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BMW strut bump stop 33506757368 is the rear axle suspension buffer listed in BMW parts catalogues for the 3 Series E46 generation, and Bonpora manufactures it to drawing data as number 4110126 in micro-cellular polyurethane. The cushion acts as a progressive auxiliary spring on the rear damper: it takes the final part of the suspension stroke, absorbs the energy that the coil spring and damper cannot fully control, and prevents metal-to-metal contact between the damper and the body. This page sets out the fitment range, the geometry of the part, the way BMW number groups separate front and rear axles, and the commercial details trade buyers verify before ordering.
At the rear of the E46, each wheel is located by a trailing arm and a coil spring arranged around a separate damper. Under normal load the spring carries the body while the damper controls wheel movement. When the suspension reaches full compression, on a deep pothole, a boot loaded to its limit or a sharp kerb strike, the tall polyurethane cushion between the damper rod and the body structure compresses progressively. Its stiffness rises through the stroke, so the movement feels firm rather than harsh, and the damper internals are spared the full impact.
A collapsed or missing buffer shows up quickly. Workshops report hard thumping from the rear over sharp impacts, a rear end that sits lower when the car is loaded, and faster wear on the rear dampers and their dust protection. Because the buffer costs little compared with the damper it protects, technicians usually renew it whenever rear dampers or springs are replaced.
Aftermarket catalogues list reference 33506757368 against the rear axle of the BMW 3 Series E46, produced from 1997 to 2005, across sedan, touring and compact bodies and engines from the 316i to the 330xi. Some sellers narrow the listing to the all-wheel-drive xi models of 2001 to 2005, while others apply it across the generation, so coverage differs between catalogues. The practical rule for a trade buyer stays the same: confirm the application against the vehicle identification number or, better still, against the removed buffer before committing to volume.
The published parameters for this replacement are summarised below.
| Parameter | Value |
|---|---|
| Product Name | Strut bump stop (rear axle suspension buffer) |
| OE Number | 33506757368 |
| Bonpora Nos | 4110126 |
| Fitment | BMW 3 Series E46, rear axle |
| Nominal Size (Bonpora drawing data) | Φ10.1 × Φ55.5 × 109 mm |
| Position | Rear axle, left and right |
| Material | Polyurethane (micro-cellular) |
| Country of Origin | China |
| Warranty | 1 year |
| Delivery Time | 15-30 days |
| Packaging | Neutral export packaging |
| Custom Service | OEM & custom design support |
Bonpora supplies this buffer inside a wider polyurethane bump stop programme that covers European, American, Korean and Japanese references, and every batch is checked for size and hardness before packing.
The drawing data of 10.1 mm bore, 55.5 mm outer diameter and 109 mm free height describes a distinctive shape. The narrow bore slides over the thin piston rod of the rear damper, while the wide outer face and tall body form a thick-walled column roughly 22 mm deep between bore and outer surface. That wall does the work: as the cushion compresses, the micro-cellular structure stiffens progressively and converts a harsh bottom-out into a controlled stop. European aftermarket listings for the same reference record a thickness of about 110 mm and a unit weight of roughly 80 g, figures that agree with the Bonpora nominal height once rounding is allowed for.
The tall profile is deliberate. A rear axle carries both passenger and luggage load, so the cushion needs a long progressive travel instead of a short emergency stop. Buyers replacing a flattened buffer should check free height with care, because a used piece loses several millimetres permanently and will never read the drawing height again.
BMW structures its part numbers by main group, and suspension buffers follow the rule clearly. Numbers beginning with 31 belong to the front axle group, while 33 marks the rear axle. The 3350 prefix of the present reference therefore places this part at the rear of the vehicle, beside the rear dampers and springs. For a wholesaler the distinction matters in two ways. Enquiries must be read carefully so the correct axle is quoted, and mixed containers can carry front and rear cushions for the same chassis side by side, because the prefixes differ at the first digit pair.
Catalogue cross-reference lists for 33506757368 include older BMW numbers such as 33502290348 and 33502290319, together with adjacent references in the 33 50 and 33 53 groups used by later platforms. The trailing digits separate cushion variants of different height and generation, so neighbouring numbers are not automatically interchangeable. When a customer quotes one of these related numbers, ask for the free height of the removed buffer or the chassis code, then match all three drawing dimensions before offering an alternative. Handled this way, a single enquiry often opens two or three order lines instead of one.
