I worked on my son's SX/4 today. The plastic hinges on both sun visors were cracked and floppy. I was able to easily replace the broken pieces with much sturdier visors from a Mopar A body (Duster, Valiant, Scamp, Dart, Demon, Dart Sport). These visors are readily available at a reasonable price and the hinge area is made of metal. I have never seen a broken hinge on any of these cars. The visor material is vinyl instead of cloth but I prefer the look better than the original.
Modification is simple. I used a cut off wheel to remove the extra metal "tab" on the inside hinge area. The hole in the roof needs to be slightly enlarged to accommodate larger pivot assembly. I used one existing screw hole and drilled two new holes to finish mounting the visors.
I hope that this can help some of my fellow Eagle members fix a very annoying issue with these cars
ps. Sorry for the crappy quality of the first pic