Freewheel hubs on Range Rover axles

Very early 110's had selectable 4 wheel drive, and freewheelng hubs were available. I've neever actually seen either, but the hubs might work - if you couls find any!

Richard

My Brother had a 150" landrover 300 tdi in 6wd. I am pretty sure he had freewheel hubs on his. He might have a suggestion. I'll email a link to this to him

Here is his website though:

madhatchetman uttered summat worrerz funny about:

I guess you are thinking rear axles but I have a pair fitted on stage one axles retro fitted to my 2a.

That probably doesn't help much I guess but it could be 2 wheels less to scrub.

Lee D

On or around 18 Mar 2007 14:53:48 -0700, snipped-for-privacy@postmaster.co.uk enlightened us thusly:

You sure it's not the turning and sideways scrub that's causing the problems?

Take a look at the arse end of a 6-wheeler lorry next time you see one in a tight turn, and see how much the tyres scrub sideways. The RR has a lot of gap between the rear wheels compared with the effective wheelbase, and that's going to make a lot of sideways scrubbing in corners.

The ideal solution is to make the rear-most axle counter-steer by the appropriate amount, then not only do you eliminate scrub from turning but you improve the turning circle as well.

Should be possible to do using a front axle but (I think, not had the chance to play) you have to invert the axle casing and then invert the diff in the axle casing so the diff is the right way up again. Not sure about the steering swivel angles, it'll tend to self-uncentre but whether that's a pro9blem depends on how you operate the steering more than anything else. I think it would track how you want with the steering swivels facing aft, provided it's stable.

If I win the lottery, I'll build one.

Try to avoid steering , that's what causes the scrubbing! My pinz is the same, no differential between rear axles, and because the rear end is light on mine, the rear-most set of wheels tends to be the ones that slide sideways on corners and consequently wear faster. If your weight distribution is more even, it won't be so consistent for you.

Take it onto some packed earth so that it leaves some wheel imprints and do a U-turn, I know that with the pinz, you can see that some wheels spend quite a bit of time going sideways.

Because of their proximity to each other the small amount of wind-up doesn't become an issue, and when you turn a corner and the wheels scrub sideways, they get a chance to unwind.

As another quick thought, you'd probably find it easier to remove the drive to the rear axle, this would allow you to test out your theory regarding the free-wheel hubs. I'm pretty sure that free-wheel hubs won't make a jot of difference, but if you want to make sure then remove the drive shaft to the rear axle for a while and see what happens.

You'd have to leave it off for quite some time to get a feel of how much a difference it makes, and of course you'd need to be able to compare it to how it was before somehow.

As another poster already mentioned, the first year that 110's were introduced, a 4-cylinder petrol version was offered with a part-time 4x4 option. So for that year only, Fairey freewheeling hubs were available too.

They are 24-spline, so they won't suit Range Rover axles of the vintage you are talking about. You would need to use the rear axle from a Ninety or a ('94-'98) Discovery. They are pretty cheap and available, and pretty much a bolt-in swap, AFAIK.

The hubs have the same working parts as the version for Series 3s, but the casings fit the 5 bolt-hole drive flanges used on coil-sprung Land Rovers.

They are rare and usually quite expensive when you do find them. I'd guess upward of £100 for a pair in 100% condition.

I believe that AVM in Brazil also make a hub to suit Defenders, but Bearmach are the UK distributors for AVM, and they are incredibly pigheaded about importing the hubs. I offered to buy a dozen sets from them, but they were unhelpful in the extreme. (Bearmach apparently sell a kit for converting an LT230 Transfer box to part-time 4WD, hence the freewheeling hubs).

It wasn't clear from your description whether the RR has (de)selectable

6x6? I gathered not, otherwise tyre scrub wouldn't be the reason for freewheeling hubs. However, if the two rear axles are permanently engaged, then you should definitely NOT run the vehicle that way. There will be wind-up between the two rear axles, despite them not being steerable. (Firstly, their speeds will be unsynchronized due to undulations in the road, and secondly, variations in exact tyre radii etc will also make them run at different speeds.)

6x6 and 6x4 trucks have a differential action beween the pair of rear axles (as well as across each of them) to take care of that problem. As Austin says, the tyre scrub you see is due to the lack of steering ability of the rear pair of axles.

