Freelander 1 Possible to do away with the VCU?

So far I've not come across someone whose done it or why you necessarily can't. And I don't mean to have only two wheel drive - I'm thinking full time drive from four wheels.

I understand how the VCU works (enabling drive to the rear etc) but is it possible to simply do away with it and run a custom prop shaft directly to the rear diff for full time 4x4 like so many other traditional setups?

Because the IRD changes the gear ratio so the rear prop is driven slower than the drive to the front wheels

PepeTheMule said:

So far I've not come across someone whose done it or why you necessarily can't. And I don't mean to have only two wheel drive - I'm thinking full time drive from four wheels.

I understand how the VCU works (enabling drive to the rear etc) but is it possible to simply do away with it and run a custom prop shaft directly to the rear diff for full time 4x4 like so many other traditional setups?

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No - when going round a corner the front and rear axles have to move at different speeds, as they sweep out different arcs. If they were solidly connected, the difference would have to be taken up by twist in the drivetrain (wind-up), or by the tyres scrubbing on the road. Either way - not good.

EDIT: Just thought - when a VCU gets old, it stiffens, giving the effect you are after. Look up any of the million threads on here describing what happened to their FL when driven like this - ruined tyres, blown rear diff/IRD.

On the road, the VCU/IRD setup allows most drive to the front wheels. If slippage occurs, power is routed to the rear wheels, so the combination acts something like an automatic locking centre diff, even a central limited slip 'diff'.

Wouldnt fancy that insurance claim when you go off the road.

Would also get hellish transmission wind up till something broke.

It would be like driving a disco or fender around with the centre diff locked always.something breaks.

So the IRD doesn't contain a diff of sorts.

I'm guessing the solution would be a lockable centre diff in place of the VCU then?

PepeTheMule said:

So the IRD doesn't contain a diff of sorts.

I'm guessing the solution would be a lockable centre diff in place of the VCU then?

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The IRD does contain a diff for the front wheels.

You could put in a lockable centre diff like a disco/defender, as long as it's only locked on slippery surfaces. Your FL would then drive on-road like a 2WD one. Slightly different handling, and a tendency to wheelspin a little at wet junctions, otherwise fine.

On the other hand, for the money and time you'd have to spend fitting it, you could just buy a recon VCU which, as I say, is a auto-locking coupling that does the job nicely.

PepeTheMule said:

So the IRD doesn't contain a diff of sorts.

I'm guessing the solution would be a lockable centre diff in place of the VCU then?

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The VCU is effectively a limited slip diff, the more slip ie when the front wheels spin (so the drive to the VCU is faster than the drive out to the rear wheels) the more it locks up.

The reason the VCU is there is because drive is biased to the front. In a straight line the rear half of the prop is being driven by the wheels and rotating slightly faster than the front half being driven by the IRD.

Its a strange system but works if looked after as it was intended....to give effective 4wd to a vehicle that feels like a front wheel drive. I'm not at all sure what answer youre looking for?

If you want better off-road performance, my humble suggestions, as a day-job off-roader, are:

Rather than farting around with what LR engineers have spent a lot of effort designing:
1. Mud tyres.
2. Lift it for better ground clearance.
3. Possibly choose an auto box - lack of low range is a problem in manuals.

I agree, Freelanders do well off road, the big limiting factors are ground clearance and lack of low box

You might be able to rig up something to engage/disengage the rear axle - which would give you switchable 2wd/4wd as with Jap trucks such as Hilux & Suziki - but that's a big backward step.

Anything is possible given enough knowledge, time and money - but basically you re not going to be able to replace the IRD/VCU setup with another form of permanent 4wd/awd. OK a DLander conversion is possible - but then its not a Freelander any more.

I have taller offroad tyres & slightly better ground clearance already - a 40mm+ lift is next & a custom exhaust. I understand that my freeby is good offroad - Ive done quite a bit both here in Spain/Portugal offroad - and think it's great. I also enjoy modifying cars and don't see why another solution can't be explored to replace the potentially troublesome VCU system, especially for those of us that think the Freelander is a great, yet limited, off-roader and a good everyday car. A friend got stranded a long way from home due to a seized VCU and with the road trips I do every summer (4000+ miles) I'm now a little circumspect (I travel with tools to ditch the props if need be). Being able to engage a full time 4x4 high mode offroad on my Freelander would be confidence inspiring & safer. I've been on a few trails where I've not been convinced the rear wheels are being driven as I'm relying on the fronts to loose traction before the rears come alive.

