Vapour overdrive project.

[Nigelw]

You'd be better off with the 1.4 transfer box, which will take an overdrive, and lower ratio diffs like 4.1 or even 4.74. Especially easy if your Disco is old enough to take a pair of diffs straight out of a SII/SIII (ie 10 spline diffs). The lower diffs will take some of the strain out of the gear box and od. They'd also reduce the ratio in low range as well as in high, which would help with the effects of the tyres.

Bugger I moved away from 10spline on grounds of strength and fitted my axles out with everything from my old 24 spline axles.

CW just gave me something to think about with a new 1.410 gear set from ashcrofts, could be interesting to rebuild the T/box completely when it comes off for a new clutch as I think this one is on it's way out.

Anyway, going back outside to do some more welding and think about the options even further before I commit her money into buying more toys for my truck

FF totally get what you are saying there, good food for thought! As well as the Maxidrive stuff, should keep me google happy when I get in later

[Anderzander]

Gosh this is interesting ....

Thinking about my low range - I almost exclusively use 1st and 2nd - I'd like a lower set of gears - and have only used the other low range gears on forest gravel roads, where I could use high range.

Maybe I should look at re-gearing low range. I'm off to google the maxi drive gears.

[Tanuki]

A truly interesting discussion - which reflects the diversity of uses to which we put our Green-Oval products.

My perspective is still that - for the situations I use the most - I want the least in the way of gears between the engine and the drive-wheels. For me, "Job One" is legal-limit-plus cruising on open roads with - more-than-occasionally - a well-loaded Bateson flatbed trailer on the back; hence my liking for a highest-gear straight-through 1:1 gearbox with no layshafts needing to be turned/mashing-up the oil, and diffs/transfer-boxes to accomodate this.

Other people's comments have been around heating of gearboxes/transmissions: my engineering ancestry has always been to see things-getting-hot and/or being noisy as signs of inefficiency. Energy generated by your engine but turned into heat in the transmission is energy-you-paid-for-but-threw-away. It's not making you faster on the open-road, or more successful on your rock-crawl. Why pay for an engine to produce energy, and pay-again for a transmission-cooler to throw away a slice of the engine's efforts?

Every gear-train loses you some energy. Every ratio-reduction/multiplication loses you energy. The fewer of these you have in your transmission the better!

[Bowie69]

Bugger I moved away from 10spline on grounds of strength and fitted my axles out with everything from my old 24 spline axles.

You can fit the series 4.7 crown wheel and pinion to the 24 spline centre, you need a spacer and replacement bolts IIRC, however they AREN'T very strong, being a thinner crown wheel.

If you want to fix diff ratios, the Ashcroft (and others) do many ratios: http://www.ashcroft-transmissions.co.uk/index.php?act=viewCat&catId=12

Just pick which one

I was tempted with a set of 4.7s, and my 1.4 transfer box, for a giggle, but thought it might make things a bit hairy with a tweaked 4.0 V8 under the bonnet That and Nige advised against it, now he has his 5.2 I don't think he could say ANYTHING about silly plans anymore

[Snagger]

Bugger I moved away from 10spline on grounds of strength and fitted my axles out with everything from my old 24 spline axles.

CW just gave me something to think about with a new 1.410 gear set from ashcrofts, could be interesting to rebuild the T/box completely when it comes off for a new clutch as I think this one is on it's way out.

Anyway, going back outside to do some more welding and think about the options even further before I commit her money into buying more toys for my truck

FF totally get what you are saying there, good food for thought! As well as the Maxidrive stuff, should keep me google happy when I get in later

I saw LRSeries advertising 4.1 diff crown and pinion sets for later diffs at about LRS' stock, though. Alternatively, finding a set of s/h 10 spline shafts should be cheap and easy, as would a pair of SIII diffs, ad with those diffs and shafts being the weak link in the transmission, you'd never have to worry about blowing the gear box. Either is viable, though rebuilding the 24 spline diffs as 4.1s would be a better technical solution and could be combined with locking diffs.

