Rebuilt AWD trans, down shift into 2nd & it'll grind? ?

[ShadeTreeDSM]

got a 1993 awd 5-spd transmission i just rebuilt. new syncro sets & shift forks. running redline MT-90 for fluid mixed with 0.3qts of heavy shockproof. also installed new shifter cables, clutch master cylinder (adjusted properly too), slave cylinder (no air in line, all bled out), new clutch shift fork & pivot ball, Mitsu throw out bearing & sbr 4000 clutch.

when i shift into every gear it will shift smooth. but when i down shift at about 15mph into 2nd it will grind. . this trans doesnt even have 200 miles on it and its grinding.

found this out today though, if im in 3rd and i want to downshift into 2nd, i put it in neutral and rev the engine to match vehicle speed, then when i go into 2nd its smooth as any other gear. what's causing this

 

[twicks69]

Did you replace the 1/2 hub and slider, keys and springs? Did you replace the intermediate shaft tapered roller bearings and properly clearance the shafts upon reinstallation? What preloads are you using?

Are you sure that the clutch is properly and completely disengaging?

 

[Cesar]

changing the 1st-2nd gear hub and slider is probably a good idea on most rebuilds.

from third to second? how fast are you shifting? if you did everything correctly, even the preloads have a fairly wide margin or error, it should shift eventually without grinds, unless the disk is dragging.

 

[Defiant]

running redline MT-90 for fluid mixed with 0.3qts of heavy shockproof.

Make up your mind. Don't mix trans fluids. I prefer Pennzoil Synchromesh.

found this out today though, if im in 3rd and i want to downshift into 2nd, i put it in neutral and rev the engine to match vehicle speed, then when i go into 2nd its smooth as any other gear. what's causing this

That's because you're shifting like you're supposed to. You have about 1/8" of metal trying to match the weight, momentum and rolling mass of a ton-and-a-half. Gee, what could make it unhappy?
If you won't double-clutch (and you won't, because you'll "hear" that you "don't need to with synchromesh"), at least speed-match.

 

[ShadeTreeDSM]

Did you replace the 1/2 hub and slider, keys and springs? Did you replace the intermediate shaft tapered roller bearings and properly clearance the shafts upon reinstallation? What preloads are you using?

Are you sure that the clutch is properly and completely disengaging?

no i didnt replace the 1/2 hub & slider keys & springs, they didnt look that beat up, all the bearings were not replaced either, everything checked out well, no signs of abnormal wear. as for clearance & preloads i had my tranny tech put it all back together, he checked over everything.

how would i go about checking if the clutch is completely disengaging ?

changing the 1st-2nd gear hub and slider is probably a good idea on most rebuilds.

from third to second? how fast are you shifting? if you did everything correctly, even the preloads have a fairly wide margin or error, it should shift eventually without grinds, unless the disk is dragging.

im downshifting normal

Make up your mind. Don't mix trans fluids. I prefer Pennzoil Synchromesh.

That's because you're shifting like you're supposed to. You have about 1/8" of metal trying to match the weight, momentum and rolling mass of a ton-and-a-half. Gee, what could make it unhappy?
If you won't double-clutch (and you won't, because you'll "hear" that you "don't need to with synchromesh"), at least

i tired pennzoil syncromesh, comes out like water, i didnt like it, made the trans shift notchy & sometimes i couldnt get it into gear. after i did redline, shifting is smooth as butter except when i downshift into 2nd gear