Thread: Centre Diff Lock

Originally Posted by rick130

I agree, but usually the advocates of engaging the CDL espouse gloom, doom and disaster if you don't engage it, at least going off previous threads.

I think it's more of a reference in regards to heading bush, I lock on most anything that isn't high speed dirt, or if pushing I'll lock it then too, far better balance and braking, but left open on general bland dirt roads

Originally Posted by rick130

The t/case is still holding up and drives ok (which I'm surprised at as it had different tyre sizes front/rear when I bought it with 76,000km on the clock. The t/case fluid was black from being overheated)

When you engage the CDL I thought the 4 tyres should be the same pressure and the SAME SIZE!

How much off road work with the CDL engaged did it do before you bought it?

Originally Posted by Beckford

When you engage the CDL I thought the 4 tyres should be the same pressure and the SAME SIZE!

That myth again. Tyre pressure within limits doesn't change the effective distance travelled per revolution of tyre. The invariant length is the tyre's steel belt.

As for engaging the CDL, I would only do it on a surface where significant slip is possible, like ball-bearing gravel or sand. The act of turning the steering makes the front axle travel a different distance to the rear axle, a much bigger effect than any minor variation in rolling diameter.

Originally Posted by isuzurover

Rick and vnx205

I suppose the consensus is that - it can't do any harm to lock the CDL whenever you drive on loose surfaces...

Originally Posted by camel_landy

Exactly... The harm comes if you use CDL on high grip surfaces.

M

Originally Posted by rick130

I agree, but usually the advocates of engaging the CDL espouse gloom, doom and disaster if you don't engage it, at least going off previous threads.

Originally Posted by rovercare

I think it's more of a reference in regards to heading bush, I lock on most anything that isn't high speed dirt, or if pushing I'll lock it then too, far better balance and braking, but left open on general bland dirt roads

Yes, I guess there are places where it is definitely necessary to engage, places where it is definitely wrong to engage and a lot of territory in between where it is an option and no harm will be done either way.

I think I was getting the same impression as Rick130. There seemed to be a body of opinion developing that you were courting disaster unless you engaged the moment you left the bitumen.

I think the fact is that those who engage on dirt roads will probably enjoy the same centre diff reliability as those who don't.

haha thanks guys clear as mud. Just Kidding

The old Land Rover chant comes to mind (and yes, first used in Land Rover training for the Camel Trophy) - "As slow as possible, as fast as necessary”.

I’ve personally based CDL selection on the speed you are planning to do. Under 50km/h I always lock the diff. The reason you are going that slow would most probably be terrain dependant and when you decide definitely need it, it would usually be too late.

Above 50kmh on gravel roads I allow the differential to decide where the power needs to be.

These were military guidelines (SADF) for driving Defenders in the late 80’s and I’ve sort of stuck to the concept.

Originally Posted by Loubrey

The old Land Rover chant comes to mind (and yes, first used in Land Rover training for the Camel Trophy) - "As slow as possible, as fast as necessary”.

Shouldn't that be "As fast as possible, as slow as necessary..."

Originally Posted by Loubrey

Above 50kmh on gravel roads I allow the differential to decide where the power needs to be.

...it don't work like that. In fact, it's the complete opposite.

A differential is a mechanical device and it will ONLY transmit the power to the path of least resistance... i.e. the wheel with NO traction. If you don't believe me, just jack up one of your wheels and see what happens when you start to drive.

M

Originally Posted by camel_landy

A differential is a mechanical device and it will ONLY transmit the power to the path of least resistance... i.e. the wheel with NO traction. If you don't believe me, just jack up one of your wheels and see what happens when you start to drive.

M

I don't disagree at all regarding the workings of the centre diff. The fact remains that on roads as encountered in rural West Australia and to a large extent the gravel roads of South Africa (where I learned to drive) you travel great distances where you need to travel between 70km/h and 80km/h or you'll never get there. To a large extent 2WD is sufficient if you have enough driver ability to keep it on the road. Very seldom, if ever do you encounter "high speed" single wheel traction loss and the best thing remain allowing the Defender's natural configuration permanent 4WD to operate as designed.

I currently drive a Puma 90 and we have roads here known as "rail access roads" with a speed limit of 80km/h which everybody including the road trains travel at. I never engage the diff lock for these journeys and I never hear a peep out of the TC, which to me indicates I do not at any point suffer traction loss on any individual wheel.

There is many schools of thought on the matter including the Mine's requirement for Hilux's to permanently remain in high range 4WD which I personally don't agree with either. As I said in my previous e-mail that's the way I've been taught and after close on a million km's travelling in Land Rovers building roads all over the world I'm still to loose a Land Rover transfer case or gearbox.