Low Tech DIY shock Nitrogen refill

[Hornd]

If you are shooting for something fairly cheap....just get a bicycle CO2 cartridge tire inflator, and then order some of the Nitrogen cartridges from morebeer.com. You need ~3 cartridges per 2.0 RR shock. So for under 50 bucks you have a setup to charge them, and can also be taken on longer more remote expeditions for trail repairs.

I guess all depends on how many times you think you'll be tearing into your shocks...I think my whole nitrogen bottle/regulator setup was less than 200 bucks.

Are your remote reservoirs steel or aluminum? If aluminum and on a day when the humidity is very low, I might be tempted to just use air and a pump. But at 24 bucks with the little nitrogen cartridges per refil of all 4 shocks, its not horrible.

I carry this one in my trail tools and used it on a trip to South America where finding a shop to charge shocks was near impossible. The inflator works really well; just threads right on to the shrader valve on the shocks, pull the trigger and it inflates.

and these 1.8g Nitrogen cartridges: 2 cartridges get a fox 2.0 remote res 8" up to about 160psi...2.5 cartridges get it up to about 200 psi.

Now you have added CO2 to the mix which is corrosive, I would stick with Nitrogen.
I use a very similar CO2 Cartridge with food grade canisters ($1 each on ebay) to pressurize my beer cans (5 gallon) when I mobile party.
Food grade cylinders omit the oil, that the BB Gun Cannisters at store have.

 

[Nay]

If you are shooting for something fairly cheap....just get a bicycle CO2 cartridge tire inflator, and then order some of the Nitrogen cartridges from morebeer.com. You need ~3 cartridges per 2.0 RR shock. So for under 50 bucks you have a setup to charge them, and can also be taken on longer more remote expeditions for trail repairs.

I guess all depends on how many times you think you'll be tearing into your shocks...I think my whole nitrogen bottle/regulator setup was less than 200 bucks.

Are your remote reservoirs steel or aluminum? If aluminum and on a day when the humidity is very low, I might be tempted to just use air and a pump. But at 24 bucks with the little nitrogen cartridges per refil of all 4 shocks, its not horrible.

I carry this one in my trail tools and used it on a trip to South America where finding a shop to charge shocks was near impossible. The inflator works really well; just threads right on to the shrader valve on the shocks, pull the trigger and it inflates.

and these 1.8g Nitrogen cartridges: 2 cartridges get a fox 2.0 remote res 8" up to about 160psi...2.5 cartridges get it up to about 200 psi.

How are you then measuring the PSI without losing some during the check?

This seems like a simple solution if it can be done accurately and you just need to boost PSI vs. a full oil and seal rebuild.

 

[coax]

Now you have added CO2 to the mix which is corrosive, I would stick with Nitrogen.
I use a very similar CO2 Cartridge with food grade canisters ($1 each on ebay) to pressurize my beer cans (5 gallon) when I mobile party.
Food grade cylinders omit the oil, that the BB Gun Cannisters at store have.

I don't use the CO2 cartridge...just the inflator I use pure nitrogen cartridges in the C02 inflator as they are the same physical size. And I hope that since I ordered them from a brewing store they are food grade and have no oil, just pure nitrogen.

http://morebeer.com/products/nitrogen-cartridge-18g.html

How are you then measuring the PSI without losing some during the check?

This seems like a simple solution if it can be done accurately and you just need to boost PSI vs. a full oil and seal rebuild.

I did a bit of testing with a fox rear shock pump for a bicycle. Put in one cartridge, measured...put in the second, was at about 160. Then just a few blasts to get about half a cartridge on the third. Worst case is you go a bit over and then let out a tiny bit with the pump (its got a small button on it to make fine adjustments). I typically use my full nitrogen bottle for my maintenance and only carry the cartridges for trail work if it was ever needed for a blown seal or something.

The point you raise is a very valid one...if using the small cartridges for your routine maintenance or adjustments, you'd have to factor in some sort of gauge to the cost (or borrow one to do some testing with the specific shocks to get your pressure correct). You would lose a tiny bit of pressure in the test, but at least with the shock pump the volume of the hose to the gauge is pretty small as a percentage compared to the size of the reservoir that is being pressurized.

