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The BMW strut bump stop 31336861727 is the front axle suspension bumper fitted inside the strut assemblies of a wide group of modern BMW platforms. In the BMW parts catalog the component appears under the name Additional Shock Absorber, front, and dealer catalogs also describe it as a suspension strut bumper or jounce bumper. Because the part only works at the very end of suspension travel it is easy to overlook, yet a worn bumper changes how the front axle feels and speeds up wear on dampers and top mounts. Bonpora manufactures the replacement under Bonpora Nos 4110222 in microcellular polyurethane, with OEM and custom design support for distributors, repair chains and suspension program buyers.
The bump stop sits on the piston rod of each front strut, above the dust cover. When the suspension compresses fully over a pothole, a speed bump or a heavily loaded corner, the microcellular polyurethane body compresses progressively and stops the travel before the strut housing, the piston rod and the top mount collide. BMW lists the reference 31336861727 (format 31-33-6-861-727) for the front axle, one piece per corner, and groups it with the 2 Series Active Tourer and Gran Tourer, the 3 Series G20, the X1 F48, the X2 and the current MINI Countryman platforms.
Within the suspension the bumper performs three jobs. First, it acts as a progressive end of travel cushion, absorbing the last part of the stroke so the body does not take a hard hit. Second, it protects the damper: without a bumper, repeated full compression drives the piston rod into the top of the strut and damages the rod guide, the seal and the top mount. Third, it keeps the ride character consistent — a fresh bumper of correct hardness keeps the front axle composed on rough roads, while a collapsed one lets the suspension bottom out with a harsh clunk. The bumper works together with the dust cover and the strut mount, and many workshops replace the three parts as a set during a front suspension refresh.
The key dimensions of Bonpora Nos 4110222 are matched to the OE drawing:
| Item | Specification |
|---|---|
| Product Name | Strut Bump Stop (Suspension Strut Bumper) |
| Bonpora Nos | 4110222 |
| OE Reference | 31336861727 (31-33-6-861-727) |
| Fitting Position | Front axle, left and right — quantity 2 per vehicle |
| Size | Φ24 x Φ72 x 95 mm (bore x outer diameter x free height) |
| Material | Polyurethane (PU) |
| Country of Origin | China |
| Warranty | 1 Year |
| Delivery Time | 15–30 Days |
| Packaging | Neutral Export Packaging |
| Custom Service | OEM & Custom Design Support |
The reference is shared across several BMW front wheel drive and all wheel drive platforms plus the related MINI model. The list below is compiled from genuine BMW dealer catalogs and BMW EPC based specialists. Because BMW assigned the part to specific suspension variants rather than to every trim level, always confirm the OE number against the VIN before ordering.
| Model | Chassis / Generation | Engine and Trim Notes | Catalog Years |
|---|---|---|---|
| 2 Series Active Tourer | F45, F45N incl. LCI | Front axle | 2013–2019 |
| 2 Series Gran Tourer | F46, F46N incl. LCI | Front axle | 2014–2019 |
| 3 Series sedan | G20, G20N | 330i, 330e, M340i; rear wheel drive without adaptive M suspension | 2017–2024 |
| 4 Series | G22 coupe, G26 Gran Coupe | 430i without M sport suspension | 2021 on |
| M3 | G80 | Base and Competition | 2021–2024 |
| X1 | F48, F48N incl. LCI | sDrive28i, xDrive28i | 2014–2019 |
| X2 | F39 and U10 | xDrive28i, M35i xDrive; US catalog rows 2024–2026 | 2018–2026 |
| MINI Countryman | U10 / U25 groupings | Per BMW parts catalog | Current generation |
Two caveats matter for buyers. The genuine BMW description carries the notes without M sport package, rear wheel drive without adaptive M suspension and without adaptive M chassis. In practice this means the 31336861727 bumper belongs to standard suspension setups, while M Sport, Adaptive Drive and lowered variants can use bump stops with different heights or hardness, sold under separate references. Second, this OE number is comparatively new and most independent aftermarket brands have not yet published their own cross reference numbers, so the OE reference remains the reliable search key. The fastest verification path is to run the 17 digit VIN through a BMW EPC catalog or a dealer parts desk, confirm the reference on the front strut drawing and then match the dimensions above. If a customer provides only a model name, ask for the chassis code and the production date, then cross check against the application table. Related references for other marques are listed in the auto parts category.
