Member Since: 31 Dec 2005
Location: South West
Posts: 23368
The Locking Rear Diff thread (combined)
I'm getting confused about the pros & cons of the locking diff. In reality my off-roading is likely to consist of fields, rough farm tracks & maybe the odd green lane. Plus I'm likely to encounter snowy roads in Scotland.
I have read conflicting views about the locking diff. I believe the cost is £495 (inc.) but iirc cannot be retro fitted?
I'd appreciate the opinions of those who use their D3 as I'm intending to & if they think the diff. is a worthwhile option. Would it help or hinder re-sale, I say hinder as vehicles that have been regularly used off-road tend to put buyers off & the diff. might suggest this.
22nd Feb 2006 4:23 pm
grommet
Member Since: 15 Feb 2005
Location: Northern California
Posts: 331
I think a search would cover most discussions already... but, in general, you probably will not miss the locking rear differential. Terrain Response does a great job even without it. I've had both off-road in tough conditions. Only disadvantage to having it might be a tiny bit of extra weight and having one more thing to break. And the cost, of course.
22nd Feb 2006 4:39 pm
BN
Member Since: 18 Mar 2005
Location: Here
Posts: 6463
Re: Locking Rear Diff.?
LT wrote:
I'm getting confused about the pros & cons of the locking diff. In reality my off-roading is likely to consist of fields, rough farm tracks & maybe the odd green lane. Plus I'm likely to encounter snowy roads in Scotland.
I have read conflicting views about the locking diff. I believe the cost is £495 (inc.) but iirc cannot be retro fitted?
I'd appreciate the opinions of those who use their D3 as I'm intending to & if they think the diff. is a worthwhile option. Would it help or hinder re-sale, I say hinder as vehicles that have been regularly used off-road tend to put buyers off & the diff. might suggest this.
The D3 in standard form is more than capable of doing anything a Defender can. The locking rear differential is an automatic type that kicks in when it thinks necessary. But as grommet says, the TR is very good and to be quite straight about it, even with a locking rear diff you can become stuck on level and flat grass if it is wet. The trick is to disengage TC and plan where you are going in the first place.
Regarding resale I doubt if anyone would really know the diff has been fitted unless they ask for it specifically or are real enthusiasts such as on this site. In that case they would want the diff no doubt. Even then only if they get into some very difficult situation and the engaged icon lights up would they know it is fitted without looking underneath for the solenoid bump. Many people would not even see it. Hope that helps.
22nd Feb 2006 5:04 pm
Mike
Member Since: 22 Feb 2006
Location: Doncaster UK
Posts: 184
cheers for this
At the risk of sounding like a right numpty - can somebody please explain exactly what difference the rear diff lock makes - don't know what they do ya see
Mike
22nd Feb 2006 5:39 pm
LT
Member Since: 31 Dec 2005
Location: South West
Posts: 23368
Thanks, I'll probably give it a miss. Just got a little confused as recent posts have been suggesting it's a worthwhile option.
22nd Feb 2006 5:44 pm
SN
Member Since: 03 Jan 2006
Location: Romiley
Posts: 13710
Mike wrote:
cheers for this
At the risk of sounding like a right numpty - can somebody please explain exactly what difference the rear diff lock makes - don't know what they do ya see
Mike
Thanks for asking thisSteve N | 21MY Defender | 08MY Discovery 3 (history) | 06MY Discovery 3 (ancient history)
22nd Feb 2006 5:47 pm
Gareth Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26701
Here goes.
When you go around a corner, your outside wheel has further to travel than the inside, this means the diff has to allow one wheel to travel faster than than the other. This is fine for normal driving.
If you get stuck in the mud, or lift a wheel off the ground when rock crawling, the power will take the path of least resistance and spin the wheel with least grip. The DSC/TC system will put the brake on the spinning wheel, and the power will transfer to the (hopefully) wheel with grip, thus allowing further progress.
If you have the locking diff, it will sense this and prevent the wheel spin. The benefit is that there will be less strain on drive shaft components, less strain on the diff itself (its locked up), and probably most importantly, you will have a locked diff from the moment power is applied. TC/DSC needs acceleration of the spinning wheel to kick in. If you have no locking rear diff, you will have to give the car a fair bit of power to get the TC to work. This is not ideal when you are rock crawling for example.
I hope that expalins it, the Land Rover Experience course does do a thouroughly good job of demonstrating the theory - I recommend you go on one.
22nd Feb 2006 5:54 pm
Pelyma
Member Since: 06 Jan 2005
Location: Patching, Sussex
Posts: 15496
I use my D3 off road for shooting mainly and a little bit of greenlaning so probably similar use to what you've mentioned. I thus far have not missed it, but when I buy a new one if funds allow I probably would spec one if funds allow. But the car is capable beyond most peoples dreams as it comes out of the factory on standard tyres once you've learnt to drive it as it is very different to driving other LR products off road.
