I cannot put my tranny on reverse, what could it be? All gears change good, but I can't put it on reverse gear.

If it is a manual transmission, try this..
Start the car.
Do NOT push the gas.
Hold the clutch pedal to the floor.
Put your shifter to reverse and put downward pressure on it, like you are trying to force it.
SLO~WLY release the clutch pedal as you keep putting pressure downward on your shifter towards the reverse position. If you go slow enough, it should catch.

I find that in some cases when I cannot get into reverse, this allows me to get there.

ah, welcome to owning a supra haha

if what Medic says doesnt work, try this:

put it in gears 3 to 4 to 5, then try reverse. this usually works for me.

if you just replaced the clutch, it might need to be adjusted...

-shaeff

Your clutch may not be disengaging completely. Adjust the clutch and you should be fine. I never knew about some of the "tricks" you guys do to get the car to go in reverse. LOL..

Sometimes I've found that if going to 1st, etc doesnt work, the car usually needs to roll about an inch. I can barely roll forward in 1st gear, then it'll slide right into reverse.