Manual Hubs install

Saves fuel, more mpg, less emissions.
You are simply not using energy for stirring a front differential full of thick oil when not in use
Well, that's why they sold freewheel hubs for early Land Rovers, but forget the emissions claim, they hadn't thought of that back then. ​​​​​​

I'm going out on a limb here but I'll wager the difference in fuel consumption and wear of having the front rotating assembly double isolated vs being driven either by the ground or engine is so insignificant as to need to be measured in additional tanks of fuel over the entire life of the jimny. What it isn't is enough to make any observable difference over the usage in a month. I suspect it is in reality a hangover from before the adoption of road going permanent 4x4 systems.

My understanding has always been that a differential doesn’t like been driven by the wheels for long periods of time, but the more I think about it I am struggling to see what the problem would be, the wheels and drive shaft will both turn, but there will be no load on it.

So that leaves the transfer box, both front and rear shaft will be turning at the same speed, but only one will be driven, again this isn’t that different to the box in 4wd.

My assumption that you don’t drive the diff from the wheels is probably because most vehicles with a diff have the drive shaft connected to the gearbox and I know that should be avoided.

There will be extra wear and drag by having the front hubs locked but I tend to agree with Lambert the extra fuel will be very small. I lock my hubs when the roads have snow, ice or a mixture of lanes and tarmac, then switch 4wd as required. However, most of the time and on a long journey the hubs are unlocked.

Robin

This is exactly why I came up with the quick and easy "locking the vacuum hubs with a bolt" method. But people would rather spend £100 on old fashioned hubs they have to get out and fiddle with. I swear most people that fit them have no idea what they actually do.

wrote:

Didn't know that.  So what's the point in having hubs that can unlock?  Just to save a bit of wear on the front axle?

 

Yes, it reduces wear, the axle doesn't have any bearings at the CV joint end like a Landrover (but no-one has ever reported a problem with wear.....)
It reduces fuel consumption because you aren't stirring up the oil in the diff and turning all that metal around (bearings or not).

The transfer is designed with synchromesh to give silent engagement and accelerate the drive shafts from stationary to road speed before the hubs pull in, which is quite nice, but it doesn't need to if they are already turning with locked hubs.

I have a vague idea that the early vitara used to have an engagement/disengagement joint in one of the front driveshafts, like some of the Dana axles, which caused massive wear of the gears in the front diff, and they had to be over filled with oil to try and reduce the problem, somewhat the worst of both worlds....



 

wrote:

I'm going out on a limb here but I'll wager the difference in fuel consumption and wear of having the front rotating assembly double isolated vs being driven either by the ground or engine is so insignificant as to need to be measured in additional tanks of fuel over the entire life of the jimny. What it isn't is enough to make any observable difference over the usage in a month. I suspect it is in reality a hangover from before the adoption of road going permanent 4x4 systems.

Your wager is correct, it makes little difference day to day, probably saves a gallon over the life of the vehicle.
But then they fit smart alternators and start stop tech to save fuel. I guess these can't be measured either, but they still do it. As the advert says "every little helps"