Common 4x4 Transmission Problems & Symptoms

The Freelander range of cars suffer from a number of common transmission problems, and so it is always important to find the route cause of the problem first, before taking the plunge with repairs. Learn more about each issue, and how Bell Engineering can resolve it below.

Freelander 1 (1997  - 2006)

Symptoms that you may experience:

  • Clonking or grinding noise when adding or letting off power, especially noticeable in reverse

  • Car feels 'tight' or that the brakes are binding

  • Intermittently losing drive

  • Loud bang followed by grinding noise

Click to enlarge the transmission schematic

Freelander Intermediate Reduction Drives (IRD's) are a common failure on these 4x4's. If the vehicle is making a clonking or grinding noise when letting on and off the power or turning a corner, especially noticeable in reverse, or you are intermittently losing drive followed by a loud bang / grinding noise, then your IRD has failed or is failing. The root cause of this failure 9 times out of 10 is a faulty Viscous Coupling Unit (VCU), which should be changed at the same time as the IRD.

What is a Viscous Coupling Unit ?

A VCU is fitted inline with the prop shaft, connecting the front and rear axles, transmitting the drive to the rear wheel. It must also allow a certain amount of slip to allow the front and rear axles to rotate at different speeds, e.g. when cornering

What does an intermediate reduction drive (IRD) do ?

An IRD takes the drive from the gearbox, reduces the drive ratios then distributes the power to the front wheels and also the rear wheels via the propshaft

If your Freelander feels "tight" or it appears the brakes are binding, especially when reversing on full lock, this means your existing VCU is past its serviceable life and you should change it as soon as possible. A damaged VCU puts massive strain on the rest of your transmission line, causing the IRD unit, rear differential and gearbox to wear at a hugely accelerated rate, and will cause a very costly failure of all these parts. A VCU's serviceable life span is usually no more than 70k miles, but it can be a lot less (we have seen cars with failures at 30k miles), depending on how the car has been driven.

If a VCU has failed it is highly likely that it will have damaged the taper roller thrust bearing in the IRD unit. There will be no obvious sign or noise and IRD failure usually occurs when reversing the vehicle upon which the thrust bearing collapses and total failure occurs, normally breaking the teeth off the crown wheel and pinion which causes the banging and grinding noise.

Another cause of IRD failure is due to bad wear in the inner constant velocity joint on the offside drive shaft. This usually results in the outer taper roller bearing (next to the CV joint) collapsing and causing the top gear shaft to break teeth, which in turn usually cracks or smashes the IRD main casing and end casing with subsequent loss of all oil.

IRD and/or VCU failure is also caused by miss matched tyre sizes between the front and rear axles. The difference in tyre diameter, and thus the rolling radius of the wheel causes a constant difference in the rotational speed of the front and rear prop shafts, this difference has to be compensated for by the VCU slipping at a higher rate than which it was designed for. The extra rotations cause the VCU to heat up and become stiffer ,which is what they are designed to do off road if the wheels start to slip and this transfer drive to the the other wheels, but as this is happening while driving in a straight line on a road it has the same effect has an old stiff VCU and transfers extra load to the entire transmission line, eventually resulting in IRD failure. This constant heating also cooks the VCU so that it does not operate correctly, even when correct tyres are fitted. You can measure the diameter of the tyres, but this can be slightly misleading, especially on worn tyres as the tyre may not be evenly worn from the inside to outside edge, so the best way to check is to check the external temperature of the VCU after driving it for a few miles on a relatively straight road, it should be virtually cold. If its slightly warm or hotter then the wheels have a ratio problem. We have seen various examples of miss matched tyre sizes such as a garage fitting different size profile tyres to the front of the car compared to the rear, putting new tyres on one end of the car but leaving the old worn tyres on the other, significantly more tyre wear on one axle, low tyre pressures and cars that have done a lot of towing (rolling radius of tyre is less due to the weight of the trailer compressing the tyres). A difference of just 5mm in diameter dramatically increases the rotational differences between the front and rear axles, so it is imperative that the tyres are always matched. Always change all 4 tyres at the same time, rather than trying to save a few pounds by changing the fronts and getting a few thousand more out of the rears. The variations between makes of tyres with the same profile can be even more than this, so tyre makes should also be matched.

Freelander rear diff failures are not as common as IRD failures, but are still a weak point. Usually the root cause of this is a faulty viscous coupling unit (VCU), which should therefore be changed at the same time as the differential.

Dispelling Some Myths

There is nothing we havent seen or heard before, so we are happy to correct some myths you may have heard :

  • Myth 1 - It is a common fallacy that VCU's seize. In all our years of experience we have never come across a seized VCU. What actually happens is the silicon viscous fluid gets thicker and thicker with wear, and slowly causes the viscous coupling to become stiffer and stiffer to rotate. More and more strain is therefore put on the gear train and failure eventually occurs to the IRD and rear differential.

