I wrote an illustrated article in the magazine about rear lower wishbone bush issues some years ago. The parts are identical for S-type, XF and X350 which all use similar bush components. Yes, they do clank if worn.
The bushes fitted to two of the three registers in lower rear arms are a patented "spherical" type. The bushes look similar to void bushes but that is where the likeness stops.
The bush is fitted with a tube which has a ball approximately half way along the tube. The bush is designed to allow rotational movement and a degree of radial or conical movement required when rear tracking is adjusted. The tube and ball sit in a nylon type antifriction cup which can wear after a prolonged period of use. Here is one I cut in half earlier.......Note the cracks in the nylon running surface.
Typical life span of a bush is around 80-100k miles. The bush is sealed and no adjustment is possible. It forms an almost solid bush when in good condition. When worn, the nylon cup breaks up and wear is noticeable when levering the wishbone with a pry bar. Little force is required when levering. If the wishbone doesn`t move within the sub=frame bracket or hub carrier mount, then it is fine. If movement can be seen, then the bush is shot.
The lower wishbones, N/S and O/S are Y - shaped. The bush located behind the car sill is a rubber Metalastic type and failure is almost unheard of. The two other bushes are located, one at the lower joint, wishbone to lower hub carrier and the other in a sub-frame bracket towards the area of the diff drive pinion.
Contrary to what a Main Dealer will tell you, these bushes ARE available but NOT via the Jaguar parts network. These bushes are available from Racing Green Cars, Winspeed or North East Jaguar Spares. Prices are around £40 each.
For years we were had over a barrel if a bush failed. We were obliged to buy complete new wishbones if bushes failed. Costs were about £500 per individual wishbone. Jaguar maintained that it was dangerous to consider bush changing as it could be possible to crack the slender aluminium wishbone castings and the issue become dangerous. Yes, you could break a casting if you were clumsy but if that were to happen you would go and buy another second hand unit and have another go! Jaguar were not best pleased when bushes became available on the after market....They were perhaps even less pleased when trade sources also started selling genuine manufactured parts at around half the cost. That situation still exists today.
Now, several years on, many independent garages change bushes as a standard service and have saved customers hundreds of pounds. Provided one is careful with fitting techniques there isn`t an issue. Indeed, the job of bush changing is not that difficult once the wishbone is off the car. Given a bench press or even just universal bush change mandrel set (about £100 on ebay) the job is in my opinion relatively easy for a man with a reasonable engineering experience and background. I`ve changed a couple of bushes recently using both bench press and mandrel set. If any one method is prefered, I think it is using the mandrel set and threaded ball raced pull units. That makes it a very controllable process. Pull the old units out having taken precise measurements between centres, then pull a new bush into the wishbone. Stop and evaluate if a jam up is felt.
If a bush has worn, you have the above options for direct replacement or repair. If you elect to repair a wishbone by fitting new bushes, you will have to come outside the Main Dealer network for that to occur.
More waffle on the subject here. Just one post on the subject from the S-type BB.
http://www.jec.org.uk/forums/viewtopic.php?f=200&t=4834
So that rear lower wishbone bushes discussed yet again. Hope this helps.
Mike