Edited version to clarify a couple things...
This may be 'old hat' for some of you but might help another newbie wanting to lower their car down in back. This is what a lot of the video's, threads etc. don't mention.
This is what I found out that needs to be done...note it can be a real pain if you have never done it before. If it helps one newbie then all's well and good
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1. Get the car as level as possible with the full weight, driver in the drivers seat and passenger in the passenger seat, on the ground and suspension settled. Now using a tape measure take measurements from the fender lip as near to the centerline of each wheel as you can get to the ground. Record each measurement. Check the camber on the rear wheels...you may have 0* to 2-3* neg camber, each car is different.
2. Now block your front wheels, loosen the rear lug nuts on both rear wheels then lift the car up and place it upon jackstands making sure the car sits firmly on the jackstands and it is at a comfortable height to work on. Now remove both rear wheels. It makes it much easier if the car is up in the air on both sides and there is less tendency for the car to 'walk' on the jack or the jackstands. Remove both rear wheels, be sure and place the lug nuts in a small container so you do not have to search for them later...been there done that trying to find 2 lug nuts I advertently kicked under the car with out noticing.
3. Decision time, this step must be done first, the e-brake cable must be loosened. You can either remove the brake drum and disconnect the cable at that point or you can remove the retaining nuts on the cable inside the car, if going this direction, once the cable is loose, underneath the car grasp the cable and pull it to the rear as far as it will go. You need the extra room to swing the axle once it is disconnected and if the e-brake is still attached it will not move far enough.
4. Now remove both shocks, some of the videos and instructions say you can get by just removing the lower shock bolt but I found the shock sort of got in the way of wrenches and breaker bars.
For the following DO ONLY ONE SIDE AT A TIME.
5. Place a floor jack under the swing plate as a safety precaution, DO NOT use a bottle jack. Slide another jackstand under the car about midway along the axle and 2-3" to the rear, you use this to rest the axle/hub upon after it is loose. Scribe a line around the axle/hub flange on the swing arm, this is a reference for alignment when re-assembling. Now loosen the 3 bolts(19mm) holding the axle/hub, note these nuts/bolts are torqued to 80-85 ft lbs so you may need a breaker bar on the wrench if you do not have an air impact wrench. I used the impact wrench, real knuckle saver.
Place the nuts, washers and bolts in a container. Once the bolts are out removed tap the bump stop assembly loose and remove it, now grasp the hub and gently rock/pull back until the axle/hub come free of the swing arm...be careful as it is heavy... and place it upon the jackstand you should've placed under the car and let it rest there.
6. Now loosen the torsion bar cover plate, backing the bolts out about a 1/2''. With the floor jack under the swing arm jack it up until the swing arm just clears where it is resting, maybe a 1/16-1/8'' max. Using a small pry bar, gently pry the swing arm out until it clears the stop. Keeping your hands and feet away, gently lower the jack, there is a tremendous amount of tension on the swing arm at this point. Once the swing arm is completely down and at rest remove the floor jack. Using a protractor/angle gauge place it upon the swing arm and record the measurement for reference if needed.
7. Remove the cover plate bolts, placing them in a container, then remove the cover plate...note it may need to be pried off, do so gently. Check the rubber inner/outer bushings if they are worn it'd be best to replace them at this point.
Before going any further check for any markings on the torsion bar, mine had a triangle pointing up with a white dot of paint upon it, 'eyeball reference' where the mark is pointing, mine was at about the 10 o'clock position. I made a corresponding white mark on the swing arm where it attaches to the torsion bar in line with the triangle, again a reference point.
8. Using the chart attached below, courtesy of the Samba, figure out how much you want or need to lower(or Raise) the rear end. According to threads on Samba the chart can be used to lower or raise the swing axle, raising you just reverse the +/- measurements, once the decision is made for measurements proceed to Step 9.
9. Grasp the swing arm, gently applying a sideways pressure while slowly pulling/wiggling the swing arm until the inside splines of the torsion bar just comes loose, try not to pull the torsion bar completely out. If it does come out don't panic, remember the marks and the 'eyeball reference' you made?... line it up and slide it back in until you contact the splines...note at this point the torsion bar doesn't care where it engages the splines yet you want to be as close to the starting point as possible. Once you have the torsion bar loose then it is just a matter of working slowly, being sort of 'touchy/feely', and count the 'clicks' of the splines until you get to the number decided upon...note drivers side rotates clockwise to lower, passenger side counter clockwise.
Slowly work the swing arm loose of the torsion bar, you may have to apply slight pushing in pressure on the torsion bar to keep it from pulling out, had that happen to me on the passenger side. Once the swing arm is loose rotate it up the number of splines needed from the chart, you may want to apply some grease to the splines, use a rag to wipe off excess. Once at the point you need rotating the splines slide the arm up to the mounting plate. Place your protractor/angle gauge on the swing arm and record the measurement for use on the opposite side. Be sure to apply Talcum powder on both rubber bushings, be generous but not over generous, try to avoid getting it on the torsion bar splines and loosely install the cover plate...note you may want to get longer bolts to start bolting down the cover especially if you use new bushings, tighten them down until the cover plate moves in then replace them with the stock bolts. Work the bolts diagonal to one another. Now lift the jack up, using a drift hammer to get the swing arm to set in position, once the swing arm is over the mount...check to make sure the swing arm rests fully on the stop...slowly lower the jack then move it out of the way. Re-install the cover plate bolted down snug, not torqued down tight.
Ok, now it is time to re-assemble but do not tighten everything completely down tight yet, just snug it up. Re-install the wheel.
10. Move to the opposite side and follow the steps above remembering the inner splines go the opposite direction. Once everything is moved, is set in position, place your protractor/angle gauge on it and check the measurement and compare it with the opposite side... the measurements should be very close if not identical. Re-assemble everything, remember just snug it down, re-install the wheel. Be sure and pull out the jackstand or stands used to sit the axle/hubs upon.
11. Now lower the car to the ground. Bounce it up and down and roll it back and forth to settle the suspension...now stand back and take a look at it...satisfied with the way it looks? Again take measurements at all four wheels with weight in both passenger and drivers side, and compare them with your original measurements. On my car I lowered the back end down about 2 1/2'' from it's starting height, the drivers side is about 1/4''- higher than the passenger side and at all 4 wheels I have less than 1/4'' difference all the way around. My car originally had 2-3* neg camber on the rear wheels and I still have that, so depending upon your car you may have 0* to 2-3* neg. camber. Each car is different.
If you are satisfied raise the car up, placing it on jackstands. Make sure your axle/hub aligns with the marks you scribed into the swing arm, if not adjust as necessary. Torque the axle/hub bolts to 85 ft lbs and the cover plate bolts to 30-31 ft lbs. Do both sides then install the wheels and lower the car to the ground, again bounce it up and down and roll it back and forth to settle the suspension. Do not forget to torque down your lug nuts and readjust your e-brake!
13. Your done!(with this project anyway)
Gordon Nichols thread should be read as there is some good information there although his thread deals with IRS suspensions.
Chart, courtesy of Samba:
