Transfer Case Question
#1
Transfer Case Question
This is how i understand the trans case to work in an AWD.
When you put the vehicle into 4hi, 4lo or AWD (labeled 4x4 on mine) the electronic shift motors sensor responds by engaging a specific plate for hi, lo or 4x4. The rotary cam in the shift motor moves a fork to the corresponding location. It then uses manifold vacuum to lock the hubs and transfer case together. (is this correct?)
If that's the case and your transfer case will not shift into the correct setting a couple of minor things could be wrong. Assuming that a different vacuum line is used for 4hi 4lo than for 4x4/AWD you could have a leaky line or the fork could be bent for just one setting? Also, could it just be the linkage since 4x4/AWD is mainly what's used?
I'm hoping a pro in here will know the answer to this. Thanks in advance!
When you put the vehicle into 4hi, 4lo or AWD (labeled 4x4 on mine) the electronic shift motors sensor responds by engaging a specific plate for hi, lo or 4x4. The rotary cam in the shift motor moves a fork to the corresponding location. It then uses manifold vacuum to lock the hubs and transfer case together. (is this correct?)
If that's the case and your transfer case will not shift into the correct setting a couple of minor things could be wrong. Assuming that a different vacuum line is used for 4hi 4lo than for 4x4/AWD you could have a leaky line or the fork could be bent for just one setting? Also, could it just be the linkage since 4x4/AWD is mainly what's used?
I'm hoping a pro in here will know the answer to this. Thanks in advance!
#2
do you have an electronic shift dial or a lever out of the floor for your 4x4 selector? i do not believe there is any vacuume involved. but i have been wrong before. on the AWD's there is a differential in the tcase that distibutes the power to the front and rear diffs. when you shift into 4hi or lo it locks the diff in the tcase and gives equal power to the front and rear wheels. thus is why so hard to turn on dry pavement when in 4hi or lo. i have open diffs in both the front and rear, not lsd. so even in 4hi-lo, i only have 1 wheel in the front and 1 in the back doing the work.
#3
What year is your Dakota?
At least in this generation Dakota there is no vacuum involved. It's either mechanical, up to 2000, or electronic, 2001+. Yes, shift forks can bend but more commonly the its a mechanical problem with the shift motor.
The hubs do not lock/unlock. They are not equipped to do so. The front drivetrain rotates as long as the vehicle is moving, you can not disconnect the hubs.
Like McNasy says, there is a differential type unit in the AWD transfer case that controls torque between front/rear. When you select 4x4 lock, this unit is locked together.
At least in this generation Dakota there is no vacuum involved. It's either mechanical, up to 2000, or electronic, 2001+. Yes, shift forks can bend but more commonly the its a mechanical problem with the shift motor.
The hubs do not lock/unlock. They are not equipped to do so. The front drivetrain rotates as long as the vehicle is moving, you can not disconnect the hubs.
Like McNasy says, there is a differential type unit in the AWD transfer case that controls torque between front/rear. When you select 4x4 lock, this unit is locked together.
#4
I know there is a gear in the tcase called the viscous gear that allows power to be transferred where needed.
So no vacuum, so if it won't shift into 4x4/AWD I could either have a bent fork or a motor issue then. I don't wanna rebuild the transfer case if I don't have to. I assumed if it was a motor issue it wouldn't work at all, it just wouldn't shift into any of them, is that right?
So no vacuum, so if it won't shift into 4x4/AWD I could either have a bent fork or a motor issue then. I don't wanna rebuild the transfer case if I don't have to. I assumed if it was a motor issue it wouldn't work at all, it just wouldn't shift into any of them, is that right?
#6
It'll shift into all them except one. I know with transmissions you can lose a gear and it'll work, but expect it to take a dump soon. Wasn't sure if transfer cases were the same way.
Also could it be the shift motor sensor is defective in some way?
Also could it be the shift motor sensor is defective in some way?
Last edited by tbeck1985; 10-07-2011 at 12:04 PM.
#7
There is no viscous drive in the transfer case. It is a geared differential.
What year is your Dakota?
What mode won't it shift into? What does it do when you try? There are reasons it may not shift into some modes, just during normal operation. If there is a load on the driveline for example.
What year is your Dakota?
What mode won't it shift into? What does it do when you try? There are reasons it may not shift into some modes, just during normal operation. If there is a load on the driveline for example.
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#9
#10
If there is any binding in the drivetrain, you may not be able to shift it. Are you moving when you're trying this? If so, back off the gas for a second as you shift.