Audi 8K0512131 Rear Bump Stop for A4 B8 A5 Q5 A6 C7 A7 | Standard Suspension | OEM & Custom Supplier

Buyers who search the bare OE number 8K0512131 are usually sourcing the tall rear suspension bump stop of the Audi B8 and C7 platform family - the piece aftermarket catalogues list at about 145 mm and group together with 8K0512131H. Bonpora manufactures this bumper under part number 4110186 in polyurethane, sized 15.5 x 61.5 x 146.7 mm, with OEM and custom design support for wholesale buyers. This page explains where the part fits, how the 8K0512131 suffix family separates standard, comfort and sport builds, what the parallel 4G0512131F and G numbers mean for A6 C7 and A7 applications, and which checks matter before ordering.

What Is the 8K0512131 Rear Bump Stop?

In the Audi parts catalogue the 8K0512131 family appears under the running-gear group as a stop buffer, and dealer diagrams list the same component as a jounce bumper for the rear suspension, left and right sides - one piece per side, two per car. The bumper slides over the piston rod of the rear shock absorber, inside the dust tube. While the damper controls normal wheel movement the foam stays clear; when the suspension approaches full compression - a deep pothole, a fully loaded boot, a sharp crest at speed - the bumper is crushed between the damper body and its collar.

That final stretch of travel is progressive: resistance builds smoothly instead of the suspension reaching metal-to-metal contact. A sound bump stop protects the damper rod and its seals, softens chassis impacts, and keeps the rear axle settled under load. Because the part is made of open-cell polyurethane foam it is also a wear item - it takes a permanent set over time and can crack with age and ozone exposure, so inspect both rear bumpers whenever the rear shocks are replaced.

Fitment: Which Models Use the 8K0512131 Rear Bump Stop

Cross-referencing aftermarket catalogues (FEBI 36722, Vaico V10-6042, SASIC 2656050, ORIGINAL IMPERIUM 35154) and dealer data for the parallel 4G number gives a consistent application map for the 145 mm standard-suspension profile:

Two cautions apply. First, Audi splits this position by suspension configuration - standard, comfort, sport - and by air suspension, so the suffix that shipped on a given vehicle varies; the same A6 C7 can appear under the 8K bare number, under a suffix branch such as B, or under the 4G number depending on the build. Second, supplier data for these numbers also covers China-built AUDI (FAW) versions (A4L, A6L) and, in Vaico and ORIGINAL IMPERIUM catalogue data, the VW Passat B6 R36 4motion and Golf VI R 4motion - applications that should be confirmed against the VIN before shipping.

Front Axle Is a Different Number Family

A frequent sourcing mistake is ordering 8K0512131 for the front of the car. The front strut bump stop of the same platforms belongs to the 8K0412131 x family - for example 8K0412131E at about 81 mm or 8K0412131F at about 72 mm. The two families differ in diameter, length and damper rod, and are not interchangeable. When an enquiry says only A4 B8 bump stop, confirm the axle first and the OE number second.

The 8K0512131 Suffix Family: Bare Number, H, A and J, B and K, D

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

The branches look alike in a photograph but differ in length, bore and damping behaviour, so a mixed shipment causes hard-to-trace warranty claims. For the 145 mm standard-suspension group the aftermarket replacement numbers are FEBI 36722, Vaico V10-6042, SASIC 2656050 and ORIGINAL IMPERIUM 35154 - each lists the bare 8K0512131 and 8K0512131H on the same product page, the clearest signal that the two OEM references resolve to one physical part.

Supersession and the Parallel 4G Number Family

Within the 8K family, supplier data lists the bare number as the previous revision of 8K0512131H, and dealers substitute the H reference automatically on current orders. For the C7-platform cars Audi runs a parallel numbering line: the rear bumper appears as 4G0512131F, which dealer supersession records replace with 4G0512131G, qualified as without air suspension, standard suspension, without electronic levelling and covering A7, S7, SQ5 and Q5 applications in that configuration. Aftermarket suppliers close the loop: ORIGINAL IMPERIUM 35154 groups 8K0512131, 8K0512131H and 4G0512131F into one 146 mm replacement.

The practical conclusion for buyers is to treat these references as routes into the same warehouse bin - the 145 mm-class rear bumper - while still confirming the suspension branch of the target vehicle. Bonpora lists the family against product 4110186 so an enquiry written with any of the numbers above resolves to the same quotation.

