My shocks went "springy" on my CEN Matrix. When I drained the fluid it was full of tiny bubbles and black stuff. The black stuff was like carbon, it didn't feel gritty like dirt.

How often do you change shock fluid? Any idea what the black stuff was?

Black stuff was probably dirt. You should replace your shock o rings. And I refill shocks when the arent perfectly smooth, usually is a couple weeks of racing.

bweiler, just check to make sure this hasn't happened to the shock body where the shaft goes in and the 0-rings sit. Usually means that it will dump all the shock oil when it's this bad, but even a small mis-shape or bend could allow air and dirt into the shocks.

I try to rebuild/refill my shocks pretty often, especially for racing. When the shock oil starts to disintegrate and things get into the shocks, it's time to rebuild them. it's a good idea to check the smoothness of the shocks when you can, especially with frequent use. It's just regular maintenance.