| Author | Message | ||
     Scott Scott (Scottoz) Member Username: Scottoz Post Number: 167 Registered: 02-2003 |
I am hoping to attach a video of a TD5 2002 Disco attempting to do a key start reverse down a steep hill after getting to the top in low range ist. The driver engaged low range reverse and key start it with the cluth out - ie starting in gear on the starter motor (the proper way to do it). The HDC was not engaged. This Disco does not have CDL. The rear wheels can be seen going backwards with traction and the front passenger side (left) can be seen driving forward!!! causing the vehicle to slew sideways and nearly roll. The HDC may have made a difference in this particular situation. The Defenders that went up before him did the same thing (advanced training course) with no problems - they have HDC AND CDL. I am not aware of the detail of the Disco's constant 4wd system - is it possible for a wheel on the rear (or both) to be going back and a front wheel to turn in the opposite direction. If this is possible as it seems to be (witnesses say that they saw the reserse lights on and driver is experienced and adamant that he was in reverse) then surely this is a grave safety issue for LR and CDLs should be retro fitted at no cost. ....I cant seem to upload, can anyone help. | ||
| Scott Scott (Scottoz) Member Username: Scottoz Post Number: 168 Registered: 02-2003 |
I thought that this was pretty interesting... | ||
| quentin charles neil ross (Qcnr) Member Username: Qcnr Post Number: 60 Registered: 10-2003 |
Have you contacted LR?????? | ||
| Dean Brown (Deanbrown3d) Senior Member Username: Deanbrown3d Post Number: 1491 Registered: 02-2002 |
He was in first, not reverse. Its easy to get confused in that kind of panic situation when you think you're going to flip over. Would be good if you had it on video though. | ||
| Chris Browne (Chris_browne) Senior Member Username: Chris_browne Post Number: 651 Registered: 02-2003 |
I agree with Dean, he was in first, with no weight on the front thereby causing all the torque to go there...and the front wheels to turn forwards gravity took the vehicle backwards making the loaded rear wheels turn backwards. The center diff simply did its job | ||
| Axel Haakonsen (Axel) Moderator Username: Axel Post Number: 1015 Registered: 02-2003 |
This is old news anyway. The "grave perils of backing a D2 without CDL down a slope" was discussed ad nauseam when the D2 was first introduced. There was a video floating around as further proof that the world was coming to an end then, too. While there is a general concensus among most that use their Disco's off road that we would have been happier if LR had never removed the CDL from the D2, I do not belive that there have been any reports of anyone getting physically hurt from it's absence. And don't hold your breath waiting for LR to retrofit a CDL for free......  - Axel | ||
| Kyle Van Tassel (Kyle) Moderator Username: Kyle Post Number: 836 Registered: 11-2002 |
One wheel will turn backwards even if you are in the right gear... Thats life with a D2 "Blow me" | ||
| jakob carstensen (Jakobc) New Member Username: Jakobc Post Number: 2 Registered: 01-2004 |
Hi - I'm pretty new to the discos. CDL is Center Diff Lock right? Which Discos have it and which don't? What does CDL do for me? Again ... sorry it this is a trivial question '98 D1 | ||
| Robbie Donaldson (Robbie) Senior Member Username: Robbie Post Number: 543 Registered: 02-2002 |
Read this Jakob, and it should help you out: http://www.discoweb.org/discovery/basics.htm | ||
| Scott Scott (Scottoz) Member Username: Scottoz Post Number: 169 Registered: 02-2003 |
No - he was definitely in reverse - the reverse lights were on. It was not a panic situation by an Australian Acredited National driving course. It was a demo by an experienced driver. There was no need to panic becuase he could have driven over the top. It was a deliberate practice of key start reverse. It was a manual box and he got it into reverse. If you jack up the rear of a rear wheel drive with open diff and turn one sides wheel one way, what way will the other side turn - yep, the other way. I am thinking that this transfers to the front also. The HDC would, if it was on, have probably saved him by braking the front wheels as they started to rotate forward and thus avoided the slide - I have never had a problem in similar situations but then again I have always used HDC. I suppose the bottom line is - If you are out on a track and it is difficult and you loose your ABS system (or break an axel) you could be well stuffed. | ||
