..this is almost my "standardized" reply for several inquiries on same subject. I had mine changed last year on warranty by KIA in Canada on my 2000. THe new Warn automechanical work fine.
so......
The automatic hubs for 1998 and beyond were vacuum actuated with all the problems that arose from that ...although in principle, it was a very interesting proposition, very flexible and totally automatic when they worked.
THe automechanical were original equipment on pre 1998 Sportages. They are activated by the rotation of the shaft and use an arrangement of cams for their operation . The new version made by Warn (
www.warn.com) is sturdier , is the ideal replacement for normal operation ; they work very well and are totally reliable. When you engage the t-case to 4wd, they engage/disengage in about 1/3 turn shaft rotation. Just open the window and you can hear them click-click when engaging and disengaging too.
www.geocities.com/lmp4203/warnlist.jpg
installation file is here:
www.geocities.com/lmp4203/hubinstall.pdf
The manuals (also made by Warn) are just that: you have to go out of the car to turn them ON and OFF with a button on the hub itself. Better choice if you go for severe offroad use.
Once done (either one) you must trim the hub caps because these hubs are a little longer than the vacuum type.
You can see what it looks here:, from outside, and close up from the inside of the hub cap to show the taper needed on the edge of the hole.
www.geocities.com/lmp4203/kiasport/dscn1696.jpg
www.geocities.com/lmp4203/kiasport/dscn1698.jpg
I did the job with a dremmel tool.