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The OE number 31336771892 identifies a strut bump stop specified by BMW for strut type suspension assemblies. The part is small and low in unit price compared with the strut it protects, yet its condition directly influences ride comfort, impact noise and the service life of the shock absorber. Bonpora manufactures the 31336771892 bump stop in micro cellular polyurethane together with a complete family of suspension foam components, supplying OE programmes, brand owners, importers and aftermarket distributors from production bases in China. This guide explains what the part does, lists the full specifications, compares polyurethane with conventional rubber, and summarises the practical routes B2B buyers use to source it: by OEM number, by vehicle model, by part type and specification, and through custom development with a factory partner.
A strut bump stop, sometimes called a spring bumper or jounce bumper, is mounted on the piston rod of a strut type suspension, sitting between the dust cover and the top mount. During normal driving the component stays outside the working range of the damper. When the suspension is compressed beyond its normal travel, for example when the wheel drops into a pothole, the vehicle crosses a speed bump fully laden, or heavy cargo loads the axle, the bump stop engages and progressively stiffens the final stage of the stroke. This progressive engagement prevents the piston from striking the top of the strut tube, protects the internal valves and seals of the damper against overload, and keeps impact noise and harshness within a comfortable range for passengers.
A worn, cracked or collapsed bump stop no longer cushions this final travel. Typical symptoms include sharp clunking noises over bumps, a harsher ride and accelerated damper wear, because the shock absorber is forced to absorb loads it was never designed to take. This is why workshops normally renew the bump stop together with the shock absorber, dust cover and strut mount as one complete repair, and why suspension repair kits supplied to the aftermarket always include the part.
The 31336771892 reference belongs to the BMW suspension bump stop series, and exact fitment can vary by market, model and model year. Bonpora therefore recommends confirming the application through the OE number printed on the original part, the vehicle identification plate, or a sample sent for comparison. The company keeps cross reference records for the BMW range, so buyers who search by 31336771892, by the Bonpora Nos 4110232, or by vehicle model are matched to the correct part quickly. The full polyurethane bump stop and spring bumper range is published on this site for browsing by category.
The table below summarises the key data buyers need for a first quotation and for catalogue listings.
| Item | Specification |
|---|---|
| Product Name | Strut Bump Stop |
| OE Number | 31336771892 |
| Bonpora Nos | 4110232 |
| Fitment | BMW |
| Size | Φ18.5 x Φ65 x 73.5 mm |
| Material | Polyurethane |
| Country of Origin | China |
| Warranty | 1 Year |
| Delivery Time | 15 - 30 Days |
| Packaging | Neutral Export Packaging |
| Custom Service | OEM and Custom Design Support |
The size notation gives the inner hole diameter, the outer diameter and the free length. The inner hole of 18.5 mm slides over the strut piston rod, the outer diameter of 65 mm must match the space available inside the dust cover, and the free length of 73.5 mm determines when the stop starts to engage during compression. Compact stops with a short free length are common on applications where suspension travel is limited, so dimensional accuracy is checked on every production batch before release.
BMW vehicles are driven worldwide in demanding conditions: hot climates with strong sunlight, northern markets where roads are salted in winter, and urban environments with frequent speed bumps. Conventional rubber bump stops harden and crack with age, a process that accelerates with heat and ozone exposure. Micro cellular polyurethane keeps a stable density and rebound behaviour across a wide temperature range, so the engagement feel of the bump stop remains predictable throughout its service life and the failure rate in the field stays low.
The cell structure of polyurethane foam can be tuned during formulation. Bonpora adjusts density and cell geometry so that the compression curve of the replacement part follows the OE specification, which means the damper is protected in the way the original engineer intended and the vehicle keeps its original ride character. This matters particularly on runflat tyre applications, where stiffer sidewalls pass more impact energy into the suspension and the response of the bump stop needs to stay close to the original design.
For distributors and kit assemblers the decisive property is batch to batch consistency. Serial production with dedicated tooling, incoming material inspection and dimensional checks on every batch keep the size within tolerance across large orders. Kits assembled from several suppliers still fit on the first attempt, which reduces warranty claims and rework at the warehouse.
The fastest route is to send the OE number directly. Buyers who quote 31336771892 receive the matching Bonpora reference, technical drawings, material data and a price within one working day. This removes guesswork from cross referencing and is the recommended method when the original part or its number is already known. Buyers working with mixed baskets of OE numbers can send a full list in one enquiry, and the team returns a cross reference table covering every line item together with a consolidated quotation, which shortens the comparison stage of the sourcing project.
When the OE number is not available, buyers can describe the vehicle brand, model, model year and the part type, for example front strut bump stop for BMW, and the sales team will match the reference from the fitment database. Describing the part by type and specification also works when only a worn sample is available: an outer diameter around 65 mm, an inner hole around 18.5 mm and a free length around 74 mm narrows the candidates quickly, and photographs of the sample allow the engineering team to confirm the match before quotation.
Importers and brand owners who need their own specifications can use the custom parts development service. A sample or drawing is reviewed by the engineering team, tooling is quoted separately, and series production follows the confirmed golden sample. This route suits suspension repair kits, regional vehicle variants and private label programmes where the buyer controls the brand and the packaging.
Production follows a documented quality process: incoming polyurethane raw material is verified against specification, dimensions are checked on samples from each batch, and density is confirmed before release. The 31336771892 bump stop is supplied with a 1 year warranty under normal use. For export shipments the parts are packed in neutral packaging without third party branding, which lets importers repack under their own label, and mixed loading with other suspension references is supported for full container orders. The standard delivery time is 15 to 30 days depending on order quantity and production schedule. Buyers who assemble complete suspension repair kits can combine this bump stop with mounts, dust covers and related items from the shock absorber parts catalogue under a single purchase order.
Storage conditions also influence the service life of foam components. Bonpora stores bump stops in a cool, dry warehouse away from direct sunlight and ozone sources, and packed parts keep their mechanical properties for years when held under the same conditions. Buyers who operate regional warehouses can therefore order in larger volumes without shelf life concerns, provided the cartons stay sealed and are kept away from high temperatures.
The reference belongs to the BMW suspension bump stop series, and applications can differ between markets and model years. The most reliable method is to confirm the number on the original part, or send the vehicle model and year to Bonpora for verification against the fitment database.
The three figures are the inner hole diameter, the outer diameter and the free length in millimetres. The inner hole fits over the strut piston rod, the outer diameter must match the space inside the dust cover, and the free length determines when the stop engages during compression.
Yes. The factory offers OEM and custom design support covering material tuning, dimensional changes, dedicated tooling and neutral or custom printed packaging. Development starts from a sample or a drawing and moves to series production after the golden sample is approved.
The part carries a 1 year warranty under normal use. Delivery time is typically 15 to 30 days depending on quantity, and quotations are provided per project with flexible order quantities for stocked references.
Send the OE number 31336771892, the Bonpora Nos 4110232, or your own requirement list to the Bonpora sales team to receive drawings, material data and a quotation. Enquiries by vehicle model, by part type and specification, and for custom development are all welcome.