| Garth Petch (Garth) New Member Username: Garth Post Number: 37 Registered: 02-2003 |
Scott If you follow your reasoning with open diffs, does the video of the other side of the disco show the front wheel in reverse and the rear wheel going forward? I haven't seen the video, but are you sure that this is not a strobe effect caused by the speed of the wheel vs the speed of the frames of the video? Garth PS: Australians spell it axle...are you doing a little Johnny? | ||
| thom mathie (Muskyman) Senior Member Username: Muskyman Post Number: 628 Registered: 11-2002 |
the sky is falling the sky is falling...T H E S K Y I S F A L L I N G | ||
| Tom Fioretti (Tom_in_md) Member Username: Tom_in_md Post Number: 145 Registered: 02-2003 |
 | ||
| Shane Lesteberg (Snwbord24) New Member Username: Snwbord24 Post Number: 35 Registered: 01-2004 |
Scott, Can you put the video on a website and post the url here so we can see it? | ||
| James (Greenmeanie) New Member Username: Greenmeanie Post Number: 1 Registered: 02-2004 |
Just to clear up a couple of things. Defenders have never been fitted with HDC. Also, I thought that only the RR3 had the ability to select HDC in reverse(?). It would seem that the best way to get a D2 down a slope backwards is to step on the brake pedal and hope the ABS slows the vehicle enough. | ||
| Shane Lesteberg (Snwbord24) New Member Username: Snwbord24 Post Number: 36 Registered: 01-2004 |
I have an 03 DII and the HDC works in reverse on it. | ||
| Alyssa Brown (Alyssa) Senior Member Username: Alyssa Post Number: 534 Registered: 01-2003 |
HDC works in reverse in all models fitted with it. | ||
| Kyle Van Tassel (Kyle) Moderator Username: Kyle Post Number: 844 Registered: 11-2002 |
See , this is the mentality that really bothers me. it shouldnt be up to some magic electronic thing to drive your truck for you... They sell this shit and then people develop a mindset around it.. Then it doesnt work,,,imagine that... "Blow me" | ||
| Alyssa Brown (Alyssa) Senior Member Username: Alyssa Post Number: 536 Registered: 01-2003 |
Absolutely right. An experienced off-road driver does not need HDC. It's just a computer program that judges the terrain & acts accordingly... something a good driver should also be able to do. | ||
| Kevin Hans (Kmhans) New Member Username: Kmhans Post Number: 31 Registered: 01-2004 |
The same could be said for fuel injection or headlights and even those fancy arb lockers. At some point they were all considered unnecessary (well maybe not headlights!) But we end up relying on some of these things none the less. HDC is a great system, particularly if you have no means of locking the center diff. It ensures that braking can be applied to all wheels which is something that the CDL can not do. If your looking for a drawback, it might be because it is a reactive system vs. proactive, like locking the diff | ||
| Alyssa Brown (Alyssa) Senior Member Username: Alyssa Post Number: 537 Registered: 01-2003 |
ETC does that, not HDC, Kevin. HDC is a computer program that tells the car when to apply brakes. | ||
| traveltoad (Traveltoad) Member Username: Traveltoad Post Number: 99 Registered: 11-2002 |
My guess is that the HDC was developed because of the dangers of using only engine compression to slow the vehicle on rough terrain. With all open diffs, all it takes is one wheel to loose traction and ALL your engine braking is lost! | ||
| Axel Haakonsen (Axel) Moderator Username: Axel Post Number: 1029 Registered: 02-2003 |
Which is why all Land Rovers come fitted with a manual brake pedal as standard equipment. - Axel | ||
| thom mathie (Muskyman) Senior Member Username: Muskyman Post Number: 629 Registered: 11-2002 |
The point here is you should learn to drive your truck not just be along for the ride. on a automatic trans truck that will coast down hill you need to pre apply the brakes and hold that amount of braking. if you add more pedal while the truck is in deceant more then likely you will lock a tire and start a slide. some times it causes the truck to move faster then someone is comfortable with ...but thats why practice makes a cool head on the trail. The technique is very similar to threshold braking as you will learn if you go take a driving course at Skip Barber or similar driving schools. fact is driving is driving in many respects and no matter how good your vehicle often a superior driver will perform better in a lessor one. MM | ||
| Chris Browne (Chris_browne) Senior Member Username: Chris_browne Post Number: 653 Registered: 02-2003 |