That's what I'm thinking about and perhaps collectively we could find a solution to make the Freelander even better than it currently is offroad.

The way I see it you're looking at this the wrong way round.

The VCU is testable for signs of stiffening up so there's no reason why you should be stranded but if you had a locking central diff you'd be stuffed in short order if it became jammed (fairly regular occurance) or forgot to disengage.

With different drive ratios front and rear the results would be gearbox mashing.

Of course it's possible but if off road ability is the aim a locking rear diff might make more sense.

Carrying a tool kit on a 4000-mile road trip is a good idea in any car, even with no VCU to worry about. Good on you. As long as you keep your tyres wearing evenly and topped up with pressure you shouldn't have much to be concerned about.

If you could devise an air or solenoid-locking central coupling, this would serve your needs. Therefore, to answer your original question - yes, it's theoretically possible, but no - I don't think anyone has done it before.

Blue beasty is right - a locking rear diff would help a lot (on my Defender too). Even if you were to have a locked central coupling, you would still be left with two-wheel-drive-on-one-side when things got really muddy. This is the result of sending permanent drive to two open diffs.

How about a winch (which I think HAS been done), waffle boards, pioneer spade and a ground anchor?

Don't forget - you already have traction control!

A final thought - as a farmer said to me when I proudly showed him my first Land Rover, a 91 200 tdi Defender - 'Yeah, them 4be4s just let you get stuck in worse places'. He drove a battered 2wd Peugeot 406 in places you wouldn't believe. Him again - 'MOMENTUM, boy - get'n going and thrash th'baastard till e's through'.

guineafowl21 said:

Carrying a tool kit on a 4000-mile road trip is a good idea in any car, even with no VCU to worry about. Good on you. As long as you keep your tyres wearing evenly and topped up with pressure you shouldn't have much to be concerned about.
...
A final thought - as a farmer said to me when I proudly showed him my first Land Rover, a 91 200 tdi Defender - 'Yeah, them 4be4s just let you get stuck in worse places'. He drove a battered 2wd Peugeot 406 in places you wouldn't believe. Him again - 'MOMENTUM, boy - get'n going and thrash th'baastard till e's through'.

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That's the key mate. The best upgrade you can get for any vehicle is driver skill.
Limited slip diff is a good thing, I'd skip over this one and go for ground clearance. Maybe keep a spare VCU.

Well, I guess its time for Landyzones monthly "I want to build a replacement for the VCU" thread.

The short answer - No. Forget it. You are wasting your time and money.

Longer answer - yes, you could. Literally anything is possible if you throw enough cash at it, but you are failing to grasp the concept of full time four wheel drive, and ****ing about removing a VCU will make the car significantly worse.

A solid prop links front and rear axles permanantly. Firstly , freelander front and rear axles have different gear ratios, so straight off, its a fail....your wheels will be trying to turn at different speeds..... At best you will get unpleasant, even dangerous handling, more likely a dead IRD. You could change the rear diff ratio to match the front, which will involve a custom crown wheel and pinion, which would probably cost several thousand pounds. But even if you did that, you still have no variation between axles when cornering. Drive a Jap 4x4 in 4hi on the road and see what happens....its struggles to move, the wheels skip and jump and eventually it will break a driveshaft. The front and rear MUST be able to turn at different speeds to allow cornering and uneven surfaces, this is why jap trucks should only be driven in 4wd on slippery surfaces where a wheel can slip, preventing the above problems.

So what else? fit a centre lockable diff....great. Good luck with that. You worry about reliability of a VCU, but will some cobbled-together home made centre diff be better? I doubt it.
But even if you could build one, what is the point? you have to stop to lock the diff ....as mentioned above, momentum is often key in difficult terrain. having to stop and faff with a lever is stupid and potentially dangerous....snowy conditions, the road is clear and your diff is open, but the road starts getting covered, looks like it might be icy ahead....are you going to stop in the middle of the road, creating a hazard to others while you lock up your diff?

You could make it like a jap truck with a solid prop and a dog box to disengage drive to the rear.... except thats rubbish too for exactly the same reasons as above, namely having to stop and engage it when moving from solid to soft terrain.


