then bash trough a section.
    But I do not think that my riding style is necessary to know because my first interest is to know what the adjustments do and not to copy somebodys settings(I have read your previous posts general lee so I dont need to say that to you, but for the other people)
     
  6. ROTFLMAO

    ROTFLMAO Monkey

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    Try this.

    Propedal between 0-3 clicks down from full open or full - (minus)
    100psi-125psi in the boost chamber
    bottom out valve halfway in (middle line)

    Propedal will increase damping in the first part of the travel helping to control bob. Too much will make the ride harsh.

    Bottom out controls the starting point of the progressive damping. More = earlier ramp up.

    Boost chamber psi more or less controls the effect of the propedal. More pressure = more initial damping. It will make each click of the propedal more or less "effective"

    This is an educated guess at what the controls do. It is what I have come to understand in my research and seem to hold true in my experience.

    SWEET bike by the way!
     
  7. jonny dh

    jonny dh Monkey

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    Couldn't put it in any other way thats where I was able to get started it was able to land me just where I needed to be on my riding style
     
  8. General Lee

    General Lee Turbo Monkey

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    first and foremost, make sure you have the proper spring. with all adjustments fully open, 100psi in the reservoir, and the bike on flat ground it should sage 30-40% when you sit on the seat (use a small zip-tie on the shaft to measure). how you tune the damping can effect how 'soft' the shock feels but damping is not a spring. get your spring rate correct first, then tune from there. even if you think you have it right i recomend trying 50lb harder and softer if you can borrow a spring from a friend. a big peiece of suspension tuning is ruling out as much as possible.

    once the pring rate is correct you have to start somewhere, so i'd suggest finding the proper pressure for the reservoir first. keeping everything open (except rebound of course, though you should experiment with as well) try running 80, 100, and 125 psi to figure out wich one gives you the feel you think you would like to start with. remember, every adjusment on the DHX (and it's contemporaries) is effected by the pressure in the reservoir; it is the 'foundation' so-to-speak of from which you can fine tune everything else. you're not too heavy so i'm guessing you'll be on the lower end of the pressure range. though by no means true comparison, i weigh about the same and use 120psi on my Sunday but for the first month i ran between 100-110. you preference might evolve as you get more used to your bike and get more in tune to how it feels.


    what others have said so far is essentially correct. on the dhx, pro-pedal is more of a low speed compression blow-off rather than a true low speed compression adjuster. i wouldn't recomend using any more than 3 clicks and if it were up to me i'd have the feature removed altogether. basically, if you feel like the bike bobs up and down tooo much when pedaling use a bit of PP to control it (though most people get bob because they have bad pedaling technique).

    the air pressure in the reservoir controls the entire range of compression damping. in adition to making the PP adjustment more prenounced it effects the entire range of (hi, low, bottomout control, etc.). if the bike wallows in it's travel try more air rather than PP and see how you like it.

    bottom out control does just that; it reduces the volume of the reservoir so the pressure increases more quickly as the shock compresses. try different position to see what you like. **always readjust pressure any time you make a change so that you are evaluating one change at a time. if you have 120psi in the resrvoir whil fully open and simply turn it all the way down your pressure will increase. your shock will now have higher pressure and more bottom out resistance, so always readjsut the pressure to keep it constant when you change you bottom out setting. you can't evaluate the adjusment if you change more than one thing at a time. however, this isn't to say that you won't eventually ecide to run different pressures depending on where you run the bottom out controls. the idea is to understand how everything you do effects the ride and the other aspects of your shock's adjustments.

    my advice: take some time to hit the trails with your shock pump and a notebook. ride the same trail several times making different adjustments at a time (1 at a time) and write down what you did and what it felt like. eventually you'll get an understanding as to what each feature does, and more importantly how it changes the ride characteristics of your bike. it is one thing to know what the features do, it is another to be able to translate that into actual tuning to match the suspension performance you are looking for.

