Edited by hewson, 29 January 2012 - 06:44 PM.
Falcon Rear Shocks
Posted 29 January 2012 - 06:27 PM
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Posted 29 January 2012 - 07:19 PM
The gas in them is nitrogen not air, and unless you drain the intact one you won't know how much oil should be in there.
I would return them to Robin, you will get a rebuild with new seals etc fresh oil and a recharge of nitrogen. I would get some proper brass hexagonal Schrader caps and do them up with a spanner. Or amputation at the wrist would also do it ;-)
Posted 29 January 2012 - 08:57 PM
Posted 29 January 2012 - 09:42 PM
There's no membrane in the trials shocks Lee, oil and gas sit in the same chamber. If you touch the valve stem even for a split second, oil will come out with the gas. They are different from motocross shocks.
They are straightforward enough to take apart and refill with oil. I can't remember the quantity but you can get it through trial and error. You won't have lost too much through the valve. Removing the damper rod assembly is a bit fiddly as you need to tap off the seal holder carefully with a drift of some sort as it doesn't screw in, it's a press in fit. Then you need long nose circlip pliers to reach the second circlip which is down inside the body, the first circlip is right at the top.
At a guess, as it's a long time since I did mine, top up the oil level to about 3/4 full. Then refit the damer rod, turn the shock upside down (as it sits on the bike) and push the damper rod in. There shouldn't be any free play caused by not enough oil and the piston travelling though an air gap, nor should the piston hydraulic lock through too much oil. It's trial and error getting the level right but doesn't take too long.
You can fill with air, it doesn't have to nitrogen in a trials shock,they work ok with air. A mountain bike shock pump from Halfords for £25 works fine. They require 90psi.
If you phone Falcon, he'll probably tell you the oil quantity if you ask.
Posted 29 January 2012 - 09:55 PM
Oil can be replaced by releasing the gas pressure with the valve as high as possible (to minimise the amount of oil that comes out with the air).
The valve body can then be unscrewed from the shock body and the remaining oil drained out the hole that the valve body came out of - no need to disassemble further.
When all oil is drained/pumped out, put 100ml of new oil of your choice in each Falcon. I use 5WT fork oil and I use a syringe to add the oil.
Screw the valve body back in and pump them up ideally with nitrogen or argon, to somewhere between 70 and 100psi. Dry compressed air will also work fine, but may cause the oil to degrade quicker than if an inert gas was used.
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