@jack VZ90 said:
Hi Dave,
A landcruiser J9 is permanently 4 wheel driven.
Cost a little more fuel, but drives great under all conditions, and has quite equal tyre wear at front and back.
Dave 2000 replies in Blue:
The 80 is also permanent 4WD but only when all four wheels have traction, I guess just like the 90, although there is a caveat here which I will come back to.
When putting your transfercase in LL the front and rear shaft grab each other.(central-diff-lock)
Again the same as the 80.
It's my experience that the front end always pulls harder then the back, mostlikely because you have more weight on the back axle (wheels) when accelerating. That creates an extra grab in the diff-lock, causing unlocking problem.
I do not agree, the load on the diff lock is varied, on a grippy surface the load is the same, if the diff lock is being used is due to poor traction then the load varies dependent on available traction. Poor traction equals less weight transfer to either end of the vehicle again dependent on traction however, the rear does not have the weight of an engine permanently on top of it.
An 80 is no 90, when i full push the accelerator, the nose comes up, and car lifts out of the front coils, so less weight on the front wheels, causing spinning on the front and not in the back .... 178 HP 3.4v6
If you reverse, you push your weight on to front wheels, so your back wheels run just a little faster. (spinning) and that's when your lock comes of,
I agree if you put your foot down in reverse and get one wheel to spin you have altered the load on the centre lock which should release it, which is exactly what happens if you reverse in a figure eight, this because the front wheels are scribing a greater arc than the rear.
When you make a left turn, your left wheel makes a shorter, and your right wheel a longer loop.
Agree, in exactly the same way as the front and rear wheels in fact, it could be argued there is more slack in the drivetrain front axle to rear axle (diffs/propshafts/gearbox internals/transfer internals), than what there is across a single axle, thus perhaps making it easier to get the load off the lock?
Something else I am not comfortable with, that is advising a non knowledgeable contributor to move the shift lever whilst reversing, whilst unlikely a problem with a manual, moving an auto from reverse to neutral opens the possibility of moving into D i.e selecting a forward set of planatery gears going backwards, could that cause damage?
At high speed it can damage the ATM, at low speed (up to about 2 km / hour in reverse) the torque converter can handle this. It's designed for this purpose ..... there's no need to speed, just moving and rolling free is enough.
Reversing in a figure 8 is a tried and trusted solution for all but the most stubborn centre diff locks IME.
I can unlock it in my own lane, and don't need a parking lot. (LOL)
The caveat about all four wheels need traction is not entirely true for some 80's that are fitted with a VC in the transfer.
A 90 by my knowledge doesn't have any kind of VC in transfer case. I've to check my workshop books for this. They might have a VC in front diff. You can check this on the prescription for use of diff oil in Max Ellery's or Haynes workshop manuals.
Regards
Dave
