D30 Disco...why would I NOT want one?
The front driveshaft turns at all times. The 4wd engagement takes place within the transfer case.
The vacuum disconnect does nothing more than join the 2 pieces of the passemger side axle shaft.
An open differential is designed to send power to the wheel with the least amount of traction. Therefore when the vac disco is malfunctioning and the collar does not slide into place, the inner shaft spins within the axle housing and the front wheels do not turn.
Locking the collar in place is NO DIFFERENT than having a later model axle with the one piece axle shaft and has no effect on normal driving.
Junior Member
Joined: Dec 2009
Posts: 72
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From: Kennard, NE
Year: 1986
Model: Cherokee
Engine: 2.8l v6 with some wiz bang additions
That is the answer I was lookin for. Good Bye vacuume disconect, Hello modification! Probably doin it tomorrow. Just wanted to make sure that lockin em together wouldn't mess with turning and such.
i dont really see a down side to this, unless the the collar on the disconnect slips off, and then all the power going the front axle will all go to the drivers side wheel, causeing a greater stress and greater chance of breaking a u-joint/axle shaft. But thats like the same thing when you have a locker and flexed out to where only the 1 tire is touching the ground anyways,...
Last edited by Mattpar; Mar 20, 2010 at 07:30 PM.
CF Veteran
Joined: Nov 2008
Posts: 7,874
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From: Northern Ontario, Canada
Year: 1990, 1999, 2000
Model: Cherokee
Engine: 4.0
it will also make it very difficult for turning right.
with my locker installed, and the posi disco'd, i usually have to make a few attempts to make a right hand turn on the trail. left is normal tho.
with my locker installed, and the posi disco'd, i usually have to make a few attempts to make a right hand turn on the trail. left is normal tho.
Junior Member
Joined: Dec 2009
Posts: 72
Likes: 0
From: Kennard, NE
Year: 1986
Model: Cherokee
Engine: 2.8l v6 with some wiz bang additions
Are you saying with your passenger shaft disconnected tht you are having troubles turning? That doesn't make sense, if the passenger tire isn't connected to the other side then they can spin separately. I know what a locker is/does, but that would only connect/lock the drivers side axle shaft with the inner passenger axle shaft.
CF Veteran
Joined: Nov 2008
Posts: 7,874
Likes: 100
From: Northern Ontario, Canada
Year: 1990, 1999, 2000
Model: Cherokee
Engine: 4.0
only while in 4 wheel drive, with all the power just going to the drivers side front wheel, making right hand turns is more difficult. it's harder to push the front end to the right than it is to the left. it's just simple physics.
Are you saying with your passenger shaft disconnected tht you are having troubles turning? That doesn't make sense, if the passenger tire isn't connected to the other side then they can spin separately. I know what a locker is/does, but that would only connect/lock the drivers side axle shaft with the inner passenger axle shaft.
Basically the rear axle will typically send power to the right wheel under normal conditions. With the front axle locked and making a left turn the left front tire has to make a wider turn than the right front and the right rear. The rear will be trying the push the front during a right turn because of the greater distance the front tire has to rotate. When making a left turn the left front tire has to travel a shorter distance than the right rear and it tries to pull the rear making the turn easier.
Much the same way that when the rear axle is locked the rear tires will scrub during a turn. The tire on the inside of the turn has to travel a shorter distance than the outside tire. Depending on which tire has the greater amount of traction, either the inner tire will slip, or the outer tire will drag. Either way you will hear the rear tires chirping around corners.
CF Veteran
Joined: Nov 2008
Posts: 7,874
Likes: 100
From: Northern Ontario, Canada
Year: 1990, 1999, 2000
Model: Cherokee
Engine: 4.0
sorry, yes, my rear is locked too.
winston explained it pretty good. but it is only noticeable while in 4wd on the trail. only the left front makes a wider turn when turning right. when turning left, that tire pulls the front very easily. i think it has something to do with the angle of the tire at full turn also.
in 2wd, it is un-noticeable.
winston explained it pretty good. but it is only noticeable while in 4wd on the trail. only the left front makes a wider turn when turning right. when turning left, that tire pulls the front very easily. i think it has something to do with the angle of the tire at full turn also.
in 2wd, it is un-noticeable.
A disco front is so the front drive shaft, and 4x4 half of the transfer case does not turn in 2WD, saving fuel and wear and tear on those components. In 2WD drive the drivers axle, spider gears, and the inboard half of the passenger side axle, are all that turns.
Again, the front driveshaft always turns when the vehicle is in motion. In 2wd or 4wd it turns. Have someone drive your Jeep down the driveway in 2wd and look at it, it will be turning.
It doesnt turn. Maybe your vac motor is stuck engaged, my whole vac disco system, T/C switch, and lines are all new, 4x4 light on the dash goes on and off as it should.
Last edited by TR1Hemi; Mar 20, 2010 at 10:58 PM.
Then something is wrong in your front diff. The driveshaft is turned by the diff when the wheels are in motion. All of the 4wd engagement takes place inside the transfer case but the driveshaft does turn.


