When to use 4WD high?

[Not_Invented_Here_]

Citing Jerry and other members from my reading on this forum here...Even on real wet pavement, you don't necessarily need 4H. This is anecdotal of course but I've driven mine in A LOT of rain since I got it and I've had zero issues on wet roads. The general consensus seems to be follow the explanation/advice in Kathy's quoted post above.

 

[mots]

Here is a VHS tape that came with the Wrangler. It has some good tips on 4WD and it’s usage. I watched this after I bought mine about 9 months ago and found it helpful. One thing I found interesting was when he talks about how to compensate if you can’t get your manual trans into reverse easily, by allowing the weight to settle in neutral and then to try again back in R. I had some local guy telling me that my transmission needed a new reverse synchro because once in a blue moon this would happen to me. I was happy to send him a link to the video

 

[mrblaine]

2H-4H is synchronized. There is nothing special to do. However, I will often press the clutch in just to satisfy the mechanical hangups in my head. I have dropped into and out of 4H at highway speeds many times. If it is isn't clear yet, I am quite cavalier in my 4H usage and implementation. I don't think much bout how I get there. 4Low is a little different.

I've reported this a few times. We have a sharp turn on gravel into the upper driveway. If you don't hit it with momentum, the rear tires spin gravel out into the street which I then have to throw back on the driveway.

When I make the turn, I don't even slow down, just grab the lever, pop into 4 hi, get up to flat ground without spinning and back into 2 hi. Works very well.

 

[mrblaine]

I'm not interested in arguing about this, I'm just encouraging the OP to do some research and make up his own mind.

If you aren't interested in arguing, then be quiet and back out of the thread because for someone who isn't interested in arguing, you are certainly resisting the point of view that it won't hurt anything in a Jeep TJ to drive it in 4 hi for extended distances.

Being one of those who has been to Moab and driven a bunch on the very phenomenal traction that is slick rock, the tires even aired down will slip when they need to and if there was any merit that driving on high traction surfaces caused damage to our t-cases, Moab would be where it shows up and it doesn't. I am one of those that puts it in 4 low/4high with both lockers on and I don't turn them off until I am off the trail. Of course, I am also one who understand how the lockers work and why turning them off, doesn't always turn them off.

 

[mrblaine]

You don't go around in Moab all day long in 4 low (at least not in a short wheelbase TJ). Making tight turns on the slick rock in 4 low is a chore. I had to shift into 2 wheel drive a couple times a day to make a sharp turn. The Jeep will just push forward. There is too much traction for it to slip. Turn the lockers on as well and you're not turning at all. It'll rip the steering wheel right out of your hand.

I have no evidence that transfer cases will blow up if you drive around on the road in 4 wheel drive but intuitively it makes sense why you wouldn't want to do it. I've forgotten to shift back into 2 wheel drive a couple of times as well. But I can immediately tell as soon as I try to take a sharp corner.

Likely my fear of heights gave me enough adrenaline strength to turn the steering wheel all day, but shifting to steer is not something I do. There again, I tend to make my steering work well.

 

[JDS123]

Likely my fear of heights gave me enough adrenaline strength to turn the steering wheel all day, but shifting to steer is not something I do. There again, I tend to make my steering work well.

I have stock steering geometry. Nothing is modified. With both my ARB's clicked in, the steering wheel will quite literally rip out of my hands if I turn too tightly. Just in 4low unlocked I can steer, but it isn't pretty, especially when trying to make a 170 degree turn on slick rock.

Would you recommend I change something within my steering setup? I will be the first to admit that my knowledge of steering is limited.

 

[mrblaine]

I have stock steering geometry. Nothing is modified. With both my ARB's clicked in, the steering wheel will quite literally rip out of my hands if I turn too tightly. Just in 4low unlocked I can steer, but it isn't pretty, especially when trying to make a 170 degree turn on slick rock.

Would you recommend I change something within my steering setup? I will be the first to admit that my knowledge of steering is limited.

We've been running upgraded boxes and pumps for a very long time. What steering linkage do you have?

 

[JDS123]

We've been running upgraded boxes and pumps for a very long time. What steering linkage do you have?

I currently have the stock drag link and a slightly upgraded tie rod that I bought a few years back. I'm looking to upgrade to Currie or Savvy steering within the next few months (still not sure which one). Everything else is stock (pump, box, etc) besides a power steering cooler (which probably doesn't make a difference).

