BMW X6M suspension secrets July 25, 2009
Posted by richard in : Technology , trackbackSTANDARD BMW X6 models, in corners, work harder, earlier, for agility.
And that, explains Head of M Development Albert Biermann, is down to how the clever torque vectoring rear axle is programmed: power is shuffled round quite considerably, to give a rear-steer effect and kick the back end into corners.
The X6M uses this same technology – but is more linear. ‘It is not as agile, so we don’t work the rear end as much early on.
‘However, once you’re within the corner, we engage it far more – here, the split happens much earlier than in the standard X6.’
Why? ‘So the driver can get on the throttle earlier.’ And feel the ‘rear drive’ balance M reckons is a characteristic of its cars.
It’s not only here where the ‘M-gineers’ (arf) have been busy. ‘Dampers and springs are stiffer – and there are bespoke EDC settings. The ABS and Dynamic Drive are specially adjusted – the stiffness of the roll bar goes hand-in-hand with the dampers.’
There are stiffer upper wishbone hearings, and stiffer rubber in the rear axle carrier. ‘This gives better off-centre feel and more precision.’ The engine mounts are stiffer, too.
‘The upper shock mounts are also completely different.’ This solution, says Biermann, was very expensive, and could be easily overlooked. It shouldn’t be.
In the standard X6, there are three components, all settled together in the upper mounting. This sees the helper spring and damper share a common rubber bearing.
It’s a compromise. The helper spring is offsetting the rubber bearing over a spring, for example.
So, with the X6M, we’ve separated the bearing and piston rod from the helper spring. This means the two bearings fit better together; and one is dedicated to the damper, the other to the helper spring.
Advantages? Considerable, especially over challenging roads. It’s particularly good for comfort – it’s at least as good as the regular X6…
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