IS Bigger Better: LET'S TALK ABOUT THE BALLS IN YOUR JAGUAR'S FRONT SUSPENSION.
The traditional Jaguar lower ball joint is assembled into the Stub axle carrier. The wearing parts (i.e. the ball, the socket below the ball and the spigot above the ball) are separately replaceable. The clearance is adjustable and is set using shims. Wear tends to be localized, so it is possible (although not best practice) to give worn assemblies a new lease of life by rotating the ball and spigot through 180. A grease nipple is provided. The procedure for assembly and adjustment of these old style ball joints is rather tedious, and in today's high labour cost environment it is not economically viable except for the do-it-yourself enthusiast. Today Jaguar uses a sealed-for-life ball joint which can be retrofitted to many older Jags including E-Types. The assembly is pre-lubricated with no grease nipple. Given the high load carried by these joints, I decided to disembowel a modern sealed unit and to compare its ball with one of the original design.
The most obvious difference is the diameter of the ball. The modern item has a diameter of 25 mm whereas the diameter of the original part is 38.1 mm. All other things being equal, the larger ball will last longer. Notwithstanding the smaller diameter of the modern ball, Jaguar have contrived to have its centre of rotation at the same point as the original, so the front end geometry of older cars is not affected if the modern ball joint is used.
Unfortunately I believe the original specification, chrome plated balls are no longer available. Therefore, those who use the larger balls are obliged to buy an inferior aftermarket copy. Gone is the hard chrome plating and the smooth surface finish. Instead you get a ball turned on a CNC lathe complete with turning marks and various "dings' resulting from careless handling in bulk. These surface imperfections benefit from some detailed dressing and polishing in a lathe. The aftermarket kits also contain a rubber boot which will perish within 12 months. Discard the rubber boot prior to use and replace it with a nylon boot.
Despite all these shortcomings, I continue to favour the larger original style ball.