Time out here folks... What we are talking about is a Failed Hill Climb. The technique is simple, but you need to mentally prepare, especially if you've never done it before to perform it in proper sequence. Slow and deliberate actions not rushed. The Ascent fails. Hold the vehicle on the brake while you move the shifter from D to R. Stick shift from whatever gear you were in to Reverse. Then and only then gently relax the pressure on the brake and descend under engine braking...take it easy. Confession time. the first time I did it I flunked ...but it wasn't until afterwards we realized what I had done. I was at the RN off road school, with Mike Hussey as my instructor (he won the CT in 1995.) I totally forgot I was in third, not D as I went up the hill and two clicks later went into neutral before releasing the brake. It was a tad exciting..... Now you see why I said be slow and deliberate....Good luck when it happens to you. | ||
| Dean Brown (Deanbrown3d) Senior Member Username: Deanbrown3d Post Number: 1500 Registered: 02-2002 |
HDC is practically useless for any real situation. On a steep downslope (where you might actually want it) its runs way too fast. There is no control over the speed. IMHO if the computer that ran the algorithm was 1000 times faster, and written more intelligently, and the sensors were much higher resolution, and you could choose the speed, then it could potentially be a pretty awesome tool. But then where's the fun in just letting the computer drive for you? I certainly am not interested in that. And what happens when the computer dies or GPFs and *gasp* you have to rely on your own experience? | ||
| Kyle Van Tassel (Kyle) Moderator Username: Kyle Post Number: 845 Registered: 11-2002 |
Exactly Dean , too many people are buying the sales hype that these trucks will make them an instant off road heavy weight. Its simply not true and just perpetuates the degradation of the true mechanically sound 4 wheel drive. The soccer moms and yupp guys listen to the hype and start getting visions of grandure.. Funny thing is , 9/10 of them never venture off road and find out that its shit so they simply go on with the "Ignorance is bliss" thing going on... "Blow me" | ||
| Chris von C. (Chrisvonc) Dweb Lounge Member Username: Chrisvonc Post Number: 443 Registered: 07-2002 |
After owning a D2 with HDC and have driven a Freelander with its HDC, the differances are amazing. Completely worthless in a D2 and I found really good in the Freelander. I think the Disco is just too heavy for it to be truely effective. You have better control with just using the engine braking in L1 or L2 depending on the slope and never touching the break. | ||
| Greg Hirst (Gregh) Senior Member Username: Gregh Post Number: 511 Registered: 10-2002 |
Sales hype? What hype? LR has truly improved the breed with it's new vehicles. That's why I can't drive my old '89 RRC underwater for 15 seconds like the new RR3... | ||
| R. B. Bailey (Rover50987) Senior Member Username: Rover50987 Post Number: 760 Registered: 07-2002 |
How, exactly could the front wheels be turning forward if he was in reverse? I think it must be the strobe effect. That in mind however, the problem still is there in potential, for the non-CDL LR's to allow an entire axle to turn in one direction while the other is doing something else if the power to the traction control is off. At least that is the way my mind is thinking today. And as far as driving under water is concerned, I have never gone in over the top of the 225/75's, but I still get water running down the inside of my windshield like I just drove off the end of a pier! Sometimes I think I'm in one of those old WWII submarine movies, with the leaks and the screaming, and the hopeless feeling after a depth-charge attack. | ||
| Kyle Van Tassel (Kyle) Moderator Username: Kyle Post Number: 846 Registered: 11-2002 |
It happens because of the diff and the brakes going off. That one wheel will spin backwards...Not under power going backwards , in fact , if you gassed it , it would go the right way.. "Blow me" | ||
| Steve Rupp (Steve_rupp) Member Username: Steve_rupp Post Number: 72 Registered: 03-2003 |
Kyle, check yor mail | ||
| Kevin Hans (Kmhans) New Member Username: Kmhans Post Number: 32 Registered: 01-2004 |
Alyssa, isn't ETC also a program that tells the vehicle when to apply the brakes? HDC works in an effort to redistribute engine braking (engine being torqued by the road wheels) and ETC works to help redistribute engine torque (road wheels being torqued by the engine). These are different parameters for sure. Both of these systems are functions of the ABS which itself only reconizes go (foot not on brake) and stop (foot on brake). Generally, the vehicle wants to go when you aren't trying to slow it down, so HDC is selectable for those times when you want the ABS to be in "stop" mode. At the end of the day, it is definately nice to have the CDL back in the O4! | ||