On the other hand, we did close to 90,000km miles on a set of BFG Mud terrains fitted to a very heavily-laden 6x6 Defender without steerable axles, so tyre scrub is not really such a big issue. Certainly not worth the complexity of trying to make another axle steerable, IMO. (Though it is a technically intriguing project. If you did as Austin suggested and made the 3rd axle steer in the opposite direction to the frontmost axle, you would indeed improve the turning circle and avoid tyre scrub, but you would have massive oversteer - it would be a nightmare at speed! Steering axle #2 at a slight angle would avoid tyre scrub without oversteer, but wouldn't improve the turning circle significantly.)

Anyway, hope this helps.

Michael... (madhatchetman's brother)

Ian, my understanding of the Pinz 6x6 is that the differential in Axle #2 has two crownwheels and two pinions, and provides a differential action fore/aft as well as left/right, so that axles #2 and #3 can rotate at different speeds. When you lock the axle diffs, the fore/aft differential action is disabled too, so you get locked drive across all six wheels.

Or do I have this wrong? Easily tested by jacking up some of the wheels and testing which ones rotate freely.

Once again, it's important to distinguish between the sideways tyre scrub you describe, (caused by steering only one axle), and rotational tyre scrub, caused by fixed gearing between the axles. Both types can be hard on tyres, but steering-scrub will put strain on wheel bearings, whereas rotational scrub will put strain on the diffs and shafts.

Agreed that their horizontal paths are similar. But as axle #2 goes over a mound, it will travel significantly further than axle #3., causing wind-up. That wind-up will be reversed when axle#3 goes over the same mound, but it's not ideal to have the gearing "locking" back and forth.

Worse still is the continual wind-up that will result from small differences in tyre wear etc. I don't believe it is feasible to have permanent 6x6 or 6x4 without some form of differential gearing between the driven axles.

M...

On or around Mon, 19 Mar 2007 10:43:45 +0000, Ian Rawlings enlightened us thusly:

I bet it's an easy mod on a pinz to fit front half-axles to the back end and arrnge for them to counter-steer.

Nope, the pinz diffs are odd beasts. The pinz diff has a solid shaft running straight through it, so whatever power goes in one end goes out the other. Halfway down this shaft a hole is drilled through it and two bevel pinions are mounted on either side of this shaft and so spin around the shaft as it turns. Wrapped around the shaft are two tubes with bevel gears on both ends, meshing with the shaft pinions to form a differential gear set. The pinions on the other ends of these tubes then mesh with large crown wheels coming in from the sides attached directly to the axles. As the axles move up and down with the terrain, these two large crown wheels change their angle relative to the rest of the differential, but as they are pivoted around the centre line of the central power shaft, they stay in mesh. There's a picture here;

In the picture, the axles are coming in from the left and right, and there is a straight thing that looks like a shaft running through the middle. This is the two tubes I was talking about with the pinions at either end, and they are rotating around the solid power input/output shaft that emerges from the front and rear of the differential. Note that in order for this to work, the axle centre lines don't line up, they are offset by a few inches, otherwise the crown wheels for each axle would mesh with each others bevel pinions. You can see this in the pic linked above.

The differential locking mechanism is acutally external to the differential, it mounts on the rear. This works by having one of the two pinion tubes extending outside of the diff housing and ending in a set of dog clutch teeth, this is then engaged via a sliding second set of teeth mounted on the power input/output shaft locking that pinion tube to the power input/output shaft, causing the diff to lock.

All the diffs on a pinz are identical and can be freely interchanged, I recently fitted a rear differential and quarter-axle set from the second axle of a pinz to the front of mine. You just unbolt the pinch bolts halfway down each axle, slide the wheel assembly and quarter-axle off leaving the diff housing and quarter-axles (as seen in the pic above) on the truck. Then you unbold that, slide it off, and slide the new one on then re-fit the wheels assemblies and outer quarter-axles, then do the pinch bolts up. It's remarkably easy to do!

I've done this, and it fits in with the above. With one set of rears on the ground and the other set in the air, rotating one wheel sends the other spinning in the opposite direction. Engaging the diff lock means that the wheels won't turn.

