This section covers only the replacement of a shock spring, using the KXF450 as an example. The shock absorber in this context has already been removed. A thorough discussion on how to remove the shock absorber is here: How to remove a rear shock.
1 As mentioned in How to remove a rear shock, breaking loose the spring retaininer lock ring prior to removing the shock from the bike makes things much easier. Clean retaining ring threads is crucial and applying WD-40 is very helpful.
If you clamp the shock in a vice, do so carefully. Use soft jaws or wood to prevent damage to the parts and pay attention to the direction of clamping. Here I have the lower shock mount clamped using soft jaws.
First, screw the lock ring away from the spring as far as it will go. Next, unscrew the spring retaining ring as far as it will go. Initially, there is a lot of spring load on the retaining ring. Sometimes, you can turn the whole spring with your hands which will also turn the retaining ring. Otherwise, you'll need a spanner wrench.
2 Now the shock is flipped in the vice and is held lightly by the upper bearing faces. You can see how the knotched retainer slides away from the shock rod. Notice the cupped washer. It must be held away from the retainer so the retainer can slip off. Dirt on the contact surfaces of these parts can make them difficult to separate, so it may be necessary to tap on them to get them free. The spring and washer can now be removed.
3 Before placing the new spring, make certain all of the parts and contact surfaces are completely clean. Slip the retaing parts back on, in reverse of how they were removed.
4 Screw the spring retaining ring down onto the spring while insuring alignment of the spring to the retaining surfaces at both ends. Once there is some spring load on the retaining ring, you may be able to continue turning it by rotating the entire spring with your hands. Turn the retainer until it is about midpoint on the shock threads. You'll set sag after installing the shock, so don't tighten the lock ring.
5 Ready for mounting.
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