 

[coax]

I also remember seeing the start of a thread where someone puts a kit together for doing his shocks "on the trail" including the tiny disposable nitrogen cartridges and a shock pump but I must have spent an hour searching and can't find it either. ?

Not sure if this is what you might have seen, but I posted more info on the trail tools/cartridges when I was researching an option in Nakman's thread here:
Fox Shox 2.0's Are On!

I did a rough calculation of how many cartridges it would take to get to the pressure I wanted based on the volume I was filling. It was accurate-ish. I didn't account for the fact that I had the shocks mounted and therefor halfway compressed, or accounting for altitude. At the end, 2-3 cartridges gets you to a usable shock with minimal cost or overhead.

 

[Springs505]

Nitrogen is not Inert but in this application your correct:

Nitrogen gas is slightly lighter than air and slightly soluble in water. It is commonly thought of and used as an inert gas; but it is not truly inert. It forms nitric oxide and nitrogen dioxide with oxygen, ammonia with hydrogen, and nitrogen sulfide with sulfur.

You are right. The important thing is that nitrogen does not react with the materials inside the shock.

 

[NLXTACY]

After doing my training over at King I learned some interesting things. Having a FULLY rebuildable shock is pretty bad ass but you pay for it. I got to see the internals of "other" shocks and it's absolutely apparent where developments diverge.

But, it was interesting that the shocks use so little nitrogen to charge. It's high pressure but very low volume. All you need to do is touch the Schrader valve for ONE second and the entire charge is gone. One quick Pfffft and done. Also, using something like a hand pump to fill the shocks doesn't account for the pressure in the hose to the piston. I got to see that there was a 30-40# charge difference between using a hand pump and the actual nitrogen service tools they use. It's a huge difference in overall performance.

Next I got to see firsthand why they use Nitrogen and it's already been discussed. It's inert, doesn't react with oils, metals, other gases in the shock. Best of all is dry Nitrogen is just that, dry.

It was easy to tell which shocks, that came back from customers, where they said F it and went with just gas station air. The corrosion/pitting was evident.

So what did I do? Went to Praxair and bought a $25 5# bottle and a $115 Nitrogen regulator kit. Done. It'll last a long long time and if I really needed to I could fill my wife's stupid Lexus tires as needed.

 

[Nay]

I don't use the CO2 cartridge...just the inflator I use pure nitrogen cartridges in the C02 inflator as they are the same physical size. And I hope that since I ordered them from a brewing store they are food grade and have no oil, just pure nitrogen.

http://morebeer.com/products/nitrogen-cartridge-18g.html



I did a bit of testing with a fox rear shock pump for a bicycle. Put in one cartridge, measured...put in the second, was at about 160. Then just a few blasts to get about half a cartridge on the third. Worst case is you go a bit over and then let out a tiny bit with the pump (its got a small button on it to make fine adjustments). I typically use my full nitrogen bottle for my maintenance and only carry the cartridges for trail work if it was ever needed for a blown seal or something.

The point you raise is a very valid one...if using the small cartridges for your routine maintenance or adjustments, you'd have to factor in some sort of gauge to the cost (or borrow one to do some testing with the specific shocks to get your pressure correct). You would lose a tiny bit of pressure in the test, but at least with the shock pump the volume of the hose to the gauge is pretty small as a percentage compared to the size of the reservoir that is being pressurized.

Makes sense - thanks for the info.

 

[wedgetail]

Not sure if this is what you might have seen, but I posted more info on the trail tools/cartridges when I was researching an option in Nakman's thread here:
Fox Shox 2.0's Are On!

I did a rough calculation of how many cartridges it would take to get to the pressure I wanted based on the volume I was filling. It was accurate-ish. I didn't account for the fact that I had the shocks mounted and therefor halfway compressed, or accounting for altitude. At the end, 2-3 cartridges gets you to a usable shock with minimal cost or overhead.

Thanks mate yep that's the one - didn't realise it was right under my nose, I was looking for a dedicated thread. Great idea though, just needs calibrating but an ingenious method I think. Wasn't even aware of those inflators.

Either way it looks like I'll be able to come up with a cost effective way of filling them. Just gotta bite the bullet now...