You'll need to get the wheels off, so make sure you lift the car safely. The Elise and Exige have some special needs covered in this article about jacking and lifting an Elise

Remove the wheels.

The ABS sensor and brake line may be zip tied onto the upper a-arm. If it is, we'll need ot make sure it has room to move so clip those zip ties.

The front uses a 10mm bolt to hold the brake line in place.

The disc is in the way when you're hammering the pickle fork.

On the rear: Remove the lower brake caliper bolt (it's a 6mm allen key) and rotate the caliper up enough to free the disc.

On the front: Remove the 2 allen key bolts, remove the disc, then loosely bolt the caliper in place again.

The order here doesn't matter too much, so we'll just start with the top. using a deep 19mm socket and a breaker bar, remove the nut on the upper ball joint.

The ball joint has a tapered shaft so it actually wedges very tightly into the spindle, we'll have to unwedge it later.

Pictured below is the rear upper a-arm ball joint. The a-arm is unbolted from the chassis because we we're changing bushings too, this is not necessary if you are only replacing ball joints.

The upper a-arms support limit suspension droop more then the bottoms, so place something under the lowers to keep them from dropping down when you dislodge the ball joint.

I used a pickle fork and a heavy hammer to separate the ball joints here, but they also make special tools for the job that are less prone to damaging the boot. This can take some serious whacking with a hammer to break loose.

The ball joint itself is pressed into the a-arm. They need to be pressed out. They slide out in the direction of the flat side. We used an Autozone rental ball joint press to remove mine, but I can easily recommend the lotus specific tool to do this job - It'll be easier to use when the a-arm is still in the car, and you won't have to spend any time finding the right spacers.

If your using the big C-clamp style press, here's how we arranged our cups in the press. Make sure the press gives the ball joint room to press out and be cautious while you exert tons of force on that poor little ball joint.

If your using the purpose built press, just slowly turn each bolt (not too much on one side at a time) until the ball joint slips out the back.

Clean out the inside of the a-arm with a brass wire brush, mine had some garbage building up so I cleaned up the mounting contact surfaces.

Using your press, slowly clamp the ball joint down and press it back into the a-arm. There is a little sight hole on the end of the a-arm that lets you see your progress. Make sure the new ball joint is completely seated.

If you're using the custom press tool, just re-arrange the parts into the install configuration and press the new joint in.

Note: The upper ball joints press down into the a-arm while the lowers press up into the a-arm.

Now guide the ball joint pin back into the spindle plinth, install the new 19mm lock nut, and tighten to 45 ft-lbs. The ball joint will spin inside it's housing, so many manufacturers add an allen key hole on the end of the shaft. You can use an allen key with a wrench or a pass-through socket set like these GearWrench Pass-Thru sets.

The lower is pretty much the exact same story except it points upwards. Loosen the nut, remove it using a pickle fork then press it out just like you did with the top.