Audi 8K0512131A Rear Suspension Bump Stop for A4 B8 A6 C7 A7 Q5 | OEM & Custom Supplier

Buyers who search for the Audi OE number 8K0512131A are usually looking for one specific part: the rear suspension bump stop, also catalogued by Audi as a stop buffer, jounce bumper or spring support. It is a small polyurethane component, but it sits at the very end of the rear damper travel, and when it fails the rear axle announces every sharp impact with a hard clunk. Bonpora manufactures and supplies this bumper under part number 4110188, with OEM and custom design support for wholesale buyers. This page explains where the part fits, how the 8K0512131 suffix family works, what the factory supersession means for ordering, and what a B2B buyer should confirm before requesting a quote.

What Is the 8K0512131A Rear Bump Stop?

In the Audi parts catalogue the number 8K0512131A appears under the running-gear group as a stop buffer, and in several official diagrams it is listed as a jounce bumper or spring support for the rear suspension, left and right sides. The component slides over the piston rod of the rear shock absorber. During normal driving the damper controls the wheel movement, and the bump stop stays clear. When the suspension approaches full compression - a deep pothole, a heavily loaded boot, a sharp crest at speed - the foam bumper is compressed between the damper body and its collar.

That last few millimetres of travel are progressive: resistance builds up smoothly instead of the suspension reaching metal-to-metal contact. A healthy bump stop therefore protects the damper rod and seals, limits chassis impact, and keeps the ride controlled under load. Because the part is made of open-cell polyurethane foam, it is also a wear item - it slowly takes a permanent set, and it can crack with age and ozone exposure. Suspension specialists recommend inspecting it whenever the rear shocks are replaced.

Fitment: Which Audi Models Use 8K0512131A

The number family 8K0 512 131 x belongs to the rear axle of the Audi B8 and C7 platforms. Catalogue data and aftermarket cross-references agree on the following applications:

Two cautions apply. First, within one model year Audi splits this position by suspension configuration - standard, comfort or sport suspension, and by drive type - so the exact suffix that shipped on a given vehicle varies. Second, fitment should always be confirmed against the vehicle VIN. Our sales team checks VIN-level fitment before quoting.

Front Axle Is a Different Number Family

A frequent sourcing mistake is ordering 8K0512131A for the front of the car. The front strut bump stop of the same platforms belongs to the 8K0412131 x family - for example 8K0412131E (81 mm) or 8K0412131F (72 mm). The two families are not interchangeable: different diameters, different lengths, different damper rods. When a customer enquiry says only A4 B8 bump stop, always confirm axle first, then OE number.

Understanding the 8K0512131 Suffix Family: A, D, H, J, K

Audi kept the same base number for this rear bumper and used the last suffix to mark revision branches that follow suspension variants. Published catalogue data summarises as follows:

*Aftermarket catalogues list the A/J group between roughly 120 and 128 mm because measurement bases differ - some cite free foam height, others include the mounting collar. Our own dimensional check of the product in this article gives 119.8 mm free height, consistent with the J-group boxed dimension of 60 x 60 x 120 mm.

OEM Supersession: 8K0512131A Was Replaced by 8K0512131J

According to VAG supersession records, 8K0512131A was phased out during 2014: replaced by 8K0512131J from January 2014 in most regions, April 2014 in Argentina and August 2014 in Mexico. The practical meaning for buyers is simple: dealers will quote and ship the J number against an A-number enquiry. The function and mounting are the same; the J number covers the comfort-suspension branch of the same rear axle.

For a supplier, this supersession is also the reason to buy by OE number rather than by a photo or a year alone. Bonpora lists both the A and the J reference against product 4110188 so that enquiries written either way resolve to the same part. If a workshop needs the taller standard-suspension piece, that is the H number at 145 mm, and the sport-suspension branch is the K number - three different foam lengths that look similar in a photograph.

Technical Specifications - Bonpora 4110188

Reading the Three Dimensions

The size string describes three independent measurements, and each one matters for fitment. The 17.3 mm figure is the mounting bore that slides over the damper rod; if it is too tight the bumper cannot seat, and if it is too loose it will slide and knock. The 60.8 mm outer diameter must pass into the damper dust-tube collar without fouling the dust boot. The 119.8 mm free height sets the point at which the rear axle goes progressive - it is the value that differs across the H, J and K branches. Quoting an enquiry with only one of the three numbers is a common cause of returns; a complete set of three, or simply the OE number, removes the ambiguity.

