Low Tech DIY shock Nitrogen refill (1 Viewer)

[wedgetail]

Thinking about a set of rebuildable shocks - more for the long term economic gains than anything else although the ability to tune them, the mono tube advantage and performance levels aren't a bad thing either. Thinking Fox 2.0 IFP non RR but that's not what I'm posting about.

I don't then want to have to purchase all the gear (bottle, reg, connections etc.) to do the normal nitrogen refill route and no one within 5 hours fills them and even then they'd want a stupid amount (being australia). So why wouldn't this work:
-Get a bike shock pump
-Sort out the correct connector(s)o
-get a disposable nitrogen bottle, maybe even a few of the tiny ones
-get a big tough clear plastic bag, zip tie it over the pump leaving just the valve outside.
-push all the air out, fill the bag with nitrogen
-pump the shock up to the required pressure, maybe 200psi. Done

I'm sure I've seen reference to this method somewhere on the internet but I can find it again. 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. But I have seen a few references to people using bike shock pumps to check or reduce 4x4 shock pressure so they obviously fit up ok, and people sometimes discuss using them to fill but the reason they don't is due to it being straight air going in. But if the pump was in a nitrogen atmosphere rather than air it would only be pumping pure nitrogen in.

Have I missed something?

 

[maxamillion2345]

I don't see why it wouldn't work but I wonder how much work it's going to be. I'm not familiar with the bike shock pumps but I'd think filling a bike shock to 200 psi vs filling even a 12" fox 2.0 ifp shock to 200 psi might be a bit of a difference. Might be worth a try but I can see there being some trial and error and a lot of pumping to getting it all dialed in.

Can always mess with one with just regular air to see how hard it will be to get to your desired pressure.

 

[wedgetail]

Yeah I guess it would take a fair bit of pumping, but I reckon with the floor standing pumps it might not be too bad (although they would need quite a "bag"). I wonder how it would rate with using a foot pump to pump up a tyre...

Shouldn't be too much guess work as the bike pumps have a gauge. As I've currently got stock suspension but will go to 2" sometime in the future I'd be looking at 8" or hopefully 10" if I can work the compressed length in is not the biggest bodies out there. Also most people report they prefer the ride at less than 200, more like 150psi

 

[LandCruisinMy93]

I just bought Bilstein 7100's with remote reservoirs to try in the rear of the truck for this purpose. Interesting thought on nitrogen recharging. I don't think you're going to be able to get the pressure requirements from a bike pump, not sure the film hose itself is rated to a high enough pressure let alone the rest of the pump. I'd be interested to see it done though, that would be a lot more economical.

 

[LINUS]

Rent a little bottle of N2 & regulate down - Nitrogen is super common in the ~10# bottles now, esp since homebrew beer guys like me have it for our white trash kegerators ( use old 5 gal Corny kegs)

If I randomly do a stout I own a bottle & the fill is under $15, with state sales tax.

I doubt you need a bigger bottle / multiple fills as it comes in @ 2K psi in about a 2/3 cubic foot of volume.

 

[wedgetail]

I don't think you're going to be able to get the pressure requirements from a bike pump, not sure the film hose itself is rated to a high enough pressure let alone the rest of the pump. I'd be interested to see it done though, that would be a lot more economical.

Not talking about a bike tyre pump but a bike shock pump - it's specifically designed for shock pressures some with a max of 300psi some with 500. Only problem as noted is they're designed for a smaller volume so may take some pumping

Rent a little bottle of N2 & regulate down - Nitrogen is super common in the ~10# bottles now, esp since homebrew beer guys like me have it for our white trash kegerators ( use old 5 gal Corny kegs)

If I randomly do a stout I own a bottle & the fill is under $15, with state sales tax.

I doubt you need a bigger bottle / multiple fills as it comes in @ 2K psi in about a 2/3 cubic foot of volume.

Everything costs heaps more here than the US - just the annual rental and reg costs are way more than I want to pay. Hence the pump idea

 

[Pin_Head]

Air is nearly 80% nitrogen and the rest is mostly oxygen. Just fill it up with air and be done. The oxygen won't matter.

 

[woody]

Is Nitrogen Better than Air in Car Tires?

Correct, "air" is 78% nitrogen. 100% nitrogen is moisture free (no corrosion) and more stable at higher temps...which is the whole reason for spending the $$ on upgraded shocks that resist fade at those temps. If you are going to save $$ and fill your expensive shocks with air, save even more and buy cheaper shocks.

A bicycle shock pump will work well, provided you can purge the impurities. The volume on a rebuildable remote reservoir shock is negligible. However, you'd need to deal with a no-pressure pure nitrogen source...unsure if that's even available, or how you would make the connection.

