Originally Posted by sosidge

At the end of a day you have a shock body that has a certain volume within in when the shaft extended, and a smaller volume within it when the shaft is compressed (because the shaft is now inside the shock body not outside it).

Working on the basis that the oil is hard to compress and the air is easy to compress, you need to fill the shock with enough oil to fill the smaller volume when the shaft is in, and enough air to compensate for the larger volume when the shaft is out. You need the air!

If your shocks are hard at the top of the stroke, it has nothing to do with the air pressure building up (think about it, where exactly can all that easy-to-compress air be coming from?) - it's simply because you have too much of that hard-to-compress oil in there.

These shocks have been in off-road for years, but people still insist on building them wrong because they don't like squeaks - and then they wonder why they blow the seals.