Bilstein South Africa, the local importer and distributor of Bilstein gas pressure shock absorbers, has warned motorists not to be misled by counterfeit versions of the brand’s Airmatic spring/damper, the fitment of which will severely compromise a vehicle’s stability and safety.
Damper assemblies with integrated height-adjustable air springs are fitted to a number of upmarket SUVS and saloons and provide the best of both worlds: extra ground clearance when off-road and the secure handling that lowered ride height provides when on the tar. These complex, sophisticated assemblies combine electronically-controlled hydraulic damping with air springing and can react instantly to road conditions, driver inputs, and speed.
Unfortunately, they are frequently copied or inadequately refurbished and sold at a price much lower than the original – often with the inference that their performance will be the same as or similar to that of the original.
These counterfeiters go to great lengths to pass their product off as a Bilstein but there are a number of key visual differences that can be used to verify the authenticity of the product. For starters, a fake “Airmatic” was 40 mm too long. Dimensional accuracy is critical and if the suspension is forced to work through an abnormal arc, it will cause not only incorrect geometry under certain conditions but also premature failure of rubber bushings and mountings and accelerated wear of other components such as constant velocity joints.
It also revealed that while the remote valve cylinder which controls the transfer of oil into the main damping tube of the shock was an original Bilstein part, it had however been harvested from a discarded assembly and had been attached to the fake in a completely non-functional manner. In fact, there was no link between the two, so while the fake unit still controlled the ride height, the all-important technology to control damping rate had been rendered inoperative.
Inspection of a refurbished assembly revealed the use of an incorrect length air bellows which was also secured by inadequately crimped retaining rings. The inflatable bellows is the suspension spring, and its integrity is therefore critical: if it is punctured, the on-board compressor will struggle to maintain the correct ride height. If the crimped-on metal retaining band fails – which it could in the event of a sudden and harsh suspension movement – the result is far more dramatic and the ‘spring’ will collapse instantly, with potentially catastrophic consequences.
Due to the safety-critical nature of the issue, Bilstein South Africa advises consumers and the motor trade to be aware of the dangers of attempting to repair these items, or fitting non-original replacement components. To this end they have issued a series of images which will assist in identifying a fake assembly.
- Key differences include:
- The extended length of the fake assembly which was found to be 40 mm longer than an original item.
- On a Bilstein unit the remote valve cylinder is invisibly laser welded onto the damping tube, whereas on the fake item uneven “spot” welding is evident where it attaches using a similar interface.
- One of the most obvious differences between the real and the fake is how the yoke, which straddles the vehicle’s suspension arm, is attached to the damper tube. The Bilstein item has an open tube which is pressed onto the shock body and then welded both above and below. The fake uses a casting which is closed at the bottom, has a longer boss and is welded onto the shock body on the upper side only.
- Viewed from below the genuine part has a dimple in the centre of the end cap, and the fake is smooth.
- The edge of the bellows on the Bilstein unit is extremely accurately and precisely aligned relative to the steel crimping ring. Extra crimping marks and a large and/or irregular overlap of the rubber are tell-tale signs that the bellows has been replaced, or that the entire unit is not a Bilstein product.
- The Bilstein unit has a satin black finish while the non-genuine item is gloss black.
- Bilstein’s trademark blue and yellow colours are prominent on the information stickers. Text includes the part number, and the word “Germany” – a reference to the country of manufacture.
The non-genuine item described itself variously as “High Quality”, “New Shock Absorbers” [sic] and “New Product”.
Some of these differences are only apparent by removing and examining the unit carefully but one of the most obvious – and important – giveaways in situ is the area at the bottom of the damper, where the fork joins the tube. The fake has a longer boss which is clearly welded to the tube on the upper side.
Consumers need to exercise caution concluded Bilstein SA: If pricing of an Airmatic assembly is very low they should carefully inspect the component using the guidelines provided. Shock absorbers are safety-critical parts, and need to be chosen with care – in this instance the counterfeit parts were not only of poor overall quality but also severely compromise the safety, comfort and enhanced road holding benefits of the OEM adaptive damping control.