Jaguar independent rear suspension

Jaguar's independent rear suspension (IRS) unit has been a common component of a number of Jaguar production cars since 1961, passing through two major changes of configuration up to 2006 and last used in the Jaguar XK8 and Aston Martin DB7. This article concentrates on the first generation Jaguar IRS, which firmly established the marque's reputation for suspension sophistication, combining as it did smooth ride with excellent roadholding and low levels of noise, vibration and harshness (NVH). The two generations overlap in time due to their being used in both full size and sports models that were updated at different times. The modern S-Type, XF, XJ and XK models, although they are also rear wheel drive with independent suspension, use the components, and their derivatives, designed for the Ford DEW98 platform so are not covered in this description of Jaguar's original in-house suspension system. The X-Type (codename: X400) also has another two versions of IRS based on the Ford Mondeo estate system, depending on whether front or 4-wheel drive.

When first introduced, it was relatively rare for British cars to have independently sprung rear wheels, most production cars of the time using live axles. Independent suspension systems offer the advantage of lower unsprung weight to improve roadholding, and when properly designed, the ability to maintain the roadwheels perpendicular to the road surface during cornering and in response to uneven road surfaces, further improving roadholding. The reduction in transfer of vertical undulations in road surface to the vehicle body also provides a smoother ride.

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