You should engage lockers for descents

#lockers #downhill4x4 #hdc
Cross-axle differential locks are usually used when ascending hills or in ruts..but did you know they have value when descending too? Watch this video to find out how and why, plus a look at electronic Hill Descent Control (HDC). This isn't a full explanation of downhill driving, just to make people aware of the effects of a cross-axle locker downhill in ruts.
Post questions as comments!
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[@nealesmith1873]

Great info as usual! One time, while climbing an uneven rock slab, without lockers, there was a spot where both axles had a tire off the ground at the same time, and the Jeep would sort of hop backwards and would be unable to ascend. It was very surprising and hard to understand at the time.

[@L2SFBC]

What happened there was differential sending drive to the wheel easiest to turn. Check my differentials video for more.

[@cameronwood1994]

I have two rules of thumb. Firstly, always use a gear lower for the descent than the ascent. First gear is a good rule of thumb but if the ground conditions are very slippery there's a real risk of the vehicle sliding out of control, second may be a better option. For such ascents you'll normally require third gear because second can cause wheel spin, but for most hill climbs where traction is less marginal I find second gear to work the best. The other part of this rule is on soft sand dunes, where in too low a gear the vehicle will simply nose into the ground. Sand has a braking effect anyway, and I've seen low third and some accelerator required in really soft going to stop this nosing in effect. Secondly, if you needed, or judge that you would have needed, an axle differential lock for the ascent, you should also use it for the descent.

[@L2SFBC]

I agree, good rules of thumb. I would not use HDC at all in sand, and in fact Land Rover say not to (don't always agree with them, but in this case I do). The old rules of 2nd low up 1st down don't really apply so much with 10-speed automatics of today, but the concept remains the same.

[@roblogie1742]

I was taught similar. Especially the bit the using a slightly higher climbing gear means the engine is inclined to be a lower RPMs and usually in peak torque band rather than power, reducing risk of wheel spin . Not sure how relevant that is theses days.

[@stevegoodwin5841]

HDC was King for sure

[@Lisa-st4td]

I love HDC, makes for a much better drive than riding the brake. Looking forward to testing out the rear locker in these situations too now!

[@kastenolsen9577]

Learned something new, I'm not dead yet!

[@PaletoB]

Quite obvious when you think about it, but I didn't think about it. Not that I have locker's. 😅

[@tdock86]

What a revelation! Can’t wait to find out soon if my new Hilux enables DAC with rear locker…

[@toyotatreehugger]

Seriously - such great content. Always. Thank you.

[@L2SFBC]

Glad you enjoy it!

[@GrenadierMichael]

Thanks, Robert, for another excellent video, which follows your pattern of providing well-researched information in an easily understood manner.

[@L2SFBC]

Very welcome, please share!

[@tommymoto83]

Thanks for your advice. It is very helpful. 👍

[@L2SFBC]

Glad it was helpful! Please share :-)

[@SPACEMIKEB]

Thanks for the video. Please note that HDC works in reverse for many vehicles. This can be really handy to know if you have to back down a hill.

[@L2SFBC]

Yes HDC always works in reverse. I might do one on HDC systems more generally.

[@nicolasbednarz9085]

@@L2SFBC yes please. i stil cant find the right obstacle to use it instead of riding the brakes when things got hard.

[@veryaware]

nailed it yet again, good factual content

[@L2SFBC]

Thanks please share 👍

[@helmydewa]

Very nice video, i learn a lot, thank you

[@L2SFBC]

Glad to hear that, please share!

[@Abu7929]

When I first got my 2017 hilux I took it up a mountain. Sudden storm hit once I got to the top. Steep muddy decent, a few km worth, scary stuff. I fiddled around with the buttons, pressed hill descent and placed all my trust in the ute. Got us down piece of cake in safety. Honestly feel like it would have been certain death trying to drive down normally, 1st low in these modern utes is fast af, as we can see here. Was convinced on the tech then and there

[@roblogie1742]

If you are caught like that and are absolutely desperate to get down safely a technique that can help is to chain a large branch (One with lots of smaller branches off it so it can't roll around etc) with a drag chain to the back to act as a anchor as you descend the slope . This sort of thing should only be used as last resort though

[@Abu7929]

@@roblogie1742 great tip I'll remember that

[@jonathanconway7256]

Great content as always HDC works really well in my Gladiator. Now I need to try it with the lockers engaged.

