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The strut bump stop catalogued under OE number 3B7412377A is the front suspension rubber buffer listed for the Volkswagen Passat B5.5 platform and the Passat-based Skoda Superb I. This page describes the part as supplied by Bonpora (number 4110027), a China-based auto parts factory producing polyurethane bump stops as original and replacement parts for the independent aftermarket, and sets out the specifications, fitment, and sourcing information wholesale buyers normally request before ordering.
Also sold under the names jounce bumper, bump stopper, and rubber buffer, the part is a moulded elastomer unit fitted inside the front strut assembly. During normal driving it hangs clear of its engagement surface. Under a hard compression event — a pothole, a speed bump, a fully loaded vehicle — it engages progressively and converts what would otherwise be a metal-to-metal impact into controlled resistance.
Elastomer parts age whether the car is driven or parked. Heat, ozone, road salt, and repeated compression cycles harden the material until it cracks and loses its progressive response, after which the damper bottoms out and damage spreads to the top mount and shock absorber. On Passat and Superb platforms that have been out of production for well over a decade, original stops have usually hardened long ago, so the component belongs in every front suspension service job on these cars. For the wider suspension range, see our auto parts catalogue.
The item described here is a front suspension bump stop for Volkswagen and Skoda applications, referenced under OE number 3B7412377A and Bonpora number 4110027. European catalogues record the same application under the formatted reference 3B7 412 377 A, which describes the identical component. The table below lists the data buyers normally request before asking for a quotation.
| Parameter | Value |
|---|---|
| Product name | Strut Bump Stop |
| OE number | 3B7412377A |
| Bonpora no. | 4110027 |
| Fitment | Skoda / Volkswagen |
| Dimensions | Φ12.5 x Φ81.2 x 50.4 mm |
| Material | Polyurethane |
| Country of origin | China |
| Warranty | 1 year |
| Delivery time | 15–30 days |
| Packaging | Neutral export packaging |
| Custom service | OEM & custom design support |
Φ12.5 mm is the inner bore that slides onto the damper rod, Φ81.2 mm is the outer diameter of the elastomer body, and 50.4 mm is the free length. The bore decides whether the part can be assembled at all; the free length decides where in the stroke it starts to work. European aftermarket equivalents for this reference list an outer diameter of about 81 mm and a height of about 51 mm, a useful cross-check when comparing quotations. Compare all three values against the part removed from the vehicle before approving any substitution, because a taller stop makes the ride firm while a shorter one lets the suspension knock.
Polyurethane suits this duty cycle well. Compared with conventional rubber it resists tearing and oil exposure better, holds its mechanical properties across a wider temperature range, and can be moulded to a controlled hardness so the compression curve stays progressive rather than abrupt. The material also suits vehicles that stand still for weeks at a time, because parked elastomer is attacked by ozone and goes brittle first at the surface — a common pattern on Passat and Superb cars still running as daily transport, taxis, and fleet vehicles.
Aftermarket catalogues list OE 3B7412377A for the Volkswagen Passat B5.5 generation — the 2000-2005 facelift catalogued in Europe under type codes 3B3 (saloon) and 3B6 (estate) and often referred to as Passat 3BG — and for the Passat-based Skoda Superb I (type 3U4, 2002-2008). The reference is fitted on the front axle across the petrol and diesel engine range, from the 1.6 up to the 4.0 W8 4motion, roughly 101-275 hp, with the genuine catalogue applying it from chassis number 3B-1-300 001. Several suppliers also extend compatibility to Chinese-market Passat B5 builds. Catalogue naming overlaps in this category: the genuine parts list groups the reference with front strut mount hardware, while aftermarket brands such as FEBEST, AUTOMEGA, TOPRAN, and VAICO catalogue it as a front-axle rubber buffer or jounce bumper — so axle position should always be confirmed against the removed part.
Demand behind this reference comes from two buyer groups: wholesalers covering the independent aftermarket in regions where Passat B5.5 and Superb I vehicles still run in daily service, and fleet or taxi operators who keep older VW-group cars on the road and need predictable wear-part supply. Both are served from the same tooling and quality system, which is what makes factory-direct supply attractive in this category.
An original-quality replacement reproduces the reference part where it counts: the same bore and free length, an equivalent material grade and hardness, and a compression curve close to the OE component. It does not carry the vehicle maker brand name and should not be presented as such — it is a replacement part manufactured to the original specification, the practical route once the vehicle maker no longer supplies the reference in a given market.
A factory with OEM and custom design capability can produce stops to a customer drawing or sample, including non-standard bore sizes, alternative hardness grades, and application-specific profiles — useful for private-label ranges as well as vehicles with modified ride heights. Stocked references ship in wholesale quantities within 15–30 days in neutral export packaging, ready for relabelling or private-label cartons; new tooling is quoted against the drawing and an agreed annual volume. When comparing suppliers, ask for the polyurethane grade and Shore A hardness, the dimensional inspection report for bore and free length, and evidence of batch-to-batch hardness consistency, since elastomer properties are sensitive to cure conditions. Our auto parts sourcing team can review drawings, samples, and cross-reference lists alongside catalogue items.
A worn bump stop is often discovered during damper replacement, but it can also be diagnosed from the driver seat before the car goes on the lift.
On the catalogued applications the stop is fitted on the front axle, one per side, two per vehicle, and European catalogues recommend replacing it in pairs. Bump stops are normally replaced together with the related dust caps and top mounts, since all share the same access procedure and a similar service life, and the work is naturally done while the front dampers are off. Support the suspension before releasing fasteners, torque the components at normal ride height, and compare the old part against the new item to confirm bore, diameter, and free length.
Aftermarket catalogues list the reference for the Volkswagen Passat B5.5 saloon and estate (2000-2005, type codes 3B3/3B6, often called Passat 3BG) and the Skoda Superb I (3U4, 2002-2008), on the front axle. Because running changes and regional naming vary, confirm the application with the vehicle identification number or the OE number on the removed part, and ask the factory for a written cross-reference list covering the models you service.
A replacement manufactured to the original specification — matching bore, free length, material grade, and hardness — performs the same function as the OE part. Ask the factory for dimensional inspection data and material details so the comparison is documented rather than assumed.
Minimum order quantities depend on whether the item is a stocked catalogue reference or a custom moulding. Stocked references ship from current stock; private-label or custom profiles are quoted against tooling and an annual volume agreed with the factory. Send the target models and annual quantity to receive terms that match your programme.
Quoted delivery is 15–30 days for stock-referenced items, with neutral export packaging prepared for sea or air freight. Confirm the shipping method and destination port when requesting the quotation so the terms match your planning.
If you are sourcing strut bump stops for VW Passat and Skoda Superb applications in wholesale quantities, or planning a private-label suspension programme under your own brand, send the OE number, target models, and annual volume. The factory can confirm availability, provide dimensional and material data, and quote on neutral export packaging or private-label terms.
