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The rear strut bump stop 1780533 is the progressive compression buffer fitted to the rear axle of the Ford B-Max and of the Transit Courier and Tourneo Courier vans. Bonpora supplies the same component in micro-cellular polyurethane as number 4110135, direct from the factory in China for wholesale buyers. This guide explains what the part does, which vehicles the reference covers and what to check before ordering.
The B-Max and the Courier models ride on a torsion beam rear axle with separate coil springs and telescopic dampers, and each rear damper carries a polyurethane buffer over its rod.
Under normal load the buffer does nothing: the coil spring carries the body and the damper controls the wheel. When a loaded van meets a sharp ridge or a deep pothole, the rear suspension can reach full compression. The 1780533 compresses progressively at that point, turning the last part of the stroke into a controlled deceleration instead of a hard knock through the floor. It also protects the damper, whose rod seals wear faster when the strut is repeatedly driven against its upper limit.
The part is a cylinder of yellow micro-cellular polyurethane with a stack of moulded ribs along its length. The ribs fold in turn, so the buffer stiffens as it shortens. Bonpora records a bore of 13.1 mm, an outside diameter of 57.5 mm and a free length of 121.5 mm, and the small bore locates the buffer on the damper rod.
A worn rear buffer rarely announces itself on smooth roads. The usual symptoms are a hollow knock from the rear over sharp compressions, a harsher ride when the van is loaded, and a crumbled or crushed buffer found during damper or spring work. Because the buffer is inexpensive next to the dampers, workshops normally renew it whenever the rear suspension comes apart.
Aftermarket catalogues apply the reference across three closely related B-platform models, as summarised below.
| Model | Body code | Body style | Catalogue years | Position |
|---|---|---|---|---|
| Ford B-Max | JK | Mini MPV | 2012 onwards, records to 2024 | Rear, both sides |
| Ford Transit Courier | B460 | Panel van and Kombi | 2014 onwards | Rear, both sides |
| Ford Tourneo Courier | B460 | Mini MPV | 2014 onwards | Rear, both sides |
Catalogue engine lists run from 75 to 140 hp: the 1.0 EcoBoost petrol, the 1.4 petrol and its LPG version, the 1.6 Ti-VCT, and the 1.6 TDCi, 1.5 TDCi and 1.5 EcoBlue diesels. Catalogue data extends to the 2021 facelift of the Courier range, so one stock line serves both build phases.
The same buffer appears in Ford records as 1 780 533, as AY11-5K570-AA and as BV21-5K570-AA. The AY11 and BV21 prefixes are Ford engineering date codes, and the 5K570 base number identifies the rear bump stop family. Aftermarket catalogues treat the three formats as one reference, so enquiries quoting any of them point at the same part.
The drawing data below summarises the part as supplied from the factory.
| Item | Value |
|---|---|
| Bonpora number | 4110135 |
| OE reference | 1780533 (1 780 533) |
| Companion Ford formats | AY11-5K570-AA, BV21-5K570-AA |
| Position | Rear axle, both sides, 1 per side |
| Nominal size, Bonpora data | Bore 13.1 x OD 57.5 x length 121.5 mm |
| Material | Micro-cellular polyurethane |
| Country of origin | China |
| Warranty | 1 year |
| Delivery | 15-30 days |
| Packaging | Neutral export packaging |
| Custom service | OEM and custom design support |
European aftermarket records for the OE reference list a length of 134 mm and an outside diameter of 60 mm, with part weights of around 86 g, while the Bonpora drawing reads 121.5 mm and 57.5 mm. The two datasets describe the same reference measured at different points on a tapered, ribbed part. The deciding check is the removed buffer: match height, outside diameter and bore before quoting.
Enquiries often arrive quoting an aftermarket number instead of the OE. The main equivalents are Febi Bilstein 175933, Fast FT12602, Vaico V25-2453, Sasic 2650227, Swag 33 10 3190, Metalcaucho 40571 and Original Imperium 37892. All describe the same rear buffer, so one stock line answers the whole family of references.
The rear buffer described here is often confused with the front stop of the same vans, and the two are not interchangeable.
