Thread: Snow chains - cheap

The point I was trying to make was that if you have chains on the front and none on the rear at some point the front will have more traction than the rear(hence why you fitted the chains in the first place). Obviously TR will kick in and limit spin of the wheel/s that are rotating faster than the program wants. At a predetermined point the TR will start limiting the slip in CD to the point where it is at maximum lockup. So basically there shouldn't be a time where there will be drive to the rear and not the front.

Initially the system shouldn't bias torque towards either axle, only when spinning occurs and the CDL starts to lock. But in some TR settings it will not fully lock.

Unless you're driving on hard ice or packed snow (unlikely in Australia), your best bet is to use Mud/Ruts for 20 kph ~ 40 kph, and Rock Crawl for lower speeds - you'll have a better chance of not digging in though, if you use command shift and stick to the higher gears (as GGS does).

You shouldn't need rear chains.

Cheers,

Gordon

Originally Posted by gghaggis

You shouldn't need rear chains.

Cheers,

Gordon

Do you know why the handbook indicates that chains are NEVER to be fitted to the rear tyres?

Originally Posted by garrycol

Do you know why the handbook indicates that chains are NEVER to be fitted to the rear tyres?

Possibly to reduce wind-up in the CDL, as you can't completely lock it. If you have to, then use it in Rock Crawl.

Cheers,

Gordon

Originally Posted by gghaggis

Possibly to reduce wind-up in the CDL, as you can't completely lock it. If you have to, then use it in Rock Crawl.

Cheers,

Gordon

Not sure I quite understand that statement. Wouldn't wind up become a risk when it is put in Rock Crawl and the centre diff is locked?

If a diff is locked, it can't "wind up".

Cheers,

Gordon

Originally Posted by gghaggis

If a diff is locked, it can't "wind up".

I might have a different interpretation of 'wind up' Gordon but rmp's 4wd Handbook implies that transmission wind up can occur when there is no centre diff or the centre diff is locked.

Also rmp says this:

So why don’t we drive around with the centre diff locked the entire time? Simple answer – windup. When a vehicle corners the front axle travels further than the rear, and thus must rotate quicker. If the centre diff is locked that can’t happen, so both front and rear axles turn as the same speed. This is ok on loose surfaces as there terrain permits the tyres to scrub slightly to equalise things. It isn’t ok on high-traction surfaces where the tyres can’t do that, and thus stress builds up in the drivetrain.

I can certainly see why having chains on both front and rear might create wind up if the centre diff was locked.

You're quite right - I'm using the wrong terminology - "slippage" is what I should have said. And thinking about it, the diff probably has little to do with the LR recommendation - it should cope with rear chains just as well as without. Rock-crawl would be detrimental on ice, but better in slushy snow.

It may have something to do with environmental damage? Front chains are generally easier on the track than rears (as we found out when they were demonstrated at one of the NightOwl 4WD competitions).

Cheers,

Gordon