Not sure what BN meant by switching off TC possibly TR was what was meant, but there are so many acronyms with this car!DS3 TDV6 HSE - Silver with Alpaca (old one) Gone
DS3 TDV6 HSE- Silver with Alpaca (new one) Gone
D4 HSE Lux - Montalcino Red Gone
Porsche Cayenne V8 Diesel S
22nd Feb 2006 6:05 pm
LT
Member Since: 31 Dec 2005
Location: South West
Posts: 23368
Thanks Pelyma, I'm sure I'll be O.K on standard tyres & diffs. & a set of chains for the snow.
I think BN means switch off the stability control is that DSC on L/R products. The only one of my current cars that have this is a Saab, who call it ESP.
22nd Feb 2006 6:13 pm
BN
Member Since: 18 Mar 2005
Location: Here
Posts: 6463
Yes, TC is known as ESP, DSC and many other initials. The switch is on the dash, just cancel it when the going gets rough and the yellow warning comes up on the dash. Difflocks are fine, but can also be a problem. The main problem is that they force the car generally in one direction and that is a straight line. So if a turn is required to get out of difficulty a difflock can actually cause more problems sometimes. That is why switchable lockers are preferred.
22nd Feb 2006 6:47 pm
simon
Member Since: 11 Jan 2005
Location: Shropshire
Posts: 18296
Its the DSC button - Dynamic Stability Control
TC - Traction Control - is on all the time and varies in sensitivity depending which Terrain Response setting you have selected. This is not DSC.
DSC will detect a slide and cut power to the engine and start using the brakes on individual wheels... not what you need when you are looking to maintain momentum say at the top of a steep slippery climb.
It is however VERY useful when driving in slippery conditions as it will do its best to stop you falling off the road when cornering.
Disable only when you need to maintain momentum or need to power out of some situation where the D3 may slide. Sometimes safety nets get in the way. Most of the time they are damn useful.
-s
22nd Feb 2006 7:20 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
The 'official' description
"The electronic rear differential has the same functionality as the open rear differential but incorporates a locking feature.
An electronically controlled multi-plate clutch provides a rear differential lock and torque biasing function to give improved traction performance and vehicle dynamic stability.
A strategy, to electronically control the rear differential multi-plate clutch assembly, has been developed to provide:
�� a pre-loading function, increasing locking torque with increased driving torque
��a slip controller to increase locking torque under off-road conditions and decrease locking torque for optimum comfort, e.g. parking.
The unit receives a torque input from the transfer box output shaft, which is passed through the unit to two outputs for the rear drive halfshafts.
The unit detects wheel slip via various vehicle system inputs to the electronic rear differential control module and locks the differential accordingly.
The electronic rear differential locking and biasing feature is actuated via a DC motor, which is controlled by the electronic rear differential control module, via a Pulse Width Modulation (PWM) signal.
The multi-plate clutch assembly for both centre (transfer box) and electronic rear differentials act in a similar way. The aim of the multi-plate clutch assembly is to prevent excessive differential slip and therefore maximise the traction performance of the vehicle. This is fundamentally different from the 'braked' traction control, 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 Anti-lock Braking System (ABS). The transfer box control module monitors the driver's demands through primary vehicle controls and automatically sets the slip torque at the rear differential via the electronic rear differential control module. The system is completely automatic and does not require any special driver input.
The multi-plate clutch assembly actively controls the torque flow through the rear differential and optimises the torque distribution in the driveline. The clutch assembly biases the torque from the differential to the wheels with the higher grip and prevents the wheels with the lower grip from spinning.
By turning the input actuator disc, via the motor shaft, the output actuator is rotated. This movement acts on 5 balls in a ramp mechanism between the input and output actuators and gives a defined axial movement. The movement forces the pressure disc to induce friction between the sun gear and differential case via the clutch plates supported by the sun gear and the plates supported by the clutch basket on the differential case. This frictional force inhibits the differential rotation; the differential case and left hand differential side gear are locked together."
Pay attention - questions later
22nd Feb 2006 7:34 pm
DG Site Moderator
Member Since: 12 Dec 2005
Location: The Gaff
Posts: 50934
zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz...............oh sorry TFC did you say something? 21 year LR veteran > D2 GS 2003 > D3 S 2006 > D3 HSE 2009 > D4 HSE 2013 > D4 HSE 2015 > D5 HSE 2018 > DS HSE R-Dynamic P300e 2021
22nd Feb 2006 7:59 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
well sombody asked
22nd Feb 2006 8:07 pm
chesters
Member Since: 03 Oct 2005
Location: The Toon
Posts: 698
Rear Locking Diff
I have been under my Disco and have taken a photo of a unit bolted to the top of the diff. I hope this is my Active Diff that cost me £495. Arctic Frost Discovery 3 TDV6 SE, Active Rear Diff, Adaptive Head Lights, Tow Pack, Ebony Leather, Roof Rails, Mantec Guard. Tasmod Stainless Sill plates. Grabber AT's. Home made mud flaps. Side Steps back on until the next time.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
| 08MY Discovery 3 (history) 
well sombody asked 
