Free TD4 auto - no rear wheel drive

I have new findings. It is really strange. I was at the track again and if I push throttle pedal lets say 25% down the front wheels spins in a muddy hill and rear nothing. But if I push it over 50% down then rear wheels starts to spin as well. Also we discovered that from my 3rd atempt to go uphill reaction of rear wheels was almost constatnt and I finaly felt rear wheel grabbing. No noises or bangs from anywhere. I inspect VCU and everything is nice and sturdy but It looks like my IRD and rear diff bleads from places where propshaft is connected. Is this normal or should them be nice and dry?

You have some oil leaks or someone has done some work on your Freelander and left oil stains.

When BOTH front wheels spin, both front and rear prop shaft's should turn at the same speed.

Working Freelander below. You don't need to rev it hard to get the vcu working:


Video: click for video

Your vcu is working like this one below where you have to rev it hard to get 4x4. Ignore the rear working before the front wheels - the bodywork is the wrong way round.

The rear diff is a reconditioned unit. So the leaking is likely down to bad seal fitted or a damaged pinion shaft.

Hippo said:

You have some oil leaks or someone has done some work on your Freelander and left oil stains.

When BOTH front wheels spin, both front and rear prop shaft's should turn at the same speed.

Working Freelander below. You don't need to rev it hard to get the vcu working:


Video: click for video

Your vcu is working like this one below where you have to rev it hard to get 4x4. Ignore the rear working before the front wheels - the bodywork is the wrong way round.

Click to expand...

Yep it definitely act like vw transporter in the video. Looks like vcu needs some ,,acumulation of energy” to transfer momentum to the rear.

PetrVIVIVI said:

Looks like vcu needs some ,,acumulation of energy” to transfer momentum to the rear

Click to expand...

Sounds like there's not enough fluid in it to me.
You can't go wrong with a quality reconditioned unit from Bell Engineering in the UK. They ship worldwide too.

On the plus side, it should be nearly impossible to blow your transmission - maybe a previous owner wanted it like that.

GrumpyGel said:

On the plus side, it should be nearly impossible to blow your transmission - maybe a previous owner wanted it like that.

Click to expand...

If this setup will not harm anything I can live with some delay to rear wheels.

PetrVIVIVI said:

If this setup will not harm anything I can live with some delay to rear wheels.

Click to expand...

If you are going to be using it regularly where you will lose traction, I don't think its a good idea. With a working VCU it kicks in immediately therefore the rears kick in as soon as traction is lost at the front and you still have momentum - so you are far less likely to get stuck. The slipping in the VCU will also cause a lot of friction and heat - much much more than it is designed for, so I could see it destroying itself.

It will also lessen ability/safety in icy conditions although the torque transmitted by the viscous fluid may still help when its not hilly.

If you are 99% tarmac driving though, I can see the appeal.

So front left sensor has been replaced and also my left break has been repaired. TC kicks in more often now. Please look at video below. It is clear demonstration of 4x4 behavior.

PetrVIVIVI said:

So front left sensor has been replaced and also my left break has been repaired. TC kicks in more often now. Please look at video below. It is clear demonstration of 4x4 behavior.

Click to expand...

if one rear wheel can spin the other will stop still, same as front,t/c is supposed to counter that by applying the brakes to spinning wheels

Your primary reason there for having very little traction looks to be your tyres.

At the start of the climb out of the stream the left rear was not turning - but we cant see if the right rear was. As JM says, torque will only go to the wheel with least restistance/traction - TC is supposed to balance it out, but I'm pretty sure the ABS pump will have a much reduced effectiveness on the drum braked rears.

To prove the VCU is not passing enough torque, you'd need to see both rears on the video and see them both not turning.

GrumpyGel said:

Your primary reason there for having very little traction looks to be your tyres.

At the start of the climb out of the stream the left rear was not turning - but we cant see if the right rear was. As JM says, torque will only go to the wheel with least restistance/traction - TC is supposed to balance it out, but I'm pretty sure the ABS pump will have a much reduced effectiveness on the drum braked rears.

To prove the VCU is not passing enough torque, you'd need to see both rears on the video and see them both not turning.

Click to expand...

exactly

Looking on the laptop in fullscreen @48 secs if you look closely there is evidence that the right rear is spinning via the disturbance of the plants around the rear RHS, before the LHS rear starts to turn slowly.

If you want to play in slimy mud, then you need tyres that are up to the job. The rear wheels show evidence of the TC working. However TC won't overcome the laws of physics.

If yer giving it too much power and the wheels are spinning then traction control will give up.

If yer need to spin the front wheels for the length of time in the OP's video above then there's a risk of shredding the tyres on hard items like stone and rock in the mud. Something to be careful of.

If yer oft road then I agree power will escape out of the rear diff to the path of least resistance = spinning wheel. But if yer give it a lot of power this will change to it powering both wheels. Strange i know but try it and yer'll see.

Hippo said:

If yer giving it too much power and the wheels are spinning then traction control will give up.

Click to expand...

I seem to remember from Rave that the only reason TC (or HDC) will 'fade out' is due to (calculated) overheating - ie it will only activate for a specified period of time before it calcs that its generated to much heat in the brakes so will disable the systems.

I haven't checked in Rave, but I suspect that TC may only operate if only 1 of the fronts has lost traction, ie if both fronts are spinning, then TC will not be activated even on the rear axle. If only 1 front is spinning then TC will be applied to it and possibly 1 spinning rear wheel. This would tie in with what @PetrVIVIVI is experiencing as I imagine both fronts are spinning like crazy and maybe one of them is occasionally seeing some grip and the TC will make a pulse at that point.

The TC fitted to the Freelander can't actually stop the spinning wheel from turning. If it could, the power would go to the wheel on the other side of the diff. Instead the TC grabs at the brake on the spinning wheels. This sends power in a series of pulses to the other wheel. However the pulses are so short, that a proportion of the power will be absorbed by slop in the gears and bushes. TC works best when the vehicle is carrying some momentum and not so effective when stuck halfway up a slimy bank.