Not much of an issue, when a four-wheeler goes over a large mound, the chassis will tilt to keep all four wheels on the ground, but when a

6x6's rear bogie goes over a mound, the chassis tilt is almost entirely down to the difference in height between the front and rear of the vehicle, so a 6x6 will tend to lift the rear wheels off the ground as any difference in height between the first set of bogie wheels and rear set has to be taken up entirely in suspension travel. Because of this, the wheels will either lift or will lose traction quite quickly because of the lessened load on them.

Tell that to the pinz, the Volvo C306, loads of lorries on the roads etc.. It's perfectly feasible, and works fine. Wind-up gets relieved when the vehicle turns as the tyres are forced to scrub sideways and so will spin a little too to unwind the transmission. There is very little wind-up however, due to the proximity of the wheels.

Maybe, but why?!

All that complexity and those flimsy CVs, just to avoid some tyre scrub? Not to mention the fact that you'll probably roll the vehicle if you move the steering wheel while travelling at more than about 30!

It's easier than you think! Each pinz half-axle is split into two parts, making quarter axles. There's some pics of my truck's diff assemblies with just the quarter axles on the following link. The two diff assemblies on the bench are identical, despite one being from the front of my truck, and the other from the rear of a donor.

The quarter-axles are held together to form a half-axle with a large pinch joint half-way down, with two bolts, and a third short tapered bolt that goes through a hole in the outermost quarter axle and into a locating hole on the diff's quarter axle -- this stops the axle rotating and makes sure it's in the right position.

Once you undo all that you can whack a cold chisel into the pinch joint to spread it a little and just pull the whole wheel, brake, portal gearbox and steering swivel (on the front) assembly off as one unit. What's left on the truck is what you see in the photos on the link above and is identical, front or rear. You could just yank the rear outer assembly off and slide on a front set instead and you'd have a steering axle ;-)

You'd then need to re-couple the suspension and also fit some steering gear of course.. (goes outside for a quick peer) the suspension fittings would be trivial, they're almost identical front/rear, just a thick tapered pin sticking up from the outer quarter axle, the leaf terminates on this at the rear, and at the front the lower coil sits on a plate resting on a similar pin.

So if you wanted to put a steering rear axle on, you wouldn't even need to remove the diffs, just the outer assemblies, do a mild bit of furtling to the suspension and arrange for a steering box to be coupled up to the steering wheel, which would probably be the hardest part.

Yep, there's no need, but if you wanted to make an 8x8 then a rear steering axle would be the best way to go. The Escaro 8x8 built with Defender drivetrain and axles took this route.

Flimsy? Relative to a solid axle perhaps but they're hardly flimsy.

You'd probably have to gear the steering down a bit but it wouldn't be that bad. The Escaro managed it.

Interesting info, Ian. I'll have to read up on this some more - I have been under the impression that all 6x4 trucks EITHER usually operate in

6x2 (i.e. one of the driven axles is normally disengaged unless extra traction is required), OR they have an inter-axle differential, usually integral with the front axle-casing of the tandem. In the latter case, the inter-axle lock may or may not be lockable, and likewise, the axles may or may not have inter-wheel locks.

In fairness, I don't know this for a fact, and I have a rather sketchy knowledge of Pinzs specifically, so I'd like to learn more - I'm especially intrigued in the light of my own experiences with a 6x6 Land Rover conversion.

So if you have the time and the interest, I'd be keen to find out a couple of things:

1) What 6x6 configuration does the Pinz use? i.e. what modes can it be run in? 6x6, 6x4, 6x2? And are the inter-wheel diff locks applied indivdually (axle by axle), or do you lock the tandem axles as a pair? (Or all 3 together, for that matter).

2) If you jack up a single axle and rotate a wheel, the other will counter-rotate (in gear, diffs unlocked). That much is clear. But what if you jack up both rear axles, and rotate a (same-axle) pair? Does the other pair counter-rotate?

Rgds,

Michael

I bought the pinz because I love the way it works, the Volvo C30x machines might have the edge off-road in many situations but they are built just like my landy, but with portals instead. The pinz is a weird machine in lots of ways, so I'll always yap on about it given the slightest pretext ;-)

On the road, the rear two axles are driven and the front isn't driven. When you go off-road, you pull the first of the three large levers in the central console to engage drive to the front axle through a dog-clutch assembly mounted on the front of the transfer box (which is part of the chassis, just in front of the first rear axle), so it's then three-axle drive with no differentials between any axles. If things start getting sticky, you pull the second lever, which locks

*both* axle differentials at the rear, so all four wheels at the back turn as one. If things get even stickier, you pull the third lever and this locks the front differential as well. You don't have to pull them in that sequence, but it's the most sensible. Front diff locked with no drive to the front for example is just silly ;-)

.. and out of gear in both gearboxes, even with the transmission handbrake off. The driveshaft in the lifted axle can't turn because it's hard linked to the other non-lifted rear axle. This only applies to the rear axles though.

