JL Rubi - driving at highway speed on snow/ice/wet with 4H

JamesWyatt

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At higher speeds, the only thing that will make a difference in winter weather is a heated windshield. I'd give up the fold-down capability to get it, too.

But "higher speeds" and "ice" go together like "higher speeds" and "being drunk".





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jaldeborgh

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Relax, the OP's question is a fair one. A lot of folks are looking at the Rubicon who are not historically Jeep buyers but who have years of full time AWD experience, in a full range of driving conditions. This demographic, myself included, are wondering the same thing, which is, the jeep is not the best handling vehicle in the world so learning when to switch to 4H when conditions deteriorate is going to be a new judgement thing, something new to the full time AWD crowd. Also, understanding how wide is the operating window, not wanting to damage the vehicle would be helpful. There are a lot of contributors on this blog with tons of experience and it would be greatly appreciated to get the benefit of their real world experiences and perspective.
 

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Using High 4 on wet slippery roads at highway speeds may slightly increase wear on driveline components but should not cause severe harm. Following Rally driver Darren Skilton in his Hemi Powered Grand Cherokee in the NORRA Mexican 1000 at high speeds through Baja I saw the benefit of High 4. I have used High 4 in my Jeep TJ at speeds of 50 to 60mph for 100 mile stretches on snow and ice with out harm. High speed cruising on dirt roads in Baja I use 4 High for better traction during acceleration and engine braking. Lastly in my thirty plus years in emergency response in the Eastern Sierra I have not seen severe damage done driving for extended periods in slick conditions in 4 High.
 

maxmk8

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Lockers don't work past 25mph so a rubicon is apparently useless above that speed.
 

Ozarkpaddler

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Just because you can drive highway speed limits in ice and snow doesn't mean you should! I've lived in northern Wisconsin and in Colorado as well as back here in my native Ozarks. I've seen too many accidents, both as a driver and as a nurse, because people mistakenly believe AWD and 4WD means you don't have to slow down. Just last Friday we had a nasty ice/sleet event and I sanely drove home in 4WD H in my F-150 at 30-45 depending upon the conditions. My commute is 91 miles and I saw probably 3 dozen vehicles, most AWD and 4WD's, on the shoulder and in the median. Maybe I should be ashamed, but my two well used tow ropes went unused that day because I'm pretty certain they didn't get there by driving 45mph? If you're driving on snow or ice, SLOW DOWN!
 

FunWagon

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Full time systems are REACTIVE. They are normally really in two wheel drive or like a 70/30 split front to back.

(by the way they can’t control left to right power to wheels... if the L wheel is slipping then all power goes to the slipping wheel... this is so your vehicle can turn when you tell it to... unless you have locking differentials like the Rubicon which allows you to lock the left to right power at 50/50, at slow speeds and in loose ground of course)

When full time systems detect slippage they react by evening out the front to back power. Hopefully at highway speeds they react fast enough, and still have no control left to right power, otherwise you wouldn’t be able to turn.

Part time systems are PREVENTIVE. When engaged they are locked at 50/50 power front and back. Their use is not a factor of speed as far as I know, but they should definitely not be used on dry pavement (ground that does not give), so to not ruin the gears. I also question myself in some conditions if the road is slippery enough to engage 4WD.

Unless you have locking differentials, like the Rubicon, no matter what 4WD/AWD system you have, if both wheels on one side of your vehicle (e.g. left) are slipping then they get all the power, and the wheels on the other side (e.g. right) that have a better grip get no power.
 

Kajmcbride

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Ozarkpaddler brings up a very good point that you need to drive at a safe speed for the conditions. I was just sharing my experience that driving highway speed driving in 4 High has not damaged the driveline. In no way am I condoning driving faster then safe for the conditions on open public highways. My high speeds in 4 high have been on closed roads and off road race courses.
 

old8tora

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Sounds like this OP dude wants to keep his AWD Subaru and LandRover . A Jeep owner just goes for it , and lets it rip , and then instinctively knows what to do whilst speeding through the snowy forest in 4-H . This OP dude must have forgotten the feeling to ask such a question .
 

old8tora

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At higher speeds, the only thing that will make a difference in winter weather is a heated windshield. I'd give up the fold-down capability to get it, too.

But "higher speeds" and "ice" go together like "higher speeds" and "being drunk".
Don't give up the fold-down capability; if you fold the windshield down in a blizzard you won't care whether it is heated or not .

Excellent point about higher speeds and ice ; that's also a barrel of laughs .
 

yell03

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I also have owned many AWD SUVs and currently my wife has a 2019 Lexus GX460, very nice to just drive in any conditions without any extra thought.
I have a 2018 Ford Raptor and a 2018 Jeep Wrangler JLU Rubicon.

In the Raptor at higher speeds I use the 4A (4 auto mode) and slower speeds 4H if it is snowing, 4A any time it is raining.

The Rubicon if it is snowing and the road is covered at all (even a thin layer like 1") I use 4H at any speed. On the highway in the Jeep in bad snow i am not going to be going that fast anyway.
My son who has owned more Jeeps than I have disagrees and only uses 4H if the road is really covered and prefers 2wd on the highway unless it is covered in deep snow.

He won't use 4H over 40mph no matter what.

I will be in 4H if there is any snow over 1" on the road and just keep my speed down.

Slowing down on my 35x12.5 Toyo MTs won't be easy anyway.
 

liquids

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My Defender and my Disco both have high centers of gravity and I drive them at highway speeds on wet/snowy roads all the time. Anyone who owns a LandRover does this routinely (whether RangeRover, Disco, Defender, LR3, LR4); they're all full time.
Do what you do with your other vehicles with your Rubi. Put it in 4H, drive like you want. It's tough enough not to care if you hit a dry straight patch for a while. If you're concerned about stresses building up on the gears, put two wheels in light now for a couple seconds to give them a chance to "slip" back into synch with the other two.

Note that snow and ice should not be gouped together as far as traction characteristics are concerned. But you probably know that already.
 

nerubi

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I've been at 75-85mph in 4 Hi on dirt in my JKU and it was fine.
Two questions - why would you be in 4wd on a dirt road and why would you be going 85 on a dirt road?
 

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