| OLIVER CLOTHSOFF (Everythingleaks) Senior Member Username: Everythingleaks Post Number: 337 Registered: 10-2002 |
On the D2 the HDC attempts to hold the vehicle at too high of a speed (5mph) to be effective and it reacts slow on start-up of the system. During one spot at TReK they told us to use HDC and the system did not react fast enough. This started a descent too fast with a turn at the bottom. At the turn the truck went into a slide setting the scene for a horrible line thru the other markers at the bottom. I had never used HDC off-road before but I will be sure to do it the "old fashion way" next time. If HDC is the way to do it in the D2, I'll stick to my classic. | ||
| OLIVER CLOTHSOFF (Everythingleaks) Senior Member Username: Everythingleaks Post Number: 338 Registered: 10-2002 |
P.S. - The New Rangie has a target speed of 2mph in low range with manual first selected. This may work a little better on flat, steep grades but I have no hands-on with it. | ||
| Jamie (Rover_puppy) Senior Member Username: Rover_puppy Post Number: 1010 Registered: 05-2003 |
I've got HDC on my D2, and it does work going uphill or reverse downhill. I don't like it and I don't use it, ever. That's just handing over too much control for me. My truck can't see and it doesn't seem to be able to make quality decisions. It allows the truck to descend too quickly. Neat feature for prospective buyers, but I don't trust it. | ||
| Craig Kobayashi (Koby) Dweb Lounge Member Username: Koby Post Number: 1103 Registered: 02-2002 |
HDC was fun to play with when I had stock tires. With 265/75 the HDC is near worthless for the reasons Oliver states above. | ||
| Christopher Boese (Christopher) Senior Member Username: Christopher Post Number: 298 Registered: 10-2002 |
HDC's only seemed helpful to me in descending steep, icy, paved, curving streets. I used HDC yesterday, in fact, in just this situation. That said, low first in my '95 (pre-HDC) seemed safe enough for these conditions. I've always had a suspicion that much of Land Rover's reason for HDC was as a reassurance for inexperienced drivers who don't know how to use the gears. | ||
| traveltoad (Traveltoad) Member Username: Traveltoad Post Number: 100 Registered: 11-2002 |
Chris Browne (Chris_browne)said: "The technique is simple, but you need to mentally prepare, especially if you've never done it before to perform it in proper sequence. Slow and deliberate actions not rushed. The Ascent fails. Hold the vehicle on the brake while you move the shifter from D to R. Stick shift from whatever gear you were in to Reverse. Then and only then gently relax the pressure on the brake and descend under engine braking...take it easy." The problem with this with all diffs open, as soon as one wheel looses traction all the engine braking is lost. The one wheel is moving at engine/gear speed, the other three roll freely because of the open diffs. When you try to slow yourself with the brakes... Big trouble for Moose and Squirrl! Using the HDC in this situation is like... Putting a gun to your head that someone else said was not loaded. HDC is great for the soccer moms on their way back from the ski mountain on snowy roads, but a CDL is "safety equipment" for off roading. | ||
| Stephen Hawkins (Madmole) Member Username: Madmole Post Number: 45 Registered: 07-2003 |
From the Rave CD Remember HDC wont hurt your normal control, you can still engine brake and you can still use CDL if you have it. Consider it a second chance for the soccer mums I have switched mine in and then gone down a very slippery slope, even with CDL I was slipping and sliding on engine breaking and then just as I was considering the use of a little throttle, wam! in come HDC and kept her in check (admittedly a bit faster than I'd like but slower than I would have had to go to get all wheels back) So I believe it does work, but I wished it was set slower when in first The HDC descent speeds in Km/h (mph) for New Discovery are: Manual Automatic Gear Selected Normal Reduced Normal Reduced 1 7.0 (4.38) 7.0 (4.38) 7.0 (4.38) 7.0 (4.38) 2 8.3 (5.19) 7.0 (4.38) 7.0 (4.38) 7.0 (4.38) 3 9.6 (6.00) 7.0 (4.38) 12.0 (7.50) 9.6 (6.00) 4 12.0 (7.50) 9.6 (6.00) 12.0 (7.50) 9.6 (6.00) 5 14.0 (8.75) 11.2 (7.00) - - Reverse 5.6 (3.50) 5.6 (3.50) 5.6 (3.50) 5.6 (3.50) Neutral 14.0 (8.75) Reduced speed 7.0 (4.38) 7.0 (4.38) detected last used | ||
