As you probably already know, these cars are set up with torsion bars instead of regular springs in the front.
The stiffness of normal springs is measured by the spring rate. Torsion bars are measured by their diameter, the thicker the stiffer. For this project, I decided to use 23mm torsion bars. These should hopefully give me ample stiffness for occasional track and auto-x use, but still be forgiving enough for street use. Other common sizes are 27mm and 29mm. I ordered mine from OPM Autosports, which are actually manufactured by Sway-A-Way company. Lightspeed also sells torsion bars.
First, take a look at the following photo. The pars I will be discussing are labeled. Note the actual torsion bar is inside the torque tube, and runs from the end cap all the way forward to the control arm. Also note the end cap faces toward the rear of the car, and the control arm is to the front. The side of the cross member laying upward here is normally toward the ground when installed (the cross member is upside-down).
1.) Remove the adjuster nut. This will relieve tension on the torsion bar, making it easier to remove. This not will probably be stubborn. I needed an air impact to get it to move.
2.) Remove the end cap and the rubber cover under it. There should also be rubber caps on the front end of the torsion bar, on the control arm. Remove these also. (they just pull off) This will expose the ends of the torsion bar.
3.) Look at the back end of the torsion bar. There is a ring clip on it that you need to remove. Use an external ring clip removal tool.
4.) You need to hammer the torsion bar toward the front of the car to remove it. There are a few ways to do this. First off, I do not recommend you hammer directly on the torsion bar to break it free! There is a chance you can mushroom the end, then it will be very difficult to remove. If you have an air hammer, great! Use the end that looks like a spike, and hammer on the dimple on the end of the torsion bar. Your other option is to use an impact grade socket, and place it on the end of the torsion bar, then hammer on that. I used an impact socket and a sledge hammer to free mine. Note that once you get the bar to move, it will move pretty easily. Hammer the torsion bar forward just far enough so that you can see the ring clip that is on the front side. Do not hammer the torsion bar all the way free of the front splines!
5.) Remove the metal ring clip from the front end of the torsion bar, by the control arm. You can pry it off with a small flat-head screwdriver.
6.) Grab the torque tube, and pull it straight back, away from the cross member. It should slide off. If it won't move, tap the front end of the torsion bar, and that should move the torque tube back, along with the torsion bar. The torque tube and torsion bar will both side out of the back side of the cross member, away from the control arms, toward the rear of the car.
That's it! Installation is the opposite of the above steps. I would recommend putting some fresh grease on the rubber seals on the ends of the torque tubes, as shown below. One thing to note on installation is that the diameter of the ends of the torsion bars, where the splines are, is different on each side, so there is a definite front and back side to each torsion bar... they will only install one way. There is also a difference for left and right sides. The side should be stamped onto an end of the torsion bar... either an "L" or an "R". Also note there is a key spline on each side, which is basically just a missing spline. You will have to twist the torsion bars some to get the key splines to line back up when reinstalling.
I replaced my stock torsion bars with 23mm bars. As you can see, they are considerably thicker.
Here is all the stuff ready to be reassembled.
After I installed my new torsion bars, I noticed a definite problem. I had installed the new torsion bars on the proper key splines, but after the torque tubes were put on, it looked like this...
Now look closely at the height of the adjustment nut location on each torque tube... one is way up, and one is way down! The problem: the key spline is incorrect on one of the torsion bars! Needless to say, I was not pleased to discover this. I had to take the torsion bar back out of one side, and make a new keyway spline. Luckily, this is as easy as finding out where you want the key spline to be, grabbing your handy dremmel, and grinding away one of the splines, to make a valley on the torsion bar that is twice as wide as normal. You can see my new keyway spline in the next photo. This fixed my problem. Also note that you couldmake a new keyway spline if you want to install your torsion bars rotated further than stock, which would allow you to raise or lower the car further than the stock adjustment allows. This is good for cars that will be used mostly on a track.