Descending a steep hill

Descending a steep hill

Author
Discussion

Ayahuasca

Original Poster:

27,428 posts

286 months

Saturday 17th June 2017
quotequote all
I was always told to keep feet off everything and descend in 1st low range under engine braking. Defender 110.

However, this instructor (minute 21):

https://m.youtube.com/watch?v=TsY5umMfUxg

States that the hill is too steep for engine braking, so goes down with the clutch pedal depressed and riding the brake!

Any views on whether this is good advice, or insane?







richs2891

902 posts

260 months

Sunday 18th June 2017
quotequote all
Using the brakes is less stress on the vehicle (this is what down hill descent does / uses on more modern off roaders),
the clip does go onto explain that would use engine braking as backup, so I do get the logic in that circumstance.
Though I think I would want to try it first in a less extreme environment first as I see the potential for a wheel locking and causing a worse situation.

Not sure if that would be the right or best technique in typical UK conditions, hopefully someone else can offer some views

KevinCamaroSS

12,287 posts

287 months

Sunday 18th June 2017
quotequote all
Insane. Use engine braking as primary speed control. If getting a little too fast a light dab of the brakes (without locking up) is possible.

Using brakes without the engine coupled to the wheels is a recipe for lockup, flip and rolling the car.

Derek Chevalier

4,109 posts

180 months

Sunday 18th June 2017
quotequote all
Ayahuasca said:
I was always told to keep feet off everything and descend in 1st low range under engine braking. Defender 110.

However, this instructor (minute 21):

https://m.youtube.com/watch?v=TsY5umMfUxg

States that the hill is too steep for engine braking, so goes down with the clutch pedal depressed and riding the brake!

Any views on whether this is good advice, or insane?
I think the reason in that clip is because the ground is undulating, and as the modern Defender has such poor articulation it was probably likely that wheels would have lifted and the car would've shot forward

Derek Chevalier

4,109 posts

180 months

Sunday 18th June 2017
quotequote all
KevinCamaroSS said:
Insane. Use engine braking as primary speed control. If getting a little too fast a light dab of the brakes (without locking up) is possible.

Using brakes without the engine coupled to the wheels is a recipe for lockup, flip and rolling the car.
I'm not aware of Land Rover disabling Hill Descent Control for safety reasons?

C Lee Farquar

4,087 posts

223 months

Sunday 18th June 2017
quotequote all
Land Rover didn't bother fitting hill descent to Defenders in the first place, so no an option in the video.

I can see his point in the video that anti stall can cause the vehicle to push on more that you'd like when using engine braking.

I like the feedback from engine braking, and on such gentle slopes they could have gone up a few gears.


Derek Chevalier

4,109 posts

180 months

Sunday 18th June 2017
quotequote all
C Lee Farquar said:
I can see his point in the video that anti stall can cause the vehicle to push on more that you'd like when using engine braking.
He is referring to anti stall when using the brakes, not when using engine braking

InitialDave

12,235 posts

126 months

Sunday 18th June 2017
quotequote all
I'm not sure how valid his point on anti-stall is. As long as you select a gear such that the engine wouldn't be trying to go below idle rpm for your intended descent speed, it should make no difference.

In those circumstances, I would use engine braking with light brake pedal pressure as needed to assist. You encounter the "engine braking is insufficient" a bit earlier with stuff that has small petrol engines, and this technique works well there, so no reason it wouldn't apply in this case.

So I think he's wrong, and his "inexperienced instructors" dig is misplaced, but I'm willing to give the benefit of the doubt if there's an oddity relating to how the anti-stall operates.

Derek Chevalier

4,109 posts

180 months

Monday 19th June 2017
quotequote all
InitialDave said:
I'm not sure how valid his point on anti-stall is. As long as you select a gear such that the engine wouldn't be trying to go below idle rpm for your intended descent speed, it should make no difference.
The anti-stall is in relation to slowing the car using the brakes, not using engine braking. His point makes perfect sense

InitialDave

12,235 posts

126 months

Monday 19th June 2017
quotequote all
Yes, I know what he said, and the context.

I'm questioning why anti-stall would be a factor provided you did not try and force the rpm below idle speed by braking.

caelite

4,282 posts

119 months

Monday 19th June 2017
quotequote all
Low range and in 1st gear, foot covering the brake with minimal pressure applied, has never failed me personally.

Of course with hill descent control allowing it to use the brakes is perfectly safe as the brakes are electronically balanced to prevent lockup, without it however I would be very careful using the brakes manually as any lockup can easily have you slipping sideways.

