Thread: Selectro front hubs

Reading these replies and driving the vehicle with my hubs engaged / disengaged - I'm leaving them engaged now. Thanks for everyone's input.

Originally Posted by Lotz-A-Landies

Which unecessary friction and wear are you talking about?

When the hubs are disengaged the diff and prop shaft find a natural position, this is almost always the same position when the universal yoke on the diff end is in the horizontal position, with the grease nipples down. This position allows the front suspension to work in its normal vertical plane. Every time the axle assembly goes up and down on each and every bump, the prop shaft spline slides in and out. This causes unnecessary friction and wear in one plane of the spline and eventually an out of balance prop shaft. The same can be said of wear within the freewheeling hubs themselves.

An unloaded well lubricated drive line causes minimal wear on the individual components, the railco bushes in the swivels get lubricated reducing unnecessary wear of the fibrous material, the crownwheel in the diff and the diff berings continue to get lubricated and the surfaces remain rust free.

I understand what you're saying but in all the years I owned and drove the Series III I never came across anyone espousing the virtues of leaving the hubs locked permanently in. I am not at all suggesting they remain permanently unlocked as your post above pretty much explains just how bad that can be. But in relation to your query about friction and wear the logic I am referring to is:
1. A moving part will wear faster than a non-moving part. We seem to disagree about whether moving via jiggling in a fixed orientation is ultimately worse than high speed constant rotation (plus jiggling).
2. It is easier to spin a wheel with the hub unlocked than one with it locked no matter how well the front axle & diff assembly is lubricated.

Surely to question the use of free-wheeling hubs at all is to question their fitment as standard equipment on nearly every part-time 4WD vehicle over the last 30 years.

I repeat my original assessment - Scallops - I don't think it really matters either way for the miles Matilda is likely to be travelling.

Originally Posted by isuzurover

As Diana points out your logic is flawed.

I have lost count of the number of toyota front ends which I have seen which have needed to be rebuilt because the diff bearings have been brinneled/rattled to death (i.e. are now indented/pitted beyond use) or the top half of the crownwheel has gone rusty. So your front end parts are likely to need replacing more often if you don't lock your hubs in enough.

I guess there are always going to be idiots who buy Toyotas and then never take them off-road. (or never learn how to use them correctly).

Originally Posted by solmanic

1. A moving part will wear faster than a non-moving part. We seem to disagree about whether moving via jiggling in a fixed orientation is ultimately worse than high speed constant rotation (plus jiggling).


Surely to question the use of free-wheeling hubs at all is to question their fitment as standard equipment on nearly every part-time 4WD vehicle over the last 30 years.

If a moving part is (a) under no load and (b) well lubricated, it will not necessarily wear.
I never noticed a difference in spinning wheels with hubs locked or unlocked.

Most/all other 4x4s beside land rovers have heavy grease lubrucating their swivel balls. Which results in lots more resistance to rotation.
However in the same vein, leaf springs are still standard fitment many nissotas, but coils are much cheaper to make, lighter, and give a smoother ride???

Solmanic

I'm not having a go at you, but I feel that a lot of the theories you espouse are the result of advertising myths and not engineering data. More than that I once thought about freewheeling hubs as you seem to now but after having had them on my vehicles from the mid 1970's onwards, I now believe that the disadvantages of freewheeling hubs far outweigh any benefits.

Originally Posted by solmanic

I understand what you're saying but in all the <snip>
I am not at all suggesting they remain permanently unlocked <snip>

Originally Posted by solmanic

<snip> I never engaged the hubs on my Series III except when needed off-road. <snip>

Well actually, with the exception of off road, you did suggest exactly that!

Originally Posted by solmanic

<snip> But in relation to your query about friction and wear the logic I am referring to is:
1. A moving part will wear faster than a non-moving part. <snip>

As Ben confirmed the bearings in the uni-joints, diff pinion and carrier bearings become brinnelled (pitted in channels where the roller sits) causing premature failure, which doesn't happen with a rotating drive train that isn't under load. While minimal wear does occur it is spread evenly around the bearing not in trenches caused by the vibration in the one spot for the static drive train.

Originally Posted by solmanic

<snip> We seem to disagree about whether moving via jiggling in a fixed orientation is ultimately worse than high speed constant rotation (plus jiggling). <snip>

I believe that jiggling in the one plane is far worse than sliding during rotation. The reason for this is that in the static shaft the wear is in one plane, the splines can become quite sloppy in that plane but remain tight in the plane at 90 degrees to it. The wear in a spinning shaft is evenly distributed 360 deg around the spline.

