Using dried compressed air in place of Nitrogen in gas filled shocks

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As we are well aware or become so, refilling the gas reservoir in shocks can be a P.I.T.A. Building a nitrogen refill kit, buying a rated cylinder, and filling it with nitrogen can get a little expensive for some. I have gone into quite a few forums to get the pros and cons concerning dried compressed air versus nitrogen. For the most part, those who are anti-DCA go on about how nitrogen handles heat generated by repeated compression and ambient temperature changes better than DCA, as well as prolonging the longevity of the seals used in shocks. From what I have read, the gas used in shocks is there for preventing the oil from cavitating, that is making tiny little bubbles that change the way the oil reacts to being compressed. The conversations then led to the more scientific. Boyles Law was discussed, how a gas reacts to pressure, heat generated, and the dissipation of that heat. The difference between heat generated and dissipation between the two gases is slight. It got deeper still, one poster discussed ionic, valent, and covalent bonds of the two. I am assuming that has to do with electrons being "stripped" off and allowing the gas to pass through the bladder to dilute the oil. Having been presented with all this information I have been drawn to the conclusion that the only reason nitrogen is used as the gas in shocks is because of the dryness and being an inert gas. Atmospheric air is for the most part nitrogen and a smaller percentage of oxygen as well as other gases. The main culprit in atmospheric air is moisture, if the moisture is removed that air could be used in place of potentially expensive nitrogen. I have found desiccants for compressed air systems used to remove moisture in the automotive painting industry. I went to the apex of cheap, Harbor Freight, and found quite a few air driers, priced from $3.99 for an inline air drier to $30-plus for moisture and oil removal filters. What do you all think? Viable or not?

I forgot to mention why the in-depth post, I have just purchased new shocks for my rappy and checked them to make sure the reservoirs were in fact filled, surprise, surprise, nothing.
 
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This is the set-up I was able to put together. Going from left to right, the first filter is an oil/debris filter, next is the desiccant/moisture remover, lastly is a particulate filter. I need to find a method to measure the moisture content of the filtered compressed air. Some type of humidity gauge I believe would work.
Total cost $72
fittings 12.00
1 coupling 3.99
single filter 5.98 (opened box discount)
moisture/oil filter 39.97 (clearance price)
pistol style inflator max 300psi 9.95
I need a no-loss coupler.
lots cheaper than a nitrogen filling kit.
 

beastlywarrior228

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It's worth a shot. I always believed nitrogen was used as its molecularly larger and oxygen has a tendency to permeate through and degrade rubber.
 
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That is a good point. Oxygen is catalyst and is reactive when in contact with a number of other elements. However, the bleed through, due to the relative difference in molecular size would be, in my opinion, slight. Both the viewpoints would have trouble being proven true or false without a proper testing process for that matter. I have called dealerships, gas suppliers, tire stores to name a few avenues I went down trying to find anybody that refills shocks. I did find out that Costco provides free nitrogen for tires but the max pressure provided is 80psi. Just doing a quick search of "home nitrogen refill stations " was eye-opening. Tanks start around 100.00 , a certified gauges can run higher still. Nitrogen is 6-8 dollars a pound, not including the cost for the rest of the gear. I am just trying to solve a problem as cheap as possible. I am looking for a way to measure the moisture in the filtered compressed air. Let's see how it works out. Any input would be appreciated, pro or con.
 
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One more thing, I got a reply to an email that I sent to the shock seller. I mentioned that the shocks had zero nitrogen gas .
This was their reply, " We spoke to our supplier, he said for you to use bicycle air pump that will make them work."
WTF, I paid for nitrogen in the shock not " bicycle pump air". Long story short, I lodged a complaint that ended with a full refund. They wanted the shocks returned and my reply was "If they told me to " just use bicycle pump air" then they can " just call an uber and come to my house to pick them up." Seller declined. So I have a set of shocks that are the no cost guinea pig for this experiment. The seller was in China. Hella uber fare.
 

