Here is a word of caution.
As you look at the end of the shock shaft, you will notice that the end of the shaft has been riveted against the the nut. In order to get the nut off, you have to ruin most of the nut by grinding the nut and end of the shaft at a 45 degree angle. After you grind a little, try and gently turn the nut. If there is still resistance, grind a little more and try the nut again and again until you have removed just enough material to get the nut to thread off the shaft. You will also need to have puchased a new nut before you begin, as the old nut will be unusable. If you remove all of the riveted section of the shaft, you have ruined the shaft, so be very careful. If you have access to a lathe, you will be able to maching the edges of the riveted section without any risk, but most folks don't have access to a lathe. Remember to locktite the nut on installation.
You may also be able to remove the shaft from the bottom fork by unscrewing the shaft (only after you disassemble the shock). The seal would then just slide right off and the new one on. However, I have never installed a seal by removing the shaft, so can't say for sure, but believe it will work. All of my shocks are revalved, so the shaft has already been modified for easy removal.
You also want to avoid damaging the seal when you slide it over the shaft past the threads, so wrap the threads with tape before you install the new seal, and lube with oil. This is the same process as when you install a new fork seal over the lower leg, but in that installation I use the corner of a sandwich bag to ensure the seal is not damaged.
As you can tell, there is some risk in this process, so be very careful. I have used the White Brothers seals before, and they work just great for a lot less money. While your in the shock, check the bladder and make sure it is not damaged. Once you install the seal, follow my old post on shock rebuilding and you should be in good shape.
One additional note. If you grind off the nut, it is critical that the shim stack on the shock valve be kept in order. Once the nut is off, push a philips screwdriver into the shaft hole a little, and slide the shims and valve onto the screwdriver all the way to the handle. Place a zipty on the screwdriver shaft to keep the shims from falling off. Once the seal is installed, put the scredriver back into the shaft hole and push everything back in place. Use spray carb cleaner to flush the shims and valve once on the shaft in order to remove an debrise. Blow down with air to help the cleaner flash, and continue with the installation.
Good Luck, and let us know if you get stuck.
Rick