Or you could have some kind of coupling between front and rear that allows a certain amount of slip as needed on road and automatically, progressively locks up on the move with no user input as the conditions demand....the above snowy road..... having to pull over on a narrow road for an oncoming truck and putting two wheels on the verge....a muddy bit at the exit of the field where the car boot sale is being held....its always there, reacting instantly.....It should be a compact unit, possibly full of plates and a silicone based flui.......oh, wait a minute, thats exactly what a flucking VCU is!

In short - leave it the hell alone.


And there is no point in a locking rear diff - traction control does that for you, applying the brakes to the wheel with least grip.

Agreed - its only those without the knowledge of why the Freelander's transmission can be fragile - that are likely to suffer transmission problems.

People on here - who know how to test/keep an eye on their VCU and know the importance of matching tyres - are very unlikely to suffer such problems.

You mention "not been convinced the rear wheels are being driven as I'm relying on the fronts to loose traction before the rears come alive" - that simply does not happen. Although the common description of Freelander is that its FWD and the VCU kicks the rear axle in once the fronts lose traction/spin - in reality there is always an amount of drive to the rear (try turning the 2 ends of a VCU by hand) plus the fronts only have to be turning quicker than the rears for about 1/4 or even 1/8 of a wheel revolution before the VCU is 'locked' - it would happen before you even know the fronts are having trouble - in the same way ABS or TC cuts in before you know its needed.

"Being able to engage a full time 4x4 high mode offroad" might give you confidence to take your Freelander offroad - but it would be false hope. Just because you are off road, does not mean you can "lock your diffs". Many surfaces off road still provide lots of traction and if diffs are locked, will destroy the transmission. You therefore can only engage it where the surface needs it. In a Pay and Play type site - you know to lock the diffs on the "obstacles" - you know where they are and its simple. Your off road though sounds similar to mine - ie there is no tarmac where you want to go! In these instances surfaces change frequently and maybe you can't see it until you're nearly on it - the IRD/VCU setup is super for this.

I do find it barmy that LR did not provide D2 with a lockable center diff - they rely on TC. In my experience with D1 I had to have the center diff locked basically all the time when on soft sand (ie the beach above high tide). In this scenrio the TC would soon overheat and render itself useless until cooled. Having said that, it is very unlikely that you'll get yourself into a prolonged time on axle twisters - so to rely on TC (as in Freelander) for 'locking the front & rear diffs' - I recon is fine.

I agree with both Dave and Grumpy.

Only one thing - Dave - TC is a good system, but I would say that a locking rear diff might just have the edge. Positively driving both rear wheels is surely better than braking one wheel to transfer torque to the other - theoretically at least. In the latter case, you are sapping some of the power to encourage traction.

In the real world, though, a good TC system is monitoring all the wheels and making sure they're all pulling their weight. This is the closest you'll probably get to real 4x4, as even the venerable Defender has open axle diffs as standard.

Yeah.....no....maybe......dunno, really. Depends.

My old Frontera had a LSD in the rear axle and while it was exceptionally capable off road, on tight turns or when parking it would lock up and was a pain in the chuff. Worst case was trying to reverse a heavy trailer round a corner, fighting against the trailers auto reverse brakes, pushing the load and then the diff binding up made life needlessly harder.

I have never had much luck with a switcheable locking rear diff, but my ony experience of one was a works vehicle L200 and it never worked properly.

If you want true four wheel drive you will need to buy an older G-wagen or a Russian Kamaz or something like that, you can lock up front, centre and rear diffs with levers in the cabin and it will go pretty much anywhere.

Yeah, diff locks are very useful. I have a 20 year-old Suzuki Quadrunner 250 that has low and super low range, and front diff lock. It has NEVER been stuck, even when carrying improbable loads of timber out of a badly rutted peat bog. All four wheels spin, and you just steer back and forth and it'll pull you out of anywhere. Great little thing.

"My old Frontera had a LSD in the rear axle and while it was exceptionally capable off road, on tight turns or when parking it would lock up and was a pain in the chuff."

Mine too ... out of an LWB on an SWB. Awesome often overlooked cheapo offroader surprised a number of folk with where i put it AND got it out of on its own.....

only issue i had with mine was its tendancy to not like accelerating out of junctions - there where wheels we often just **** you and throw the car sideways......great fun !