Why Polyurethane Instead of Rubber

Modern European-platform bump stops are almost universally microcellular polyurethane foam (ester or ether systems depending on supplier). Compared with natural rubber of the same stiffness, PU foam offers a more progressive force-stroke curve, lower permanent compression set, and stable behaviour across a wide temperature window - our standard material is validated from -40°C to +90°C for passenger-car use. The material is also markedly lighter, which matters at OEM line rates where every gram of unsprung mass is counted. Bonpora produces to an IATF 16949 framework, with static stiffness curves, compression set and hardness checked at incoming and outgoing inspection. You can browse the full range in our polyurethane bump stop catalogue.

Symptoms of a Worn Rear Bump Stop

A rear bumper rarely fails in a way that triggers a dashboard warning; the evidence is acoustic and dynamic:

• Hard clunk over sharp edges. A crumbled or missing bumper lets the suspension reach its mechanical limit, and the damper collar takes the hit.
• Knocking that grows with load. A fully laden boot compresses the travel further; a worn bumper shows up first when the car is loaded.
• Visible cracking, powder or flattened foam. Ageing PU foam develops surface cracks and loses height; any bumper that has taken a visible permanent set should be replaced.
• Uneven behaviour side to side. If one side collapsed and the other did not, the rear axle feels inconsistent over successive bumps.

Workshops typically replace bump stops in pairs together with the dust boots and the rear dampers, since disassembly labour is shared. Bonpora supplies the complete shock absorber parts group - bump stops, dust cover kits and strut mounts - so a single order can cover the full rear-axle service.

Wholesale Supply and Custom Manufacturing

Bonpora is a manufacturer-side supplier of suspension rubber and PU components. For the 8K0512131A programme, standard supply is neutral export packaging with our own part number 4110188 marked on the bag and box label; customer-branded packaging is available for volume orders. Lead time for stock programmes is 15-30 days depending on order size and destination port. Typical cooperation models:

• Repeat wholesale orders against framework agreements, shipped with mixed container loading across part numbers.
• Private-label programmes where the buyer supplies artwork and we print neutral or branded packaging.
• Custom development for OE numbers outside the current range: tooling and sample stages run against a drawing or a physical sample, with stiffness targets agreed in advance.

Beyond bump stops, the same tooling base covers strut mounts, stabiliser links and spring seats; see the custom parts service for the development workflow.

How to Request a Quote

Send an enquiry with four items and our team replies with pricing, packing data and lead time: the OE number (8K0512131A, or 8K0512131J where the vehicle has been updated), the target quantity, the destination port, and any packaging or labelling requirement. For fleet or workshop buyers without a part number, the VIN of one reference vehicle is enough for us to confirm the correct suffix branch before quoting.

Frequently Asked Questions

Is 8K0512131A a front or rear bump stop?

It is a rear suspension bump stop, fitted one per side on the rear dampers, left and right. The front axle of the same Audi platforms uses the separate 8K0412131 x family (for example 8K0412131E at 81 mm and 8K0412131F at 72 mm). Confirming the axle before ordering prevents the most common cross-order error.

What replaced 8K0512131A?

VAG supersession records show 8K0512131A was replaced by 8K0512131J during 2014 (from January in most regions). Within the same family, H is the taller standard-suspension branch at about 145 mm and K covers the sport-suspension branch. Dealers substitute the J number automatically when an A-number part is ordered.

Does 8K0512131A also fit the A5, Q5 and A4 allroad?

Major aftermarket cross-references - for example the Vaico V10-6042 listing against 8K0512131 / 8K0512131H - include A4, A5, A6, allroad and Q5 applications on these platforms. Coverage depends on the suspension configuration of the individual vehicle, so we confirm each enquiry against the VIN before shipping.

Why do catalogues show different lengths - 120 mm, 128 mm, 145 mm?

Two reasons. First, the suffix branches are physically different parts: the H number measures about 145 mm while the J group is about 120 mm. Second, published heights for the A/J group range from roughly 120 to 128 mm because suppliers measure different references - free foam height versus height including the mounting collar. The reliable way to order is by OE number and VIN, not by a single length figure.

Need 8K0512131A / 8K0512131J rear bump stops in wholesale quantity? Send your enquiry with the OE number and quantity to Bonpora - manufacturer supply, OEM and custom design support, 15-30 day delivery with neutral export packaging.