Why Toyota is wrong about the LC70’s manual/automatic hubs
Toyota changed the LC70’s hubs from manual to automatic/lock. That’s a backwards step.
A PART-TIME 4X4 like the LC70 has to run in 2WD on the road and can only engage 4WD on surfaces that permit slip between the front and rear axles. This is because it lacks a centre differential or other system to permit the front and rear axles to be driven at different rotational speeds when the vehicle takes a corner.
So most of the time the LC70 runs in 2WD. That means the front wheels rotate, which rotate the front axle, which rotate the front differential, and rotate the front propshaft. All needless turning which wastes a little bit of energy.
That’s why the manual locking hubs were invented:
When set to Free these hubs isolate the wheel from the combination of front axle, differential and front propshaft. All of those stay stationary when the vehicle is driven in 2WD, so no wasted energy.
Manual hubs also means you can put the vehicle into low range and still be in 2WD, handy for backing trailers. And if you have broken front transmission components – say a front differential – then you can isolate that problem and just drive in 2WD.
You can also leave the hubs locked permanently and just drive in either 2WD and 4WD when you see fit. If the vehicle’s transfer case is in 2WD then even if the hubs are locked then the front wheels won’t be driven. There’s no need to unlock the hubs every time you switch from 4WD to 2WD or because you finish a track and turn onto bitumen.
In fact, Toyota (and others) say that vehicles like the LC70 should be driven with the hubs in for a while every month or so. This is to ensure that the front drivetrain doesn’t simply seize up over time through lack of use – it’s good to splash oil around the cogs every so often. Personally, I never used to unlock my hubs when I had a vehicle with them in as the fuel consumption improvement was too small to be measured in real-world conditions, it’s not like the difference between road and mud tyres or fitting a roofrack.
So that’s manual hubs. What Toyota have done with the LC70 is follow Nissan’s example with the GU Patrol and fit manual/auto hubs. These manually lock as usual, but instead of a ‘Free’ setting you get an ‘Auto’ setting (see title photo above).
The idea here is that when the transfer case is put into 4WD (4H or 4Lo) the hubs switch into ‘Lock’ mode but when the lever is in 2WD (2H) the hubs switch back to ‘Free’. This is done not electronically but simply by mechanically reacting to whether the front wheels are being driven or not – if they are, then the front axle is trying to turn a bit quicker than the wheel so the hubs lock, if the front wheels aren’t being driven then the hubs unlock as the wheels are trying to turn quicker than the axle.
All this sounds wonderful but it is not without drawbacks. First, the flexibility to use low range and 2WD is taken away. Second, you can’t isolate front transmission components in the case of damage. And third, for really tough offroading you need the lock position anyway, as in some situations the hubs can unlock, notably when the front wheels attempt to turn faster than they are driven, such as when rocking the vehicle back and forth. This however was not a problem on our recent LC79 test.
The main advantage to the new auto/manual system is that you don’t need to get out and manually unlock the hubs. However, that’s a small advantage as the fuel saving is minimal, and it’s very easy to switch hubs in and out. There’s also a usability advantage as it has been known for people to engage 4WD with the transfer case lever but leave the hubs free, and that means the vehicle is actually in 2WD. Then they get stuck and can’t work out what happened.
There is a third option. Here it is:
Remote operated hubs. Part of the Mark’s 4WD Adaptors portal kit, these hubs are locked and unlocked from inside the cab. That’s the best of both worlds, manual flexibility with no need to leave the cab!