A rear shock absorber on a two-wheeler is a spring and a damper in one housing. The spring carries the load; the damper controls how fast the spring is allowed to move. Almost every complaint that arrives as a bad shock is really the damper having given up while the spring carries on regardless - which is why a broken shock still holds the bike up and still feels roughly the right height.
How a worn unit presents. The bike wallows through a corner and takes two or three movements to settle after a bump. It bottoms out over speed breakers with a pillion. The rear tyre wears in a cupped or scalloped pattern. There is a clunk over sharp edges. And the most reliable sign of all: an oil film or wet streak on the damper shaft, which means the seal has gone and the damping oil has left.
How to check properly. Push down hard on the rear and release. A healthy unit returns and stops. A dead one carries on for a second bounce. With the shock removed, compress it by hand through its full travel - the resistance should be firm and even in both directions, with no dead spot and no sudden give. Compare left and right on a twin-shock bike; a noticeable difference between them condemns the weaker one, and in practice both.
Replace in pairs. On a twin-shock bike, fitting one new unit against one worn one gives you a rear end that is stiffer on one side than the other. The bike will pull under braking, the tyre will wear unevenly, and the new unit will be doing more than its share of the work. It is a false economy every time.
What actually decides fitment. Four numbers and one type. Eye-to-eye length in the extended position; the mounting arrangement at each end, which is usually eye-and-eye or eye-and-fork; the bush inner diameter or stud diameter, because a shock with the right length and the wrong bush will not go on; and the spring rate. Get the length wrong and you change the ride height, the geometry and the chain slack all at once.
Spring rate and duty. A bike that carries a pillion every day, or a delivery rider carrying a loaded box over Mumbai speed breakers, needs a heavier rate than the same model doing solo commuting. Many units offer preload adjustment - use it before assuming the spring is wrong. Where a heavier-duty option exists for a model, it is usually the right choice for working vehicles, and it will feel firm when solo. Tell the customer that before they ride it, not after.
Fitting notes that decide how long it lasts. Replace the mounting bushes with the shock; worn bushes transmit shock loads straight into the new unit and produce the clunk the customer came in about. Never clamp the damper shaft in a vice - it scores the shaft and destroys the seal. Torque the mountings to specification with the suspension loaded, not hanging. On a front fork job, replace both fork oil seals and both dust seals together and refill with the specified fork oil quantity and grade; topping up with the wrong viscosity changes the damping.
What we stock. Endurance shock absorbers and fork assemblies, Monroe units through the DRiV range, and UCAL shock absorbers, covering the common two-wheeler and three-wheeler applications along with fork pipes, fork oil seals and fork oil. Three-wheeler suspension is stocked separately - the loads and the part numbers are different.
To order, send the eye-to-eye length, the mounting type at both ends, the bush inner diameter and how the vehicle is used - or simply the part code off the old unit, which carries all of it.
On a twin-shock bike, yes. One new unit against one worn unit gives uneven damping side to side, causes the bike to pull under braking and wears the rear tyre unevenly. Replace both.
There is no fixed figure - it depends on load, road surface and how often the bike is ridden two-up. In Mumbai conditions, check for shaft oil weep, second-bounce behaviour and cupped rear tyre wear at every service rather than working to a kilometre number.
We stock it. Send the part code for same-working-day confirmation.