beastlywarrior228

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One more thing, I got a reply to an email that I sent to the shock seller. I mentioned that the shocks had zero nitrogen gas .
This was their reply, " We spoke to our supplier, he said for you to use bicycle air pump that will make them work."
WTF, I paid for nitrogen in the shock not " bicycle pump air". Long story short, I lodged a complaint that ended with a full refund. They wanted the shocks returned and my reply was "If they told me to " just use bicycle pump air" then they can " just call an uber and come to my house to pick them up." Seller declined. So I have a set of shocks that are the no cost guinea pig for this experiment. The seller was in China. Hella uber fare.
I hope it wasn't a set of the cheap Chinese shocks? I don't blame you, I wouldn't have been happy if they told me to use a bike pump either.
 
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Welllllll, the shocks are in fact Chinese, they were not the 30 bucks "lipstick on a pig" Chinese shocks, about 150 for the pair. I filled them up with dried air to 130psi using a 25.00 no-loss chuck.The desiccant is pulling the moisture out really well. So far, let's see how far, they are not bad. good travel handles all the limestone rocks we have in Central Texas pretty well. We shall see how long they last, I needed to replace the original shocks badly. I think the OEM shocks are rebuildable, not sure. I am having a tough go finding a rear shock. The one that is on it, has a reservoir with a Phillips screw in it , I am nervous about messing with it. It has a little sag, not much but I need to replace it. Any advice I am having fits trying to find one
 

beastlywarrior228

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Welllllll, the shocks are in fact Chinese, they were not the 30 bucks "lipstick on a pig" Chinese shocks, about 150 for the pair. I filled them up with dried air to 130psi using a 25.00 no-loss chuck.The desiccant is pulling the moisture out really well. So far, let's see how far, they are not bad. good travel handles all the limestone rocks we have in Central Texas pretty well. We shall see how long they last, I needed to replace the original shocks badly. I think the OEM shocks are rebuildable, not sure. I am having a tough go finding a rear shock. The one that is on it, has a reservoir with a Phillips screw in it , I am nervous about messing with it. It has a little sag, not much but I need to replace it. Any advice I am having fits trying to find one
The rear shock is rebuildable. If you can find a banshee rear it's a good upgrade.
 

beastlywarrior228

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Nope any year banshee. You just need to heat up the airbox and put a dent in it or trim the bottom to make room for the reservoir.
 
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thanks, I found a suspension shop that can rebuild my rear shock. Going to meet with them today to check on the price. The shock should be the last bit of neglect left to correct. The next project is getting to know about the carb before messing with it. It runs well now, so I will get more familiar with the fuel delivery system.
 

beastlywarrior228

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thanks, I found a suspension shop that can rebuild my rear shock. Going to meet with them today to check on the price. The shock should be the last bit of neglect left to correct. The next project is getting to know about the carb before messing with it. It runs well now, so I will get more familiar with the fuel delivery system.
The carb is easy. I can help with that.
 
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The carb is easy. I can help with that.
whats up?
I bought another raptor, an 06 grey plastics, 350, with a tusk adjustable rear axle. it has balls , runs well. i am designing a graphics kit for it to jazz it up a bit. i did not go back to the shock shop, but i am looking around for a banshee shock. they are kind of pricy, rebuild or replace?
As for the carb. I cleaned it and rebuilt it back to what was in it. 90 main, 42.5 slow. if my memory is correct.
the white raptor has a 4.1 FMF exhaust header on back. grey is stock header, with what sounds like an old glasspack exh. . My big bore for my chino 250 arrived. waiting for my buddy to assist since he has done it before as i have not. while working on my bear tracker doing valve clearance, i saw that it was out of time so i tried to rotate the chain on the cam sprocket and now i have to retime it. lots on my plate. I am going to sell one of the raptors do not know which.
 

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you never use compressed air for a number of reason. Many shocks require more PSI than a home compressor will put out anyways.
 
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you never use compressed air for a number of reason. Many shocks require more PSI than a home compressor will put out anyways.
I respectfully disagree, my shocks need 140psi, with the no loss valve attached it takes 2 quick blasts and I am at 140psi. I filter the air and remove the moisture before filling up my shocks. My set-up works very well.
 
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