Engine Braking For Steep Downhill Grades with a 2013+ Range Rover

[greynolds]

I posted a question similar to this on the L405 (2013+ Range Rover) forum at RangeRovers.net, but so far the answers haven't been exactly enlightening for something that I would have expected people to have run into by now (unfortunately, many on that forum are more interested in which 22" rims they should get rather than going out exploring...). So I figured I'd run this by you guys...

With every other car I've ever owned, I've just changed from D to a lower top gear selection (so typically from D to 4, 3, or 2) to handle steep grades and used the brakes as needed when engine braking wasn't sufficient. By steep grades, I'm talking about a long downhill grade at speed, such as the 6% (or steeper) grades on the Bear Tooth Highway, the Million Dollar Highway, Wolf Creek Pass, etc.

With the 2013+ Range Rover (mine is a 2014 HSE, with the V6 SC engine), it looks like I've got a choice of leaving the transmission in D (normal drive) mode and using the paddle shifters, switching the transmission to S (sport) mode and using the paddle shifters, or using ASL (Automatic Speed Limiter, which is essentially an alternative version of cruise control). This is my first vehicle with paddle shifters. In my driving so far, I've just used D mode and haven't bothered to use the paddle shifters as I really haven't had a need (I live in the Boston area where the roads are more or less flat). I'm preparing for a trip to Newfoundland the middle of next month and though I don't think we'll run into many steep grades, I want to plan ahead rather than come across a steep grade and not know what to do, especially since my brother and father will be doing some of the driving.

In D mode, you can use the paddle shifters to go into "temporary manual mode". It reverts back to automatic mode if you don't actively use the paddle shifters. So on a long grade, this wouldn't be a good choice as the transmission would revert to automatic mode after a relatively short time and engine braking would be lost and I'd be forced to just ride the brakes which obviously isn't ideal.

If I switch to S mode and use the paddle shifters, the owner's handbook implies that permanent manual mode means that I have to do ALL up and down shifting manually, rather than setting the top gear and letting the transmission taking care of any down shifting and up shifting to the top gear that I've chosen, which is how all other previous vehicles I've owned have worked. So this doesn't seem exactly ideal either.

I think ASL may do what I'm looking for, but there isn't much of a description in the manual to indicate how it functions. The manual does include this warning:

"In certain conditions, such as a steep downhill gradient, the vehicle speed may exceed the set speed limit. This is because engine braking is unable to maintain or reduce the vehicle speed, driver intervention may be required."

That warning certainly implies that ASL will downshift the transmission as needed to maintain the user selected maximum speed, but only to the point where it won't damage the engine / transmission. So on a really long, steep grade, I might have to use the brakes to help it out - which is what I would expect.

I'm sure lots of the people on this forum have dealt with long steep grades before. So any advice on the best way to handle them with the options I have available?

 

[tacr2man]

Land rover have obviously found during testing that engine braking when in ASL will not deal with all scenarios , and therefore will require braking assistance from driver . In trucking it used to be that you went down hill in the gear that you went uphill , this had the side effect that it was slow down as it was up . That led to modifications that could boost engine braking , eg exhaust brake , jake etc . That option isnt available for a Range rover or other small vehicles . Therefore the only answer you are going to get it either put in ASL and use brakes when needed , or select a very low gear and have a slow trip downhill. I am sure from experience that brakes on Landrovers since the intro of disc brakes has always been adequate for the usage of vehicle . HTSH

 

[greynolds]

Land rover have obviously found during testing that engine braking when in ASL will not deal with all scenarios , and therefore will require braking assistance from driver . In trucking it used to be that you went down hill in the gear that you went uphill , this had the side effect that it was slow down as it was up . That led to modifications that could boost engine braking , eg exhaust brake , jake etc . That option isnt available for a Range rover or other small vehicles . Therefore the only answer you are going to get it either put in ASL and use brakes when needed , or select a very low gear and have a slow trip downhill. I am sure from experience that brakes on Landrovers since the intro of disc brakes has always been adequate for the usage of vehicle . HTSH

I guess my question is more along the lines of whether ASL is intended to be used for this purpose or not, as it isn't exactly clear in the owner's handbook. Searching the web for ASL, the results were mostly about Jaguar vehicles. I got the impression that ASL is largely intended to be used to avoid getting speeding tickets by not letting you exceed a set speed when you press down on the gas pedal (unless you stomp on it, in which case ASL will be temporarily disabled).