    do the same thing with your fork as well, and eventually figure out how to get you suspension 'balanced' so the front and rear supension are on the same page so to speak. however, for dh/fr it is common practice to have the rear a bit softer since your weight shift forward when you get going downhill.

    and remember, every time you make an adjustment you sacrafice performance somewhwere else. super supple at low speeds might not pedal as well, but firm suspension under pedaling might feel over damped on small bumps. lots of bottom out control might be great for big hits but might feel to progressive at slower speeds. higher pressure in the reservoir can feel great on smooth pedally tracks or wide open moto-style stuff but might be harsh at med. speeds or on steeps when the rear is unweighted. . . etc. etc.

    no shock is set up perfect for all trail conditions at all times. Suspesion set-up is a compromise and the more you understand what adjustments effect what aspect of performance the better you will be able to tune everything to your liking.

    not trying to be anti-PUSH, but i wouldn;t consider that an option until you really understand what you can do with the stock damper and its adjustments. if and when you really know what you are doing (and what you want) and cannot achieve it, by all means, sent it away. but doing this in advance will cost you a lot of money and leave you just as clueless as when you started. you've probably read the 'i got it back from so-and-so and it was perfect, i haven't had to change a thing.' what nonesense. sure, i bet it feels better but but with a little time and patience they could learn to make it great. bottom line, don't spend $$ on an upgrade you cannot take advantage of to its fullest.

    merry christmas
     
  9. davep

    davep Turbo Monkey

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    great wite-up Lee!

    Single parameter adjustment/isolation is KEY (ie read paragraph 5 several times and understand the idea..this is the ONLY way to understand what each adjustment does)
     
  10. djamgils

    djamgils Monkey

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    Thank you general lee, that is what I was looking for. I couldnt get any usefull info out of the fox manual and pushing it before I completely tested the shock is a waste of money.
    It would be nice of some manufacturers would include dyno tests with their shocks so you could really see what the adjustments do.
    I hope that at my universaty they have a dyno that I can use to test a dhx or something in it but that will probably not happen in the upcoming year.

    I have about 35% sag with a 300lbs spring, so that should be about right. I will start experimenting with the settings soon, first on a short christmas break.

    And a merry christmas to you all.
     
  11. djamgils

    djamgils Monkey

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    After reading an article in Dirt I have some question regarding the dhx.

    In the mag somebody(guess a tech guy from fox) says that the pro pedal is actually a lsc adjuster and the boost valve pressure is the hsc adjuster.
    I haven't seen the shock on the inside but my guess would be that the boost valve is some sort of a treshhold bypass off the lsc circuit and by increasing the pressure you make it more difficult to open the treshold. And the pro pedal is just a needle ... dont know how you call it, and controlles the lsc. But this is my conclusion according to the dirt interview.
    Anybody would like to clarify this for me?
     
  12. davep

    davep Turbo Monkey

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    Pro-pedal is a valve between the body and reservoir of the shock. It meters the oil from shock shaft displacement. It is in all reality, a control valve just like what is inside a 5th or spv shock...that is there is an air space in a two piece (piston inside a cyclinder) valve that changes with the internal air pressure of the shock. The pressure obviously changes (goes up) when the shock is compressed (due to the shaft volume). This is what causes/controls the position sensitivity/damping progression of the DHX as well as the other shocks mentioned.


    So essentially the pro-pedal adjustment sets how far open the valve is at zero travel (via preload of a coil spring that acts on the valve). As the shock goes through its travel, internal pressures build (overcoming the mechanical pre-load), providing more pressure to close the valve.

    Now, high speed impacts create high fluid pressures that can push the pro pedal valve 'open' causing a transition to the high speed damping curve. As the shaft velocity lowers, the 'static' internal pressures tend to dominate and want to close the pro-pedal valve.
     
  13. demo 9

    demo 9 Turbo Monkey

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    thats the best idea :clapping: