What part of the front crossmember? There are three parts to it. The front beam #5, rear beam #2 and center beam #1.
I've replaced the rear beam of the front crossmember in my 95 EX 4cyl. I had slid on ice and hit a curb. Resulting in a bent LCA, bent radius rod and damaged rear beam where the LCA mounts to. I had other things I planned on doing, had plenty of time to do it all so I just pulled the motor to do all the work and also did a timing belt and other things. You can do it with the motor in there you'll just want to help support it while your replace whichever beam it is your replacing.
The center beam is obviously the easiest to replace. Just unbolt it, remove it from the exhaust hanger and replace in reverse order.
The front is probably going to be the next easiest to replace. Remove the splash shield, remove the center beam, then remove the radius rods from both sides. Then you may want to support the motor while you unbolt the motor mount. Once the motor mount is disconnected, unbolt the front beam from the frame and remove it from the car. Take the old motor mount off the beam and put it on the new one and then put the new front beam back in the car in the reverse order.
The rear beam is most likely going to be the hardest of the front three crossmember beams. Remove the center beam, unbolt the downpipe from the exhaust manifold and then unbolt the downpipe support from the block, unhook a couple hangers so the exhaust can rest on the ground (you'll need room to remove the rear beam), take off the front rims/tires, unbolt and pop the tie rod ends away from the knuckle, remove the rod end from one side of the car, unbolt the LCA's from the rear beam (I'm not sure if the LCA will need to be removed from the car or not to get the rear beam out, my entire front suspension was removed for other reasons so my LCA's weren't there but I'm think they will need to be removed, just unbolt them from the radius rod and unbolt and pop it free from the lower ball joint. You'll then need to support the knuckle so it's not just dangling there putting stress on the upper ball joint), drain the PS fluid, unbolt the lines going to the steering rack, go inside the car and remove the rubber boot from the lower part of the steering column, unbolt the connection between the steering column and rack (keep wheel straight so it is lined up when you reinstall it, mark it with a marker just to be sure) then unbolt the steering rack from the car and work it out of the rear beam. Now you may want to support the motor while you unbolt the rear motor mount. Once the rear motor mount is unbolted, unbolt the rear beam from the frame. Remove the rear motor mount from the beam and install it on the new rear beam, then install the new rear beam in the car in reverse order.
It's been a while so I may have forgot something but you get the idea.
Overall, it's not a very hard procedure, just lengthy if your replacing the rear beam.
Make sure you allow plenty of time. Use PB Blaster or some other penetrating oil on rusted bolts. I recommend you have a Helm manual present, or at the very least a Haynes/Chiltons manual. Look up and follow the specific instructions for each component your going to be removing, there is no specific instructions on how to replace the crossmember just a page with the torque specs.
I'm thinking you'll also need to remove the front sway bar. Just unbolt it from the LCA's and then unbolt the sway bar mounts.
Also, when you reinstall the suspension parts like the sway bar and that, I believe it's recommended that you have the weight of the car on the suspension while doing the final torque on the bolts. To do this, I just used two jacks under both LCA's and lift equally until the suspension was under the weight of the car. I left the jack stands inplace incase and then went under to tighten all the suspension bolts that need to be torqued.
Modified by TouringAccord at 10:49 AM 3/30/2006