Nitrogen in Shocks

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Just a conversation and questions:

I run Triple Bypass Kings on my Funco gen 4, I always try to keep them at 150psi of Nitrogen, which I check every season.

My question, if you add 175psi, how does it change the performance? Not sure you can without doing damage to seals, but interested to know how this affects the shock's performance?

Another question, since I run airbags, would it change the performance to run Nitrogen instead of Air?
 
My understanding is nitrogen is a "baseline" and then you get the tune from springs/airbags and then valving adjustment (on the adjusters and if you need more, tear down and revalve).

I've never heard of Funcos having much issue and most everything is solved by adjusting the pressure in the airbags.

@Grease Monkey
 
Nitrogen in your air bags wouldn't gain any performance, nitrogen is usually used in racing because it is a known element over outside air that can have more or less humidity and is a lot more stable.
 
Changing the nitrogen pressure in the shocks for sure makes a difference.
Less nitrogen will essentially soften the shock, making the valving work differently.
 
As stated above changing the shock pressure will change the performance. Adding nitrogen to your air bags will not make any difference whatsoever, other than cost money.

Nitrogen is used in shocks because it is an inert gas and will not corrode, expand or contract with temperature fluctuations. Oxygen does all those and will change pressure. You can see it if your car/truck has a TPMS system. It is also a fairly large molecule and tends to leak less then O2. Years ago some trucking companies were running N2 in their tires to improve tire life. RV shops started doing it as well. I remember seeing the N2 tire filling stations. Never took off.
 
AlpineFunco said:
Have you adjusted the bypass tubes?
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I am not really thinking of changing anything, I was just thinking about other possibilities and was curious more than anything.
 
Another question, what PSI would you put into your Kings?
 
Goatpoker said:
150psi is standard. Tuning with N2 is not the best way. The pressure is really there to manage cavitation. Less pressure = cavitation at slower shaft speeds.
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Depends on the size. Bigger shocks take 200psi.
 
More nitrogen will slow down your shock shaft speed as the shock compresses. Slower shaft speeds will make your shim stacks /valving react differently. Fox does not recommend using nitrogen pressure as a tuning tool ( air shock excluded). When your shock is fully compressed, nitrogen pressure is well over the initial nitrogen PSI setting. I wouldn’t worry about damaging your seals at 175 PSI.
 
Cookie said:
Just a conversation and questions:

I run Triple Bypass Kings on my Funco gen 4, I always try to keep them at 150psi of Nitrogen, which I check every season.

My question, if you add 175psi, how does it change the performance? Not sure you can without doing damage to seals, but interested to know how this affects the shock's performance?

Another question, since I run airbags, would it change the performance to run Nitrogen instead of Air?
Click to expand...
What size shocks? I assume 2.5 with 2 compression and one rebound.

Just had Karl at Shock Talk redo my king 3.0's

Omg what a difference on my Funco.
 
All of the nitrogen is on top of the piston in the reservoir and just keeps the fluid under pressure. As the shock compresses the shaft displaces fluid and it goes into the wet bottom side of the reservoir. Changing the nitrogen pressure does change the stiffness of the shock in general but not because of the valving but rather because of the more or less resistance of fluid trying to move into the reservoir. Using the valving and/or bypass tubes is how the shock was engineered to dampen shaft movement not the pressure above the floating piston. If you want more dampening give the bypass adjusters another half or full turn at a time and retest, and which ones to adjust depends on if you want more compression or rebound dampening, bypass tubes are typically set up with the longest compression tube being near closed to act as a bump stop when it's near the end of it's travel. A good way to determine if your car needs adjustment is to film it driving over whoops and then go back and look at the video, you can get a good idea where an improvement can be made if you find the back wheels buck over the tops of whoops, you need more rebound dampening to slow the suspension movement down. Just the opposite on the compression if it rides harshly. I'm far from a suspension guy but I've played with mine enough to know what the tubes do.

And I do not like the idea of removing valving from the coil over shock, it places all of the dampening responsibility on the bypass and overheats the fluid unnecessarily.
 
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KLC said:
bypass tubes are typically set up with the longest compression tube being near closed to act as a bump stop when it's near the end of it's travel.
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Damping is fairly consistent throughout a bypass zone (assuming consistent shaft speed through the zone) and does not increase at the end of the zone other than the additional resistance created by the shock shaft displacing fluid. Tube placement in relationship to the end of the shock determines the bump zone and this is where the damping is solely dependent on the piston and shim stack.
 
That's all dependant on how open or closed the tubes are. I keep the longest tube closest towards the end of travel closed more than the short tube because I want the dampening from the valving so the shaft slows down and won't bottom out as easily. In other words my bypass shock gets much stiffer when the valve moves past the longest tube because the spring loaded bleed in the bypass is closed more than the short tube is.

I think we mean the same thing.
 
What's the complaint you're trying to address?


KLC said:
That's all dependant on how open or closed the tubes are. I keep the longest tube closest towards the end of travel closed more than the short tube because I want the dampening from the valving so the shaft slows down and won't bottom out as easily. In other words my bypass shock gets much stiffer when the valve moves past the longest tube because the spring loaded bleed in the bypass is closed more than the short tube is.

I think we mean the same thing.
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The longest tube is usually in the ride height zone, which most prefer to keep open as much as possible to allow the suspension to move on chop/chatter bumps. The short tube is usually just before the bump zone, and closing this tube will help the most on easing the transition to the bump zone and prevent bottoming with less impact on your back.

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Newer Kings have a lot more overlap on bypass tubes so they share more through the travel of the shock.
 
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