this is called thread hijacking... do some reading first...youll find your answer on this forum... but if for whatever reason you dont then ask your own question... not in someone elses thread...

 

let me see if i understand this completely. the cad system works like a syncro in a trans by joining a split shaft correct? so would it be better to use a posi lock on the open diff and have 2 wheel low, or weld the front and be able to disconnect the passenger wheel for driving on the road in the winter in 4wd, but still have a fully locked front offroad?

 

just depends man... will you have the cable conversion or still use the crap vaccum setup... posi lock or lockER... if your going to install posi you may as well install a lunchbox locker...

 

I have seen the CAD fail more time then I care to talk about. Sure it is easy to fix, but I like wheeling not wrenching. If you choose to keep the CAD, expect it to fail. It is easy enough to swap in a solid shaft on that side.

For me I dont want a CAD axle cause there are more things to fail and go wrong.

 

teggy84"let me see if i understand this completely. the cad system works like a syncro in a trans by joining a split shaft correct? so would it be better to use a posi lock on the open diff and have 2 wheel low, or weld the front and be able to disconnect the passenger wheel for driving on the road in the winter in 4wd, but still have a fully locked front offroad?"

Yup. I did the cheap perma -lock fix with my last XJ with some washers and RTV. It's not hard once you look inside the vacuum lock and see what it's all about. I did that because it quit working and I was too broke to replace it. I have never needed 2 wheel low, though. Or 4 wheel high now that I think about it. I guess I'm all or nothing. Anyway, I'm probably going to weld the spider in my current D30 and keep the vacuum disconnect and see if that blows up my skirt.

 

i have a disco axle sitting in my back yard and i am able to spin the yoke without either wheel turning. if your disco axle is truly disconnected and your transfer case is in 2wd then with the jeep parked you should be able to spin the front driveshaft.

zedpapa

 

So with all of this talk about differentials and welding and lockers and what not i realized that some people dont know a whole lot about how they actually work. so i found an amazing video of what happens inside the differential under our jeeps. its really interesting!

skip to time 1:50


so i can see where he is getting the idea that if you have the passenger side disconnected only one wheel is putting resistance and the shaft is not spinning.

lets list what we know for a fact:
-the transfer case is disengaged and the driveshaft can spin freely in the case with no worries.
-the drive side axle is disengaged and the drive side wheel can spin freely without affecting any other component
-the passenger side wheel is the only real force acting on the ring/pinion/spider gears
-the whole system has no power acting upon it from the engine.
-if the spider gears are moving so must the ring and pinion


So now when in 2wd the only force acting on the ring/pinion is the passenger side wheel. Since nothing in the world is truly frictionless and metal upon metal has a high friction, hence why lubricate was created, this will turn the driveshaft thru friction. Both the drive side half shaft and the drive shaft will spin do to friction. There is not enough force from the half shaft to stop moving. Also, try to turn your spider gears without turning your ring and pinion. While under the vehicle you can turn the drive shaft freely with out any issues while in 2wd and it is parked that is because the driveshaft will be turning the ring and pinion and spider gears, but since there is resistance from the passenger side tire on the ground it is going to send the power to side with the least resistance- your half shaft.

-so i promise you that while moving the drive shaft is moving, while parked the drive shaft can be spun freely.

So now when in 4wd and the axle is disconnected you are still only going to have 2wd because it will take less power to spin the ~0 resistance half shaft than to spin the entire wheel, making both wheels spin freely when 4wd is engaged and the drive shaft spins with the motor but does not transfer power to anything but the half shaft.

-when in 4wd and it is connected it will act like a normal open differential.

 

hahaha amen...

 

so i can see where he is getting the idea that if you have the passenger side disconnected only one wheel is putting resistance and the shaft is not spinning.

lets list what we know for a fact:
-the transfer case is disengaged and the driveshaft can spin freely in the case with no worries.
-the driver side axle is disengaged and the driver side wheel can spin freely without affecting any other component
-the passenger side wheel is the only real force acting on the ring/pinion/spider gears
-the whole system has no power acting upon it from the engine.
-if the spider gears are moving so must the ring and pinion


So now when in 2wd the only force acting on the ring/pinion is the passenger side wheel. Since nothing in the world is truly frictionless and metal upon metal has a high friction, hence why lubricate was created, this will turn the driveshaft thru friction. Both the drive side half shaft and the drive shaft will spin do to friction. There is not enough force from the half shaft to stop moving. Also, try to turn your spider gears without turning your ring and pinion. While under the vehicle you can turn the drive shaft freely with out any issues while in 2wd and it is parked that is because the driveshaft will be turning the ring and pinion and spider gears, but since there is resistance from the passenger side tire on the ground it is going to send the power to side with the least resistance- your half shaft.

-so i promise you that while moving the drive shaft is moving, while parked the drive shaft can be spun freely.

So now when in 4wd and the axle is disconnected you are still only going to have 2wd because it will take less power to spin the ~0 resistance half shaft than to spin the entire wheel, making both wheels spin freely when 4wd is engaged and the drive shaft spins with the motor but does not transfer power to anything but the half shaft.

-when in 4wd and it is connected it will act like a normal open differential.

 

TR1hemi is exactly correct. When the CAD is disconnected, there is nothin driving the drive shaft. The only force that would make it spin are friction and the drag from the thick gear lube. If you think the driver's side is locked in, you don't fully understand how spider gears work.

When the CAD is disconnected, you can crawl under the jeep in 2wd and spin the drive shaft by hand and not have the jeep want to move.

This is the very same reason why you can raise up your auto xj (with open diff) with it in park and spin the rear wheels and have the drive shaft NOT move. It is all the same idea. If you have an open diff, the CAD disengaged, t-case in 2wd, and you front drive shaf is lock in and turning, you have a problem with you spider gears. They are stuck.

I broke an axle shaft once in a rear axle with an open diff. If the opposers to TR1hemi are correct, my one good axle shaft should have pushed the vehicle and made it move. It did not move, because the spider gears were functioning.

Bottom line, the only thing that is gonna turn that drive shaft is friction and oil drag.

 

but it turns...

 

It does "turn". That is from spider gear friction and oil drag. When sitting still, you can freely spin the drive shaft and have the jeep not move. The resistance you feel is spider gear friction and oil drag. If what you are saying is correct, the drive shaft will not turn without the jeep moving. It does turn without moving the jeep.

 

I think the question was, "will it turn?" I know how a diff works.

Oh and the OP wanted to know why you don't want a disco axle. If you put a LSD or a locker in there. It will turn the driveshaft with power. I don't think anyone has the paws to stop that one from turning. Or to turn it while its in park.

OP! I don't think the disco axles is dependable enough to use as a selectable locker. But I don't know from experience. Maybe we can get a few chimes on that one.

 

huh? all i am saying is that when it drives down the road it turns... that was the argument... he said it doesnt... i say it did... i dont care how... thats been said over and over again... but yet he still said it didnt...

 

What I am saying, is I bet you could hold it. It is only oil drag spinning it. It was said in previous posts that it was mechanically spun by the driver's side wheel turning. This is false.