Disco Dilemma

Submitted: Monday, Feb 23, 2004 at 23:01
ThreadID: 10741 Views:1956 Replies:7 FollowUps:8
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A word of caution to Disco owners of vehicles circa 2000 - 2002. Those without the facility to lock the centre diff.

Just returned from a weekend driver training event. As an aside it was excellent, well run by accredited trainers and afforded a wealth of tips and know-how on most facets of off road driving. I have been driving an assortment of the mongrels for more years than I care to remember, but am the first to admit I came away knowing more than when I went, however I digress ....

During key start recovery techniques, a Disco went into what can only be described as a totally out of control backwards descent with the brakes fully locked on, with absolutely NO pedal application by the driver. bleep s were almost trumps when it can within an ace of rolling over.

The cause remains, at this stage unknown, however there is a strong suspicion the traction control/hill descent/ABS braking mechanism went beserk by incorrectly interpreting the wheel slip in reverse, possibly due to the lack of a centre diff lock which in turn allowed the rear axle wheels to rotate at a different speed to those on the front axle.

To cut the story short, the net result may well have been very different, especially in different circumstances .... at best a very bent vehicle, at worst very bent bods.

Interestingly no other vehicles, out of the assortment suffered anywhere near the same fate, including the Fender with a centre lock. Perhaps more interesting is my understanding that LR has reintroduced the centre diff lock on the more recent models.

As I said above ... a word of caution

CheersFidei defensor

Rosco
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Reply By: Willem - Tuesday, Feb 24, 2004 at 08:29

Tuesday, Feb 24, 2004 at 08:29
Bloody technology!!!!!Next you will need a special licence to drive Disco's...hhahahaha

Glad to see you have gone and gathered some knowledge on how to drive a 4by. They should make it compulsory for all Landrover owners!!! LHAMOJAWFARFR(Laughing at my own joke and waiting for a response from Rosco)

Cheers,
Willem
Little Dip Cons Park S.A.
AnswerID: 47826

Follow Up By: Rosco - Bris. - Tuesday, Feb 24, 2004 at 09:29

Tuesday, Feb 24, 2004 at 09:29
That's just it me ol' mate.

It is compulsory for the very reason they appreciate the fact they're addressing VIFWDNLOWHTTINW .................................................

(Very intelligent four wheel drivers not lumps of wood hence their time is not wasted)

:-))))))))))))))))Fidei defensor

Rosco
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FollowupID: 309777

Reply By: Member - Bradley- Tuesday, Feb 24, 2004 at 13:37

Tuesday, Feb 24, 2004 at 13:37
Hmm, similar problems that some of the soft roaders are facing, get stuck halfway up a hill, go to recover in reverse with no low range, vehicle starts to run away, apply brakes, fronts lock with lack of load and the abs kicks in, dropping brake pressure, vehicle gets quicker and quicker. one of the 4x4 mags just struck this as well with their 4x4 of the year tests, on multiple vehicles. As smart as all this new tech is, it still can't match the grey matter up top. Wonder if the power on / brakes modulated approach would help in these situations, i've only seen it used in forwards up till now.Just killin time till easter...............go and play in the dirt, instead of workin in it......
AnswerID: 47867

Reply By: Baldrick - Tuesday, Feb 24, 2004 at 14:01

Tuesday, Feb 24, 2004 at 14:01
Even though I am happy to embrace new technology, things like this do show that there is no substitute for driver skills.

I read a review of a new Range Rover a few years ago, which posessed (or was posessed by) no less than 6 onboard computers. While attempting to reverse down a failed hill climb, the computer controlling the gearbox decided that the speed was too fast for reverse, so slipped it into neutral. The driver tried applying brakes but of course the ABS wasn't having that so the result was an undignified but fortunately undamaging uncontrolled descent!
AnswerID: 47870

Reply By: Wayne (NSW) - Tuesday, Feb 24, 2004 at 18:40

Tuesday, Feb 24, 2004 at 18:40
Rosco,

I thought that if the Disco was in low range the centre diff would be automatically engaged.

WayneAlways Out'N About
AnswerID: 47918

Follow Up By: StephenF - Tuesday, Feb 24, 2004 at 23:03

Tuesday, Feb 24, 2004 at 23:03
The Disco is more intelligent than the Japs. Low range and centre diff lock (where fitted) are independent - you can engage one or the other or both. Low range with centre diff unlocked is handy for moving big boats or caravans up steep driveways.

Stephen.
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FollowupID: 309884

Follow Up By: Wayne (NSW) - Tuesday, Feb 24, 2004 at 23:19

Tuesday, Feb 24, 2004 at 23:19
Stephen,

That is correct, when the transver lever had a H patten gate. One side high and low range locked the other side high and low range unlocked. Then they went to a two postion transfer lever high and low. In high range it relied on traction control but in low range I thought it locked the centre diff. The biggest problem with the transver lever is that it is very short and most of the time very hard to engage,more so when trying to select low range.

