Step by step instructions start here
First of all, some notes.
- The stock rear bump stops have to be shipped to Ground Control or machined by you. This must be precise, as the bump stops hold the coilover tubes in place. A hacksaw is not acceptable, and I don't think a dremel would do the trick either - you'll probably need a lathe.
- If you live near Sacramento (or are willing to drive), you might want to do the install at U-Do-It Auto Repair. John, the owner of U-Do-It, can help you with the install or even do it for you (for a price). U-Do-It is located very close to Ground Control, so we were able to bring them the bump stops and get a kit back in ~30 minutes. While they worked on it, we got to hang out, ask questions and get install tips. The guys at Ground Control are really cool, so you should definitely make the trip if you can.
- If you don't live near Sacramento, you can still drive the car even without the rear bump stops. Just don't take any jumps or go flying over speed bumps/etc.
Rear Bump Stop Preparation:
We need to get the rear bump stops out so they can be machined. You can leave the rest of the rear suspension intact if you still need to drive the car while the bump stops are at Ground Control.
I. Jack/lift the rear of the car up.
Don't touch the front suspension unless you don't need to drive your car, or Ground Control is close to you, or you have a lathe at home. The rear wheels can probably stay on for the entire procedure.
II. Remove your rear bump stops
Each spring perch has a nut (14mm) underneath that holds the bump stop on. After you get the nut off, the bump stop is free, but will be stuck inside the spring. There are two choices here.
a) Remove the shock lower through-bolt (14mm) so that you can pull the wheel hub down further than the shock would have allowed. If you do both sides the whole rear suspension will droop down pretty low. This lets you remove the spring along with the trapped bump stop.
b) We used giant pliers to compress one coil high up on the spring, then (forcefully) pulled the bump stop out between the other newly-widened coils.
III. Get the bump stops machined
Give Ground Control a call and make shipping arrangements. I just drove over there with the bump stops and they machined them right on the spot. If you know what you're doing, you could buy the kit from them and machine the bump stops to fit the kit.
IV. Receive machined bump stops
Once you get the bump stops back, you can proceed. If you had to ship the bump stops out, you can still drive the car without them until they come back - just don't forget to reinstall the shocks if you followed step IIa instead of IIb.
Here's how the machined bump stops should look:
Rear Coilover Installation
When you get your rear bumpstops back, you can install the rear coilovers pretty easily. You'll pretty much just unbolt the shocks, pull the suspension down, and swap the springs for the coilovers.
0. Jack/lift the car up.
Probably easiest to do this on a lift with the whole car in the air, but not required. The rear wheels can stay on if you're lazy, but you can remove them to make the rear suspension lighter/easier to work with. The fronts will have to come off at some point.
I recommend you do both rear corners at the same time. Otherwise, the torsion-beam suspension will fight against you.
1. Disconnect the rear shocks at the bottom
The rear shocks are held in by 14mm bolts. The nuts are welded to the chassis (not removeable). I recommend lifting up on the wheel hubs to relieve stress/pressure on the bolts while you turn them. After that, the rear shocks can be wiggled free from their holders. After this step, the suspension will now be able to drop lower than before. Earlier, the shocks were limiting their downwards travel.
In this pic you can see the shock bolt partially removed.
2. Remove the rear springs
You'll probably need a pipe or pry bar or strong hands/feet for this. With both shocks removed, you can push down on the rear suspension until it pivots down low enough for the springs to basically fall out. The rear springs and the upper spring perch cushions (rubber) will not be re-used.
3. Prepare the lower spring perches
The rear coilovers have the longer springs and come with a rubber top hat (spring perch cushoin). Your machined bumpstops should also be inside the springs (hidden by the paper they're wrapped in).
Spin the gold spring perches and red tubes to a height/position that you like. You should probably set both at the same time so they're even.
The highest position seems to equal stock height, so you can probably set these pretty low. Mine are currently set in the middle, and I'll probably move them to the bottom (maximum drop).
After you set the perch heights, tighten the set screws to lock the gold spring perches down against the red tubes. Do NOT overtighten - aluminum is soft and will strip. I ussed only the short end of the included allen wrench for tigtening. My set screws already had anti-seize on them, but I added more to be safe.
4. Install the rear upper spring cushions
The rubber cushions that came in the box slide over the upper spring perch cones (just like the stock cushions did). The flat side faces DOWN. These arrive kinda oily - don't clean them off on the inside diameter, as the oil makes install easier. It's okay if you can't get them all the way in - the springs will do the work for you.
5. Install the lower rear bump stops.
The bump stops can go back in the car. The rotation does matter. Make sure you line up the little dot on the bottom of the bump stop with the hole in the lower spring perch. Torque: 29 ft lbs
6. Install the lower spring perches
These simply slide over the rear bump stops. You may want to wrap the machined edges of the bump stops with electrical tape for a tighter fit, then hammer the spring perches down onto the bump stops. I forgot to do this.
7. Install the rear springs
You'll probably want to do both sides at the same time, so you'll probably need a helper. Pull down on the rear hubs so that the entire rear suspension swings down. If you pull down on one side, both sides will come down. Sandwich the springs between the lower and upper perches, then let the suspension back up.
Install tip: Stick a long pry bar, pipe, breaker bar, etc into the hole/tube behind the brake drum, and use that to pull the rear suspension down.
8. Reinstall the rear shocks
You'll have to lift the suspension upwards so that you can get the shocks back into place. Line up the holes, then reinstall the 14mm shock bolt. Torque: 43 ft lbs
. With the shocks bolted in, the springs should sit nicely between the perches, but might still be lifted slightly off the perches. After that, the rears are done. Pretty dang easy.