| Big Ed (Sandman) Member Username: Sandman Post Number: 49 Registered: 02-2004 |
Roverheads...the jets I fly practically fly themselves these days. Boeing even installed a warning system that alerts the pilot when he hasn't touched anything for a while! The trucks we drive are heading the same way. We are losing the last real "seat of the pants" wheeling to computers and gimmics and that really sucks! I hate going out on trails with these idiots that rely on TLA components. (TLA = Three Letter Accronym). It's impossible to predict their next move. Learn to drive the car, not the machine! Know your limits and the limits of your rig, not the processor speed of your ABS or how fast and when the computer will apply the brakes for you. SandMan P.S. Don't worry about failing to climb a sand dune because you won't roll back down anyway! Pick whatever gear you want, steering is completely useless, just go with the sand slide baby. Ride that golden wave! | ||
| Kyle Van Tassel (Kyle) Moderator Username: Kyle Post Number: 848 Registered: 11-2002 |
The problem is that these are sales points on the new trucks and make the average Joe (that knows damn well that he cant drive) feel he can do anything. This is what we will call "The new Land Rover Experience" "Blow me" | ||
| Reid Walkenhorst (Runningmule) New Member Username: Runningmule Post Number: 33 Registered: 05-2003 |
I have used HDC on my 2000 D2 quite extensively trying to figure it out...I can't say that I'm real impressed either. One thing that I have noticed for sure, is that since going to to 265's both the HDC and ETC work less effectively. With the stock tires, ETC and HDC engaged a lot more frequently, now it engages at least half as often. Particularly HDC has become down right scary to rely on, thus I've basically quit using it. Since both systems are engaged by engine RPM Does anyone know the optimum gearing set-up to take the best advantage of HDC and ETC. I know there both gizmo's but...A lot of guys on this board could use the info. I'm curious if for instance a lower gearing than stock may be an advatage. I was planning on 4.1, but maybe lower would even yeild more benefits?? Good to have some nice reading on here...thanks to all for the discussion. RPW | ||
| Kevin Hans (Kmhans) New Member Username: Kmhans Post Number: 38 Registered: 01-2004 |
Reid, The electronic systems that you mention are all actuated by differences in voltage measured at the wheels, and not by engine rpms. This is why HDC can work in neutral and why ETC can operate even at idle. Because of the bigger tire size, the vehicle is traveling further with each rotation of the wheel which translates into more speed. I have heard of tuning the target speed for HDC, but guess what...You need even more computers to do it! | ||
| Scott Scott (Scottoz) Member Username: Scottoz Post Number: 172 Registered: 02-2003 |
Kyle - I could not agree more BUT if you cant lock the centre diff then you must rely on the electronic gadgets to simulate the ability of a locked CDL - otherwise you have bugger all. | ||
| Scott Scott (Scottoz) Member Username: Scottoz Post Number: 173 Registered: 02-2003 |
I just want to make this clear - CDL is the only way of taking and all wheel drive and making it a true four wheel drive in the traditional sense - its like jumping into a 40 series landcruiser after locking the front hubs in and then selecting 4wd. OK. Without centre diff lock, it is possible on my thinking for the differential affect to cause the problem that was experienced here. He did have it in reverse - the reverse lights were on and the front and rear wheels on the passenger side did turn in opposite directions. If someone could please tell me how to put the video on the web I would gladly do it. Kyle and others - If I could activate my CDL in my d2 I would (I have a d1 with it also) - but without spending heaps of cash for another transfer case that has the innards and the exterior lug I cant do it - SO, I have to rely on HDC to brake the fronts that want to go forward, when reversing down steep hills. Without CDL you CANT in these steep slippery conditions reverse down the hill SAFELY without using HDC (because the centre DIFF is not locked and you are otherwise driving, potentially a 1 wheel drive that in bad conditions wants to drive front and rear wheel in different directions because of differential effect!) And for those who like braking down hills when loss of traction is occurring, good luck to you. S | ||
| Runnerma (Runnerma) New Member Username: Runnerma Post Number: 15 Registered: 12-2003 |
