Gas Shocks

[lhanscom]

I have a 3 wheeler with a nitrogen charged rear shock, and I'm wondering what the gas does? More specificly when you know it needs to be recharged. Currently it doesn't feel like much damping is going on at all. Would a recharge fix this? TIA

[Anonymous]

The nitrogen is used to prevent the oil foaming up with air. The oil and nitrogen are separated by a piston which keeps them from mixing and the nitrogen compresses as the shock is compressed and expands as the shock extends. This eliminates the need for an air space over the oil to accommodate travel and keeps the oil from foaming, providing more consistent damping.

The nitrogen would need to be recharged only if it has leaked out. The only way to tell is to measure the pressure. Aftermarket shocks typically have a Schraeder valve somewhere on the body (or on the reservoir if it has one) that you can use to check pressure and top it up if needed. OEM shocks often don't have a valve and the only way to access the nitrogen chamber is to drill a hole into it and let it bleed out, then tap in a valve to recharge it. Normally, you would never need to recharge the shock in between rebuilds.

If you have no damping, then your oil has degraded to the point where its viscosity is too low to do any good. It will need to be torn down and rebuilt with new seals and oil or replaced with a fresh unit to restore the damping.


Mark

[lhanscom]

Thanks for the reply, are typical mono shocks something that the home mechanic can rebuild, without special tools?

[Anonymous]

Thanks for the reply, are typical mono shocks something that the home mechanic can rebuild, without special tools?

Not normally. You require some "special" tools that you can make yourself or buy and some knowledge of how the shock is put together before you take it apart. Without the equipment or knowledge, you would be better off having a shop do it for you. Locally I can get an OEM shock rebuilt (oil and seal change, no valving alterations) for $40CDN plus parts, which is cheaper than I can make the tools, so I don't worry about it.

Check around for a local suspension tuner who can do the rebuild or check out Race Tech (http://www.racetech.com) for a mail order option.


Mark