TCase Quadra Trac Question

[rcazparts]

New CJ7 owner as of yesterday. It is a 1979 AMC 304 , auto, quadra trac, 35s, some lift. We spent on the very low side of money expecting stuff. I enjoy working on stuff. It has locking hubs and 2.73 front gear with 3.54 rear gear. Missed that Sunday night...buyer beware. I will deal with that eventually. Obviously, can't engage front hubs. Vacuum switch is in glove box, but does not appear to change anything. I guess hard to tell without locking hubs. Until front gear change, am I okay to run it with hubs disengaged? Will this cause issues? Is there a way to easily disengage front output on quadra trac? Maybe take off front drive shaft? How best to temporarly continue to sort the jeep without destroying something in the front diff?

 

[CJ]

New CJ7 owner as of yesterday. It is a 1979 AMC 304 , auto, quadra trac, 35s, some lift. We spent on the very low side of money expecting stuff. I enjoy working on stuff. It has locking hubs and 2.73 front gear with 3.54 rear gear. Missed that Sunday night...buyer beware. I will deal with that eventually. Obviously, can't engage front hubs. Vacuum switch is in glove box, but does not appear to change anything. I guess hard to tell without locking hubs. Until front gear change, am I okay to run it with hubs disengaged? Will this cause issues? Is there a way to easily disengage front output on quadra trac? Maybe take off front drive shaft? How best to temporarly continue to sort the jeep without destroying something in the front diff?

Ouch, stinks about the different ratios I'd go with 354 as the final ratio (probably going to use larger dia. tires).
Your ok to run without locking hubs as it won't bind the drive line.
It's ok to engage 4 wd without hubs locked and see if the front drive shaft turns to check the Transfer Case .

 

[rsf]

Im pretty sure that should have permanent drive flanges, so someone had to have done a part time 2wd conversion to the borg warner case, or they somehow locked it into "emergency drive " permanently

if it was still fill time 4wd with the emergency drive disabled it would have destroyed the internal Transfer Case diff quickly with the hubs unlocked

 

[CJ]

I agree , in the 1st post it was stated it had locking hubs so as you have, I assume it has had some modifications.
Like you said, with different gears the drive line would be destroyed if put in to actual locked 4 wd with the hubs engaged.

 

[rcazparts]

Ouch, stinks about the different ratios I'd go with 354 as the final ratio (probably going to use larger dia. tires).
Your ok to run without locking hubs as it won't bind the drive line.
It's ok to engage 4 wd without hubs locked and see if the front drive shaft turns to check the Transfer Case .

The jeep has 35s on it. I am guessing he put the 35s on, realized it needed more gear and changed only the rear. Once the read gear was changed, he had to put locking hubs up front to be able to drive it.
Turning the rear tires will turn the front drive shaft. First impression is the PO changed the hubs only. Need to start it and see what changes with the switch in glove box.

 

[CJ]

Sounds good, one can only hope the Transfer Case has a part time 4 wd kit installed.

 

[rcazparts]

Im pretty sure that should have permanent drive flanges, so someone had to have done a part time 2wd conversion to the borg warner case, or they somehow locked it into "emergency drive " permanently

if it was still fill time 4wd with the emergency drive disabled it would have destroyed the internal Transfer Case diff quickly with the hubs unlocked

The switch is set to emergency. Can it safely be driven with the hubs unlocked? This assumes the switch works.

 

[CJ]

The switch is set to emergency. Can it safely be driven with the hubs unlocked? This assumes the switch works.

Even if the switch does not work it can be safely driven. It can't bind but it's just always rotating the front dif.

 

[rsf]

The switch is set to emergency. Can it safely be driven with the hubs unlocked? This assumes the switch works.

Jeep calls it emergency drive, the rest of the world calls it center diff lock. Its basically an ARB locker in the Transfer Case with the front and rear driveshaft instead of axle shafts.

With the emergency drive locked (or Transfer Case tampered with to stay in lock) it wll drive fine with the front hubs open.

With emergency drive unlocked and the front hubs open the rear driveshaft won't spin and the front will spin 2x normal speed.

Unlocking it and trying to drive would be a reasonable test to see if the case has been permanently changed to part time. If it does not move and spin the front driveshaft don't let it go very long. The Transfer Case differential shims aren't very big and will fail in minutes doing that.

 

[rcazparts]

Jeep calls it emergency drive, the rest of the world calls it center diff lock. Its basically an ARB locker in the Transfer Case with the front and rear driveshaft instead of axle shafts.

With the emergency drive locked (or Transfer Case tampered with to stay in lock) it wll drive fine with the front hubs open.

With emergency drive unlocked and the front hubs open the rear driveshaft won't spin and the front will spin 2x normal speed.

Unlocking it and trying to drive would be a reasonable test to see if the case has been permanently changed to part time. If it does not move and spin the front driveshaft don't let it go very long. The Transfer Case differential shims aren't very big and will fail in minutes doing that.

Thanks for the detailed response. Going to swap front gears before I go any further. A 4x4 with only 2x4 is useless. Good thing Summit is in town! I spend too much with those guys...