Technical Specifications - Bonpora 4110186

Reading the Three Dimensions

Each figure in the size string carries fitment meaning. The 15.5 mm bore slides over the rear damper rod; a dust cover kit listed for the same OE group (OPEN PARTS DCK5124.04) cites an identical 15.5 mm inner diameter, which confirms the match at the rod seat. The 61.5 mm outer diameter must pass the dust-tube collar cleanly - published figures across the supplier group range from about 57.5 to 62 mm because manufacturers measure at different stations along the taper. The 146.7 mm free height sets the point at which the rear axle goes progressive; catalogues cite 145 mm for FEBI, Vaico, SASIC and OPEN PARTS and 146 mm for ORIGINAL IMPERIUM, and the spread reflects free foam height versus height including the mounting collar. Ordering by OE number plus VIN avoids the ambiguity.

Why Polyurethane Instead of Rubber

European-platform bump stops of this generation are almost universally microcellular polyurethane foam. Compared with rubber of equal stiffness, PU foam gives a more progressive force-stroke curve, lower permanent compression set and stable behaviour across a wide temperature window - our standard compound is validated from -40°C to +90°C for passenger-car use, and the foam is markedly lighter. Bonpora produces under an IATF 16949 framework, with static stiffness curves, compression set and hardness checked at incoming and outgoing inspection. The wider range is browsable in our polyurethane bump stop catalogue.

Suspension PR Codes: Why One Model Can Need Two Different Parts

VAG assigns suspension PR codes on the factory build label, and catalogue notes for this family quote them directly: the sport branch (B / K) carries codes 1BD, 1BV and 2MS, the D branch appears against 1BL and 1BV, and standard builds carry the 145 mm piece under the bare and H numbers. Suppliers of genuine stock accordingly warn that the part fits certain PR codes only and ask buyers to check before ordering. For a wholesaler the workflow is simple and worth writing into the sales SOP: capture the PR code from the option label or the VIN, map it to the suffix branch, then quote. This single check prevents the majority of returns in this category, because a comfort-branch bumper installed on a standard build sits permanently preloaded and fails early. The same discipline applies across the suspension range - see our shock absorber parts group for related bump stops, dust cover kits and mounts.

Symptoms of a Worn Rear Bump Stop

A worn rear bumper rarely triggers a warning light; the evidence is acoustic and dynamic:

• Hard clunk over sharp edges. Crumbled foam lets the suspension reach its mechanical limit and the damper collar takes the impact.
• Knocking that grows with load. A laden boot compresses the remaining travel, so a tired bumper shows up first when the car is loaded.
• Visible cracking, powder or flattened foam. Ageing PU loses height and develops surface cracks; any bumper with a visible permanent set should be replaced.
• Inconsistent behaviour side to side. One collapsed bumper makes the rear axle feel uneven over successive bumps.

Replace both sides together with the dust boots and the rear dampers: the disassembly labour is shared, and mixed old-and-new foam heights disturb axle balance.

Wholesale Supply and Custom Manufacturing

Bonpora is a manufacturer-side supplier of suspension rubber and PU components. For the 8K0512131 programme, standard supply is neutral export packaging with part number 4110186 marked on bag and box label; customer-branded packaging is available for volume orders, and lead time for stock programmes is 15-30 days depending on order size and destination port. Typical cooperation models include repeat wholesale orders against framework agreements with mixed-container loading, private-label programmes against buyer artwork, and 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. The development workflow is described on our custom parts service page.

Frequently Asked Questions

Is 8K0512131 the same part as 8K0512131H?

For ordering purposes the aftermarket treats them as one part: FEBI 36722, Vaico V10-6042 and SASIC 2656050 each list both numbers on a single 145 mm rear replacement, and one supplier data set names the bare number as the previous revision of H. In the OEM system the suffix encodes the suspension branch, so the safe habit on a mixed fleet is to confirm the branch by VIN or PR code and then order against the covering number.

What replaced 8K0512131?

Within the 8K family the successor revision is 8K0512131H for the standard-suspension branch; the comfort branch moved from A to J during 2014 and the sport branch from B to K. On C7-platform cars the parallel 4G0512131F was superseded by 4G0512131G. Dealers apply these substitutions automatically.

Does 8K0512131 fit the Q5 and the A6 C7?

Yes for standard-suspension builds without air suspension: dealer listings for the 4G number cover Q5 and SQ5 in that configuration, and aftermarket crosses list Q5 8RB plus A6 C7 saloon and Avant applications. Air-suspension cars use a different component set at the same position, so confirm the build by VIN before ordering.

Why do catalogues show 145 mm, 146 mm and 146.7 mm for one part?

The difference is the measurement basis, not a different part. SASIC and OPEN PARTS cite a 145 mm body height, ORIGINAL IMPERIUM lists 146 mm, and the figure in our specification table - 146.7 mm - is the free height including the mounting collar. Where a customer works to a drawing, state the measurement basis in the enquiry so both sides compare like with like.

Need 8K0512131 / 8K0512131H rear bump stops in wholesale quantity? Send the OE number, quantity and destination to Bonpora - manufacturer supply in polyurethane, OEM and custom design support, 15-30 day delivery with neutral export packaging.