Why no-name air suspension modules from the internet present a risk to safety

We did the test

People looking for new air suspension modules online will quickly find numerous cheap products: there are plenty of online sales platforms offering car parts. On one of these numerous portals, for example, air suspension modules for the Mercedes-Benz brand are offered for the equivalent of around € 235. This is an astonishingly cheap price for, as stipulated, “brand new” products. A price that should set all alarm bells ringing. We wanted to know what’s behind the supposed new parts, so we carried out a test.

To do this, we began by ordering an air suspension module which was tagged as “new”. What the seller didn’t expect: the cheap air suspension module was not just installed blindly into the car; it had to withstand one endurance test after another.

The first noticeable difference between the competitor’s product and our factory-new BILSTEIN B4 air suspension module: our products are delivered in an elaborately designed box, the competitor’s product from the Far East came in a plain box, which was also torn. And whilst our products are always accompanied by extensive installation instructions, our competitor’s contained no installation guide.

Alongside further qualitative differences, the electronic connection exhibited striking differences: on the air suspension module from the internet, we immediately noticed an old connector with an older production date and dirt entrapments. Our first suspicion arose: is the supposed new part not a new part at all, but simply a refurbished used part?

In our first test, the overall spring characteristics of the air suspension were measured: during the load test on the load-path testing machine there were large deviations in the spring lengths. Other than this, the folds in the protective collar pulled together in an irregular manner and even inward. BILSTEIN Workshop Manager Marco Kunert: “This could result in the protective collar coming into contact with the air spring bellow, rubbing and then destroying it.” On the other hand, in our BILSTEIN B4 air suspension module, the protective collar regularly folds together.

The differences between the two products became even more astonishing on the acoustics test bench. The measurement showed that the competing product was clearly louder than the BILSTEIN B4 air spring module. The reasons for this are high friction due to a non-original built-in seal and oil loss.

The result of the test could only draw one conclusion: the air spring module ordered online – and let’s remind ourselves this was officially a new part – barely absorbed the oscillations and appeared to already be very worn.

These observations coincide with the results of the last test. The dynamic measurements of the characteristic curves on a load-path machine disclosed a high damping force loss: the competitor’s product purchased online only disposed 29 percent of the required damping force. It’s obvious: The nameless air spring module was simply inoperable and thereby dangerous.

After the tests, the air suspension module was disassembled. The assessment brought alarming things to light here too. For example, in the installed thrust rubber bearing around an original but used part, we were dealing with a circumferential tear. Viewed under light, we could also see an indentation in the pipe, which indicates an accident. In addition to this, we were able to determine that a new closure package had been installed, although unprofessionally: the shock absorbers were therefore missing approx. 10 millimetres in overall length.

Marco Kunert’s summary is clear: “As we have seen, the shock absorber has no damping force. Many of the further attachments are used parts or poorly made replicas. For that reason, these parts are a significant risk to safety.”

With a lot of detective legwork, we have ultimately been able to establish that the competitor’s product is actually an old shock absorber from BILSTEIN, which was finished by us in Mandern, Germany in 2005. So much for a new part…