Someone had a thread about changing the steering rack themselves, I have never done it. I have done lots of steering/suspension work on other vehicles.
Out of curoisity, why did your rack go bad? I see a lot of confusion on PS fluid on this forum and lots of others, did you add something other than the owner manual recommended specific fluid from the dealer?
Yes, flush and refill the system with the proper fluid. The owners manual says there is a specific fluid for the Commanders, NOT the standard ATF+4 that most late model mopars use for PS fluid, you'll have to go to the dealer to get it. I "think" the specific fluid is because some commanders have a hydrualic fan that is run off the PS pump, if your Commander does NOT have an hydrualic fan, then "maybe" you could run ATF+4 and be fine. Honestly if your replacing the rack because it went bad and you don't know why, fluid could be the cause, so used the exact fluid recommended.
When you disconnect the lines most of the fluid will drain out. All you have to do to flush the system (with the engine off) is to run the return line from the reservour to a bucket, add a little new fluid to the reservoir and turn the steering wheel lock to lock (obviously this is far easier with the front wheels off the ground). Reconnect the return line, add the fluid and turn the steering wheel lock to lock to circulate the new fluid and work out the air, keep adding fluid to replace the air working out until the reservoir is at the proper level. Then you can start the motor and let pump pressure work out the last of the air, again, you have to turn the steering wheel lock to lock.
- Disconnecting the outer tie rods from the steering knuckle requires a special tool. They are taper bolts and they will be wedged into the steering knuckle and will have to be forced out. You can improvise with hammers or pry bars, but its easy to damage something if you do, ask for advice if your having problems before you do something that risks damage.
- There are several techniques to trying to get tie rod adjustments close to what they were before so that the toe is close enough to drive to a alignment shop.
- The Steering wheel has a "clockspring" in it (an electrical connector for connecting the air bag and buttons on the truning steering wheel) as well as steering angle sensor in it. You have to center the steering wheel before disconnecting it from the rack and keep it centered and then connect the rack centered when you mate them back up, otherwise you'll break the clockspring and the steering angle sensor will be off and your BAS/ESP and traction control will NOT work. I've seen people put a strip of tape over the column and steering wheel to hold the wheel centered and NOT let it spin when if someone accidentally bumps it. You don't pay attention to this, you can connect the steering wheel one full turn off to the rack, it will look centered but you'll break the clockspring when you drive it.
- I removed the steering wheel from my Commander to replace the evaporator, maybe I made a mistake with the connectors, but I blew the fuses for the steering wheel, which resulted in things like the BAS/ESP and traction control not working. I wasted a lot of time looking for connectors I thought I missed or connected wrong, instead of looking for blown fuses first.
- Removing or Connecting inner tie rods to the rack itself, there are flats on the rack for a wrench, you have to put a wrench on the rack itself and use that wrench to counter the torque on the rack that you have to put on the inner tie rod to tighten it down on the end of the rack. If you don't put a wrench on the rack and counter the torque being put on the rack, it will twist the rack inside the housing, and the rack is connected to stuff that is NOT designed to be able to withstand that twisting, i.e. you can damage the new rack.