Thread: Front drive shaft disconnected

Thats always been my belief, that it'll get you out of a pickle in 2wd. Apparently they do awesome circle work in 2wd too

If you've got two big and two small tires you can put one on the front and the other on the back and itll be fine.

I read of one bloke on rrnet in his classic, he drove around for a week before he got a front diff fixed and the vc was fine with it.

That's good to know because I fear with the off road ventures the chances of something going wrong in the drive line is always looming.

I would also think it safe to use with no front propshaft connected.

Doesn't the drive from the transfer box always go to the rear propshaft and only connect to the front propshaft through the VC?

The VC is fairly stiff even in its unlocked state so would behave as locked with no propshaft and no load connected so the front would just rotate at the same speed as the rear, no speed differential means no viscosity increase in the fluid and no locking up.

With a front propshaft in place the drive to the front would only be through this baseline stiffness of the VC and speed differences between front and rear would be allowed but any speed differential would cause progressive stiffening of the VC.


Sorry, just rambling on here but that's my basic understanding of the system......

What about the rear disconnected? There would be no wind up but the vc would stay fully locked I guess in this state. So does the continual fully locked up state and elevated temperature damage the vc? Or is it the wind up that kills it? I'm thinking the rear disconnected and having the vc fully locked and at an elevated temp will damage it over time?

hmmm....
With only the front propshaft connected all drive would initially go through the disconnected rear, this would create a huge shear force within the fluid in the VC and lock it up, so drive would go to the front.

In a locked state the fluid has no shear force and cools which allows a speed differential to exist again, once it does the VC will lock again.

I'm not sure whether this would cycle continuously locking and unlocking or keep the VC in a permanent state of partial slipping, either way it sounds like it would give the VC quite a workout, possibly leading to failure and permanent locking.

I'd be interested to know if anybody has run this configuration as a failure in a rear drive component could mean returning from a bush trip like this.

Rc42 thats exactly how the freelander one operates. The p38 and later classics have a centre differential that allows torque to go to front and rear. The outer casing of the vc transmits torque to the front diff, and the rear output shaft that is driven by the centre diff extends through the centre of the diff and into the inner spline of the vc. So at the end of the day the vc only limits the speed difference between the front and rear but doesn't 'power' any diff.

benji, you're absolutely right, I misunderstood and thought that the VC was instead of the center diff (CD) but its 'in addition to'

My new understanding is that the transfer box drive goes to the CD and is divided between front and rear propshafts but in addition the VC is also connected to the front and rear propshafts to limit the speed difference between them, essentially converting the CD into a limited slip diff with auto full lockup.

If this is correct then removal of either propshaft will require the VC to heat due to speed differences and lock up for long periods, which would provide drive but could result in damage or permanent locking of the VC.

Thats a good diagram, I haven't seen that one before.

Yes it would need to heat up, but from others experiences they can take it. I would imagine whilst driving along in 2wd it would go through a heating cooling cycle.

Oh how I would love a centre locker, I wonder if Justin from lucky 8 is still chasing this.