Thread: Type of diff lock in 2010 130 pumas and constant 4x4 ?

Originally Posted by pc3

Folks I am just trying to understand the center diff lock is it a rear or front difflock ? Is it same as an after market arb diff lock ?
No, it isn't the same. It is there to make the front prop shaft turn at the same speed as the back prop shaft when it is locked. It doesn't lock the two wheels on the same axle.

Also is the constant 4x4 of the defender just the same as when you have locked the hubs on a land cruiser ?
No. The centre diff is there to allow all four wheels to be driven without breaking something on hard surfaces. The centre diff lock makes the Defender transmission behave like other 4x4s. If you lock the hubs on a Land Cruiser and engage 4WD, you have something like a Defender with the centre diff locked. The Cruiser doesn't have a mode the same as a Defender with the CDL disengaged.

Dumb questions I know

Constant 4WD is different, more flexible and better.

So can the constant 4x4 be effective at all in the mud or do you really need to lock the center diff so really a defender is not in 4x4 unroll you lock the center diff and then really just in normal 4x4 then ? So how does constant 4x4 actually help/work ?

Saying a constant 4WD vehicle is not really a 4WD unless the CDL is engaged is a bit like saying that a car isn't a 2WD unless it has a diff lock.

Just as there are times when it is useful for each wheel on one axle to turn at different speeds (like when going around corners), there are times when the front wheels need to turn at different speeds (like when going around corners).

Just as there are times when it is useful to have a way of stopping one wheel with no traction on an axle from spinning, there are times when it is useful to have the front pair on a 4WD turn at the same speed as the back.

If there is going to be a significant amount of wheelspin, then the CDL needs to be engaged.

Constant 4WD is useful when there will be some slippage, but not significant wheelspin (like a dirt road). It can also be useful on sealed roads where an ordinary 4x4 in 4WD with no centre diff would destroy the transmission.

Landrovers are constant 4wd with a "centre diff" in the transfer case to allow for different speeds of the front and rear diffs such as going around corners etc. Locking the centre diff is required where there would be a loss of traction in either the front or rear axle which would cause the centre diff to just spin with no progress either forwards or backwards.
Locking the centre diff essentially does the same thing as putting a non constant 4wd into 4wd with the transfer case lever and the front hubs locked.
You do not drive in this mode on any hard surface that will not allow slip between the front and rear axles to equalise the rotation difference.

I hope that explains it a little better.

The def. will go most places without locking the centre diff. Its only in real rough/rocky/mud that you will need the centre diff locked. A few times I have gone through some pretty loose/muddy/steep stuff then went to unlock the centre diff and found I had forgotten to engage it. Its amazing where a defender will take you.

So defe can still benefit from a arb diff lock...... Basically it's like a suberu all whelk drive and the cfl is just like locking the hubs in and putting it in 4 h on a cruiser ?

another way of seen how CDL works is lift one wheel at the back,, with CDL out it will just spin and the car wont move off the jack, put CLD in and as both front wheels are still on the ground,, the car will move ford and roll off the jack, this is how it works in a offroad sence, as you can lift a wheel but as long as the other end has traction you will go ford

this is NOT taking into acount traction control

and yes, a locker will help as you will have at least 3 wheels allways driving

Originally Posted by pc3

So defe can still benefit from a arb diff lock...... Basically it's like a suberu all whelk drive and the cfl is just like locking the hubs in and putting it in 4 h on a cruiser ?

Spot on. Of course, with a def you can have low range with open centre diff, not an option on any other 4wd. This is good for towing on hard surfaces (e.g. on a boat ramp or caravan on a very steep slope). A diff lock, like ARB, will always get you further (or do the same job easier).

F.Y.I. - I fitted a Detroit Locker to mine about a year ago and it makes easy work of what used to be difficult. You can attack things slower as you can do the job without needing momentum. The lastest Detroit is a lot quieter than the old. It was fitted at Graeme Coopers (Sydney L/R specialists) and when I picked it up they commented that it was the smoothest and quietest Detroit they had ever fitted (also commented they could see changes made to the diff internals). Lot cheaper than ARB but blew some of the savings on hardened Maxi drive rear axles and drive splines (just to make sure). Off to Cape York, once the wet finishes, the OTL track'll test it out.