centre locking differential explained

I am a little confused so i could use some help, last year i bought my first disco, a 1996 and it had CLD, my understanding was that once the centre diff was locked all four wheels would spin at the same speed then i read that if a front wheel was spinning and the opposite rear wheel was spinning you would still be stuck even with the centre lock diff. i now own a 2002 with now CLD and i was told the traction control would be better because the abs stops the spinning wheel and applies torque to the non spinning wheels. my dad has a toyota fj cruiser and it only has a rear diff lock but also uses traction control and i know that my 1996 disco was better in deep snow with the diff locked compared to the fj so can someone please clear this up for me

My understanding (right or wrong) is that the diff lock, locks the front and rear propshafts together. it does not lock the diffs.
this gives a 'locked' 50/50 split front and rear.
this gives better traction, it does not however lock all 4 wheels like a 'locker' in the front and rear diff would.
I run lockers in my wrangler and it is like night and day compared to 'open' diffs.


I think

slobodan said:

My understanding (right or wrong) is that the diff lock, locks the front and rear propshafts together. it does not lock the diffs.
this gives a 'locked' 50/50 split front and rear.
this gives better traction, it does not however lock all 4 wheels like a 'locker' in the front and rear diff would.
I run lockers in my wrangler and it is like night and day compared to 'open' diffs.


I think

Click to expand...

That's as clear a description of the centre difflock as I've heard in a long time. Well done !!

slobodan said:

My understanding (right or wrong) is that the diff lock, locks the front and rear propshafts together. it does not lock the diffs.
this gives a 'locked' 50/50 split front and rear.
this gives better traction, it does not however lock all 4 wheels like a 'locker' in the front and rear diff would.
I run lockers in my wrangler and it is like night and day compared to 'open' diffs.


I think

Click to expand...

So why would it be bad to run with the centre diff locked on pavement if all it does is split the power between front and rear, each wheel would still be able to spin independently right?

slobodan said:

My understanding (right or wrong) is that the diff lock, locks the front and rear propshafts together. it does not lock the diffs.
this gives a 'locked' 50/50 split front and rear.
this gives better traction, it does not however lock all 4 wheels like a 'locker' in the front and rear diff would.
I run lockers in my wrangler and it is like night and day compared to 'open' diffs.


I think

Click to expand...

Good description... You'd think 'diff lock' meant it locked all four wheels really. I couldn't believe it didn't the first time I found out.

and I thought discovery's had LSD's in addition to the front rear lock .... did I get that wrong?

mjltigger said:

and I thought discovery's had LSD's in addition to the front rear lock .... did I get that wrong?

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????

mjltigger said:

and I thought discovery's had LSD's in addition to the front rear lock .... did I get that wrong?

Click to expand...

YES !! You can lock drive to be 50/50 split as has been said, but, if you have two wheels on the same of the vehicle and they are both slipping on mud - you ain't going nowhere boy

oh

simonk23 said:

So why would it be bad to run with the centre diff locked on pavement if all it does is split the power between front and rear, each wheel would still be able to spin independently right?

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No, the front and rear 'driving' wheels would be 'locked'. as you turn a corner the front driven wheel could turn at a different speed to the rear 'driven' wheel.
There is no 'centre diff' (transfer box) slippage.

Man, this confuses me.

I know that when my front diff is locked (proper diff lock) I can't even turn the flippin thing

and the front driven wheel is opposite to the rear driven wheel is that right.. so going round a corner normally one would be on the outside of the turn and one on the inside.. hence diff wind up if you corner on tarmac with them locked...

have I got it...

slobodan said:

No, the front and rear 'driving' wheels would be 'locked'. as you turn a corner the front driven wheel could turn at a different speed to the rear 'driven' wheel.
There is no 'centre diff' (transfer box) slippage.

Man, this confuses me.

I know that when my front diff is locked (proper diff lock) I can't even turn the flippin thing

Click to expand...

My understanding is that it's the propshafts that are locked together when you lock the centre diff, the two axle diff are still open which would allow the left side and right side wheels to run independantly as they are not locked together, which is what you need to allow a car to turn a corner.

The front and rear wheels on each respective side will run at the same speed because they are covering the same distance, whereas the left side wheels on a right hand corner will cover more distance than the right side ones, which is why there needs to be a diff on each axle.


See why I said slobodan's description was clear

thebiglad said:

My understanding is that it's the propshafts that are locked together when you lock the centre diff, the two axle diff are still open which would allow the left side and right side wheels to run independantly as they are not locked together, which is what you need to allow a car to turn a corner.

The front and rear wheels on each respective side will run at the same speed because they are covering the same distance, whereas the left side wheels on a right hand corner will cover more distance than the right side ones, which is why there needs to be a diff on each axle.


See why I said slobodan's description was clear

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No they don't. The rear wheels will normally run slightly tighter than the fronts (next time your on soft ground or snow, take a tight turn and look at your tyre marks) so the front and back axles will cover slightly different distances, so turn at slightly different speeds.
This is why with selectable 4WD you must run in 2WD on the road, and with permanent 4WD you must have a differential (or some kind of viscous coupling)

Davec said:

No they don't. The rear wheels will normally run slightly tighter than the fronts (next time your on soft ground or snow, take a tight turn and look at your tyre marks) so the front and back axles will cover slightly different distances, so turn at slightly different speeds.
This is why with selectable 4WD you must run in 2WD on the road, and with permanent 4WD you must have a differential (or some kind of viscous coupling)

Click to expand...

Thanks for that, I can see what you mean now.

Unfortunately it still isn't as good as having a couple of LSD's tho'

Cheers

Dave

mind you don't lsd's wind up more often? and (from memorey on the nissan) you can't turn them off....