Front Sway Bar (Anti-Roll) Bar Upgrade
87-94 XJ6, Sovereign and Vanden Plas
Jaguar Specialties manufactures front sway bar upgrade kits for several Jaguar models, and all of these kits greatly enhance cornering stability and give the cars greater composure in the turns, while not affecting overall ride quality at all. The standard Jaguar sway bar/anti-roll bar in most models is far too small considering the size/weight of these car, and these upgrade sway bar kits completely address that deficiency. Each kit is designed as a bolt-in upgrade (no modifications are required to install), and mounts in the stock location on the vehicle. Installation can be easily accomplished by the home mechanic and the end result is very satisfying. The sway bars are made exclusively for Jaguar Specialties by a world-renowned aftermarket suspension parts company with over 30 years experience in the industry. Each bar is manufactured using specially made bending jigs (to assure accuracy for a good fit), and is finished in a black oxide coating that looks great and is very durable. The kits are supplied with all new polyurethane mounting hardware for good response and long life. The XJ40 kit is an easy install and reuses the stock Jaguar end links.
The XJ40 upgrade kit is centered around a 1" diameter unit to replace the much too small 7/8" diameter original Jaguar unit. While this may seem like a rather small increase in diameter (1/8"), it is important to remember is that torsional stiffness of a sway bar (the ability to control body roll as the car goes through a turn) is related to the 3rd power of the diameter. That means that seemingly small changes in diameter actually yield very large changes in torsional stiffness, and as a result mean less body roll of the car as it negotiates a turn. In the case of the XJ40, (7/8" stock to 1" upgraded) is only a 15% increase in diameter, but yields a 53% increase in stiffness. This change makes the car's improvement in handling and composure in turns very noticeable. It is a very worthwhile upgrade
Here's a photo of the XJ40 kit: