Air vs nitrogen rear shock

[mog]

Actually that isnt correct all gasses expand with heat , it's called Boyles law ?

 

So say you use 145 psi and you get the shock hot and measure it ,it will be at around 175psi 

 

This is partly down to the oil also expanding at it gets hot ,it's a fixed volume system and when you hear it ,the pressure goes up ,thus makes the compression harder ( but the oil thins) and the rebound will increase the most ,as the pressure is higher and the oil is thinner 

 

But dry air and nitrogen the difference is small 

[turbo dan]

On 4/29/2020 at 8:40 AM, RacingDVD said:

Sure, but it is a valid question why WP would use air in de forks and nitrogen in the shock.

I imagine people would riot if the manufacturer required nitrogen in the forks.

 

[William1]

Dry air is fine. Nitrogen from a bottle is inherently dry. I also recall there is less leakage through the bladder when using nitrogen but... air is what, 70% nitrogen naturally. The big issue is moisture and how water expands when hot. Pollutants too in the air can cause bladder failure ('Dry Rot') though I've never seen it.

You can 'dry your air' by using a compressor and a portable air bottle. Run your compressor, drain off any water. Now fill you air bottle, passing the compressed air through a dryer medium (dessicant) and filling the bottle. You can get a moisture level under 1% this way.

[DEMI]

Some very reputable folks in this thread... I have N2, but used Air in the past with no issues. Mention this in other forums and the pitchforks come out. 

[turbo dan]

Just now, DEMI said:

Some very reputable folks in this thread... I have N2, but used Air in the past with no issues. Mention this in other forums and the pitchforks come out. 

Tell them about using ATF instead of $30 a can suspension oil.  That'll really piss em off.

[DEMI]

Just now, turbo dan said:

Tell them about using ATF instead of $30 a can suspension oil.  That'll really piss em off.

Haha...exactly. Whaatttttt? No!!!

[Turboloader]

On 4/27/2020 at 9:16 PM, tsorpi said:

it would make big difference for an average rider if you put air instead of nitrogen in the bladder of the rear shock?

What does the shop manual call for? Air or nitrogen? When in doubt, do as the manual tells you to do....

[mog]

So we must use motorex oil ,nothing else 

[rjg]

I put 139psi of air into shock reservoir and it rises to 147psi when hot.  Works good enough for me, no complaints. 

[Moar Rotella]

Thanks everybody.  I have two shocks I have been wanting to rebuild, but could not find anywhere local to get them nitrogen filled.  I had done some research on home filling, but decided against it as it was going to cost about 300 dollars (as I remember) which seemed like a total waste for two shocks.

[Smoking 2's]

1 hour ago, Dixon Cider said:

Thanks everybody.  I have two shocks I have been wanting to rebuild, but could not find anywhere local to get them nitrogen filled.  I had done some research on home filling, but decided against it as it was going to cost about 300 dollars (as I remember) which seemed like a total waste for two shocks.

As said I use a fox air pump but before that the scuba shop would fill them if you have one of those around and need nitro

[rebelbanshee]

Used fox air pump for a few years now.  No problems, and waaaaaaaaay cheaper than any other option.

[GP]

On ‎4‎/‎30‎/‎2020 at 9:34 PM, Smoking 2's said:

As said I use a fox air pump but before that the scuba shop would fill them if you have one of those around and need nitro

I've spent years diving shipwrecks, working on a dive boat, in a shop on gear, and mixing breathing gas.  Never saw a need to have HP N2, that's what you get from air.  That said, good point though, if you have a SCUBA tank to fill, air quality doesn't get much better.  Plus, in many cases, the regulator 1st stage can be tuned for the correct pressure.   I now work for an industrial gas co so have an N2 setup.

[William1]

N2 can also be had at most tire shops. They upsell customers on N2 fills.

[mog]

Some won't go to 142 psi though 

[Smoking 2's]

2 hours ago, GP said:

I've spent years diving shipwrecks, working on a dive boat, in a shop on gear, and mixing breathing gas.  Never saw a need to have HP N2, that's what you get from air.  That said, good point though, if you have a SCUBA tank to fill, air quality doesn't get much better.  Plus, in many cases, the regulator 1st stage can be tuned for the correct pressure.   I now work for an industrial gas co so have an N2 setup.

Well then not sure why he had, he is also a fire fighter so maybe had something to do with extinguishers or something, I recant my scuba shop ideal 

[William1]

2 hours ago, mog said:

Some won't go to 142 psi though 

They all do. They have liquid nitrogen. They just need to open the regulator.

[DEATH_INC.]

10 hours ago, William1 said:

They all do. They have liquid nitrogen. They just need to open the regulator.

We don't, we have a machine that filters it from the air. It won't fill a shock...I tried. I think the lack of volume confuses it, it throws an error without doing anything.

[mog]

10 hours ago, William1 said:

They all do. They have liquid nitrogen. They just need to open the regulator.

I've asked some won't , they don't like the idea of it 

[willie]

Nitrogen is an inert gas and is much preferred  over air for pressure vessel fill or purging applications. Air contains 78 % nitrogen 20.9 % oxygen and remainder is carbon dioxide and a variety of trace compounds. The oxygen by itself or combined with trace elements may corrode (oxidize) or degrade the internal components over time. Dry air may be fine but nitrogen leaves no doubt .