WayneAlways Out'N About
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FollowupID: 309885

Follow Up By: StephenF - Wednesday, Feb 25, 2004 at 10:58

Wednesday, Feb 25, 2004 at 10:58
When the Disco II came out in '99 LR figured that traction control would make a centre diff lock redundant so they removed the linkage from the lever to the actuating nut on the transfer case, but left the nut in place. You could crawl under with a spanner to actuate/disengage the CDL or buy an aftermarket kit to do it from inside the vehicle (much more convenient!). Other kits have no driver control and automatically engage the CDL when low range is selected. However, from the factory, the Disco II had no centre diff lock operation at all.

It's interesting that after crowing about how ETC would replace the CDL, LR quietly reintroduced the CDL on the current model Disco!

Stephen.
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FollowupID: 309917

Reply By: Slunnie - Tuesday, Feb 24, 2004 at 20:23

Tuesday, Feb 24, 2004 at 20:23
Its a problem, and there was a lot of talk about it amongst Disco series II owners and the associated safety. The center diff actuation was removed from this model and there were many that reconnected the centre diff. It seems Landy didn't like this and then removed the locking nut off the transfer case in the 2002 models on until the updated 2003 model where funnily enough they reintroduced the CDL.

The Discos that lock the CDL like mine, are the ones that are running the actuators from John E Davis Motor works (now Bruce Davis performance)

Regards
Slunnie
AnswerID: 47934

Reply By: Pete G - Tuesday, Feb 24, 2004 at 21:21

Tuesday, Feb 24, 2004 at 21:21
Rosco,
I don,t kmow much about Disco's, however, something to be careful about are the auto lock/manual lock hubs. Auto lock front hubs only work in the forward direction ( ie on the GU patrols) after a 4wd session the vehicle must be reversed to ensure 4wd unlocks (ie the front hubs). Hence if reversing it is possible that the front hubs have disengaged by running backwards (This will happem in a Patrol), If doing serious work lock on manually ( with the spanner)so that they will work in reverse as well as forward. The reason that front hubs are not locked in always are for fuel economy on the highway (supposedly) so that the whole diff is not turning.
My son in his 4wd Firey's experience has seen a Disco refuse to go down (or up for that matter)in a stall recovey on a slippery slope - attributed to ABS and the electronics of this. Some very serious recovery work was required in this instance = yet conventional Patrols and Cruisers did it easily.

Regads

Pete G
AnswerID: 47943

Follow Up By: Wayne (NSW) - Tuesday, Feb 24, 2004 at 22:20

Tuesday, Feb 24, 2004 at 22:20
Pete,

Disco's are constant 4wd no manual locking hubs or auto hubs. The front axle is attached to the front hubs all the time. GU do have auto hubs which engage when 4wd is selected via the transfer lever. They can disengage when reversing. There is a manual lock on the hubs,in the form of a nut which must be turned to the lock postion with the wheel brace.

WayneAlways Out'N About
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FollowupID: 309879

Reply By: Wayne (NSW) - Tuesday, Feb 24, 2004 at 22:55

Tuesday, Feb 24, 2004 at 22:55
Rosco,

I don't doubt what happened, but if the Disco was stopped part way up the hill with the motor stalled (part of key start recovery techniques) and reverse gear engaged and with the foot brake covered how did it pick up so much speed that it was out of control when the key was turned to restart the motor? We have had all models of Disco,s do reverse stall recovery and never a problem. Was there a trainer sitting in the front passenger seat watching what the driver was doing? Did the driver rely on hill decent only and not "feather" the brake. Does hill decent work in reverse?

Wayne Always Out'N About
AnswerID: 47960

Follow Up By: Rosco - Bris. - Tuesday, Feb 24, 2004 at 23:44

Tuesday, Feb 24, 2004 at 23:44
Wayne

All was according to the book i.e. last stage ... brake off and in reverse holding against the compression of the engine, then hit the key. That's when the bleep also hit the fan.

There was no trainer on board but the driver swears he didn't touch the brake. The trainers said they had encountered it before but only with Discos. I had a S1 Disco and have to say I never encountered the problem, but then again I also have to admit I never tried the proceedure.
Usually just selected reverse and calmly descended backwards .... but it didn't have all the black box wizardry.Fidei defensor

Rosco
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FollowupID: 309889

Follow Up By: Wayne (NSW) - Tuesday, Feb 24, 2004 at 23:57

Tuesday, Feb 24, 2004 at 23:57
Rosco,

I am not saying the methiod we use is any better, but we always sit in with the driver and watch that the procedure is carried out in the correct order. May be it jumped out of gear when the torque of the gear box was increased when starting, again may be due to the small transfer lever.

WayneAlways Out'N About
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FollowupID: 309892

Follow Up By: phil - Wednesday, Feb 25, 2004 at 06:50

Wednesday, Feb 25, 2004 at 06:50
I have a 2001 Disco series II TD5 Auto .
I have had a linkage fitted which results in diff lock being engaged whenever low range is selected.
Apart from not being able to use low range on "non slip" road surfaces,does this setup have any other disadvantages?
Phil
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FollowupID: 309901

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