I've got an old (discontinued) nitrogen kit from Rubicon Express. It uses a normal tank or the small 18# cylinders and works excellent. If you were in my area, you could stop by and I'll trade a you a shock fill for a 6-pack

You can make your own nitrogen fill setup for ~$150 (plus tank)...wish I could find the link offhand...hmmm

......edit...

NO-LOSS CHUCK 400# NITROGEN AIR SHOCK FILL TOOL BLEED VALVE FOX KING STRUT MX | eBay

$100 seems like a good price for what you are doing.

 

[Pin_Head]

Compressed air can be 100% water free too. Use a scuba air tank. The tiny bit of air isn't going to make any difference either. Pump them up and be done unless you are OCD. In that case you can use 100% argon or C25 welding gas.

 

[woody]

breezed thru a dozen threads on race-dezert on shocks...moisture free seems to be the key.

Question is: why does EVERY shock manuf ship their product with N2?

I know getting my N2 tank filled was a pain....no one local does it, had to ship it out and wait 2 weeks.

 

[Pin_Head]

Question is: why does EVERY shock manuf ship their product with N2?

It is because dry nitrogen is dirt cheap. If you come over to my work, I have two 160 liter dewars of liquid nitrogen on hand 24/7 and several 300 cu/ft bottles of nitrogen gas. The nitrogen bottles are about $10 a fill, which is enough to fill 50 tires or 1000 shocks.

 

[Springs505]

Question is: why does EVERY shock manuf ship their product with N2?

I agree with Pin_Head that cost is probably a factor here. A few advantages of nitrogen over air:
1. Nitrogen will not react with oil, seals, or metals like air (containing 20.9% oxygen and possibly water) will.
2. Woody is right about water. Water in a shock is a bad deal because of possible corrosion, but also because of the potential for cavitation during movement, which can cause pitting on the surfaces inside the shock. Over time, this could be a big downside of just filling up with from an air compressor.
3. Nitrogen molecules are larger than oxygen, and less likely to find a way past seals and out of the shocks...I don't think this is a major factor here, though since the difference in size is minimal.

Edit:Nitrogen is not Inert

 

[LINUS]

breezed thru a dozen threads on race-dezert on shocks...moisture free seems to be the key.

Question is: why does EVERY shock manuf ship their product with N2?

I know getting my N2 tank filled was a pain....no one local does it, had to ship it out and wait 2 weeks.

N2 is more stable as the temp change (theoretically that ~19.5% O2 is going to expand under heat / load cycles - but also as was mentioned above a side benefit for tire filling is the N2 molecule is bigger, and so that slim amount of missing O2 makes for "stable tire pressure at heat cycle" in addition to possibly not deflating as fast.

Really more a market gimmick for us guys who aren't doing laps at a track.

I never have run into an issue getting N2 - local weld shop has most all common gas in stock, or worst case scenario it's overnite from Seattle (I'm 75 miles N of there)

@wedgetail - But like all mentioned methods, I wouldn't have an issue with compressed air or any of the non-volatile gases. But if you are bucking up for shocks worth rebuilding, why chintz on a N2 fill since what, annual rebuilds at most?

Or are you using your 80 as a stop-gap until you get some Pro-4 or KOH worthy rig up & going?

Also, if homebrew beer is popular in your country, call a homebrew shop - N2 & CO2 are the gases we use (exclusively as I know, been at it awhile) - and home kegging is extremely common as it beats bottling for time, effort, work, etc.

I'm in the same camp as pin_head - I'd take dry atmospheric over non-desiccant N2 if I was in a bind for gas to install. But I'm just a ex-operating engineer, not a shock industry pro.

 

[normiex]

You can pick up a shock fill kit for about $190 bucks+P&H off ebay Fill_kit, a disposable nitrogen bottle, you will need an adaptor from the regulator to the tank which shouldn't be too hard to source. Just contact the bottle supplier and I think they would be able to point you in the right direction.

To do it with a bag over a hand pump you would have to buy a regulator because full pressure nitrogen into a plastic bag would freeze it so after you buy a pump, a fill tool as was posted earlier and a regulator (and maybe an adaptor) you find yourself doing a sketchy job for the same price or more.

ps. Just an FYI, Australia has a population density of 3.15 people per square km with 25 milion people, compared with USA with 33.01 people per square km with 325 million people. Sourcing things in Australia is a whole different ball game and deliveries are very rarely a matter of days here, anything under a week and I'm checking the order date to see if it's just a dream.

 

[wedgetail]

Yeah I've done a bit of reading on gases and would be happy with dry air or Argon. But N2 seems cheaper/easier to get and I use Argoshield (25% CO2) in the welder.