[Snagger]

A truly interesting discussion - which reflects the diversity of uses to which we put our Green-Oval products.

My perspective is still that - for the situations I use the most - I want the least in the way of gears between the engine and the drive-wheels. For me, "Job One" is legal-limit-plus cruising on open roads with - more-than-occasionally - a well-loaded Bateson flatbed trailer on the back; hence my liking for a highest-gear straight-through 1:1 gearbox with no layshafts needing to be turned/mashing-up the oil, and diffs/transfer-boxes to accomodate this.

Other people's comments have been around heating of gearboxes/transmissions: my engineering ancestry has always been to see things-getting-hot and/or being noisy as signs of inefficiency. Energy generated by your engine but turned into heat in the transmission is energy-you-paid-for-but-threw-away. It's not making you faster on the open-road, or more successful on your rock-crawl. Why pay for an engine to produce energy, and pay-again for a transmission-cooler to throw away a slice of the engine's efforts?

Every gear-train loses you some energy. Every ratio-reduction/multiplication loses you energy. The fewer of these you have in your transmission the better!

Heat and noise are energy that has come form the engine, so are a sign of inefficiency. Unfortunately, even in 4th and driving straight through the box, the lay shaft and main shaft gears will still all be spinning as they are in constant mesh, and the free-running main shaft gears will all be turning at different speeds on their bushes, so there is always some energy loss through friction, mesh generated noise and oil stirring. However, the energy loss will still be least in whichever gear gives straight-through drive. And yes, the more gear trains you have, the more the losses. However, efficiency can be gained by having an extra set to raise the gearing if the engine has sufficient torque to pull it in the peak rev range, such as with an overdrive.

[bill van snorkle]

A truly interesting discussion - which reflects the diversity of uses to which we put our Green-Oval products.

My perspective is still that - for the situations I use the most - I want the least in the way of gears between the engine and the drive-wheels. For me, "Job One" is legal-limit-plus cruising on open roads with - more-than-occasionally - a well-loaded Bateson flatbed trailer on the back; hence my liking for a highest-gear straight-through 1:1 gearbox with no layshafts needing to be turned/mashing-up the oil, and diffs/transfer-boxes to accomodate this.

Other people's comments have been around heating of gearboxes/transmissions: my engineering ancestry has always been to see things-getting-hot and/or being noisy as signs of inefficiency. Energy generated by your engine but turned into heat in the transmission is energy-you-paid-for-but-threw-away. It's not making you faster on the open-road, or more successful on your rock-crawl. Why pay for an engine to produce energy, and pay-again for a transmission-cooler to throw away a slice of the engine's efforts?

Every gear-train loses you some energy. Every ratio-reduction/multiplication loses you energy. The fewer of these you have in your transmission the better!

I certainly agree with your opinions regards efficiency, and IMO they would be at their most valid if our main objective is to propel a vehicle along the road at minimal cost in energy and fuel usage. But if that was the main aim, then we wouldn't have a vehicle with an energy sapping transfercase, extra differential, propshafts, halfshafts cv joints,largish grippy tyres etc in the first instance. We would all be driving 2wd econo boxes.

For us well hard types Lol, who often push the envelope of our 4wd's cross country abilities, low axle ratios offer a significant advantage regards vehicle stability in extreme terrain, due to reduced propshaft induced 'torque roll' which happen to be my buzz words for this month.Lol. Less strain on the puny LandRover main gearboxes and propshafts is another advantage of low axle ratios.

So to retain our low axle ratios and yet still have a vehicle with an acceptable sealed road performance, a transmission with direct drive top gear won't cut the mustard, and that is where the overdrive/splitter trans comes in.

[Snagger]

How about high torque electric motors on each diff and a turbine powered generator? Independent drive on each wheel, so no transmission at all, miminal power loss and extreme torque at low speed with very high rpm available... Now that's the future!

[ejparrott]

Next years F1 is having a 165bhp electric motor avaliable on demand apparently, and an electric motor to drive the turbo so as to reduce turbo lag, so not such a bad idea!

