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The source row describes a shock piston rod as the moving component of a damper, connected to the piston assembly inside the cylinder and passing through the oil seal and guide seat to the vehicle body or suspension. It is made from carbon steel such as S45C or S55C or an alloy steel such as 40Cr, with induction hardening or carburising, and the row states a service life of 80,000 km or 5 years under normal conditions with a warranty of 2 years or 80,000 km.
For a distributor or a rebuild workshop, the buying decision is not simply which reference to stock. It is which dimensions, which surface treatments and which end connections to hold, and how to verify a supplier whose product is judged by a surface the customer cannot see until the damper is open.
List the vehicles your customers actually repair, then extract the rod dimensions used by those damper families. Rods cluster strongly by diameter and by end connection, so a small number of dimensions covers a large share of demand.
A rebuild line needs the common diameters in stock, because the workshop cannot wait for a rod while the vehicle occupies a lift. A special order line covers discontinued or performance parts, quoted individually with an agreed lead time. Mixing the two in one stock policy ties up working capital in slow references.
| Line type | Stock policy | Service expectation |
|---|---|---|
| High volume rebuild rod | Depth stock, monthly replenishment | Same week availability |
| Common but slower reference | Small shelf quantity | Within the agreed lead time |
| Special order by drawing | No stock, quoted on demand | Stated production lead time |
| Discontinued reproduction | No stock, minimum batch | Sample approval before batch |
The source row lists hard chrome, nitriding and special coatings as options. Chrome covers the majority of rebuild work, while nitriding and special coatings serve heavy duty, off-road and performance customers. Carrying a limited mix rather than every option keeps the range manageable.
Piston rods are quoted by dimension, material and finish. An enquiry that omits one of those will receive either a price that does not apply or a question that delays the offer. The list below is the minimum.
Where the original part is the reference, a sample with measured dimensions is often faster than a drawing, because the supplier can measure the sample and confirm the specification against a real part.
A first article is the cheapest risk control in this product line. Order one to three pieces per candidate reference, then measure them against the drawing or against the sample dimensions. The measurements worth recording are diameter at three positions, length between the defining features, runout, surface hardness and visual condition of the running surface.
Set the acceptance criteria before the sample arrives, and record the decision in writing. A supplier who willingly participates in first article approval is usually the one who will handle a claim reasonably, which is an early signal of how the relationship will run.
Unit price is only one line of the purchase cost. Compare offers on the same basis using the structure below.
| Cost element | What to confirm |
|---|---|
| Unit price by quantity break | The break applies to the reference you are ordering |
| Minimum order quantity | Per reference or per shipment |
| Setup or tooling charge | Whether a drawing based rod carries a one-off cost |
| Sample charge | Whether it is credited against the first batch |
| Packaging | Sleeve, bulk carton, individual tube |
| Freight and insurance | Method and transit time, which is critical for plated surfaces |
| Duty and clearance | Rate and broker |
| Warranty handling | Claim process and who pays return freight |
A piston rod is a precision surface sold in a cardboard box only because someone decided the packaging would be good enough. Sleeves, tubes and separators are not cosmetic. A rod that has moved against another rod in transit arrives with marks that will be blamed on the factory, and the argument costs more than the packaging would have.
The source row gives a warranty of 2 years or 80,000 km whichever comes first, covering material and manufacturing defects, under an IATF 16949 quality system. In a resale channel there are two layers of warranty, the one your supplier gives you and the one you give your customer.
Three practices keep the two layers consistent. Record the batch or production reference on your own sales document, so that a returned part can be traced. Keep the failed rod rather than discarding it after the vehicle is repaired. And separate defects from damage, since a rod that failed through a bent mounting or an impact is not a manufacturing defect and should be discussed as a vehicle issue.
| Criterion | Evidence to request |
|---|---|
| Material control | Mill certificates linked to production batches |
| Hardening control | Recipe plus case depth and hardness results |
| Grinding control | Diameter, taper and roughness records |
| Plating control | Thickness and adhesion results, bath maintenance records |
| Straightness control | Runout measurement at release |
| Traceability | Batch number on the part or its sleeve, linked to records |
| Sampling discipline | First article and periodic requalification practice |
| Commercial conduct | How previous claims and shortfalls were handled |
A supplier who can produce these documents routinely, without preparing a special file, is running a controlled process. That is what a quality certificate is meant to indicate, and it is the only version of the claim that can be verified from outside.
Rods are durable but their surfaces are not indestructible. Store them horizontally on a rack that supports the full length, in sleeves, away from moisture and away from areas where metalwork produces airborne dust. Rotate stock so that older batches are sold first, and inspect any sleeve or tube that has been opened before it is returned to the shelf.
Because the design life quoted in the source row is measured in years as well as distance, a rod that has sat on a shelf for a long period should be checked for surface condition before it is sold, even though the material itself does not expire.
Enough to cover the rebuild lines of the vehicles your customers service, which is usually a smaller set than a full catalogue suggests. Depth on common dimensions serves customers better than breadth with one piece of everything.
It can be, when the saving comes from a thinner coating, a shallower case or thinner packaging. Those differences are not visible in a sample photograph, so compare process records and first article measurements rather than price alone.
Usually yes, because the source row confirms that custom lengths, diameters, surface treatments and end connection types are available from drawings or samples. Send the original part or its measured dimensions and ask for a first article before committing to a batch.
It depends on whether the reference is a catalogue line or a drawing based production part. Agree the lead time in writing for both cases, and keep a buffer of the fastest moving references so that a production delay does not stop your customers.
Bonpora Parts and Components supplies shock piston rods to drawing or sample in S45C, S55C and 40Cr, with induction hardening, carburising, hard chrome, nitriding and special coatings, and offers custom lengths, diameters and end connections. Review the piston rod range, read the selection guide and the manufacturing guide, or compare the shock absorber component range. Send your reference list and annual quantities through the contact page, or use the custom parts service for reproduction work.
