JVAB Xratty Coilovers - Gas Pressures?

So - being curious and clueless, what N2 gas pressure is run in the JVAB Xratty coilovers (rear, specifically)? Also - what effect does the gas pressure have versus spring rate and valving?

Also - is the gas pressure something that should be "topped off" occasionally (I have the tool and N2 to do it)? I know you can't really "check" it without altering it, so...

Gas pressure is a function of how much sugar you put in your coffee and how much pork and beans you eat..
I've know guys which seemed to like real high gas pressure. Tomas Pettersson
my neighbor on Hagvägen in Upplands-Väsby who worked at Öhlins Mekaniska back when Öhlins was first gearing to to make shocks always seemed to like a lot of gas pressure.
In fact it was hard to ride in the car or van for very long distance because he'd let loose with the vilest, loudest most disgusting farts, smile and say ''Aaaah, gas shocks''
Yeah it was we who were in shock!
Seriously we'd be opening the windows in 10*F weather
Goddamn..(there had to be something wrong with the poor guys gut flora cause we all ate the same thing..Or something crawled up there and died)

But anything from 80 to 200psi is OK....you will never notice the difference.
I tended to set shocks around 160-175 when I did the whole builds..and had good tools.

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

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john vanlandingham
But anything from 80 to 200psi is OK....you will never notice the difference.
I tended to set shocks around 160-175 when I did the whole builds..and had good tools.

Like John said. We set them at 185 during a damper service, along with most monotubes. But they are still OK down to 80psi or so.

How does gas pressure change the damper? It doesnt really change the damping much on inverted, big-body shocks. But if you have a non-inverted strut (22mm shaft), or dampers with big shafts and have a relatively small volumn oil cavity, you can introduce a "gas spring" into the damper. This is something we commonly do with Motons for SCCA stock class autocross. And the higher the initial pressure, the higher the gas-spring rating.

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Jason McDaniel

It is worth mentioning the high the pressure the oil is "under" the higher the boiling point will be. keep the pressure on the higher end to reduce foaming. My Ledas were recommended to be at 10 bar~ 147psi.

Werd up. Thanks, all. I'll be careful with the pork 'n' beans too

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BJosephD
It is worth mentioning the high the pressure the oil is "under" the higher the boiling point will be. keep the pressure on the higher end to reduce foaming. My Ledas were recommended to be at 10 bar~ 147psi.

Uh, no.
Faoming--or aeration can only occur is there is some air-or gas to MIX with the oil to make er uh FOAM...
The deviding or floating piston means there is oily oil where the working piston is.

I have gotten shocks so hot that the rods---ya know the 10 or whatever mm rod that is chrome turned straw to blue from heat---no foaming. No fade.

( I couldn't believe I had blued the steel and wondered if there was some film of oil or something....so I stuck my finger tween the coils and touched the rod. PSSSST! You could see the smoke come off my finger.
Insta-burn...big ugly blister...)

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

My bad, sorry about the blister, sounds like it hurt. would you like to hear about my injuries? we could go back and forth

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john vanlandingham

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BJosephD
It is worth mentioning the high the pressure the oil is "under" the higher the boiling point will be. keep the pressure on the higher end to reduce foaming. My Ledas were recommended to be at 10 bar~ 147psi.

Uh, no.
Faoming--or aeration can only occur is there is some air-or gas to MIX with the oil to make er uh FOAM...
The deviding or floating piston means there is oily oil where the working piston is...

Well, that's sort of true. But in reality there is plenty of plain "air" disolved in the oil. And a good run on the dyno with negligable nitrogen pressure will show it pretty quick. In fact the best demo I've seen is the same shock run on the dyno without any changes except nitrogen pressure. Without pressure it foamed very quickly, and with pressure it did not foam.

If you ever want to see this disolved air, do what we do. After pouring the oil in the shock body, but before putting the piston and shaft in, we stick a sealed lid on the body and apply a vacuum. The air bubbles magicly appear in the oil, like a beer poured in a glass, and the bubbles rise to the top and leave the solution.

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Jason McDaniel