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The OE number 20371-FC000 identifies a strut bump stop specified on Subaru vehicles. The part is compact and low in unit price compared with the strut assembly around it, yet its condition directly affects ride comfort, impact noise and the service life of the shock absorber. Bonpora manufactures the 20371-FC000 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 20371 prefix is used by Subaru for suspension bump stops, and the FC suffix identifies the application group within that series. Related references in the same family appear across Subaru model lines, and exact fitment can vary by market and model year. Bonpora therefore recommends confirming the application through the OE number on the original part, the vehicle identification plate, or a sample sent for comparison. The company keeps cross reference records for the Subaru range, so buyers who search by 20371-FC000, by the Bonpora Nos 4110239, 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 | 20371-FC000 |
| Bonpora Nos | 4110239 |
| Fitment | Subaru |
| Size | Φ21 x Φ52 x 119.5 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 21 mm slides over the strut piston rod, the outer diameter of 52 mm must match the space available inside the dust cover, and the free length of 119.5 mm determines when the stop starts to engage during compression. These three dimensions control fit and function together, so dimensional accuracy is checked on every production batch before release.
Subaru vehicles are popular in regions with demanding conditions: snowy northern markets, coastal areas with salt laden air, and markets with high ambient temperatures. 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 is particularly relevant for all wheel drive vehicles, where suspension loads are distributed differently compared with two wheel drive layouts and the bump stop is called into service more often on rough roads.
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 20371-FC000 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 Subaru, and the sales team will match the reference from the fitment database. Describing the part by type and specification, such as outer diameter around 52 mm and free length around 120 mm, also narrows the match when only a worn sample is available.
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 20371-FC000 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 Subaru 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 20371-FC000, the Bonpora Nos 4110239, 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.
