Downhill driving help!

My rule of thumb is to go down a hill with the same number of lockers on as you used to go up it. Same gear too, or one lower if needed. If you're talking steep off-road downhill sections, then yes, you shouldn't need to use the brakes much at all if you have the right gear, but you I would say you can use a gear to prevent gaining speed if you are going slow enough, it doesn't tend to help you scrub speed. So say you are in second, and still gaining speed, at that point I would not just shift to first, I would slow down considerably, shift to first, then ease off the brakes. If you keep gaining speed them you are geared too high, or just have too small of an engine possibly to hold your speed.

When I am going down steep hills I am usually in 4-low, 1st or 2nd gear and that keeps me around 3-6mph. That said I have had trucks that just didn't have enough engine braking or a low enough gear for that to work. That's actually how hill descent control got invented according to a story I heard once, Land Rover was embarassed that one of their new models of soft roaders wouldn't control it's speed well when following their Defenders down hills, so they asked their engineers to come up with a fix (it didn't have a transfer case with a low range) so they made hill descent control.

Also, if you have that feature, use it.
 
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That was the right move: shifting the auto to 1. You want engine braking in order that you can minimize use of the brakes. Importantly, you want to be able to go slow, but without sliding a tire(s), so you want to be light on the brakes unless you really need them. If you've got a reduction drive/transfer case, 4 low is often the right call for descending.
 
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Downhill issues were the main reason I switched my Subaru Forester to a true 4x4 with a low gear transfer case. While with a simple AWD vehicle with decent ground clearance like a forester, Outback you can visit many places and have a lot of fun, descending long slopes in a controlled low speed is a another issue. Coming down in the Pyrennes mountains in Spain, I had a 2007 Forester, automatic, 4 gears only. Had to stop like every 15 min to cool off the brakes to avoid brake fading.
Some newer vehicles with a 8, 9 even 10 speed auto, do a bit better.
 
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The use of lower gear is definitely the right way to go and a light touch on the brakes. That is the reason that you have to stop part way down Pike's Peak for the brake check, people using brakes instead of gears to control their speed on descent and overheating the brakes.
This was a great question.
 
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IMHO, people are far too hesitant to use 4LO, and depend on braking far too much. Ideally I like to go downhills using the service brakes as absolutely rarely as possible, saving them for a potential emergency. I'd rather go into 4LO and be able to shift between a few gears in the trans to dial-in the engine braking than be up in 4HI or 2WD and be stuck with just what 1st gear can do, for better or worse. Also, depending on your rig you'll find getting into 4LO means you can get into torque converter lock, which makes the engine braking more effective/consistent. In my pickup I find I run 4LO and mostly between 2nd and 4th in the trans, in the WJ it's 4LO and more like 2nd/3rd with 1st being hyper aggressive in both.

-TJ
 
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MIght not be directly related to this, but at least in Europe most 4x4 are diesels with a huge down low torque, so many people don't fell the need to go low when off-roading, unless there is a very difficult terrain, or big slopes. This is a mistake, specially on vehicles with an automatic gearbox, it will overheat or at minimum, stress the gearbox. Best is go low, even if it is not a very difficult terrain but you drive for hours at maximum 30 km/h...
 
4Lo and the appropriate gear. Otherwise, Crawl Control is your DAC in a 22 T4R TRD Off Road.
 
tjZ06 said:
IMHO, people are far too hesitant to use 4LO, and depend on braking far too much. Ideally I like to go downhills using the service brakes as absolutely rarely as possible, saving them for a potential emergency. I'd rather go into 4LO and be able to shift between a few gears in the trans to dial-in the engine braking than be up in 4HI or 2WD and be stuck with just what 1st gear can do, for better or worse. Also, depending on your rig you'll find getting into 4LO means you can get into torque converter lock, which makes the engine braking more effective/consistent. In my pickup I find I run 4LO and mostly between 2nd and 4th in the trans, in the WJ it's 4LO and more like 2nd/3rd with 1st being hyper aggressive in both.

-TJ
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Saw this phenomenon on Highway 14 above Ceder City UT. A 24 ft U-haul box truck used their service brakes coming down the S grade above the college annex, and was pulled onto the side with smoking brakes. I bet they were glad to get it stopped, as you could smell the brakes a mile up the road from where they had stopped. I am sure they never took it out of "DRIVE". Lesson learned.
 
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