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Old 09-27-2014, 07:49 PM   #1
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4 Low driving down a mountain?

I'm driving the Mt. Washington auto road tomorrow and was wondering about using 4 low for the drive down. Seems like it would be a great means of engine breaking but I've never done this before and don't know if its a good idea or not.

Thoughts?

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Old 09-27-2014, 07:51 PM   #2
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How steep is the downhill?

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Old 09-27-2014, 07:57 PM   #3
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As a rule of thumb for me, I'd generally recommend staying out of 4L on a road suitable for passenger cars.
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Old 09-27-2014, 07:58 PM   #4
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When I drive down our local mountains I use engine breaking using in 2nd or 3rd gear but in 4 Hi. 4 Lo will most likely be way to low, especially if you want to go over 20 MPH
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Old 09-27-2014, 07:59 PM   #5
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With my manual, 4L I usually have to use the gas to go down a hill. How fast you planning on going?
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Old 09-27-2014, 08:00 PM   #6
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Quote:
Originally Posted by Off Pavement View Post
As a rule of thumb for me, I'd generally recommend staying out of 4L on a road suitable for passenger cars.
I think this is the right advice. 4 Lo will have you crawling and if it is a paved road it might mess up your tires. If fact, if it is paved stay out of 4wd all together. Just downshift and let the Jeep hold itself. I just came back from driving Colorado 550 near Ouray and I was manually shifting my Auto from 1-3 depending on the curve and downhill slope. I doubt you will have any more slope than highway 550.
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Old 09-27-2014, 08:00 PM   #7
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I'm not familiar but quick image searches show that at least some of that is paved.

4wd and pavement is a BIG NO! You'll put extreme stress on your drive train and because there is no give on the road, steering will feel like it's "binding" and be extremely tough to turn.
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Old 09-27-2014, 08:15 PM   #8
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Its all paved. Don't use any 4wd at all.2nd or 3rd gear. It is possible to wipe your brakes out too. last time i went up there were no guard rails so try not to fall off. your passenger will have some nerve racking views.
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Old 09-27-2014, 08:36 PM   #9
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You should NOT use 4Lo on any surface that does not allow for tire slippage (i.e. pavement) unless you can maintain a perfectly staight line which is rarely feasible. Use your transmission by limiting to the top gear.
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Old 09-27-2014, 08:47 PM   #10
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Yes, use you transmission, not your transfer case. Never on bare roads......
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Old 09-27-2014, 08:53 PM   #11
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I've seen plenty of mini vans do it- you should be fine in high range 2wd in a low gear. Chances are you'll end up behind a brake happy day tripper in a Honda Pilot... Worth the view up top though- when I was up there in August it was 40F late afternoon, so be prepared.
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Old 09-27-2014, 09:32 PM   #12
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Just use 2 HI and drop down to what ever gear is necessary to drive at a safe speed depending on the road conditions without touching the brakes. That could range anywhere between 2nd gear to 5th. Using low range, you won't get up to double digit speeds.
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Old 09-27-2014, 09:40 PM   #13
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dont over think this. Drive up, drive down , call it a day
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Old 09-27-2014, 10:17 PM   #14
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Hmmm, I never like discussions about engines breaking.

I do love the exhaust brake on my truck though.
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Old 09-27-2014, 10:51 PM   #15
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dont over think this. Drive up, drive down , call it a day
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Old 09-28-2014, 06:17 AM   #16
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dont over think this. Drive up, drive down , call it a day
Heh. I almost didn't post this because I thought maybe I was over-thinking it. I've only used 4 Low once in the Jeep I currenly own, when I got hung up on a boat ramp.
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Old 09-28-2014, 06:18 AM   #17
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Thanks everyone for the feedback.
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Old 09-28-2014, 06:21 AM   #18
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Paved road with nothing slippery on it like snow, sand, gravel etc. = NG for 4WD. Use a lower gear in 2WD and the brakes if needed.
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Old 09-28-2014, 07:37 AM   #19
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Quote:
Originally Posted by Winston Smith View Post
I'm driving the Mt. Washington auto road tomorrow and was wondering about using 4 low for the drive down. Seems like it would be a great means of engine breaking but I've never done this before and don't know if its a good idea or not.

Thoughts?
Good rule of thumb....... whatever gear it takes to drive up the hill, use that gear to drive down the hill. Generally works pretty good.
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Old 09-28-2014, 08:21 AM   #20
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Originally Posted by Winston Smith View Post
Heh. I almost didn't post this because I thought maybe I was over-thinking it. I've only used 4 Low once in the Jeep I currenly own, when I got hung up on a boat ramp.
Enjoy the view
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Old 09-28-2014, 10:39 AM   #21
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Good rule of thumb....... whatever gear it takes to drive up the hill, use that gear to drive down the hill. Generally works pretty good.
Nice.

Added to my memory banks.

