The FOX Replacement Chrome Shaft, part 229-19-089, is a single chrome-plated shock shaft with a 0.875-inch outside diameter and a 16.038-inch overall length. It is meant for restoring a shock whose shaft is damaged rather than replacing the whole damper. Owners on user forums report that a pitted or rusted shaft can tear up the seals and let air or contamination into the shock, so a fresh chrome shaft during a rebuild goes after that root cause. Confirm fitment with the manufacturer before ordering, and measure your existing shaft end to end, along its chrome section, and at the post and mount threads. Searches for a 7/8 inch chrome shock shaft, a 16.038 inch shock shaft, or a Fox shock shaft rebuild will point you to this part number.
Swapping the shaft is a full shock rebuild, not a bolt-on job. Owners on user forums say you need shaft clamps, a nitrogen charging setup, an IFP depth tool, and a caliper, along with common shop tools and fresh shock oil. Fox's published service procedures for other Fox shocks call for only a small drop of red thread locker on the shaft threads, and owners warn against striking the shaft because that can damage the bearing. The payoff is a shock that holds its damping and sealing after the old shaft has been retired, which is usually a better outcome than reusing a compromised shaft.
Owners on user forums who have rebuilt Fox shocks say yes. Beyond common shop tools, they describe needing a nitrogen cylinder with a regulator, hose, and needle filler valve, plus an IFP depth tool and a caliper.
Owners on user forums point to pitted or rusted shock shafts as a common reason for a rebuild. They note that worn floating pistons and a bad seal head can be found alongside a damaged shaft, so inspect the whole damper before reassembly.
Owners on user forums report that a shock without proper nitrogen pressure can cavitate, which can damage the piston or shims inside. Air drawn past a weak seal can also reach the hydraulic side of the shock.
Difficulty: advanced. Replacing this shaft means disassembling the shock, draining the oil, removing the shaft and piston assembly, replacing the seals, and recharging the nitrogen before refilling. Clamp the shaft carefully in shaft clamps and clean it with isopropyl alcohol before reinstalling. Work the shaft slowly and avoid pulling it out quickly, since that can shift the reservoir cap. Keep the IFP at the correct depth, and pre-fill the piston assembly with oil to prevent air pockets.