A bump stop is a wear item rather than a lifetime component. Polyurethane compresses thousands of times during normal driving, slowly takes a set and eventually loses its protective function. Workshops and fleet operators usually discover the problem when a customer reports new noises from the front axle:
Inspect the bumpers whenever the front dampers, coil springs or strut mounts are replaced, and whenever a knocking complaint is confirmed on a lift. Compare the free height against the 95 mm specification: a bumper that has lost several millimetres no longer protects the strut. Because the left and right bumpers are the same reference and work as a pair, replace both sides at the same time to keep the axle balanced. During the same service it is efficient to renew the dust covers and the strut mounts, since they share labor access and age together. Bonpora also supplies the wider range of chassis and suspension components for workshops that prefer to consolidate suppliers.
Microcellular polyurethane has become the standard material for modern bump stops because of how it behaves under compression. The cell structure collapses progressively, so the force rises smoothly instead of spiking, and the part returns to shape after each stroke. Compared with basic rubber compounds, polyurethane resists oil, ozone and temperature swings better, which matters for components mounted inside the wheel arch where water, salt and heat combine. Bonpora compounds and molds its polyurethane bump stops in house, controls cell structure and hardness batch by batch, and produces the 31336861727 replacement to the Φ24 x Φ72 x 95 mm drawing so the compression curve matches the original part.
Bonpora is a suspension components manufacturer with dual production bases, an annual capacity above 25 million pieces and production under an IATF 16949 certified quality system with full process inspection. For the BMW 31336861727 application the company supplies the OE replacement under Bonpora Nos 4110222, packed in neutral export cartons that support distributor private label programs. Standard catalogue items cover the most requested applications; buyers with their own programs can also order:
Beyond the catalog part, Bonpora develops custom polyurethane parts for customers who need modified dimensions, different hardness grades or their own branding. Custom projects start from a sample, a drawing or an OE number; the engineering team confirms the compression curve, produces first articles for approval and then scales to series production. Incoming material checks, in process inspection and final dimension audits keep batch consistency at the level expected by OE buyers and repair chains.
Standard delivery time for the strut bump stop program is 15 to 30 days, depending on order quantity and season. Send the OE number 31336861727 or Bonpora Nos 4110222 together with the target quantity and the destination market, and the sales team returns a quotation, a packing plan and a firm lead time. Sample parts are available so buyers can verify bore, outer diameter, height and material before committing to a volume order.
Catalog data covers the 2 Series Active Tourer F45 and Gran Tourer F46, the 3 Series G20 sedan including the 330i, 330e and M340i, the 4 Series G22 and G26, the M3 G80, the X1 F48, the X2 and the current MINI Countryman generation. Most applications are standard suspension variants without M Sport or adaptive M chassis. Always verify by VIN, because suspension package codes change which bump stop reference applies.
Yes. The bumper rides on the damper rod, so the strut is removed and stripped, the worn bumper is slid off and a new one is fitted, and the strut is reassembled. The damper itself does not need replacement unless it fails its own checks. Many workshops replace the bumper, the dust cover and the top mount together as a service set because the parts age at a similar rate.
Yes. The left and right bumpers are the same reference and age at a similar rate. Replacing only one side creates an imbalance in end of travel stiffness, which shows up as uneven behaviour when the suspension bottoms out. Order in pairs for each axle — one vehicle uses two pieces.
Yes. Bonpora offers OEM and custom design support for polyurethane bump stops, including modified heights and diameters, hardness adjustments, compounds for special climates and customer branded or neutral export packaging. Standard delivery is 15 to 30 days, and custom projects follow sample approval before series production begins.
Send the OE number 31336861727 (or Bonpora Nos 4110222) together with the required quantity, destination port and packaging requirement to receive specification, unit price and lead time in one reply. Compare related references such as the Volvo strut bump stop 31340308, browse the full auto parts range, or submit a drawing for a custom manufacturing quotation.
