SITRAK WG9925522132002 LEAF SPRING
Product Specifications
| SITRAK | WG9925522132002 |
The LEAF SPRING is a multi-leaf spring suspension assembly — the primary load-bearing and wheel-locating element of the beam axle suspension system used on light commercial vehicles, trucks, pickups, minibuses, and rear axles of heavy-duty passenger vans that require high payload capacity and robust suspension geometry under varying load conditions. The assembly consists of a stack of graduated-length spring steel leaves — the main leaf (longest and thickest) forming the structural backbone, with progressively shorter helper leaves below it that contribute to the spring rate as deflection increases — clamped together at the centre by a U-bolt and centre bolt passing through alignment holes in each leaf's centre section. The spring is attached to the vehicle's chassis at its front eye — the rolled eye at the front of the main leaf that bolts to the chassis front hanger bracket through a threaded pin or silent block bush — and at its rear through a shackle that allows the spring's effective length to change as it deflects under load, connecting the main leaf's rear eye to the chassis rear hanger through a pivoting link. The axle is located at the spring's mid-point by the centre U-bolt clamp, making the leaf spring simultaneously the suspension spring element and the primary axle-locating link that controls longitudinal (fore-aft) and lateral (side-to-side) axle position relative to the chassis. The multi-leaf design's spring rate increases progressively under heavy loading as the upper main leaf contacts the lower helper leaves, providing a soft ride when unladen and a firm load-carrying rate when fully laden — the progressive rate characteristic makes leaf springs inherently suited to commercial applications with widely varying payload requirements.
This unit — SITRAK WG9925522132002 — is manufactured to OEM-equivalent specifications: main leaf and helper leaf dimensions (width, thickness, free camber), leaf count and graduated length sequence, spring rate at defined deflection points, centre bolt pattern, front and rear eye bore diameter and bush type, overall free length and loaded height at rated payload, and material specification — chromium-vanadium or silico-manganese spring steel with shot-peened surface treatment — are matched to the original part. Supplied as a complete spring pack assembly. Available wholesale from 31.33 USD, MOQ 100 pcs, production lead time 30-45 days.
Leaf springs fail through fatigue fracture of the main leaf — the highest-stress component that initiates at the surface corrosion pits created by road salt attacking the shot-peened surface layer; through elastic fatigue (sag) where the spring's free camber reduces from accumulated high-cycle loading below the maximum payload, causing the vehicle to sit lower on the affected corner and alter the suspension geometry; through silentblock bush failure at the front eye and shackle that introduces play into the axle location, causing handling instability and knocking; and through inter-leaf fretting corrosion on unsealed leaf packs where road moisture migrates between the leaf contact faces and removes the protective graphite or plastic inter-leaf sliders, causing leaf squeak and accelerating leaf surface fatigue.
- Support the axle on a trolley jack before loosening any spring attachment — the leaf spring simultaneously carries the vehicle's rear body weight and locates the axle; removing the spring without supporting the axle allows the axle to drop suddenly and rotate forward under its own weight, potentially pulling the brake hoses, ABS sensor cables, and propeller shaft beyond their travel limits; position a trolley jack under the axle differential housing or axle tube at a rated lifting point before loosening the front eye bolt or shackle nuts.
- Replace springs in axle pairs simultaneously — both rear leaf springs carry the same payload loads, experience the same road inputs, and accumulate the same fatigue cycles from the same mileage; a spring that has sagged from elastic fatigue has a matching spring on the opposite side that has sagged by a similar amount; fitting one new spring against a sagged original produces a permanent left-to-right ride height difference and asymmetric handling under payload that cannot be corrected by shackle adjustment; always order and fit both springs as a matched pair to restore symmetric suspension geometry and matched spring rates on both sides.
- Replace the front eye silentblock bushes and shackle bushes simultaneously with the springs — the bushes are fully accessible when the spring is removed from the vehicle and are significantly harder to replace with the spring installed; a bush that has worn to produce a knock alongside a fatigued spring has typically worn from the same mileage that fatigued the spring; fitting new springs against worn bushes retains the axle location play that causes handling instability and produces a follow-on knock complaint within a short period.
- Apply graphite grease or the OEM-specified inter-leaf lubricant between all leaf contact faces before assembly — the inter-leaf lubricant reduces fretting friction between the leaf contact surfaces, eliminating the inter-leaf squeak that develops on unsealed leaf packs in wet environments; apply lubricant to both contact faces of every leaf before stacking the pack; on leaf packs supplied with plastic anti-squeak interleaf pads, confirm the pads are correctly positioned between each leaf pair before centre-bolting.
- Torque the centre U-bolts, front eye pin nut, and shackle nuts to OEM specification with the vehicle at its unladen ride height — leaf spring attachment fasteners must be tightened with the suspension at normal static ride height so the bushes are at their neutral pre-stress position; tightening with the spring fully deflected or at full droop pre-stresses the bush in one direction and reduces its effective service life in proportion to the pre-stress magnitude; lower the vehicle to its laden ride height — or simulate it with weight — before applying final torque to all spring fasteners.
- Install the new LEAF SPRING (SITRAK WG9925522132002) on both sides of the axle simultaneously, torque all fasteners with the vehicle at normal ride height, lower the vehicle and measure the ride height at all four corners confirming both sides are within the OEM specification and symmetric, road test laden and unladen confirming no squeak, knock, or handling pull, and retorque the U-bolts after 500 km as new spring packs settle slightly under initial load cycling before returning the vehicle to service.
| Part | Reason for Combined Replacement |
|---|---|
| Front Eye and Shackle Bush Set Silentblock or rubber-bonded bushes — OEM ref. varies | The silentblock bushes at the spring's front eye and rear shackle provide the elastic connection between the spring and the chassis that absorbs road noise, damps small-amplitude vibrations, and allows the spring to deflect without imposing bending loads on the chassis mounting brackets. A bush that has worn to metal-to-metal contact transmits all road vibration directly to the chassis and allows axle movement that degrades steering stability. With the spring removed for replacement, all bushes are fully accessible for simultaneous renewal at negligible additional labour cost. |
| U-Bolt and Nut Set Centre U-bolt with nuts — OEM thread and length | The centre U-bolts that clamp the spring pack to the axle pad are single-use fasteners on many commercial vehicle applications — the bolt shank stretches to a defined elongation during the initial torquing to provide the designed clamping force; retorquing a previously used U-bolt to the same torque achieves a different elongation and clamping force from the permanent set the bolt has taken. Always replace U-bolts and their nuts with new items at every spring replacement; used U-bolt sets are also subject to thread corrosion from the underbody environment that reduces their torque-to-tension efficiency. |
| Shock Absorbers Rear axle pair — OEM ref. varies by vehicle | The shock absorbers on a leaf-sprung axle are accessed simultaneously during spring replacement and should be assessed for hydraulic performance while the axle is lowered for spring access. A shock absorber that has been working alongside a fatigued spring has been compensating for the spring's reduced damping by operating at higher deflection velocities and greater stroke amplitudes than designed; this accelerates oil bypass wear in the shock absorber's valve system. Test both shock absorbers by pressing the vehicle body at each corner after spring installation — a serviceable absorber settles in one controlled movement; a worn absorber bounces one or more additional times before settling. |