  • Myth 2 - It has been reported on some internet sites that it is possible to test the VCU by jacking up one back wheel of your Freelander without the handbrake applied, and that you should be able to turn the rear wheel - with the reasoning that if you cannot turn the wheel, your VCU has seized - this is a complete myth! You would hardly be able to do this by hand as you would need a 2 foot breaker bar and have to stand on it. The wheel will move very slowly, however this still does not indicate whether the VCU is any good or not, as all wheels will turn regardless of the condition of the VCU.

  • Myth 3 - Another common fallacy for testing VCU's is the 'Tipp-ex test' whereby you place a Tipp-ex mark on the shaft next to the front prop shaft, and one opposite on the viscous coupling, to observe if these marks have moved out of line after being driven round.

Freelander 2, Evoque & Discovery Sport

Symptoms that you may experience:

  • Drumming or humming sound coming from the rear

  • 'All terrain mode disabled' message

  • Juddering noise on full lock

  • Drumming or whirring noise from the front footwell

  • The car operates with front wheel drive only

​If there is a drumming or humming sound coming from the rear of your Freelander 2 or Evoque, the chances are the rear diff bearings are failing. This is very common on the 2007-2011 models and can occur even in very low mileage vehicles. According to Land Rover The damage is caused due to the way in which the Haldex coupling unit applies torque when moving away from standstill or during slow speed manoeuvring. We actually believe the main cause of the failure is that the size / load rating of the nose bearings on these units were too small when designed and manufactured by Land Rover. At Bell Engineering we have devised a method to modify the diff to allow us to fit a larger nose bearing that can withstand 25% greater loading, greatly improving the life of these diffs. These up-sized bearings are fitted to all our diffs from April 2015 onward. At present Bell Engineering are the only company offering the up-sized bearing.

What does a Haldex Coupling Unit do ?

A Haldex unit is fitted between the prop shaft and rear differential, connecting the front and rear axles, it transmits the drive to the rear wheel. It is an electronically controlled clutch with a predetermined and variable amount of slip to allow the front and rear axles to rotate at different speeds, e.g. when cornering.

What is a Haldex pump ?

The Haldex pump creates the hydraulic pressure required to activate the Haldex unit clutch

Freelanders from 2009 model onwards the Haldex unit was upgraded to the 4th generation, which if taken to a Land Rover dealer will accept updated software (early models have the 3rd generation fitted which cannot be re-flashed) which Land Rover state will also reduce the load on the pinion. All Evoques up to 2015 were fitted with the gen 4 haldex. Evoques post 2015 and Disovery Sports are fitted with generation 5 units, unless they have the upgraded Active Driveline option. The Generation 4 haldex units cannot be updated to to a 5th generation.  

An "All terrain mode disabled" message appearing on the dashboard signifies an issue with the Haldex unit. There are several reasons for this;-

  • The wiring loom between the Haldex unit and the car loom rubs between the rear sub-frame and the body, causing a short in wiring

  • The fuse to the Haldex unit - Fuse FB6 (or FB1/2 on later cars), in the rear fuse compartment has blown

  • The Haldex electric pump has failed

  • The Haldex pressure sensor has failed (3rd Gen Only)

  • The Haldex unit requires a full service

​If the car is suffering a juddering on full lock and there are no error messages displayed this is a sign that the Haldex unit is failing / failed internally, unfortunately the only solution is to change the complete unit for a reconditioned or new unit.

At Bell Engineering we consider the low cost servicing of the Haldex unit imperative to sustain the correct operation and future life of the component and recommend the Haldex unit has the fluid and filter change every 20k miles. Land Rover do not state the Haldex unit and fluid as a serviceable item, but other manufactures who use the same unit do.

A drumming or whirring noise from the front footwell area of the car, that can over time develop into a banging or graunching noise is a symptom of the front transfer box (otherwise known as power transfer unit, PTU, front diff or IRD) nose bearing failing. If treated quickly enough the unit can be fully reconditioned with new bearings and seals throughout. However if this is left unaddressed, this will fail catastrophically. The splines from the gearbox to this unit also wear, if the transfer box is failing it can also cause damage to this spline (see below).

What does a PTU do ?

A PTU is fitted on the output side of the gearbox to transmit the drive to the prop shaft, that drives the rear wheels

What does a rear differential do ?

A rear differential is fitted to the end of the prop shaft which then drives the rear wheels

What is a Prop Shaft ?

The prop shaft transmits the power from the front of the car to the rear differential

If the car is suffering from front wheel drive only, there are several possible reasons:-

  • The splines between the gearbox and front transfer box have stripped

  • The crown wheel and pinion have stripped inside the transfer box

  • The Haldex unit has failed or been disabled

  • The propshaft, diff or rear driveshafts have been removed

  • You have bought the 2wd version of the vehicle

If you are experiencing any of these faults, simply contact us for a friendly chat and confirmation of the repair needed, or go directly to browse our products in the store.