Topic: Tcase Problem

[86turboyota]

86 4runner w56 5spd, dual cases with a marlin adapter and 23 spline 4.7 gears in the rear case, front case is topshift, rear case was converted to topshift.   

The problem is that when the hubs are unlocked and i try to move the rear case into 4wd while moving the gears grind and it wont go in.  If i lock the hubs it will slide into 4wd at speed with no problems.  I know this doesnt seem like a big issue, but im worried that this is the start of a bigger problem.  It never used to grind or have any problems going into 4wd with or without the hubs locked.
Thanks,

[Cheesemaker]

First of all, what is "at speed" mean? 

With hubs locked in and your moving, the front and rear d-lines are rotating at the same speed.  When hubs aren't locked in, the front d-line isn't rotating at all.  So, you are trying to engage a rotating force into a gear that isn't rotating.  Hence the gears not engaging.  You really aren't supposed to engage or disengage the gears while moving.  You can to a small degree, but gear'd t-cases don't like it.  4WD gears do have synchro's, not sure about 4LO.

But if you had a chain drive you can engage 4wd in at 60mph.  That is the one thing I miss about having a chain drive T-case, but they are weaker because of it.

[86turboyota [OP]]

First of all, what is "at speed" mean? 

With hubs locked in and your moving, the front and rear d-lines are rotating at the same speed.  When hubs aren't locked in, the front d-line isn't rotating at all.  So, you are trying to engage a rotating force into a gear that isn't rotating.  Hence the gears not engaging.  You really aren't supposed to engage or disengage the gears while moving.  You can to a small degree, but gear'd t-cases don't like it.  4WD gears do have synchro's, not sure about 4LO.

But if you had a chain drive you can engage 4wd in at 60mph.  That is the one thing I miss about having a chain drive T-case, but they are weaker because of it.

By at speed i mean 10-20mph, although with the hubs locked i have engaged and disengaged the 4wd at 40+ without problems.  I get what you are saying about being the driveshaft not turning without the hubs locked, but this never used to be an issue, which leads me to believe something inside the case has changed.

[79coyotefrg]

By at speed i mean 10-20mph, although with the hubs locked i have engaged and disengaged the 4wd at 40+ without problems.  I get what you are saying about being the driveshaft not turning without the hubs locked, but this never used to be an issue, which leads me to believe something inside the case has changed.

sounds to me like its working properly now because the tcase when trying to shift into 4wd hi SHOULD grind when the hubs are unlocked thats why your NOT supposed to shift into 4wd when moving

[MC387]

Do not shift into 4wd when you are moving and the hubs are unlocked.  It is normal for it to grind.  There is no reason that you can not shift into and out of 4wd while moving if the hubs are locked.  As long as you are not spining the rear wheels.