i just rebuild my t-56 because the keys were bad in one of the syncros but now i have another problem. 1-2-3 shifting/downshifting is perfect now but once i shift into 4th i cant downshift without the gears grinding. from 4th i can shift up to 5th and 6th without grinding but you cant downshift 6-5-4 at all without grinding. also once you get into fourth it wont downshift without grinding either.......................any ideas.

 

nobody?

 

Bad synchros, or clutch not releasing fully. Learn to double clutch like the drivers of 18 wheelers and forget about grinding gears. lol

 

I agree with Pete. I've had this problem with a warped pressure plate.

Here's the test I use:
Quickie Test 1) Hold the clutch pedal down for 5 seconds before trying to shift and see if it still grinds. Sometimes this delay helps things "slow down" and it will not grind..that is for hairy edge situations. If it shifts ok after 5 seconds, you are not disengaging the clutch properly (air in line is possible...might need to bleed clutch).
Engine Off Test 2) Be careful where you try this one.... Get on a low trafficked road, press the clutch in FIRST, then SECOND, turn ignition key off while holding clutch pedal in, wait a short second and then try to downshift......if you can downshift with the engine off and no grind, your clutch is not disengaging properly (the engine being off guarantees no input rotation to the trans). NOTE: DO NOT turn the key back on right away though or you could blow your muffler off....stop and wait a full minute for the gasses to clear out a bit. This actually happened to me....seriously, I literally blew a 6 to 8 inch slit in my muffler - split the side right out of it and it hurt my ears something fierce.......I mean it was deafening like a bomb went off under the car...and I have to admit it scared the crap out of me.