Re: Does anybody know anything about tuning air shocks?
I'm nothing special but I am kind of picky about my air shocks and I've remounted them 4 or 5 times so I feel like I've done it right and wrong. Forgive me if you know all of this already.
Nitrogen and oil work together to set the ride height, it's really about taking space. Obviously nitrogen compresses and oil doesn't so as you add more oil you need less nitrogen to achieve the same ride height. The other thing that happens is the spring rate changes. If you run a lot of oil and a little air it's going to be harder to bottom out the shock. Of course, the shock will bottom easily if you don't run much oil and use all nitrogen to get the height you want.
(Images stolen from billavista)
The other thing to look at is the way the spring rate changes with the ratio of oil to nitrogen.
Don't pay too much attention to the numbers but check out the curve. When you have a lot of oil and a little nitrogen the compression happens quickly (in a short amount of travel) and you get a steep curve like this:
When you have a lot nitrogen and a little oil you get a flatter curve like this:
I'm guessing the poly bumps are a big part of the problem. They are just undampened springs that make the axle want to rebound aggressively when you get to full compression. On the other hand, they are nice because they help you from bottoming out on the air shocks and getting a rough ride. (Air shocks are pretty durable, you probably won't break them by bottoming out, they break when you pull them apart at full extension.) So now that they are pulled you have to find another way to handle the hard hits. My answer is more oil. I've never even seen your rig in person so I can't tell you how much to add but I'd do about 10cc at a time and get it to where the suck down winch struggles to get it to full squat.
So this is what I'd do:
1) Pull the poly bumps.
2) Add oil.
3) Adjust nitrogen to ride height
As for the fill kit, I haven't used the bling screw kind but I'm just positive that I'm not missing anything. I just set the regulator to the proper PSI, put on the straight chuck, pull the trigger for 2-3 seconds until I hear it equalize, then pull it off. I'm not losing anything but the air in the hose. You can easily hear what's on and it's working well for me. FWIW, this is a pic of my regulator and hose setup. Don't pay much attention to the beat up tank, it just gets traded in when it's empty.