@wedgetail - But like all mentioned methods, I wouldn't have an issue with compressed air or any of the non-volatile gases. But if you are bucking up for shocks worth rebuilding, why chintz on a N2 fill since what, annual rebuilds at most?

Or are you using your 80 as a stop-gap until you get some Pro-4 or KOH worthy rig up & going?

Also, if homebrew beer is popular in your country, call a homebrew shop - N2 & CO2 are the gases we use (exclusively as I know, been at it awhile) - and home kegging is extremely common as it beats bottling for time, effort, work, etc.

I'm in the same camp as pin_head - I'd take dry atmospheric over non-desiccant N2 if I was in a bind for gas to install. But I'm just a ex-operating engineer, not a shock industry pro.

Well buying 2.0 smooth bodies from the US isn't SO expensive in the world of 4x4 shocks, although it is significant for me. But you're right it's not worth really scraping it with the gas, but I am looking at the viability of the whole thing at the moment.

I do have a confession though... It's a 105 not an 80. I've put it in this forum as the 100 forum is almost entirely 100s not 105s and in this case the 105 is far more like an 80 as it shares almost all chassis and suspension components. But it's certainly no stop gap - it's our family car that has to cope with a large diet of appalling roads often at high speed and with heavy loads doing about 50k km a year (about 13.5k of them on the said bad dirt roads) so the suspension is worth doing something with. Yeah people do homebrew, not so sure about the home kegging though... I might look into it.

You can pick up a shock fill kit for about $190 bucks+P&H off ebay Fill_kit, a disposable nitrogen bottle, you will need an adaptor from the regulator to the tank which shouldn't be too hard to source. Just contact the bottle supplier and I think they would be able to point you in the right direction.

To do it with a bag over a hand pump you would have to buy a regulator because full pressure nitrogen into a plastic bag would freeze it so after you buy a pump, a fill tool as was posted earlier and a regulator (and maybe an adaptor) you find yourself doing a sketchy job for the same price or more.

ps. Just an FYI, Australia has a population density of 3.15 people per square km with 25 milion people, compared with USA with 33.01 people per square km with 325 million people. Sourcing things in Australia is a whole different ball game and deliveries are very rarely a matter of days here, anything under a week and I'm checking the order date to see if it's just a dream.

Yeah I can see that would be the best method, but adds significant expense to the whole thing, and hopefully I won't even need it for a long time and then not often... To fill my proposed bag, could I not borrow one off a welder or oxy? Even if it meant getting an adaptor for a bottle. Or just use a tiny disposable and let it off in there, even if it freezes it will soon melt and boil off.

Yeah sourcing and supply is fun here compared to the US or even UK. We only get post twice a week and when it rains not at all - couriers don't even come to our local "town" bar star track so getting stuff delivered takes a lot of negotiation... Wouldn't live anywhere else but

 

[Hornd]

I agree with Pin_Head that cost is probably a factor here. A few advantages of nitrogen over air:
1. Nitrogen is inert and will not react with oil, seals, or metals like air (containing 20.9% oxygen and possibly water) will.
2. Woody is right about water. Water in a shock is a bad deal because of possible corrosion, but also because of the potential for cavitation during movement, which can cause pitting on the surfaces inside the shock. Over time, this could be a big downside of just filling up with from an air compressor.
3. Nitrogen molecules are larger than oxygen, and less likely to find a way past seals and out of the shocks...I don't think this is a major factor here, though since the difference in size is minimal.

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.

 

[Pin_Head]

N2 is more stable as the temp change (theoretically that ~19.5% O2 is going to expand under heat / load cycles - but also as was mentioned above a side benefit for tire filling is the N2 molecule is bigger, and so that slim amount of missing O2 makes for "stable tire pressure at heat cycle" in addition to possibly not deflating as fast.

All gasses expand and contract the same according to temperature. That is why there is a "universal" or "ideal" gas constant relating temperature to pressure. It is the R in the famous gas equation:

pV = nRT

Where p is pressure; V is volume and n is the number of gas molecules; R is the gas constant and T is the temperature.

Oxygen (O2) is 32 Daltons molecular weight while Nitrogen (N2) is slightly smaller at 28 Da.

 

[coax]

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.

Edit: more info here if interested : Fox Shox 2.0's Are On!

 

[LandCruisinMy93]

Oh wow!! I know I'm not on here a whole lot anymore but I don't think I've seen @woody chime in on a conversation in a long while. You know your post is interesting when the man himself chimes in.

 

[LandCruisinMy93]

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.

That is a really interesting idea and some good info. Never seen one of these before.