FD shift knob fitting
 

I recieved my FD shift knob and tried fitting it on my S4 shifter, and it seems that I can barely screw on the FD shift knob because the stock shifter is a bit bigger, plus it has different threads. I screwed it on somewhat, but it had play from side to side, but it's def. not something I can use w/o fixing it to work.

Any one have an idea of what I can do to get it to fit? Would a FD shift knob fit on mazdatrix short shifter?

s4 shifter threading is bigger. s5's, FD's and RX8's all share the same size...and my crx:p: so you will either have to tap the knob, or switch the shifter.
-Ben

So switching the shifter to an S5 will work? or if I get a short shifter for an S5 will that work? Need those details.

Yes the s5 short shifter will work.