 

[Scott Brady]

Shift into sport, but do not activate a paddle shifter. The car will downshift nicely when you depress the brake pedal, and hold a lower gear. All of the modern Rovers will downshift aggressively in sport mode and provide assistive compression braking.

 

[shogun]

I sorta question why the burning need to avoid accelerating. On a highway in a vehicle that can handle higher speeds, just let it run, its easier on the machine. If the speed limit is so important than the price for that is wear and tear on the machine.
In general, to avoid continuous braking and potential overheating, you use moderate braking to a lower speed then let it run up again and repeat rather than "riding" the brakes.

 

[greynolds]

Shift into sport, but do not activate a paddle shifter. The car will downshift nicely when you depress the brake pedal, and hold a lower gear. All of the modern Rovers will downshift aggressively in sport mode and provide assistive compression braking.

Thanks Scott - I suspect that will address my question.

 

[greynolds]

I sorta question why the burning need to avoid accelerating. On a highway in a vehicle that can handle higher speeds, just let it run, its easier on the machine. If the speed limit is so important than the price for that is wear and tear on the machine.
In general, to avoid continuous braking and potential overheating, you use moderate braking to a lower speed then let it run up again and repeat rather than "riding" the brakes.

Have you never driven down a steep mountain pass with an extended (as in several miles) 6% or steeper grade? If you do nothing to curb acceleration, you'll end up going way too fast and lose control of the vehicle. Many of the scenic mountain passes have very sharp drop offs on the edge of the road, so losing control means you could fall thousands of feet over a cliff if you lose control of the vehicle, which I wouldn't consider desirable .

On normal roads, you're right that there's really no need to worry for the most part.

 

[shogun]

Have you never driven down a steep mountain pass with an extended (as in several miles) 6% or steeper grade? If you do nothing to curb acceleration, you'll end up going way too fast and lose control of the vehicle. Many of the scenic mountain passes have very sharp drop offs on the edge of the road, so losing control means you could fall thousands of feet over a cliff if you lose control of the vehicle, which I wouldn't consider desirable .

On normal roads, you're right that there's really no need to worry for the most part.

Yes, I have. Mostly foot off the pedal will keep it within reason, but sometimes they still accelerate. In which case the moderate braking technique should reign it in. Brake pads are cheaper than engine/trans internals. Now, throw in a heavy trailer and the brakes are likely to go away also, which leaves you with the engine/trans like you originally posted, and Scott addressed.

 

[RoyJ]

Have you never driven down a steep mountain pass with an extended (as in several miles) 6% or steeper grade? If you do nothing to curb acceleration, you'll end up going way too fast and lose control of the vehicle. Many of the scenic mountain passes have very sharp drop offs on the edge of the road, so losing control means you could fall thousands of feet over a cliff if you lose control of the vehicle, which I wouldn't consider desirable .

On normal roads, you're right that there's really no need to worry for the most part.

I live in BC, where most highway grades vary between 6% to 10%+, and can last for miles on end. I have driven them in everything from sport bikes, my Z06, various family sedans / SUVs / pickups, to 50,000 lbs tour coaches, to 100,000 lbs heavy spec semis.

In my experience, with anything less than 10,000 lbs, brake fade is not a real concern. As long as you're in A gear, and not neutral, most would reach a terminal velocity of 70 - 85 mph. Downshift to a point where you're taching 3000 rpm at 70 mph, and most vehicles of decent power to weight ratio would hold itself with very minimal braking required.

You RR being a fairly high performance vehicle, I wouldn't be worried the slightest about not being able to hold itself. Like others have suggested, tap the brakes in Sport mode and let the transmission downshift a little, and you should be good for just about any grade. If need be, brake. Those big rotors you have will take anything you throw at it.

The manual have to word things in a way to meet legal liability requirements; a lot of things are blown out of proportion. In terms of braking force and rotor swept area, your truck has more than double of say, a 90's Explorer or Jimmy. And yet, even those trucks rarely run into brake fade. Come for a ride in my 28,000 lbs bus with a Detroit 2 stroke, ZERO engine braking, and no jakes, then you'll see what brake fade and down shifting is all about!