[@L2SFBC]

Give it a shot with and without, all combinations. But to see the effect you'll need to find a hill where you lift wheels (maybe leave the swaybar connected :-) )

[@sheerwillsurvival2064]

Excellent video

[@L2SFBC]

thanks please share

[@cyclemoto8744]

Thanks Robert. Cheers

[@L2SFBC]

You are very welcome

[@AlphGen]

One of the problems is the torque converter doesn't lock up in many autos hence the runaway feeling

[@nicolasbednarz9085]

great info, Robert! thanks. this things are still kinda black magic. i wish there were some kind of standarization of the systems.

[@L2SFBC]

hah will never happen!

[@stewartj3407]

I have a Jeep tj. I’ve always engaged front and rear lockers going down steep hills, especially if it’s slippery, I want as much traction and every tire trying to slow me down through engine braking. Front locker can be disengaged if I have a tight turn to steer around. I Also consider braking the last resort on slippery stuff, if those front wheels lock up and start sliding it’s hard to command your brain to release the brake so you can steer.

[@L2SFBC]

Agreed, definitely a good technique!

[@neutronstorm]

Another good topic is - if you are using hill decent control, should you use 1st gear low as well (especially in an automatic). The advantage of using 1st low as you get the engine braking as a backup/assist to the brakes. The disadvantage is that if you are decending a very slippery steep slope, the hdc may need to allow the wheels to spin faster than 1st low will allow if the vehicle slips down and gains too much speed in a slick section. If the vehicle was in Drive, it's more likely the hdc could allow the tires to go fast enough to stop slipping and then the brakes could apply to retard the vehicle. In 1st low, it's possible the vehicle would end up with 4 wheels locked up and hdc would I presume have a harder time dealing with it.

[@L2SFBC]

Yes, use low gears with HDC to reduce braking effort and heat buildup. Whether you choose 2nd or 1st...choose what you'd use without HDC. I wouldn't use Drive.

[@technopsychobedlam]

Yeah, I just use hill descent control ;-)

[@waynehobbs5175]

Great video content and presentation thank you Robert. Could using HDC and rear diff locker be better still?

[@L2SFBC]

Yes that could be best of all. But not all cars allow it. The Ranger PX does not the PX2 and later do.

[@josem6929]

Amazing explanation. Question in very muddy hills with very very low traction is HDC still an option?

[@L2SFBC]

Very much so. In fact, HDC is better than lockers in those situations as you retain directional and steering control. It is also better than human braking.

[@351tgv]

Great advice Rob, on a different topic, how is that PX Ranger holding up? positive, negatives? a review about it would be good to watch.

[@L2SFBC]

It's going well. May video review

[@351tgv]

please do so, always good content here.

[@DarrenCoull]

Thanks for the video Robert, would driving through the brakes also be an effective way of controlling this type of descent on older vehicles without HDC or lockers?

[@L2SFBC]

Yes but that technique is less and less relevant these days with lower auto gears and HDC. Still useful though.

[@Malc664]

Impressive tutorial Rob. It seems the Ranger goes fast in 1st gear low. Is it because of the weight of the vehicle on a steep decline pushing it along ? edit. nevermind, I read an explanation further in the comments. The gearing is not low like a Defender or Rubicon.

[@L2SFBC]

Yes, the crawl ratio is I think 33:1 or so compared to Toyoya/LR of about 45:1. And the Defender/Rubicon has better flex so less likely to wheel lift.

[@NigelNaughton]

This is some excellent info. I've always wondered about this. Do you think it would help just as much if you didn't have a wheel off the ground? Like it was just a steep hill?

[@L2SFBC]

The wheel doesn't need to be off the ground for the locker to be of benefit, just a difference in traction across the axle. I should have mentioned that. The effect is more noticeable the greater the traction differnece...and air has very little traction!