[Nigelw]

Right been whirring this around in my pea sized brain and so far all I can find is planetary geared O/Ds available, so it seems the flaw we have found with them is that they cook the oil in the transfer box rapidly and then seek to self destruct once they have ruined the oil, now is there any other problem with them other than the cooking of the oil?

[Bowie69]

Just switch the whole lot to hydraulic drive, problem solved, no?

[bill van snorkle]

Right been whirring this around in my pea sized brain and so far all I can find is planetary geared O/Ds available, so it seems the flaw we have found with them is that they cook the oil in the transfer box rapidly and then seek to self destruct once they have ruined the oil, now is there any other problem with them other than the cooking of the oil?

Can't comment on electric drive, as electric and me just don't get on. Both it and hydraulic are getting a long way from the original subject, and IMO if either were viable for relatively compact road/offroad vehicles, would have been in mainstream production long before now.

Nigel,Fortunately for me, the GKN brand overdrives, just like the Fairey brand before them, do cook themselves in hot climates. Because of that, I have been able to collect their 'co axial' bits, the bits that don't cook to make up a few crawler boxes.

The GKN uses auto trans fluid for lubrication, so does not share the larger oil volume of the transfer case to attempt to keep the unit at a safe operating temperature.The GKN isn't strong enough to be used as a splitter in 1st or 2nd gears and has electro mechanical lockouts to prevent this.

The Rocky Mountain overdrive has larger planetaries and input shaft,and is strong enough to be used as a splitter. Also it shares its lubricant with the transfercase and circulates it via an Archimedes type screw that has been machined onto the output gear. For covering distance in very hot climates, I believe these could be made to live a long, healthy life by fitting an external pump and circulating the lubricant via an auto trans type cooler. A mate of mine who used his series 2 A for towing his horse box around, kept his Fairey OD alive for a long time by connecting an oil cooler and fuel injection pump from an old Triumph 2.5 PI saloon. Maybe there is a contemporary equivelant ?

[De Ranged]

I was going to say automatic trans's use planetary gear sets and all they do is use a rad cooler to keep oil cool, I have a nice short 2:1-1:1 planetary drive out of an auto I've been saving for either an over drive or under drive, being from an auto box its bigger (major dia about 200mm) since you guys are concerned about heat, bigger less stress, less heat add an aftermarket electric oil pump and a cooler core just working off the oil pan with a temp trigger and bath the lower gear in the sump for lube

set this up between gearbox and transfer why not do two one under and one over they are big enough and being planetary plenty strong enough to run as a spliter box the catch is its a big split lol but maybe there is an auto trans out there that has a friendly'er ratio

Forget hydraulics you can have power or flow not both well not to a level of a road going vehicle... mate who was a hose doc used to swear about the JCB wheel'd diggers because they would cook them selves when the operators tried drive between jobs and thats in NZ lol nothing like outback Aussy

Electric hmmm this has possibility's incredible torque to wait of power source just the issue of fuel..... but as bill said off the point of the thread

[Nigelw]

You see I was thinking along the lines of a separate cooling rad or tube for the O/D but I was struggling to find a pump that would cope with EP90 as the only current O/D on the market shares the same oil as the transfer box then that will have to do, now if that O/D were to be sealed away from the transfers EP90 and running a ATF then for me it could well be as simple as a pump being engineered off the back of the O/D to a reservoir very similar to what we have with power steering fluid reservoirs and a cooler tube in front of the rad same as an auto, then you have a volume of fluid and a heat ex-changer built in to the system, the pumping could be temp triggered by a thermostat with bypass valve or simply flow when ever the O/D is running.

I suppose the cooler subject is a wide open field as it could be a plate and fin arrangement with an electric fan to boost cooling when driving long gradients where it is not necessary to change down but also hard going on the O/D.

Bit of fodder to keep you going

[bill van snorkle]

As I mentioned earlier Nigel. my mate used a Triumph injection pump to circulate the EP90 between his 2A transfercase and OD. I don't know for certain, but I assume he only switched the pump on when things had warmed up, in which case EP 90 must have been thin enough for the pump to cope.

