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Charging shocks, fully extended vs not. How critical and how different are the results?

makemeknowit

Kwisatz Haderach
Joined
May 19, 2020
Member Number
72
Messages
278
Loc
Memphis, TN
I searched here and didn't see this addressed:

I've heard the proper way is to have the shocks fully extended but haven't heard an explanation as to why. When I got my current buggy (first/only rig with air shocks) it only had about 2" of chrome visible at all 4 corners (Fox 2.0) Would beat you to death. A guy we were riding with that weekend had a tank with dual no loss chucks. Hooked it up and bumped them up to between 4-5" of chrome. Sitting on the ground as we had no way to fully extend them. Needless to say the ride improved tremendously. Thing is he had to crank the gauge reading to nearly 400 psi to get the 4-5". 200 is what is recommended but he only had the tank with its 2 gauges and lines and no separate gauge. Fast forward to another trip and my front driveshaft disengaged from the slip, flayed the slip out to unusable but we fixed it with a "lucky to find it" slip in the parts box back at the place we stay in Clayton. After the fix we decided to play it safe and further limit my limit straps. We dumped the shocks, put limit straps over the tube then ran the mounting bolt thru the strap eye. Again, we don't have the ability to fully extend so we recharged sitting on the ground and again it took well over 200 psi to get any chrome showing. Round 3, have my own tank/dual no loss now, I dumped them yesterday to reroute the strap back to normal, same deal, 400 psi to get 4-5" of chrome. I ordered a gauge so when it gets here I'll see what the shocks actually read vs the tank gauge's 400. I could load the buggy up and take it to work and use the forklift to get full extension and will. Just curious as to why full extension is mandated/suggested and would full extension unloaded get me 4-5" of chrome at the recommended 200psi?
 
Fully extended for lower pressure when charging and more for consistency and knowing what you're starting from when you change things. Matters more for air shocks, more yet for air bumps, less important for reservoir coilovers but consistency is still a good thing.

To illustrate the extreme end, my air bumps are at 100psi extended. Full bottom out they'll be at about 1000psi. (Maybe) obviously, I can't charge them at 1k psi, but I can easily charge them at 100. But as fast as the rate ramps, 1/4" difference in travel might be a difference of 20psi or of 200psi depending on where in the travel they are. And air shocks are little more than long travel air bumps.
 
Fully extended. At full extension your volume is guaranteed. At ride height, any variation in ride height dramatically effects how consistent they are from side to side.
 
Depending on if you have the divider piston for the gas from oil as well. Like on an air shock you'll could loose oil out the Schrader when charging.
 
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