 

[greynolds]

I live in BC, where most highway grades vary between 6% to 10%+, and can last for miles on end. I have driven them in everything from sport bikes, my Z06, various family sedans / SUVs / pickups, to 50,000 lbs tour coaches, to 100,000 lbs heavy spec semis.

In my experience, with anything less than 10,000 lbs, brake fade is not a real concern. As long as you're in A gear, and not neutral, most would reach a terminal velocity of 70 - 85 mph. Downshift to a point where you're taching 3000 rpm at 70 mph, and most vehicles of decent power to weight ratio would hold itself with very minimal braking required.

You RR being a fairly high performance vehicle, I wouldn't be worried the slightest about not being able to hold itself. Like others have suggested, tap the brakes in Sport mode and let the transmission downshift a little, and you should be good for just about any grade. If need be, brake. Those big rotors you have will take anything you throw at it.

The manual have to word things in a way to meet legal liability requirements; a lot of things are blown out of proportion. In terms of braking force and rotor swept area, your truck has more than double of say, a 90's Explorer or Jimmy. And yet, even those trucks rarely run into brake fade. Come for a ride in my 28,000 lbs bus with a Detroit 2 stroke, ZERO engine braking, and no jakes, then you'll see what brake fade and down shifting is all about!

On relatively straight sections of road on highways with steep grades, getting up to 70-80 mph obviously isn't a concern. Where I'd be concerned about keeping the speed down is on roads with steep grades, sharp turns, and steep cliffs like some of the roads I've driven out in the Western part of the USA on vacations . The roads I'm talking about generally aren't classified as highways and on many of those roads, the general speed limit may be 50 mph (60 mph is usually fine, but 70 or higher is often not well advised), but will drop to 20 mph on the curves and the posted limit is that low for good reason.

 

[RoyJ]

On relatively straight sections of road on highways with steep grades, getting up to 70-80 mph obviously isn't a concern. Where I'd be concerned about keeping the speed down is on roads with steep grades, sharp turns, and steep cliffs like some of the roads I've driven out in the Western part of the USA on vacations . The roads I'm talking about generally aren't classified as highways and on many of those roads, the general speed limit may be 50 mph (60 mph is usually fine, but 70 or higher is often not well advised), but will drop to 20 mph on the curves and the posted limit is that low for good reason.

Ah I see. Well, my opinion on the RR still stands - it's probably one of the most capable SUVs for this type of work, right up there with the smaller X5s and Cayennes. I wouldn't worry about brake fade at all - if you see any other "normal" cars on the road, then chances are your RR is far above them in terms of braking abilities.

If you're simply worried about wear and tear, then you have to look at it both ways - the less shifting a transmission does, the less wear and tear on its clutch packs. Using it to slow down may end up costing more than brake pads in the long run. Personally, I'd downshift if I'm trying to hold a steady downhill speed. But I won't downshift to slow down the truck before a turn (unless in a sports car for rev matching).

 

[greynolds]

If you're simply worried about wear and tear, then you have to look at it both ways - the less shifting a transmission does, the less wear and tear on its clutch packs. Using it to slow down may end up costing more than brake pads in the long run. Personally, I'd downshift if I'm trying to hold a steady downhill speed. But I won't downshift to slow down the truck before a turn (unless in a sports car for rev matching).

Right, I've always downshifted to a gear that will keep me around the speed limit for the grade and use the brakes when needed for the sharp curves that require going slower. The transmission setup on the new RR is just different from what I'm used to, so I wanted to check what the proper technique is.

Thanks for all the replies everyone!

 

[unseenone]

Does that model have hill descent control?

 

[greynolds]

Does that model have hill descent control?

Yes, but hill descent control is for really low speed (as in keeping the speed below 5 mph), not the sort of thing I'm talking about.

 

[discotdi]

Don't use ASL for this purpose. Use sport mode and manual mode when needed. The new RR is really no different than any other LR since 2005 equipped with manual and sport mode.
Maybe you are over thinking this. If still concerned contact the LR Driving Experience. They can tell you the preferred LR way.
Enjoy your sweet new ride and Newfoundland.