I have a 1996 Disco in a 5 speed and I would be grateful if you guys could explain how the diff lock works. Does it just slide left and right? WHen do I use it? Etc..

 

Hi,

The Diff lock is first of all for OFF ROAD use only, Ie sand, gravel, mud, snow etcwhere the wheels on either axles can spin / slip at different rates. This is why you DONT use it on tarmac / hard surfaces as it will "wind" up the transmission as the wheels cannot rotate at different speeds between the front and rear axles as they normally do when cornering etc.

To use it , simply push the transfer lever to the left, to remove it, push backto the right. When the diff lock is in, you will have a symbol on the dash telling you so. You can engage / disengage the diff lock whilst on the move in High or Low gears up to a MAX of 40Mph, I always engage / disengage at a slower speed than that.

What it does basically, is mechanically LOCK the front and rear propshafts together inside the trasnfer box so they rotate at the same speed. Its designed to assist off road driving as it ensures equal traction to the front and rear axles.

Its not the be all and end all as you can still get whats called "cross axled" when off road, where 1 wheel spins on each axle through the action of the front and rear differentials. Thisis wherewhats called Diff lockers or Air lockers help again, as they LOCK the 2 wheels together on either front, or rear or BOTH axles. So if you had front and rear Air lockers in your diffs, and a CDL (difflock) engaged, then all 4 wheels MUST turn at the same speed and that is 100% pure 4 wheel drive.

If you ever use the difflock, and you disengage it and the light on the dash does not extinguish after moving of again for say 100yds, then select reverese and reverse for a few yds (50) or maybe more and that will "unwind" the transmission and put the light out. If the light is out the difflock is disengaged.

And as I said, DO NOT use it on normal road surfaces !!

 

Like Panzer said do not use it on dry roads, I use mine on heavy snow covered roads as well as off road.
Low is for high tourqe situations. Low locked and you can almost pull a house off its foundation.
Exserciseit once a monthto keep it working properly. Just go to a empty parking lot, engage the CDL in Hi, drive a few yards, shift to CDL Lo, drive for a few yards, shift to Lo un-locked and drive a few yards then go back to normal Hi and then go about your day. By going through all the gears you will help ensure years of trouble free driving.

 

You have five places the diff lock can go.

1. High unlock-backright road use.
2. Low unlock-forward right road use slow <30mph.
3. High locked-back left off road/loose/low traction snow ect
4. Low locked-forward left off road max traction needed.
5. center Neutral- out of gear no go.

 

here is a artical from discoweb.org.

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.

 

Ok, cool, thanks guys!

 

I tried putting the truck into diff lock and nothing lit up on the cluster. I tried low and high as well....

 

Did it actually engage? While moving foraward under 5mph put the trans in neutral and the move the CDL towards you, pull hard.
So you will move it from right to left. It goes in easier if you are moving.
The light will come on eventually. Mine didnt at first, then after a couple of uses it started working.
Be paitent, dont force it, you could break the linkage.

 

it goes in fine. I did it while the truck was stationary.

 

Ok, I wouldnt worry about it then. The light might start to work later.