Remember, the triumph 2.5 PI hailed from the days of Lucas Electrics, so pumping hot EP90 mustn't have been too arduous.

[ejparrott]

I've been wondering for some time about fitting an oil cooler to the OD, not so much because of the climate in the UK, but because of the small oil volume, and the tendancy to self destruct. I recon'd the drain plug and modifiying the top plate for a return, thereby retaining the dipstick.

[Team Idris]

We provide cooling packs like that, sucking oil from the drain and returning via the filler. And they work because they are on a thermostat switch, as VG420 treacle gear oil doesn't go through a rad when cold

(Haven't anything in the automotive range though)

I'm surprised there isn't a transfer box lid with a load of big fins welded on?

But there are 12volt gear pumps out there.

[tacr2man]

They had problems with reduction planetry hubs on crop sprayers in Australia about 15 years ago, that was fixed by going to full synthetic . I cant remember the manufacturer.

Synthetic oil for use in transfer box and diffs , (I use Redline) is about as thin as engine oil but is rated as 75/140 . It was not about when I ran series /RRC with O/D' s but would have used it if it had been. So that would seem to solve the pumping problem , and probably improve the lubrication into the bargain . JMHO

[De Ranged]

I'm a cheap person. to me all I'd do is a cheap thermal switch with the sensor tapped into the transfer case sump a cheap low pressure low flow 12v diesel lift pump that turns on when the oil is warm enough and if you don't want it to wear it out an override switch so if your not using the OD and you don't need it don't use it

If the diesel pump can't handle it make up a little sludge pump and power it with a wipper motor because they are cheap to get lol

My answer.... with my PTO to oil it I'm going to run open bearings so the oil can pass, I'm clocking the case level, filling some of the open dead space (mainly because good oil is expensive and I don't mind playing in rivers) so the oil level comes up and fill it up so that the oil is through the bearings into the PTO

[bill van snorkle]

Good oil is expensive! And the problem with LandRovers is actually keeping that expensive oil in.

With the LT95, I have found it useful to drill/tap and double up on the quantity of bolts securing the lower circumference of the rear output housing to the main case. There doesn't seem to be enough bolts to cope with the endthrust generated at this area to prevent distortion of the joint flange when the unit is hot. On my series t/case I modified both front and rear oil seal retainers to accept twin seals, fitted back to back. One seal mainly keeps the oil in, the other keeps the water and crud out. I also fitted a grease nipple that feeds grease into the cavity between the seals to prevent the outer seal from running dry.

[elbekko]

Could you fit a heat exchanger with a water pump and small radiator somewhere? It would solve the problem of pumping oil around.

[landroversforever]

Good oil is expensive! And the problem with LandRovers is actually keeping that expensive oil in.

With the LT95, I have found it useful to drill/tap and double up on the quantity of bolts securing the lower circumference of the rear output housing to the main case. There doesn't seem to be enough bolts to cope with the endthrust generated at this area to prevent distortion of the joint flange when the unit is hot. On my series t/case I modified both front and rear oil seal retainers to accept twin seals, fitted back to back. One seal mainly keeps the oil in, the other keeps the water and crud out. I also fitted a grease nipple that feeds grease into the cavity between the seals to prevent the outer seal from running dry.

I like your idea of the double seals Bill!

[Snagger]

The Roverdrive, now known as the Roamerdrive because of LR's overzealous legal department, it pretty robust - a lot more so than the Fairey. The innards of the Series and Defender models are mostly the same, I believe, with just the front sections and torque couplings differing. Now, if Ray was to introduce an oil cooler port in the back of the main casing that would allow cooled oil to be pumped at a low rate directly into the rear bearing, which it the one furthest from the existing oil supply, then I think this would make the unit nearly indestructible. The port could be simply plugged for base models with an accessory cooler kit for users of heavy vehicles or in hot climates.

[ejparrott]

I'm surprised there isn't a transfer box lid with a load of big fins welded on?

There is, standard replacement for a series t'box, and a high capacity one for the LT230. Rocky Mountain I think.

[Nigelw]

Also available from Ashcrofts