Thread: Centre diff lock on defender 300tdi

Got this from exploroz.com

"The basic problem is that a 4WD's front axle travels further than the rear axle when going around any corner. If both axles are driven at the same speed, stress results in the drivetrain (transmission windup).

Therefore, some form of device is needed between front and rear axles to permit the front axle to rotate faster than the rear during cornering. This is a centre diff, referred to as such to differentitate (sic) it from the diffs all cars have between wheels which do exactly the same job, permitting the outside wheel to travel faster around a curve than the inside whilst maintaing drive to both.

Differentials do have a major disadvantage for offroad use, and that is the fact they direct most drive to the wheel that is easiest to turn. So if you have one wheel on mud and another on rock, the differential will send almost all the drive to the wheel on mud, and you'll be going nowhere.

Difflocks prevent this by effectively "locking" the differential, so it doesn't act as a differential at all. In the previous example, equal amounts of drive would go to each wheel, so you could still move. Turning ability would be restricted becuase the wheels would be forced to move at the same speed."


Ben....

Centre diff lock come into play through the use of a mechnical shifter/lever located near the gearbox lever. When you lock the centre diff the power/torque split is equal to front and back axle, when not locked a differential action in the centre diff allows for the difference in distance covered by the front/back wheels. On hard surfaces like bitumen all diff locks should be disengaged to allow the differential action to occur and prevent transmission wind up and tyre scuffing.

Just reading this thread. I had the same question as well, but i have another to do with CDL. How do diff locks and traction control work together?.
I have a TD5 110 with TC and ABS. I ask this question because I go to engage the diff locks but nothing on the dash indicates if they are engages or not. Do I have a problem with my Diff locks or what...
Thanks
Mark...

if you get to a point where your traction control should be kicked in, you have the diff locks turned on and the TC doesnt come on then your difflock is working.


TC works by sensing the differnt speeds at each wheel if the difflock is on the wheels turn at the same speed so TC doesnt detect any loss of traction and doesnt come in.

Originally Posted by Snake2093

Just reading this thread. I had the same question as well, but i have another to do with CDL. How do diff locks and traction control work together?.
I have a TD5 110 with TC and ABS. I ask this question because I go to engage the diff locks but nothing on the dash indicates if they are engages or not. Do I have a problem with my Diff locks or what...
Thanks
Mark...

like Dave has said the TC want come on if your diff locks are on.
the diff locks are arfter market and want have any lights on the dash, the only lights that you should see are the one on the switches for the lockers.

Originally Posted by Snake2093

Just reading this thread. I had the same question as well, but i have another to do with CDL. How do diff locks and traction control work together?.
I have a TD5 110 with TC and ABS. I ask this question because I go to engage the diff locks but nothing on the dash indicates if they are engages or not. Do I have a problem with my Diff locks or what...
Thanks
Mark...

Firstly, unless you vehicle has had aftermarket cross axle diff locks fitted, you only have one diff lock, which is for the centre diff located in the transfer case.

Secondly, I am not familiar with defenders and the indication lamps they have, and I don't have a vehicle with traction control - I do have vehicles with centre diff locks and cross axle diff locks.

Traction control works by sensing if any one of the wheels is spinning. When spinning is detected, the brake is applied at the particular wheel.

This can be a problem in sand where wheels may be spinning but still providing some drive, or when applying the brake to a spinning wheel will make driving through heavy going more difficult. AFAIK this was more of a problem with the early implementations but is more refined now.

When the centre diff is unlocked, on a vehicle without traction control if any one wheel looses traction and spins, all drive torque goes to the spinning wheel and the vehicle fails to proceed.

When the centre diff is locked, then if a wheel on one axle looses traction, you will still have drive torque to the other axle.

The centre diff is a small unit and is not intended for use when a wheel on one axle is spinning - it is only intended for use on hard surfaces where all wheels have sufficient traction to prevent wheel spin.

Therefore the centre diff should be locked when driving on loose surfaces off road. In these situations there is no gain and everything to loose by not locking the centre diff - locking the centre diff will not affect steering or or restrict turning ability off road (unlike a cross axle diff lock on the front), despite what was quoted in the 2nd post.

In my Range Rovers and Disco there are lamps to indicate when the centre diff is locked.

I believe that there will also be a centre diff lamp on a Defender, because it is a warning to the driver to unlock when you reach hard surfaces.

Generally the lamp has an icon to resemble 4 wheels, front and rear axles and the front and rear drive shafts - in other words it is telling the driver that he/she is in 4 wheel drive. Conversely if the centre diff is unlocked, then you do not have 4 wheel drive (in the accepted norm.).

When Land Rover introduced traction control in the Disco 2, they thought the centre diff lock was unnecessary, but later learnt the error in this assumption and bought it back again.

The centre diff lock and traction control work in harmony - there are no conflicts.

Yeah should come up with a light when the diff is locked. Correct me if i'm worng on this one still leaning myself. If 2 wheels leave the ground(diff locked) on oposites FR and RL thats when the abs should kick in on those wheels in the air, push the power to the wheels on the ground?
Trying to work it out only driven a 130 they don't have ABS, but my 110 when it gets here will.