vert' s13 5spd acting rough, is it a bad trans?

[nissan_star]

I have a 1993 240sx convertable with a 5spd manual transmisson swap. It doesnt shift into 1st at all when i am already moving, explain: i cannot downshift into first unless stoped or rolling below 5mph. It is also seems that shifting when in high rpms can sometimes be difficult. I raced an 01 civic si hatch on the highway starting in 3rd and i went up to 6k and it was as if 4th gear was blocked of. the high rpms shake the stick and maybee i just missed . The car also has a short throw shifter on it.

My questions are:

Is it normal to not be able to downshift into 1st gear?

Do all s13 5spd trans shake the shift knob at higher rpms?
Modified by nissan_star at 1:41 AM 11/23/2008