How are you determining the positive chamber is losing pressure? By putting the gauge back on or is it a change in fork performance?
Air Leak when compress/decompress
I have a SID and I was checking the air chambers the other day - when i pressurize them and let the fork sit on its own they hold air fine. However if I cycle the fork the positive chamber looses pressure. What does this indicate?
thanks.
thanks.
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i put the pump back on it the next day for some other reason. and the pressure went from 150 down to about 40.
Prior to cycling the fork I had pumped each chamber up and left the pump attached - no loss when the fork is resting.
Prior to cycling the fork I had pumped each chamber up and left the pump attached - no loss when the fork is resting.
when i remove the pump i lose 5 PSI in the positive chamber and 20 in the negative chamber. Maybe you removed your pump too slowly.
What I was thinking but wasn't sure what symptom caused the conclusion...and still not sure. What happens when you ride the fork after setting pressure?
My SID holds the pressure perfectly, the only loss in PSI is when i remove my pump. If i put it back on 10 seconds after i put air or 1 week it's still the same pressure. Try to put more air than you want and to remove your pump quickly, you should get used to it.
If it's actually losing air only when you ride it, that makes me think maybe the air piston o-rings are dry, so it could be quick and easy to test by adding some oil to the air chamber. Check the service manual for the oil volume and type, I think RS calls it Red Rum, which I think I've heard is the same as Torco assembly lube?jbsmith said:I have a SID and I was checking the air chambers the other day - when i pressurize them and let the fork sit on its own they hold air fine. However if I cycle the fork the positive chamber looses pressure. What does this indicate?
thanks.
I'm with fsrxc on this one. I think it's likely that you have some O-rings that are in need of lube, or perhaps need to be replaced.
I was seeing a migration in pressure from the positive to negative chamber on my dual air Pike. I overhauled the air spring cartridge, replacing all O-rings. (There's a kit for this.) It took maybe two rides for the new seals to bed in, but now the problem seems to be solved.
With regard to checking air pressure, you'll lose air into the hose, and get an inaccurate reading, if you screw the shock pump's fitting all the way onto the valve.
You can get a more accurate reading by screwing the fitting part way on, just to the point where it's screwed on enough so that you can pump air into the hose without it leaking out... you can then pressurize the hose to a point near to that of the expected air pressure inside the fork (or rear shock). Once you've pressurized the hose, you can then continue screwing the fitting on until the valve opens. As soon as the valve opens, the shock gauge needle will jump a little bit. Assuming that the jump is indeed small, the reading you obtain on the gauge will be a lot more accurate than if you had not pre-pressurized the hose.
I was seeing a migration in pressure from the positive to negative chamber on my dual air Pike. I overhauled the air spring cartridge, replacing all O-rings. (There's a kit for this.) It took maybe two rides for the new seals to bed in, but now the problem seems to be solved.
With regard to checking air pressure, you'll lose air into the hose, and get an inaccurate reading, if you screw the shock pump's fitting all the way onto the valve.
You can get a more accurate reading by screwing the fitting part way on, just to the point where it's screwed on enough so that you can pump air into the hose without it leaking out... you can then pressurize the hose to a point near to that of the expected air pressure inside the fork (or rear shock). Once you've pressurized the hose, you can then continue screwing the fitting on until the valve opens. As soon as the valve opens, the shock gauge needle will jump a little bit. Assuming that the jump is indeed small, the reading you obtain on the gauge will be a lot more accurate than if you had not pre-pressurized the hose.
Thanks for the insight guys. I am geting ready to put enduro seals on it because it has been leaking oil at the stanchions. Sounds like It may not have enough or any at this point (it has been sitting for a while too), so when I redo the seals, i will replace the oil and see if that fixes the issue. If not I will get a seal kit and redo the seals.
thanks.
thanks.
Be aware that stanchion oil seals/wipers are not the same thing as the air spring o-rings and seals. If you are planning to replace the oil seals, while you have the lowers off is a good time to service the air spring with an o-ring kit like was mentioned above.jbsmith said:Thanks for the insight guys. I am geting ready to put enduro seals on it because it has been leaking oil at the stanchions. Sounds like It may not have enough or any at this point (it has been sitting for a while too), so when I redo the seals, i will replace the oil and see if that fixes the issue. If not I will get a seal kit and redo the seals.
thanks.
It would be good to read the service manual for your fork, so you understand the parts and work involved before starting the job.
thanks fxrc...i do understand that the stanchion seals are not the same as the air spring seals.
I just recieved the enduro seals today and Kevin at suspension experts (they do great work) said he can rebuild the shock and install the enduro's if i send them to him with the fork.
I am leaning toward suspension experts because a) after reading and reading I dont know that I have the correct tools to get into the air spring and damper to do a good rebuild. b) if the bushings are bad, I know I dont have a good way to replace those. c) I have worked with Kevin before and he runs a tight ship at Suspension Experts - good prices, excellent work, fast turnaround.
I just recieved the enduro seals today and Kevin at suspension experts (they do great work) said he can rebuild the shock and install the enduro's if i send them to him with the fork.
I am leaning toward suspension experts because a) after reading and reading I dont know that I have the correct tools to get into the air spring and damper to do a good rebuild. b) if the bushings are bad, I know I dont have a good way to replace those. c) I have worked with Kevin before and he runs a tight ship at Suspension Experts - good prices, excellent work, fast turnaround.
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