ok let's see who can figure this one out

here is the symptom, 88 rx7 turbo ii, about 300whp, exedy multi plate clutch, stock transmission, os giken lsd.
MazdaMotorsport harden rubber motor mount, trans mount, diff mount, all are fairly new, in good condition.

only when shifting hard, 1st to 2nd or 2nd to 3rd, there is a huge clunking or knocking sound coming from the rear of the car it feels like.
shifting hard as in slip the shifter out of gear just as you push in the clutch.
if i depress clutch fully, then shift, no problems.
if shifting 3rd to 4th or 4th to 5th, even hard shifts, no problem.

ideas?

i'm thinking driveshaft u joints, any other possibility?

the center spring appears to be broken, when shifter is in neural, pushing left feels very light with minimal tension, pushing right feels normal.

 

diff mount is the first thing to check

 

Is the clutch disengagement point near the bottom of the travel?
I had a similar issue after replacing the clutch master and had to adjust the rod at the pedal to get enough travel.

 

diff bushing are all new, and all Mazda motorsport hardend rubber part

clutch has been adjusted with travel near the top of the travel (new clutch MC as well)