Wholesalers building mixed containers often order buffers by dimension, because one geometry can serve several references across brands. For this reference the checklist is short: measure the bore that slides over the damper rod, measure the outer diameter that seats against the body or spring seat, and measure the free height on a new part. Compare the three figures with the drawing data above and confirm that the material is micro-cellular polyurethane.
Two precautions keep the measurement honest. First, never take the height of a flattened used cushion as the reference value, because cellular material takes a permanent set after years of compression; use the catalogue height or a new sample instead. Second, check where the buffer locates in the assembly: a 10.1 mm bore suits a specific rod diameter, and a cushion that slides loosely will wear off-centre and fail early. If the original marking has worn away, send all three measurements to the supplier for verification before the order is placed.
Ordering by the OE reference removes the ambiguity of model year ranges and body styles and is the fastest route for most trade buyers.
The original buffers on many E46-era applications were cellular rubber, and aftermarket catalogues already describe this reference in PU. Both materials do the same job, with different behaviour along the compression curve.
| Property | Cellular Rubber | Micro-cellular Polyurethane |
|---|---|---|
| Compression behaviour | Progressive, softer initial stage | Progressive, firmer late-stage support |
| Shape retention | Permanent set possible over time | Holds shape through repeated cycles |
| Ageing and ozone resistance | Cracking possible at high mileage | Generally strong |
| Oil and grease contact | Swelling possible | Better resistance |
| Typical market role | Original equipment material | Common replacement material |
Neither material is automatically better. Rubber remains fully serviceable, while polyurethane is chosen where firmer late-stage support and longer shape retention are wanted, and much of the aftermarket supply for this reference is already listed as PU. Buyers who need a defined hardness receive the data sheet with the batch, and the shock absorber parts catalogue lists matching bump stops, dust covers and mounts for consolidated shipments.
Beyond catalogue supply, Bonpora runs a custom service for buyers who need their own part number, a modified geometry or branded packaging. Engineering starts from a dimensioned drawing, a physical sample or an existing reference such as this one, and adjusts bore, outer diameter, height and hardness to the application. Tooling is produced in-house, so sampling and revision cycles stay short. Options include customer part number marking, private label bags and cartons, and consolidated loading with other suspension lines; the custom parts page describes the process and the information needed for a quotation.
Suspension cushions work in a demanding environment of wide temperature swings, continuous compression cycles and contact with dirt and moisture, so batch control concentrates on the properties that decide service life. Incoming polyurethane is checked against specification, dimensions are sampled with calibrated tools, hardness is measured on every batch, and visual inspection covers pores, cracks and flash. Finished goods are packed only after the batch record is complete, which keeps every shipment traceable to its production batch.
Standard packing is a poly bag per piece with export cartons sized for stable pallet loading; at roughly 80 g per piece, several hundred units fit a single carton. Neutral export packaging is the default, which lets distributors sell under their own brand where regulations allow. Production lead time is 15 to 30 days from order confirmation and samples usually ship sooner. Bonpora quotes ex-works, FOB and CIF terms and can consolidate these buffers with front axle references and dust covers from the same production base to reduce freight cost.
Catalogues list the reference for the rear axle of the BMW 3 Series E46 generation, produced from 1997 to 2005, including sedan, touring and compact bodies and engines from the 316i to the 330xi. Some catalogues narrow the listing to the xi all-wheel-drive models of 2001 to 2005. Confirm the application against the VIN or the removed part before ordering in volume.
The nominal drawing data is a 10.1 mm bore, a 55.5 mm outer diameter and a 109 mm free height. European aftermarket catalogues record a thickness of about 110 mm for the same reference, which agrees within rounding. Measure the removed part at the same points and request a sample where the figures are critical.
It is a rear axle component. In the BMW number system the 33 main group covers the rear axle, while 31 covers the front, so the 3350 prefix places this buffer at the rear of the vehicle. Buyers mixing front and rear lines for the same chassis should quote both prefixes separately to avoid warehouse confusion.
Trial orders stay small: sample quantities and mixed trial shipments are accepted so buyers can verify fitment first. Production completes within 15 to 30 days depending on volume, ships in neutral export packaging and carries a 1 year warranty. OEM and custom design support is available for buyers who need their own branding or a modified design.
For prices, drawing data and samples for the 33506757368 rear buffer, send the reference, the quantity and the destination port to the Bonpora sales team. Quotations for stock items usually go out within one working day, and this line can be combined with other suspension references in the same shipment.
