How to work a Diff Lock Switch???

jhcabs

I have a Dihatsu Terios 1.3 2000 that I'm taking on this years Mongol Rally www.mongolrally.ie

We brought it offroading today up in Glenmalure in Wicklow. Roads weren't too bad and never needed to turn the Differential Lock Switch on. We were told to only use it when in tricky spots but i really have a few questions that i would love if someone could clear up.

Why should you on turn it on when in tricky spots?
Why do you have to stop before turning it on?
Can you drive around and turn directions when its on?
If there is a 200 yard track of pretty harsh muddy, rocky roads in fornt, can you turn it on navigate though it and then turn it off after or will this break the car?

I'm afraid to turn the bloody thing on incase i break the car but if we could just turn it on for a while every now and then it would of made some of the terrain a bit easier. The manual didn't really explain it very well..

Slidey

Because it had to lock 2 gears together you need to be stopped so as to not damage the teeth.

In a normal diff the power will always take the path of least resistance. This means once one wheel looses traction, you stop.

What a diff lock does is lock the 2 wheels together meaning whatever one wheel is doing the other has to do too.

This has the disadvantage of pushing you straight on when you try to go left or right on hard smooth surfaces such as tar.

The diff lock was designed to do exactly as you described. It will minimise the risk of you getting stuck in the tricky spots

peasant

A 4WD with open diffs is essentially just a 2WD. As soon as one front wheel and one rear wheel loose traction and start spinning ...that's it, you're stuck

This can easily happen on very ondulated or mucky terrain, see here (the left rear is also spinning, but you can't really see that)

https://www.youtube.com/watch?v=nxx6D-EgEyQ

The best practise is to engage the difflock when you are approaching a difficult section, as the locked diff will make it easier to keep momentum going. Waiting until you are stuck might be too late, because if you're really stuck (like in heavy mud) even the locked diff might not get you out.

As long as you're driving on loose ground, you don't have to worry about the difflock, as the loose surface will allow for some tyre slip and prevent windup.

Difflocks should not be engaged on tarmac or other solid surfaces. After a while your transmission would just wind up and something will break.

One word of warning ...be very careful when using difflocks on a slippery surface on a side slope. The locked axle might actually spin both wheels and once that happens you slide sideways (and that's a hard one to get out of)
The same applies to very steep descents.

CJhaughey

Sorry for asking a stupid question but this could have some bearing, does the difflock on the Terios lock an axle or the centre differential?
It is possible that difflock only engages the centre differential similar to the TLC setup, and that both front and rear diffs are still unlocked and able to spin unless you have a locker on front and rear diffs.

Jonty

More than likely it'll only lock the centre diff not the axles.