[@NigelNaughton]

@@L2SFBC awesome.. thanks! Great work as always. 👍

[@neutronstorm]

Thank you for content. Probably a good idea to mention that it's a good idea to lock center diff as well for the same reason when assending or decending. With diffs locked, does using the foot brake to slow the vehicle further have any disadvantages? Many advocate using engine braking only for hill decents and hill stall recovery. Is this a technique from the past where open diff vehicles were more common? Should we be teaching hdc and/or lockers with brakes for a hill stall recoveries?

[@L2SFBC]

Yes, definitely lock centre diff. I didn't cover that as otherwise where do I stop...and not all vehicles have centre diffs. You can always add braking yes, but yes but use a low gear, and that's always been a technique. The "NEVER BRAKE DOWNHILL" people are wrong then, now, and into the future. Instructors should teach everything; HDC, lockers, braking, engine braking and show how to mix and match techniques depending on the hill and the vehicle.

[@G-force_Motorsport]

I've always been a fan of using brakes on difficult descents, if you start off really slowly, ie on idle 1st low, you can always fall back to just pure engine braking. Also does make up a bit for open (non-locker) axles.

[@L2SFBC]

Agreed!

[@prbha1034]

Prado 150- Centre diff must be locked for Rear diff to be engaged

[@geofflines60]

Lockers down hill. Nice. 👍

[@jbjb3372]

Have you ever considered/reviewed the Lokka front diff?

[@L2SFBC]

No and no.

[@brunoterlingen2203]

Robert, could you do a video on the Aussie "Lokka" product, a locking device fitted inside the diff. Re HCD, why don't manufacturers use a simple rheostat so that the driver can "dial-in" the decent speed - much like the old hand-throttle technique?

[@L2SFBC]

No, because there wouldn't be much demand for such a video. I have to think of what most people would want. I only have a limited amount of time!

[@brunoterlingen2203]

@@L2SFBC Thank you for your reply.

[@impactodelsurenterprise2440]

Can you use the HDC for offroading other than hill descent? They look awfully similar to jeep's bracking lock differential.

[@L2SFBC]

HDC is only for descents. BLD is Brake Traction Control, see my video on that.

[@jamesmcmillan2656]

How would twin lockers have performed compared to traction control? Enjoy your stuff.

[@Agent.K.]

I think it’ll be more controlled 🤔

[@L2SFBC]

Would have been even slower as the front would have been controlled in the same way as the rear. But I've only got a rear locker.

[@Ozjourney]

@@L2SFBC I find using both lockers it is more controlled but it is very difficult to judge when you are about to loose traction and should this happen you are suddenly in a 4 wheel slide and have to power out of it, not for the faith hearted.

[@L2SFBC]

Definitely, you have identified something to be careful of with lockers - it's all traction or none. You see this when acending, the back end can slide out for example.

[@r1chardarcher]

How about using the brakes yourself, not HDC downhill? You mention that in the Facebook post. I drive a manual 105 petrol Cruiser, and I’d almost have to drive down that hill, as my 1st low is actually very slow. No lockers though.

[@L2SFBC]

Absolutely you can brake downhill - if the wheels slide then reduce slight the brakes (NOT jump off) then reapply. The old "never brake downhill" advice is wrong.

[@operation4wheelz]

That’s your first gear low? 😮

[@L2SFBC]

yes - the Ranger doesn't have a super low crawl ratio like a Defender or Rubicon.

[@contributor7219]

@@L2SFBC That said, I think your generation Ranger has around 43:1 reduction in low first and the most-used combination in Landcruisers is around 38:1, so for factory reduction the Ranger is pretty good.

[@franciscogrez1831]

Is there a reason you didn’t do rear locker and HDC together

[@L2SFBC]

My car won't do it

[@anthonyking9284]

Hdc is rubbish down very long decents, it will burn the brakes out and get you in some serious trouble

[@davidhastings7714]

HDC where is the fun in that, you may as well stay home and play Xbox.