1-How did you support the axle when you removed the shock absorbers so as not to cause the damaged mentioned above by mbzse?
The damage can be caused if the axle is allowed to drop down hard (it can crack the diff casing). If you lower it slowly, then there should be no problem.
Regardless of whether or not you plan to remove the rear axle with the comp. spring attached, you will probably need some kind of rear axle support, in addition to a transmission jack (or the like). There are commercially available axle supports (attached to your transmission jack), that supports the axle tubes as well. This is best.
However, each time that I've done this, I've simply used a home-built wooden contraption that sits on my hydraulic jack and spans across the entire axle to support everything. This allowed me to wheel out the axle whilst still attached to the jack, once I lowered it. (without accumulating yet another specialized tool!)
If you plan to remove the comp. spring, I would disconnect the shocks and the diff. mount (in the trunk) absolutely last:
- Remove all the springs, disconnect lateral support rod, disconnect driveshaft, etc.
- Raise both axles until they match the profile of whatever axle-support/jack setup you're using.
- Place your axle-support/jack under the diff and axles until everything is securely supported.
- Finally, disconnect the shocks and diff mount in trunk, and then lower the axle and wheel out.
If you
do not plan to remove the comp. spring:
- Remove the two suspension springs, disconnect lateral support rod, disconnect driveshaft, etc.
- Place hydraulic jack underneath axle half (near the trailing arm support).
- Disconnect shock, and then slowly lower until it reaches the stop (do not allow it to simply drop).
- Your axle-support/jack will look very different due to the "upside down V-shape" of the axle.
- Place your axle-support/jack under the diff and axles until everything is securely supported.
- Disconnect diff mount in trunk, lower the axle and wheel out.
2-How high must you raise the vehicle to remove the axle with the comp: spring in situ?
Good question. I've done this with comp. spring attached only once, and I don't quite remember. I do remember that my craftsman jack-stands (the big yellow ones) were about sufficient to give me that height. However, even though I'd already removed the fuel tank, I
still needed to extract the axle through the side (wheel well opening) due to the height constraints. My feeling at the time was that this type of extraction is best served by a shop lift supporting the car.
It must be noted that if at any point (before disconnecting the diff trunk mount) you feel that the clearance is insufficient, you can always lift up the rear end underneath the differential, and raise your chassis supports from the rear.
If you ask me, I would remove the comp. spring. If you plan to do anything on the rear axle whilst it is out (replace rubber parts, clean/paint, etc), I would feel much more comfortable working
without having a loaded spring so close by. But I can be over-cautious at times. So, do what makes you feel comfortable.