Scott The same effect one can be see in LAND ROVER's "under control" tape. There is a steep downheel with wet grass. 2 D90's going down. The one with cdl in locking position. The 2nd with cdl in unlocked position. In the attempt of the 2nd 90 one can clearly see the one wheel turning in the opposite direction of the downhill. And the teacher in the tape mention it clearly, that u must have the cdl in locked position for not being in a situation like this. | ||
| Barto de Koning (Bart) New Member Username: Bart Post Number: 9 Registered: 12-2003 |
Hi Scott I found this thread quite amuzing, like many postings on this site. For a moment, let's forget about HDC and traction control. You drive your D1 down a steep hill with the CDL locked, using engine braking, and you cross axle lifting 2 wheels off the ground. At that moment your truck surges forward. The engine revs stay the same but you move faster. All that extra speed is coming from the wheels that aren't touching the ground. Most cases the lifted wheel just turns slower than the other wheel on that axle, but if the vehicle moves fast enough the wheel will turn in the opposite direction for a moment. I'm not going to explain in detail why this happens, you all should at least know how a differential works. Now, take the CDL out of the equation and this will happen when only 1 wheel lifts off the ground, and this is what happened in your case. I don't own a SII disco myself, but I have been at training session with guys who have SII disco's. Here some of the things the instructor told us: With the disco 2 many of the conventional driving tecniques need to ignored.When going up a steep hill and you reach a point where the vehicle just spins, you must put your foot on the brake before taking your other foot the gas pedal, because as soon as you let go of the gas pedal, TC thinks it is no longer needed and lets go of the brakes it was holding to maintain traction. If do not do this, and 1 wheel is the air when the brakes let go, you will again surge backwards. We were also told that when you go down steep decents you must use your brakes, but also switch on HDC as a safety net. You should also have some slight pressure on the brake when doing an in-gear start. HDC only starts working at a certain speed, until you reach that speed and with 3 open differentials things can get quite scary. What you saw is quite common and although it will happen more often to vehicle without a CDL, it will also happen to vehicles with a CDL engaged and no axle diff locks. Add axle difflocks together with the CDL and this problem is solved. And that, ladies and gentlemen, is my 2cents. | ||
| Kyle Van Tassel (Kyle) Moderator Username: Kyle Post Number: 853 Registered: 11-2002 |
You forgot to mention bart that braking is more even with a CDL lockd truck and therefore your scenario can be avoided. | ||
| Scott Scott (Scottoz) Member Username: Scottoz Post Number: 174 Registered: 02-2003 |
I'm delighted that you found it so amusing Bart. I on the other hand, did not quite see the humour. LR is sold as a true all terain vehicle, and with a CDL AND HDC/ETC they are better in stock form than pretty much any other proper four wheeler in my opinion. Without CDL there is a flaw in down hill reversing, especially in key start reverse. BTW whoever told you to brake in the D2 going down hill should qualify his comments. You may brake when it gets to a really steep point in an auto - although the preferred method in Australia is to use gradual hand brake pressure, acting directly on the drive train. I am lucky - I have a v8 with manual trans in my DII with 42:1 reduction (or thereabouts) in low range first and with no torque converter to slip it idles at less than walking pace down the steepest of hills. Somtimes a wheel or 2 will drop into deep ruts on a steep downhill and HDC with chatter with ABS for a second or 2 and make things more comfortable. All comments are capable of being taken out of context or over-simplified - for example you say if going up a steep hill, if the vehicle spins, brake before getting off the Gas. I have had the same situation many times - the unlocked DII become for a few seconds a one wheel drive and spins, you then GET ON the gas progressivly harder and make the ETC work for you to get going. If things are not going your way then you stall it in the gear that you are in and then do a key start in reverse. My view is that when LR took out CDL from the DII they removed an element of control and safety that was there in the D1 (I have a D1 and can compare). Cheers |
