All Features Great and Small


All Features Great and Small

On first impressions, it would be remiss to compare a suspension bushing — each individual piece no wider than five inches across — with a pair of chopsticks. There is, however, more of a common ground between the two than you may realise. As Mazda’s Yasuyoshi Mushitani explains, there is far more to suspension bushing than meets the eye

Set on the table are five pairs of chopsticks, ascending from the lowest perceived quality to the very highest. The first set is from a Bento box set, the next from a convenience store. The third and fourth are from upmarket restaurants and the fifth set, remarkably, is a custom-made pair of handmade bamboo chopsticks, once altered and contoured by one specific user — Shunji Tanaka, the designer of the original Mazda MX-5. Made from bamboo tree, it took Tanaka around 40 years to find the right design; and they’re arranged as such so that Yasuyoshi Mushitani, Senior Principal Engineer, Chassis Dynamics Development Dept. at Mazda, can describe the importance of suspension bushing: a palm-sized, yet vitally essential, part found in the suspension system of any vehicle that seems to bear little resemblance to a set of chopsticks.

In order to strike the right balance between car and driver, suspension bushing can be adjusted in 0.1mm increments

Yet the chopsticks, Mushitani enthuses, are the ideal representation of how responsive touch, even at the smallest level, can be utilised when driving. Slim, tapered and lightweight, the user instantly knows how much pressure to apply to the dish and can receive instant touch-feedback on the food the chopsticks are touching. Even the material used to manufacture the chopsticks, such as bamboo, can change how the food tastes and how the overall meal is perceived. Chopsticks, it’s said, should also act as an extension to the human touch, rather than a simple device for eating food. It’s these similarities, Mushitani believes, that align with Mazda’s philosophy toward suspension bushing and that also help the driver feel more comfortable, in control and ‘as one’ with the vehicle, whether it’s tackling undulating roads, rough tracks or tight corners.

For those unaware, bushing is a small, cushioning part of the overall suspension system that’s designed specifically to absorb bumps in the road, to reduce noise under the car, and to control the amount of movement the vehicle chassis experiences during a drive, particularly when cornering. These elements, it would be fair to say, are just as important as any of Mazda’s head-turning exteriors. That each piece bushing plays such a large role with a small presence is yet another wonder of engineering.

Each small piece of suspension bushing, with a few examples pictured, is vital for reducing noise, controlling movement and cornering safely. (Image for illustrative purposes)

For this, there’s Mushitani to thank. His vision for Mazda’s suspension bushing system was conceived shortly after he first joined Mazda in 1988, with the iconic MX-5 releasing one year after in 1989. Surprisingly, it wasn’t the MX-5’s debut that sparked Mushitani’s imagination when he eventually joined the Chassis Dynamics Department in 1997. Instead, it was the Mazda Titan Dash — a commercial truck that rolled off the production line in 2000 — which he was assigned to work on. He quickly made a few adjustments to the Titan Dash, most notably with the suspension bushing, to change the typical toughness of a commercial vehicle to a smoother, more comfortable ride. “I changed just one bushing structure and I got a lot of improvement, not only in the vibration, but with the vehicle motion also,” he explains. “It’s a very small part, but has a big impact on driving.”

Over the last three decades, Mushitani’s brainchild has been passed onto those around him and has been developed further, proving that suspension bushing has a significant impact on driving experience, even when tweaked and tuned with 0.1mm differences. It’s all about improving driver comfort, Mushitani says, as well as playing an additional role to communicate to the driver, while “contributing to safety,” he says. While there are approaches to shut out vibration and input reaching the driver, Mazda’s approach to bushing, he explains, is designed to “communicate” and to convey road surface conditions so that safer decisions can be made on the move. Conversely, this feedback can’t cause any discomfort to the vehicle’s occupants, and Mazda’s approach to bushing has struck the sweet spot between informative and non-invasive. Comfortable and safe, it provides a true Jinba Ittai experience between car and driver.

“We need to determine the geometry and configuration in the bushing, so we depend on the human sense. When it comes to bushing, it’s all about intuition and keeping things simple”

What’s more surprising is that the process of making bushing isn’t all about machine-made parts. Rather, the human touch, as Mushitani describes, remains vital for ensuring the correct measurements and angles are used in each bushing prototype before manufacture. “We need to determine the geometry and configuration in the bushing,” says Mushitani, “so we depend on the human sense.” When it comes to bushing, it’s all about intuition and keeping things simple, he says.

It’s this car-to-driver connection and communication that Mazda continues to champion. When it comes to bushing, it’s a mutually beneficial relationship between the vehicle and its driver. The vehicle, through the suspension, handling and dynamics, communicates to the driver, and the driver can adjust and remain in control. “The vehicle shouldn’t become too advanced,” finishes Mushitani. “Because if the performance of the vehicle is too good, the driver feels ‘driven’ by the vehicle, but instead needs to operate the vehicle themselves. This leads to our philosophy of Jinba Ittai.” With safety in mind and allowing the driver to experience a joy in driving, this small piece of suspension bushing says everything there is to know about Mazda.

Words Ed Cooper / Lol Keegan

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