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Old 09-28-2014, 02:02 PM   #22
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Quote:
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Good rule of thumb....... whatever gear it takes to drive up the hill, use that gear to drive down the hill. Generally works pretty good.
Never heard that but it sounds right. Or let your auto trans decided for you

I often downshift my auto on steep hills to minimize use of the brakes. Nice thing about the new auto is it won't let you over rev
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Old 09-28-2014, 02:33 PM   #23
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IMO.... last I checked - brake pads are fairly cheap. Engines/Transmissions not so much.
I'll "stress" that which is easily and inexpensively relaced before I will unnesesarily load my drivetrain.
Only caveat I can think of is IF I am descending a paved road towing a load that might cause a brake failure - then I say get some help spreading the work.
Same holds true with downshifting coming to stops, that's what brakes are for.
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Old 09-28-2014, 03:29 PM   #24
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Originally Posted by scapegoat32 View Post
Its all paved. Don't use any 4wd at all.2nd or 3rd gear. It is possible to wipe your brakes out too. last time i went up there were no guard rails so try not to fall off. your passenger will have some nerve racking views.
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You should NOT use 4Lo on any surface that does not allow for tire slippage (i.e. pavement) unless you can maintain a perfectly staight line which is rarely feasible. Use your transmission by limiting to the top gear.
^^^Both of these have great advice!

You don't use 4 wheel drive on dry pavement!!!!!!!!
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Old 09-28-2014, 03:36 PM   #25
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IMO.... last I checked - brake pads are fairly cheap. Engines/Transmissions not so much.
I'll "stress" that which is easily and inexpensively relaced before I will unnesesarily load my drivetrain.
Only caveat I can think of is IF I am descending a paved road towing a load that might cause a brake failure - then I say get some help spreading the work.
Same holds true with downshifting coming to stops, that's what brakes are for.
Gotta be a flatlander.

No offense, but people who live in mountains get amused at the folks who get up in the mountains and refuse to downshift going downhill. You can smell their vehicles 1/2 mile away. You aren't going to do any damage at all to the drivetrain. Not downshifting on a long mountain downgrade will get your brakes hot enough to warp rotors and brake drums within a few minutes, even unloaded. It is much safer, and less stressful on the vehicle, to put it in a gear that keeps you at a safe speed and drive for miles without touching the brakes.
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Old 09-28-2014, 08:54 PM   #26
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Gotta be a flatlander.

Not downshifting on a long mountain downgrade will get your brakes hot enough to warp rotors and brake drums within a few minutes, even unloaded
The surprised look of someone experiencing "brake fade" for the first time is almost as precious as watching them deglaze their rotors afterward.

I've seen some folks ride their brakes all the way down a good sized mountain and you could smell the pads burning off before too long.

The clutch (or clutch pack) isn't going to be exposed to any more stress going down that it was going up. The clamping force has to be the same, but in the opposite direction. The friction surfaces are not directionally biased.
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Old 09-28-2014, 09:33 PM   #27
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Yup, the smell of burning brakes. Oooooh that smell. Downshift folks, downshift or die! When in real mountains you cannot survive on brakes alone. I always keep a wary eye on vehicles in front of me on long down hills. Watch the brake lights and you can quickly see who does not know how to drive mountains. In my opinion you should be 90% gears and 10% brakes coming down the hill.
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Old 09-28-2014, 11:33 PM   #28
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Do NOT do this on a paved road. Your drive line will bind and you may likely break something at an inopportune time. Off road use is perfectly fine.
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Old 09-29-2014, 06:10 AM   #29
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Looks like you've got a 6-speed so this probably does not apply, but the folks with the automatic transmission might be able to use that Hill Descent Assist button next to the hazzard lights.
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Old 09-29-2014, 09:48 AM   #30
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Well, we made it up and down the mountain without incident. The drive itself was different than I expected, more extreme in a way I hadn't ever experienced. I used to ski a lot, so I'm pretty familiar with driving in the mountains, but the auto road is a much different kind of driving experience.

Mt. Washington auto road is 8 miles from the base to the parking lot at the top. Average grade is 12 and 22 at times. The road is very, very narrow, with two-way traffic, no guardrails, and sheer drops literally inches from the edge of the pavement. My kids loved it. My wife was shitting bricks all the way up (and down).

I made the entire ascent in first gear. I averaged about 15 mph. With traffic, grade and switchback turns it was not possible to get into 2nd gear and 15 mph was the comfortable max speed in 1st. The Jeep ran a little hot on the way up, but we stopped frequently to let it cool down and take in the absolutely stupefyingly beautiful scenery. We explored the peak for a couple hours, had a picnic lunch and headed back down.

The trip down was also 1st gear all the way. I'd let it wind up a bit, then pump the breaks hard to get my speed back down to a manageable level (about 10 mph), and stopped frequently to let the breaks cool down.

At the toll booth to get onto the road, they provided us with a CD that provided both narrative on the history of the road and region as well as driving tips for the climb and descent.

And no, 4 low was not employed. There's a stretch of road near the peak that isn't paved, and I experimentally tried 4 high to see if it would slow my descent, but it didn't. I guess Wrangler 4WD has come a long way since my first Wrangler back in 1994 - 4WD drives much like 2WD, in terms of power, handling, etc.

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