This is one of those jobs that you pray you never have to do. But my Land Rover failed the MOT on the drop arm ball joint and not wanting to pay the garage to do it (what seemed a simple job) nor wanting to buy a whole new steering box, I decided to do it myself. I wasn't expecting to have to replace the arm to begin with, but it makes a lot more sense based on the problems you can have with an older vehicle.
There is a potential upgrade where you can fit a drop arm from a Discovery, which uses an inverted track rod end and easier to maintain. I went with the Defender arm because I think part of me wants to keep the vehicle in standard form, but it's certainly an option worth considering.
This job had me lying on my back in a puddle with 5 hours on a Sunday in April, whilst the rain soaked my legs and dripped onto my chest. I'm hoping i've solved the problem for good!
The ball joint would not come apart from the track rod, so I had to cut through it and bash it out.
This is the point at which I found out that on the earlier 300Tdi drop arms, there should be a metal lip which fits around the rim and gives the boot something to grab to. A lot of these are not replaced from the kit when doing the job and now don't come in ball joint kits. This causes the degradation of the rim to the extent that the lip would now never fit and there is nothing for the boot to hold onto.
Sure enough, the boot didn't stay where it should. The later Defender drop arms have an integral lip in the casting, so putting on a new one would do away with this issue in future.
The fun begins. First off, the drop arm nut is 34mm and done up really tight. You need an extension bar to get access and it need s to be at least 1/2 inch drive or this happens:
The angles for cutting are ridiculous! Cutting through the actual arm wouldn't actually create that much extra room to work with.
5 hours later. Get some copper grease all over those splines!
Sure enough, it passed the MOT!
Update: 2 years later the lock washer holding the arm on had come loose. I would recommend using a new lock washer. The boot also split and it took me a while to find a boot for sale without having to buy the entire kit. The MOT changed sometime around 2013 to fail on any dust seals that are split. Keeping an eye on it will prevent me from having to replace with an entire ball joint kit in the future.