I am shortly going to go outside and become the victim of this setup; I want to replace and adjust the rear brake shoes, which requires me to be able to turn a wheel. In order to do this, I have to jack up both wheels on an axle because if I just jack one wheel up, it won't turn because the diff's driveshaft is fixed to the axle that's not been jacked up. I've done this before so I know what happens. I don't have to do this at the front, I can lift and turn one wheel there because the drive shaft isn't connected unless I throw the first lever.

I know for sure that the drive shaft going into the diff is solid and emerges from the rear without interference from the diff, because a) I have the parts and workshop manuals and they show the solid shaft quite clearly, and b) because I have a diff on my bench and played with it, watching all this stuff going on. I'm going to put it in a case and make coffee table out of it I reckon ;-)

What you saw in the pic I posted the link to was not a power input shaft with a differential in it, it was a power input/output shaft with a differential *around* it.

On or around Mon, 19 Mar 2007 12:52:14 GMT, snipped-for-privacy@none.com (Madhatchetsbrother) enlightened us thusly:

1) no tyre scrub 2) reduced turning circle.

those are the main reasons. If you take the one I'd like to have a crack at building one day, it's a 100/140" wheelbase. a 140" LR would have a turning circle the size of an oil tanker's - 110s are unwieldy enough, in a tight space. By countersteering the rearmost axle, the turning circle stays the same as the original 100" you get with the RR/disco chassis, which is not too bad, but you gain the extra 40" of length and payload capacity in the vehicle.

The rearmost axle doesn't steer much - it's a ratio of 2.5:1 compared to the front. When the front one steers to say 25 degrees lock angle, the back one is only at about 10 degrees - this is managed with suitable linkages from the front steering gear, I'd think. I'm not sure what the max lock angle on the disco/RR chassis is but it's not a great lot more than that.

As for it tipping, I doubt it. The middle axle remains a non-steering one and the rear one follows the correct track compared to the front. A side benefit is less sideways loading on everything, from the front wheels through the chassis to the back wheels - a conventional 6x6 on good terrain generates a lot more side loads when turning sharp corners. Look at the back end of a tri-axle semi-trailer for an example, when taking a tight bend

- the tyres get shoved all out of shape, and shoving truck tyres like that which are typically over 100 pps takes a lot of force.

conventional 6x6 lorries have less problem with scrub and so forth mainly 'cos they're usually a lot longer wheelbase overall - but a lot of them these days have lift axles for when they're running light.

On or around Mon, 19 Mar 2007 13:12:33 +0000, Ian Rawlings enlightened us thusly:

are they power steering or can they be made to be?

on the LR idea, I had in mind a mod to the front end steering to take an additional drag link down to the back, with the connection points suitably chosen to get the right ratio of turning angles. But with a manual steering box, steering 4 wheels instead of 2 might be a bit like work.

They're not power steered as standard, but some owners have fitted their own setups, it's apparently not that hard to do. One chap up in Scotland used G-Wagen parts, some in the states have used generic non-specific kits and adapted to suit. The second generation ones have power steering factory fitted.

Personally, despite being a weed, I don't have a problem with it as it is, but if you wanted to add a rear-steer then that might be difficult to turn. The stock pinz 6x6 can easily out-turn my Defender 110 though, so not that much of a need for it.

Would you really need rear axle steer though if it's just a 6x6 or are you talking 8x8?

And is this before, during or after the bigfoot minibus? ;-)

On or around Mon, 19 Mar 2007 19:05:24 +0000, Ian Rawlings enlightened us thusly:

yes, to keep the turning circle decent. The 100" chassis is reasonable, especially if you fit wheels with a bit more offset and ignore the manufacturer's recommendation as to lock stop settings :-)

after. There's a photoshop mockup of it somewhere...

oooh, this is almost topical again:

another 6x6 idea:

here's a very crude mockup of the long disco:

I'm sure I had a tidied-up version, but I can't find it.