The spheres have nitrogen and hydraulic fluid in them. A moveable bladder separates the nitrogen and the fluid. When a bump is hit, the fluid cannot compress but gets pushed against the bladder wall which compresses the nitrogen on the other side of the bladder giving a very smooth ride. Picture a basketball filled half way with oil, a sheet of rubber across the half way point sealing the oil and nitrogen on the other side of the sheet of rubber. If the ball is bounced on the oil side the rubber will flex and compress the nitrogen absorbing the "slam" from the Hydraulic/non-compressible liquid.

As the spheres age the nitrogen escapes and when it is gone the hydraulic fluid which will not compress takes up the space where the nitrogen was by pushing the bladder and gives a very stiff ride.

It is opposite of what we expect, when a shock wears out the ride gets very "wallow like." When the spheres leak out the ride becomes very hard because the fluid cannot compress.

The hydraulic struts control the ride height, the spheres soften the ride. If the struts that look like shocks are not leaking I would not change them.

Hope this helps.

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