The front struts of the B-Max and the Courier models carry their own polyurethane stop, and aftermarket catalogues list it at around 75 mm long against roughly 120 mm at the rear. Ordering by model name alone risks receiving the wrong axle. Quote the OE number, or state the axle position together with the measurements of the removed part.
The export desk checks every enquiry against the reference and the drawing. Buyers who cannot read a worn part should send the model, the year and the axle position, plus any legible number from the buffer, and the factory confirms the match before quoting.
The same component appears under several names, which matters when a buyer searches one term and the catalogue indexes another.
Buyers usually search for a rear strut bump stop, a jounce bumper or a shock absorber buffer. Ford records group the reference under the 5K570 rear bumper family, and trade listings add names such as coil spring damper. The function is the same in every case: a progressive end-of-travel cushion on the rear damper. The article keeps the trade term in the title and body so that every search route leads to the same page.
European aftermarket catalogues file the reference as a rubber buffer for the suspension, even where the material is polyurethane. When building enquiry lists it helps to search both terms, because a hit under either name points at the same position in the exploded drawing. Colour is not a fit-relevant specification.
Bonpora moulds this buffer in micro-cellular polyurethane rather than filled rubber, a choice that changes how the part behaves on the vehicle.
| Property | Polyurethane (Bonpora) | Conventional rubber |
|---|---|---|
| Compression set | Low, recovers shape after repeated hits | Higher, takes a set over time |
| Ozone and heat ageing | Strong resistance | Cracks sooner in hot climates |
| Oil and fluid contact | Good resistance | Swells and softens |
| Load consistency | Uniform batch to batch | Varies with compound |
| Unit cost | Moderate | Lower |
Rear buffers on delivery vans work harder than those on passenger cars: the load varies all day and the axle bottoms more often. A compound with a low compression set keeps its free length stable through repeated compressions, protecting the travel reserve of the damper. The full polyurethane bump stop range applies the same approach across other platforms.
A correctly sized buffer only works at the end of the stroke, so a polyurethane replacement does not change normal ride comfort. What decides the fit is the geometry: height, outside diameter and bore must match the removed part.
Buyers want a faithful replacement sourced directly from a manufacturer with OEM capability.
Bonpora moulds buffers against the published OE data and ships them from its own production line, without trading layers in between. Every enquiry is checked against the reference before dispatch, and buyers can request samples and measure them against the drawing figures above.
For distributors with their own brands, the factory offers OEM labelling, branded boxes and private moulding. Custom design covers changes of compound hardness, free length or outer profile: send the sample or the drawing, and the tooling, minimum order and lead time are confirmed before production. Details of the programme are on the custom parts page.
Standard supply ships in neutral export packaging on a 15-30 day schedule with a one-year warranty, and pricing is quoted against order volume so that distributors can plan their season.
Send the OE number, the model year, the quantity per vehicle and the destination port to the export desk. If the number has worn away, quote the height and the outside diameter and the factory will match the drawing. Buyers building a wider Ford programme can browse the shock absorber parts catalogue alongside this line, where buffers, mounts and related hardware are grouped for one-stop purchasing.
Yes. The AY11 and BV21 formats are Ford engineering codes for the same rear bump stop family, and catalogues list them beside the numeric form 1 780 533. Febi 175933, Fast FT12602 and Vaico V25-2453 are common aftermarket equivalents.
No. This reference covers the rear axle, one buffer per side, two per vehicle. The front struts use a shorter stop of about 75 mm with its own reference, and the two are not interchangeable. Confirm the axle and compare the removed part before ordering.
The reference is a tapered, ribbed part, and suppliers measure the free length at different points. Both datasets describe the same OE number, so match the removed buffer against height, outside diameter and bore rather than against one published number alone.
One per rear side, two per vehicle, and the part is not handed. Workshops normally renew the pair together whenever the rear dampers are dismantled, because mixing a new buffer with a worn one upsets the end-of-travel behaviour.
Bonpora manufactures and exports suspension buffers from China for wholesale buyers worldwide. Quote 1780533 or 4110135 with your quantity and destination, and the export desk will return unit pricing, packing details and the next available shipment. For the material background behind the range, the polyurethane bump stops overview is a good starting point.
