diff lock

[zukiny]

Hi all, i have just got a 98 disco which goes very well but the centre diff does not lock The lever moves fine and somtimes the light even comes on. any ideas.

 

[NHESS81]

how did you determine it is not locking if you can move the lever left and the light comes on? mine may not be locking either, i can move the lever left, but my light doesnt turn on and i cant tell a difference in driving, i have to find enough jack stands to get it off the ground and test it fully...but how did you check it?

 

[zukiny]

i jacked 1 wheel off the groud (left front) put the car in low lock and in drive and the wheel off the ground turned freely, which it should not do if the centre diff is locked.

 

[NHESS81]

hmm..i thought there was some issue with this test, as the open diff on the front/rear would allow this to occur no matter what the center diff did...i thought the only way to tell was to get all four wheels off the ground...i hope someone can chime in with the official way to do it on our trucks, i need to test mine too...

 

[zukiny]

tomorrow ill jack the whole thing up and see if makes any diff.

 

[joey]

If you jack one wheel and lock the center diff, the odds are you vehicle will move if working correctly.

Basically all open = the wheel that loses traction will spin.
With center locked = front wheel that loses traction will spin and a rear wheel that loses traction will spin...

If you apply the brake, then all wheels in theory will spin (it is called traction control in a D2)

 

[bdog]

http://www.discoweb.org/discovery/basics.htm

Center Differential Lock

The gearbox of the permanent 4x4 system drives the front and rear driveshafts, which are linked to the four halfshafts throughout the differentials in the front and rear axles. When turning corners, ouside wheels travel further than the inside wheels, the axle differentials on all cars enable this to happen while at the same time retaining drive to each wheel.

However, while cornering, the rear wheels travel less distance than the front ones. If the front and rear axles are linked solidly, as in many part time 4x4s when in 4-low, this causes excessive tire wear and lead to drivetrain wind up that can put a lot of stress in the system.

The center differential overcomes this in the same way as the axle differentials compensate for individual wheel speeds on the same axle. The problem is that, in some situations, the action of the center differential leaves only one wheel driving the vehicle.

The Discovery is equipped with the manual center locking differential to overcome the above problem. The center differential lock only locks the drive to the two axles, but doesn't have any effect on the individual axle differentials. Therefore, in a typical cross axled situation, where only one front and one rear wheel are in contact with the ground or getting sufficient grip to maintain traction, you can still lose all traction because the axle differentials are taking the drive to each axle to the point of least resistance. The wheels not in contact just spins, even with the center differential locked.

The center diff lock ensures that if both wheels on one axle have traction, they will continue to drive the vehicle even if traction is lost in the other axle. this means that use of the center diff lock will keep you going in many situations. But remember, if you lose grip in one front wheel and one rear wheel, the center diff lock can't help you.

The center differential lock can be operated on the move at any speed as long as there is no difference in speed between the wheels. so, make sure the wheels are all rotating at the same speed.

AVOID center differential lock on normal road surfaces.

 

[Moose]

Thanks for the post. Similar information is also posted here.

 

[zukiny]

Yeah i know how it all works, i just dont know if it is all working.

 

[zukiny]

I had a chance to have a look at my diff problem today. i jacked the disco up and put it on axle stands, with the motor running, shifted it into locked low, jump out and stoped the one front wheel that was spinning. the wheel on the other side started to move but not as fast as the rear wheel was moving. so no diff lock. i then sprayed all the linkages with crc and then tryed again, this time when i shifted i got a loud clunk and the light came on, tryed the front wheels again this time it went as fast as the back YAY.
so this means when i change into lock and the light does not show the diff is not locked, im glad i have it sorted as im taking it out on its first off road trip this weekend.