Check the rear shock absorbers

Home mechanic (basic tools) · Time: 15 to 30 min (editorial estimate) (estimate)

The rear wheel is held by the swingarm, which pivots on the frame. One shock (monoshock) or two shocks (twin shocks) connect the swingarm to the frame. Each shock is a coil spring (carries the weight) around a damper (oil inside slows the movement so the bike does not keep bouncing). Most commuter shocks are sealed: when the damper wears out or leaks, the whole shock is replaced. This check tells you if the shocks, their rubber mounting bushes and bolts are good.

Safety

• Support the bike securely. Never remove both shocks with the bike on its wheels: the rear will drop.
• A loose shock bolt can let the rear collapse. If a bolt is loose or missing, do not ride until it is fixed.

You need

• The shock mounting torques for your bike. No value is given here: the K-Light 125 manual gives two different values for the upper shock nut on different pages.

Steps

1. Look at each shock body and rod. Oil on the body, below the seal or on the spring means the damper is leaking.
2. Look at the shiny rod (if visible). Rust, pits or a bent rod: replace the shock (K-Light 125 manual: bent or damaged rod, or tired spring, means a new shock; it is not rebuilt).
3. Look at the spring for cracks or broken coils.
4. Check both shocks (twin shocks) are on the same preload setting. See Adjust rear spring preload.
5. Bounce test: with the bike on its wheels, push down hard on the seat or rear rack and let go. A good shock comes back up once and stops. If the rear bounces up and down more than once, the damping is worn.
6. Push down slowly. Listen for squeaks or knocks, and feel for any sticking.
7. Mounting check: lift the rear wheel off the ground. Hold the wheel and lift it up and down a little, and rock it side to side. Watch each shock's top and bottom mount. Movement at a mount means worn rubber bushes or a loose bolt. The K-Light 125 manual also uses this rocking check to find loose engine mounting bushes.
8. Check each shock bolt is tight with a spanner. Tighten only to the model torque.
9. If the rear rocks sideways at the swingarm pivot, go to Check the swingarm pivot.

Check your work

• No oil on either shock.
• Rear settles in one movement after the bounce test.
• No movement or noise at the mounts.
• Both shocks on the same setting.

If it did not fix the problem

• Shock leaks, bounces, or rod damaged: replace the shock. On twin shocks, replace both together so the rear stays level.
• Rear sits low: Rear sits too low and Measure suspension sag.
• Clunk remains: Clunk from the rear suspension.