An open question ...

[AK83]

Open diff question that is:

As I remember then, if you had open diffs, ie. no locked in any way, I always thought that the wheel not on the ground should always turn quite easily.

Yesterday I had the car up on each side(doing some work).
Handbrake on, centre diff unlocked, still in high range.
Handbrake doesn't work when car(D1) is in said position, so grounded wheels were chocked.
Had the wheels chocked on the grounded side, car rolled a few millimeters before the chocks did their thing, as per normal.
So with the two upside wheels now in the air, I couldn't turn either of them more than the amount of slack that the driveline has.
I could easily tighten the wheel nuts up to a safe amount without the need to ground the car again(but I did double check once the high side was back at ground level).

I have a nice long breaker bar, and wanted to check this as far as I safely could, so using the breaker bar, I put more and more pressure on a wheel nut of one of the wheels that were in the air and once the slack was taken up(about 10-ish degrees of turn), and once it reached its locked position I could put enough force on the breaker bar(backwards) to make the car rock a little ... as in it wanted to move (backwards).

Is this normal operation?
I was sure that if diffs are of the open type, the freewheeling wheel could always turn .. hence the need to undo the over tightened wheel nuts before raising it.

Thanks,
Arthur.

[bee utey]

Perfectly normal behaviour. With the handbrake on and the transfer case in gear you have stopped the rotation of both the front and rear drive shafts. The wheels in the air can only turn if the wheel opposite can turn exactly the same amount in reverse. A differential is not a freewheel, it constrains the two outputs (=wheels) to average out to the same speed as the differential carrier, which you have locked to zero.

Next observation: if your handbrake is engaged and you had one side up on castors, moving the car forwards or backwards would make the raised wheels turn exactly the same amount, but in reverse.

[AK83]

Thanks bee utey!
I thought they allowed freewheeling as well.

[bee utey]

I thought they allowed freewheeling as well.

That's called a "broken" diff. [biggrin]