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When a front suspension compresses to the end of its travel, the strut bump stop is the part that takes the final impact. On Audi and Volkswagen models built on B5-era front strut platforms, a worn or collapsed bump stop can turn into harsh bottoming, knocking noises, and faster wear of the damper itself. This guide explains what the strut bump stop 8D0412131E does, which vehicles it is commonly listed for, how to source it by OE number, and what to expect when buying from a Chinese auto parts factory such as the Bonpora auto parts catalog.
A strut bump stop, also called a jounce bumper or strut bumper, is a compressible component mounted on the piston rod of a MacPherson strut. When the suspension reaches full compression over speed bumps, potholes, or under heavy load, the bump stop contacts the strut housing and absorbs the remaining energy before metal components can touch.
The part does three jobs at once: it limits suspension travel, softens the impact at the end of that travel, and protects the internal seals of the strut from shock loads. When the bumper is missing, collapsed, or hardened with age, the strut can bottom out, the ride becomes harsh, and the damper may wear out sooner than expected.
Bump stops are usually molded in rubber or polyurethane. Rubber is the common factory choice because of its low cost and predictable behavior. Polyurethane, the material used for the part described here, is denser and generally more resistant to compression set and tearing, which can mean longer service life in demanding conditions. Neither material is better in every situation; the right choice depends on the vehicle, the operating environment, and the quality of the compound.
The strut bump stop covered in this article is supplied by Bonpora under item number 4110000 and references OE number 8D0412131E. Buyers use both numbers: the Bonpora reference for ordering, and the original equipment number for cross-referencing with the vehicle.
| Product Name | Strut Bump Stop |
| Country of Origin | China |
| Bonpora No. | 4110000 |
| OE | 8D0412131E |
| Fitment | Audi / Volkswagen |
| Size | Φ16.7 × Φ58.2 × 80.8 mm |
| Material | Polyurethane |
| Warranty | 1 Year |
| Delivery Time | 15–30 Days |
| Packaging | Neutral Export Packaging |
| Custom Service | OEM & Custom Design Support |
The 8D0 prefix of the OE number points to the front suspension family used on Audi and Volkswagen models of the B5 platform generation. In practice, this bump stop is commonly cross-referenced for models such as the Audi A4 (B5) and the Volkswagen Passat (B5), as well as related vehicles sharing the same front strut assembly. Fitment can vary by year, engine, and suspension option, so always confirm the application before ordering: check the OE number stamped on the old part, or ask the supplier to verify against your vehicle identification number (VIN).
Different markets and model years may use a superseded or alternative OE number. If your old part carries a different number, a supplier with OEM reference data can help you cross-reference 8D0412131E to the correct equivalent.
Sourcing teams typically find this part through several search patterns: part type plus specification (“strut bump stop 8D0412131E”), part type plus supplier (“polyurethane bump stop manufacturer”), vehicle model plus part (“Audi A4 strut bumper”), and OE number lookup (“8D0412131E replacement”). Ordering by OE number is usually the most reliable route because it ties the part to the original specification regardless of brand naming differences.
When you compare quotes, ask for three things: the exact OE reference, material and hardness data, and dimensional confirmation against a drawing. A supplier who can provide all three is easier to evaluate than one who only lists a fitment range.
Because polyurethane compounds vary between manufacturers, the raw material grade matters as much as the shape. Key points to review with the supplier: hardness (usually expressed in Shore A), resistance to compression set, low-temperature flexibility, and tolerance on critical dimensions. A part that is too hard can transmit more harshness; a compound that softens under heat may not hold up in heavy use.
The Bonpora strut bump stop for Audi/Volkswagen is molded from polyurethane and supplied with dimensional data for incoming inspection. If your application needs a different hardness, color, or compound, custom molding is available – see the custom service section below.
Buying directly from a Chinese auto parts factory gives procurement teams more control over specification, packaging, and price. Bonpora offers OEM and custom design support for strut bump stops: existing OE references can be reproduced, and new shapes or compounds can be developed against drawings or samples.
It is common practice to begin with a sample. Before mass production, a sample inspection covers material, dimensions, and fit. This is also the stage to agree on inspection criteria so that the production batch matches the approved sample.
For volume orders, buyers can request neutral export packaging, custom labeling, or private branding according to their market. Discuss the requirements with the supplier before production so the final goods match your distribution channel. More suspension components are listed in the suspension parts section.
For the 8D0412131E strut bump stop, standard delivery time is 15–30 days depending on quantity and stock status, and the product carries a 1-year warranty. Packaging is neutral export packaging by default, with customized options for repeat orders. As with any overseas purchase, confirm lead time, Incoterms, and payment terms in writing before production starts.
To request a quote, send the OE number or Bonpora item number 4110000, the quantity, and your target delivery date. The supplier will confirm price, lead time, and shipping options.
A bump stop rarely fails with a warning light; it wears gradually. Common symptoms reported by workshops include a metallic or knocking sound when the front suspension compresses fully, a noticeably harsh ride over speed bumps, and visible cracking or crumbling of the bumper when the strut is removed for inspection. The damper itself may also start to leak earlier if it has been repeatedly subjected to hard bottoming.
Because the bump stop sits inside the strut area, it is often replaced together with the strut mount or the complete strut assembly during suspension service. For a buyer sourcing replacement stock, it is worth asking whether the supplier also offers related components such as strut bump stops in other sizes, so multiple line items can be consolidated into one order.
The bump stop and the strut mount are both located around the top of the strut but serve different purposes. The strut mount (also called a strut bearing or top mount) connects the strut to the vehicle body and carries the load of the vehicle through the suspension; the bump stop limits and cushions the compression stroke. They are separate parts with separate OE numbers, even though they are often replaced at the same service event.
When a customer orders by part name alone, there is a risk of receiving the wrong component. Ordering by OE number, or by a supplier reference that maps to the OE number, removes most of that ambiguity. For the part in this article, referencing 8D0412131E together with Bonpora item 4110000 lets the supplier confirm exactly which component is needed before shipment.
It is the original equipment reference for a strut bump stop used in the front strut assembly of certain Audi and Volkswagen models. Cross-referencing this number against your old part or VIN is the safest way to confirm fitment.
A bump stop is installed on each front strut. If both struts are being serviced, two pieces are normally required. Check your application and order the matching quantity.
Yes. The factory supports OEM and custom design service, including reproduction of OE references, custom compound or color, and private labeling on larger orders.
Standard delivery is 15–30 days. Stock availability, quantity, and destination affect the actual lead time, which the supplier confirms before you place the order.
Ready to order? Send your OE number or Bonpora item number 4110000 to the Bonpora team for a quote, or browse more auto parts from the factory.