It does get really interesting trying to descend a steep gravel slope with a heavy trailer mind, we tend to push the brake pressure in the trailer brake controller way up so the trailer wheels lock up, then drag the trailer down like a sled allowing it to slow you down.

brrapp

3,701 posts

169 months

Monday 19th June 2017
quotequote all
I think that in situations where skill and judgement are required, you shouldn't make generalized statements on what should or shouldn't be done. In off road driving, there are a lot of different factors to take into account and seldom find exactly the same set of circumstances on two or more separate occasions.
Saying that though, I can't think of an instance where I would 'freewheel' down a steep, slippery slope using just the brakes. Why not use a higher gear to give some retardation without locking the wheels completely and use the brakes to give the finer control?
I occasionally do descents of shale slag heaps, often 50m+ of 45degree+ slope on loose shale. My usual way to descend these is 3rd low (series landrover), some revs, and left foot braking for fine control, but I wouldn't tell anyone to do this every time. It's more important to read the situation and use your experience to decide which gear/brake combination to use.

Derek Chevalier

4,109 posts

180 months

Monday 19th June 2017
quotequote all
InitialDave said:
I'm questioning why anti-stall would be a factor provided you did not try and force the rpm below idle speed by braking.
It wouldn't

Derek Chevalier

4,109 posts

180 months

Monday 19th June 2017
quotequote all
caelite said:
Of course with hill descent control allowing it to use the brakes is perfectly safe as the brakes are electronically balanced to prevent lockup, without it however I would be very careful using the brakes manually as any lockup can easily have you slipping sideways.

.
I'd be surprised if there were much difference in the ABS calibration between you applying the brakes manually and HDC doing it for you.

InitialDave

12,235 posts

126 months

Monday 19th June 2017
quotequote all
Derek Chevalier said:
It wouldn't
So why is he saying to descend on the brakes only, with that as the justification?

That's the bit I don't understand. Brakes in addition to engine braking is perfectly sensible and useful.

caelite

4,282 posts

119 months

Monday 19th June 2017
quotequote all
Derek Chevalier said:
caelite said:
Of course with hill descent control allowing it to use the brakes is perfectly safe as the brakes are electronically balanced to prevent lockup, without it however I would be very careful using the brakes manually as any lockup can easily have you slipping sideways.

.
I'd be surprised if there were much difference in the ABS calibration between you applying the brakes manually and HDC doing it for you.
Honestly I can't comment from experience on that one, none of the motors I frequently offroaded with had/have (working) ABS. Although judging from my own experiences utilising ABS on gravel and other less than ideal road surfaces I would say it's a different system designed for a very different task (i.e it'd be shyte on a slippery slope).

Then again I've never driven anything with HDC either. Hopefully someone with more experience driving stuff built within the last decade offroad can come and enlighten us, that is if they aren't stuck halfway up a hill with leccy troubles. biggrin

Ayahuasca

Original Poster:

27,428 posts

286 months

Monday 19th June 2017
quotequote all
There is a clip on Youtbe somewhere of a Defender descending a steep quarry hill under engine braking, then the guy applies the brake near the bottom and the vehicle goes out of control and topples over.





Derek Chevalier

4,109 posts

180 months

Monday 19th June 2017
quotequote all
InitialDave said:
Derek Chevalier said:
It wouldn't
So why is he saying to descend on the brakes only, with that as the justification?

That's the bit I don't understand. Brakes in addition to engine braking is perfectly sensible and useful.
If you listen to the bit afterwards he mentions the cross axle. Before going down the hill I believe he had spotted it and therefore concluded that engine braking wouldn't be ideal during this section as it would be inconsistent when wheels lost grip

If you watch at 04:28 here - he blames the anti stall, but watching the vid I'm convinced it's wheels losing traction on the uneven ground

https://www.youtube.com/watch?v=PMhOhT5nwZk

LandRoverManiac

402 posts

99 months

Monday 19th June 2017
quotequote all
I don't get it either - going down any slope with the clutch down would have got me a good telling off. Anything that entails suddenly loading/unloading the drivetrain such as dipping-in-dipping the clutch would potentially unsettle things.

My instructor always said to use the gears/engine-braking to regulate your speed (selecting the relevant gear beforehand - not changing your mind halfway down), with a foot covering the brakes as backup only if you REALLY, REALLY need them. In most cases it's fighting your natural instincts to dab the brakes - keeping your feet off the pedals and ensuring you go down at a near-as-perfect perpendicular angle.

Just to add - if the hill is *that steep* that you can't tackle it in low-1st in a Defender (which is incredibly low-geared as it is), perhaps don't go down it in the first place if you're worried about damage to the vehicle?

Derek Chevalier

4,109 posts

180 months

Monday 19th June 2017
quotequote all
LandRoverManiac said:
Just to add - if the hill is *that steep* that you can't tackle it in low-1st in a Defender (which is incredibly low-geared as it is), perhaps don't go down it in the first place if you're worried about damage to the vehicle?
I don't think the steepness is the issue, more the fact that the surface is uneven.