Originally Posted by solmanic

<snip>2. It is easier to spin a wheel with the hub unlocked than one with it locked no matter how well the front axle & diff assembly is lubricated. <snip>

You are talking about resistance to rotational forces, yes that is true during the initial acceleration. However once the drivetrain is in motion (a rotating mass) it will tend to stay in motion unless some other force acts upon it. This is born out by the lack of evidence of significantly improved fuel economy with freewheeling hubs disengaged.

Originally Posted by solmanic

<snip> Surely to question the use of free-wheeling hubs at all is to question their fitment as standard equipment on nearly every part-time 4WD vehicle over the last 30 years.<snip>

Land Rover never fitted freewheel hubs to it's vehicles and for the last 25 years Land Rovers and many other makes have been constant 4WD. But it is true as a result of market pressure many car dealers (including Land Rover dealer networks in Australia-for about 10 years) offered aftermarket freewheel hubs as optional extras and the Japanese manufacturers even went so far as to make them standard equipment for private buyers in many markets.

I think we are all missing the point here. We are not talking about pristine bearing and gear surfaces that need to be protected to get us through the next 50 years.

Dan's vehicle has not had the driveline touched in the resto, so who knows what uneven or even wear has occured. Given the fact the vehicle is occasionally driven, I would leave them locked to lubricate the upper bushes, joints, bearings and such. If on the occasion you are going to partake in a drive of some distance(say to Blinman) unlock them. You will probably notice less vibrations more than anything else.

CC

Originally Posted by Lotz-A-Landies

Well actually, with the exception of off road, you did suggest exactly that!

Actually no... what I didn't include in that comment was that I was off-roading about once a month. Ergo I was locking in the hubs each month.

Originally Posted by Lotz-A-Landies

The wear in a spinning shaft is evenly distributed 360 deg around the spline. As Ben confirmed the bearings in the uni-joints, diff pinion and carrier bearings become brinnelled (pitted in channels where the roller sits) causing premature failure, which doesn't happen with a rotating drive train that isn't under load. While minimal wear does occur it is spread evenly around the bearing not in trenches caused by the vibration in the one spot for the static drive train.
I believe that jiggling in the one plane is far worse than sliding during rotation. The reason for this is that in the static shaft the wear is in one plane, the splines can become quite sloppy in that plane but remain tight in the plane at 90 degrees to it.

I'm not disputing this will happen if some peanut never engages their hubs, only questioning the idea the hubs should never be disengaged or that there is no benefit in disengaging hubs.

Originally Posted by Lotz-A-Landies

You are talking about resistance to rotational forces, yes that is true during the initial acceleration. However once the drivetrain is in motion (a rotating mass) it will tend to stay in motion unless some other force acts upon it. This is born out by the lack of evidence of significantly improved fuel economy with freewheeling hubs disengaged.

This is physics 101. More moving parts no matter how well lubed will have a higher rolling resistance than less moving parts. And I thought there was a wealth of evidence that they improved economy. I just Googled this out of curiosity and got no hits suggesting otherwise.

Originally Posted by Lotz-A-Landies

Land Rover never fitted freewheel hubs to it's vehicles and for the last 25 years Land Rovers and many other makes have been constant 4WD. But it is true as a result of market pressure many car dealers (including Land Rover dealer networks in Australia) offered aftermarket freewheel hubs as optional extras and the Japanese manufacturers even went so far as to make them standard equipment for private buyers in many markets.

I said part-time 4WDs. As far as I am aware the standard fitment of free-wheeling hubs to Japanese 4WDs accounts for the majority. Incidentally, what part-time 4WDs have been marketed without free-wheeling hubs since, say 1980? This is a genuine question as I can't think of any.

There seems to be two furphys about free wheeling hubs:
1. That they reduce wear on the front axle. Quite clearly they do not, as Diana has pointed out and as Ben says, brinelling of bearings will occur. When new assembled cars were shipped to Australia from Britain, they were often found to have damaged wheel bearings from the vibration of the sea voyage! The advice given in a previous post to disengage them for long drives, seems to me to be the time which will promote maximum damage to the prop shaft; bearings and railko bushes.
2. That they promote fuel economy. In my experience of driving a Land Loser with hubs engaged, or disengaged over hundreds of kilometres along the same routes, there is no difference discernible at all in the fuel consumed.

In addition to the above; having the useless things disengaged when you desperately need 4WD in a hurry, such as when approaching boggy ground, or deep sand on a track, either leads to a tedious halt or an unexpected bogging. Many fire services for this reason weld or fasten the free wheel hubs in the locked position, after losing lives whilst a bogged vehicle is burnt-over.