Cheap imports of scrap zinc-based balancing weights are poor quality and contain dangerous levels of heavy metals, such as cadmium. Premium weight manufacturers told Tyres & Accessories that preliminary research shows such imports may contain 50 times the level of cadmium currently allowed in the products.

After the relatively successful introduction of the End of Life Vehicle (ELV) directive earlier this year, it seemed as if all but the most unscrupulous companies had followed the necessary legal guidelines and switched to lead-free weight alternatives. However, there was a problem. Intense raw material demand from the emerging markets like China means the cost of the metals used in weight production has skyrocketed. Prices of Zinc, the most common lead substitute, have quadrupled in the last two years, forcing the leading weight manufacturers to try and recoup some of their costs through price increases. In turn tyre wholesalers have reportedly begun importing large quantities of low-price non-lead weights from China. These dramatically undercut the prices of leading brands, but some are based on scrap zinc leading to question marks over the safety, legality and quality of these products.

For Trax JH managing director, John Halle, alarm bells began ringing when he noticed that some Chinese wheel balancing weights were selling for less than the cost of the zinc ingot his products are made from. This inevitably led him to the conclusion that the non-lead weights he had encountered were not made from high quality zinc alloy at all, but rather re-formed zinc scrap. This is exactly the problem. Scrap zinc is by definition impure. And, due to the kind of applications that zinc is used in, recycled zinc is commonly contaminated with heavy metals such as cadmium – a very poisonous product indeed (see textbox).

The University of Aston is currently testing samples of balancing weights available in the UK market, however, preliminary research conducted by Trax has found that six different sources of imported weights contained up to 50 times the amount of cadmium currently tolerated. The research also points towards a rather unpleasant trend – the cheaper the weights, the higher the cadmium content.

T&A has also seen the results of research conducted by another leading balancing weight manufacture, Dionys Hofmann. This company’s research, conducted completely independently of Trax’, confirms John Halle’s suggestions that some cheap imports contain dangerously high levels of cadmium.

Helmut Ringwald, sales and marketing director at Dionys Hofman, explained that his company sent out mystery shoppers to buy boxes of 20, 40 and 55 gram “zinc” weights from certain distributors. Researchers then took two weights from each box and repeated spectral content analysis tests five times on each weight.

The supposedly zinc weights were so contaminated that the R&D department had to recalibrate their equipment to measure the high levels of cadmium. While the machine is normally set to test for cadmium contamination up to 0.06 per cent, the sample weights were producing results as high as 0.2 per cent. Where you consider that the legal cadmium tolerance in Germany, where the tests were being carried out, is 0.00001 per cent, readings like this are staggeringly high.

Further investigation shows that the cheap imports simply weren’t all they were cracked up to be. For example, the supposedly lead free weights actually contained between 1.3 and 2 per cent lead. Zinc levels varied widely between 78 and 95 per cent. Premium products are usually around 98.9 per cent zinc and 1 per cent aluminium.

The worst offenders were 20 gram weights, but as the above research shows, none of them faired at all well.

You won’t save any money

It is not only a question of how poisonous the weights are, but also the quality of the products. Market leading weight manufacturers like Trax and Dionys Hofmann have other good reasons for avoiding scrap zinc as a material. Yes it might be only a fraction of the cost of good quality zinc, but you get what you pay for.

The problem with having cadmium in the zinc mixture is that it doesn’t mix properly, John Halle told Tyres & Accessories, explaining that this leads to what is known as “inter-granular corrosion.” To you and me this could otherwise be described as the sugar-cube effect. In other words it means that the weights are not proper alloys and don’t lend themselves to being a stable material. It is like mixing oil and water, Cadmium and other metals found in cheap weights such as lead and tin do not mix with zinc creating an unstable metal weight. The result is that balancing weights based on scrap zinc are brittle and therefore not fit for purpose.

While, pending the results of research at centres such as Aston University, it is difficult to say how long any inferior products might last before they break, failure is just a question of time.

Then there is the economic question. Do you actually save anything by buying cheap? The manufacturers T&A spoke don’t think so. You see, as soon as you start mixing lead and other heavy metals in with scrap zinc it throws the whole measuring system out. The manufacturers might have the right volume of molten metal to make a 20 gram weight, but when the alloy is only 78 per cent zinc it will probably weigh nearer 25 grams. As a result you will have to do another balance spin and therefore use more balancing weights.

Cheap imports are also likely to have similarly cheap clip design, according to John Halle. Trax’ managing director gave T&A examples of how he had fit such weights by hand only for them to come lose during braking, leading to an un-balanced wheel and a dissatisfied consumer.

And that is exactly why Halle has taken steps to alert dealers and weight distributors to the problems associated with such low-budget non-lead weights. In recent weeks he has given detailed presentations to bodies including the BTMA and Pirelli Driver steering committee informing them of the danger and advising businesses of how to spot low quality products.

Making Trax

Since 2004 Trax, Europe’s second largest weight manufacturer has ramped up production to 100 million units a year. As a result the company agreed an OE deal with a large French car manufacturer earlier this year.

According to managing director, John Halle, another direct result of producing quality non-lead weights is that the clip design has become more critical than ever before. Halle is confident that the hard work his company has put into developing its new lead-free products solves this problem. And Trax must have got something right. For the first time in 26 years, 2006 saw Trax gain three distributors in Italy, which were won purely on product performance rather than price, says Halle.