what is the difference of a ACT LCKG DIFF W/TVBB ? ON 2015 DYNAMIC SPORT ? than a normal l494 diff

What is its special feature ?

Does it have a special oil rather than 75-90?

just looked at the original build spec and it has it just curious

anyone know?

The standard rear diff is an open diff, the clever one is a locking diff that also uses Torque Vectoring By Braking (TVBB). The diff can be locked for maximum traction (like the centre diff does) and also works in combination with the brakes to help on road nimbleness - by braking the inside wheel, more torque can be moved to the outer wheel which usually has more grip. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

many thanks

good option to have

The active diff with TVBB is what makes the Dynamic model, well, dynamic. The non-Dynamic HSE doesn't have it (or low range) although it can all be added to the SDV6 HSE for the princely sum of £3750. The 2.0 HSE can't have it added. The 2.0 PHEV has it all in all versions, rather confusingly. The 3.0 petrol HST doesn't get TVBB or the active rear diff but does get low range and the Terrain Response 2.

Wow, Land Rover's model line up is really weirdly specified. Most odd. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

from the workshop manual:

Quote:

Electric Differential

The electric differential has the same functionality as the open differential, but it also incorporates a locking and torque
biasing function to give improved traction performance and vehicle dynamic stability. Operation of the electric differential is
controlled by the RDCM (Rear Differential Control Module).

The basic construction of the electric differential is similar to the open differential. However, the electric differential also has
the following:
Two additional planet gears in the differential carrier, to cater for the higher torque through the differential during
locking events.
A multi-plate clutch and actuator assembly installed on the left-hand sun gear.
A motor and reduction gearbox, attached to the cover.
An oil temperature sensor installed in the cover.

The RDCM operates the motor of the electric differential under the control of the (ISCM) Integrated Suspension Control
Module.

The multi-plate clutch is contained in a clutch basket attached to the differential carrier with the crown wheel securing
bolts. Alternate plates of the clutch pack are keyed to the clutch basket and the left-hand sun gear. A pressure disc is
installed on the outer end of the clutch pack and keyed to the clutch basket. A thrust race on the end of the clutch basket
incorporates lugs which extend through the clutch basket onto the pressure disc.

The actuator assembly is mounted on bearings on the outboard end of the clutch basket, against the thrust race. The
actuator assembly consists of input and output actuators separated by five ball bearings. A locking pin in the cover engages
with a slot in the output actuator to prevent it turning, but allow it to move axially. The input actuator engages with the
reduction gearbox and is free to rotate relative to the cover. Ball bearings locate in curved grooves in the mating faces of
the input and output actuators. The bottom surface of each groove incorporates a ramp. Rotation of the input actuator
forces the ball bearings up the ramps in the grooves and induces an axial movement in the output actuator. The thrust race
and pressure disc transfer the axial movement from the output actuator to the clutch pack.

The motor is a 12 V DC motor that adjusts the frictional loading of the multi-plate clutch, via the reduction gearbox and the
actuator assembly, under the control of the RDCM. Adjusting the frictional loading of the multi-plate clutch adjusts the
locking torque between the crown wheel drive gear and the sun wheel.

Four bolts attach the motor to the reduction gearbox, which is located in position on the cover with two dowels, and
secured with four bolts. An O-ring seals the joint between the motor and the reduction gearbox.

The motor is driven by a 12 V DC feed direct from the RDCM. The motor also incorporates the following connections with
the RDCM:
A motor temperature sensor, to prevent excessive use from damaging the motor.
Two Hall effect motor position sensors, to enable closed loop control of the motor.

The temperature sensor provides a differential oil temperature signal to the RDCM, to prevent excessive use from damaging
the multi-plate clutch.


OPERATION

The multi-plate clutch prevents excessive differential slip and therefore maximizes the traction performance of the vehicle. This is fundamentally different from 'braked' traction control systems, which can only counteract differential slip when it
occurs.

A certain amount of differential slip is required to allow the vehicle to turn corners and to remain stable under control of
the ABS. The system is completely automatic and does not require any special driver input.

The multi-plate clutch actively controls the torque flow through the differential and optimizes the torque distribution in the
driveline. The clutch biases the torque from the differential to the wheel with the higher grip and prevents the wheel with
the lower grip from spinning.

 --
2010 Defender Puma 90 + BAS remap + Alive IC + Slickshift + Ashcroft ATB rear
2015 Range Rover Sport Supercharged V8 HSE Dynamic



Defender Puma Workshop Manual: https://bit.ly/2zZ1en9
Discovery 4 Workshop Manual: https://bit.ly/2zXrtKO
Range Rover/Sport L320/L322/L494 Workshop Manual: https://bit.ly/2zc58JQ

It is also hugely effective and even on road it is interesting to see both of the diffs opening and closing even in quite benign weather conditions.
Do look out for oil leaks on the rear diff though, there seems to have been a batch of cars that is prone to an oil leak and out if warranty dealers want in excess of £5000 to fix it. My local indie charges £600 including 2 hours labour to replace a complete diff. 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
2018 Melting Silver Mini Countryman PHEV - soon to be replaced
2015MY Corris Grey SDv6 HSE Dynamic, the best car I have ever owned, totally reliable only a cou0le of rattles in 3 years, now no longer in my care
Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW

I removed the fill plug today as I thought it had no oil . due to a whine I believed to be the diff
And oil came out . No sign of leaks before

So on ramp. - I removed plug drained and refilled until usual it came out of fill level plug

The oil was a dark Amber ish colour surprised the magnet on the drain plug only had few tiny bits of metal

So now all refilled whine still there. It has always recently been slight but if you know your car you here it

Stumped now is the diff gone or is it coming somewhere else rear wheel bearing ??

Any ideas where to start next

Or let dealer find it ???

Hi All

Does anyone on here have a list or know each location on the rear of 2015 sport

Where a bearing or bearings to look at to try and single down this whine

Be much appreciated

Then I can start process of elimination

Because bearing noises can be so easily transmitted through the casings they sit in, I doubt you would be able to ID a particular bearing within the diff. MY2016 HSE D SDV6 - gone due to fuel dilution problems.

By the age of 50 you have the face you deserve - George Orwell.

Hi will
I have ruled diff as probable but was really trying to find other items I've wheel bearing ,prop input or other bearings in that rear section

So I can look into those bits so in other words any other bearing instead of diff

I have a 2015 3.0 diesel autobiografy with 40000 miles. When i drive very slowy up a steep hill. The car sounds strange, like abs is kicking in or one of the tires is slipping/rubbing. Has this something to do with the electric differential? Or is it the traction control? On flat roads the car runs fine. Is this normal?

I don't know of that sound could be

So haven't been on here for bit this is latest

I took car to LR dealer and asked for a tech 4 to come on a test drive to listen to the whine I have

He said probably the diff gone but needs to be run up on ramp and then listened to to confirm but said most probably.

So he looked under car and was suprised no leak from diff I asked how can a 3 yr +9month old car with under 35.000 on clock with every service interval carried out @LR have a diff go ...? He couldn't awnser

So it's booked in to go in for diagnosis

Does anyone think it would be covered by Landrover or even a goodwill contribution ? As this is a non maintance integral part of the car so legally is it mechanical failure from manufacture ???

Be good to get some constructive thoughts on tackling this

Anyone ???

Seems everyone gone quiet on here

Just received car back today new differential fitted free of charge