 

[mrblaine]

I currently have the stock drag link and a slightly upgraded tie rod that I bought a few years back. I'm looking to upgrade to Currie or Savvy steering within the next few months (still not sure which one). Everything else is stock (pump, box, etc) besides a power steering cooler (which probably doesn't make a difference).

Before you start adding more power, the linkage has to be able to handle it. It would not be uncommon to bend the draglink at the adjuster with more power. Wait until you get the stronger stuff before you start making it turn when you want it to.

 

[JDS123]

Before you start adding more power, the linkage has to be able to handle it. It would not be uncommon to bend the draglink at the adjuster with more power. Wait until you get the stronger stuff before you start making it turn when you want it to.

Would you recommend Savvy or Currie for a linkage upgrade? From my understanding the Savvy stuff is stronger but it only makes sense to get it if you get stronger stuff upstream as well. When you say "add more power" are you talking about hydro assist or just putting a better pump in?

 

[98TxTJ]

I am very new to 4x4's so I was actually going to ask that question, about rain and using the 4 hi. I was curious if it would give me better traction during a rain storm or should I just stick to 2H? I drive freeway part of the way to work, then down a city street the rest of the way. I wasn't planning on using it in a light rain, but if we had a down pour, I was thinking it may help to be in 4H?

By the way, my used Jeep didn't come with an owners manual, need to find one.

It will help you go. It won't help you stop. Have to adjust speed for the conditions.

Dallas, like Sacramento where you are, goes long periods without rain. Then when it does, the roads are treacherous because of the accumulation of oil, antifreeze, and other crap that has collected during the dry spell. They're plenty slippery for 4Hi.

 

[AndyG]

Around town, usually I'll throw the Jeep into 4H after a slip or a spinning start at a stop sign. Then I'll go back into 2H sometime later when I remember that I don't need 4wd anymore.

The 4wd system isn't fragile. Use it when you need it. Run it until you don't.

Also, it's good to work out the 4wd system occasionally .

If you haven't looked into the cable system that replaces the linkage , check it out (Savvy makes one , there are others)

Lastly , I'd rather use 4wd and risk anything than smash up my Jeep.

Remember what Leslie Nielsen once said ..."you take a chance every time you stick your face in the fan"

 

[JEEPCJTJ]

Yesterday my son needed his mother's (my wife's) car to get to an interview over two hours away. She took my Jeep to work because she couldn't drive his 1995 YJ with the stick shift. I took son's YJ to a friends house and back about 35 miles total round trip. The road wasn't dry but at the most I'd say it was damp. The only time I felt anything weird was backing out of friend's driveway with the wheels turned all the way. He asked me this morning if I took it out of 4wd when I left. Well the answer was no and even with 12.5" wide tires I never even thought about it being in 4wd. Neither of us even thought it would have caused any problem. A nice dry day I'm sure I would have known to get out of 4wd before I got out of my driveway.

Today we started getting snow a couple hours before a 20 mile round trip in my TJ. I switched back and forth from 2wd to 4wd hi while moving several times. I even put in 4wd low at a red light and locked both axles a couple of times for short distances just to make sure everything keeps working. I wish we'd have gotten more than 4 inches

 

[AndyG]

Basically a synchronized 4 Hi is designed to be accessible most anytime, anyplace , any speed. It’s there for all the times 4 lo is impractical.

I have never , ever seen transfer case damage from 4hi use ....not saying it can’t happen...just never seen it.

I totally agree if traction were the killer , more Jeeps would be towed out of Moab than any where. Those rocks are like 50 grit sandpaper .

My thought is use it any time you feel like you need it ...it’s part of the fun of owning a Jeep or any 4WD.

 

[tworley]

Only if I notice that I start slipping/sliding will I put it in 4hi, and I'll do it at whatever speed I'm traveling. On the trail I'm in 4lo and I won't switch back until the end when I'm aired up and back on pavement

 

[Mr. Bills]

@jjvw and @RubiconMike are both correct. The transfer cases in Jeep TJ's/LJ's are not fragile and need not be babied. 4WD high range should not be used on clean, dry pavement.

The 2006 Jeep Wrangler Owner's Manual reads, at pp. 196-197:

2H Position
Rear Wheel Drive High Range — Normal street and highway driving. Dry hard surfaced roads.

4H Position
Four Wheel Drive High Range — Locks the front and rear driveshafts together. Forces the front and rear wheels to rotate at the same speed. Additional traction for loose, slippery road surfaces. NOTE: This range should not be used during dry pavement operation.

N (Neutral)
Position Neutral — Disengages both the front and rear driveshafts from the powertrain. To be used for flat towing behind another vehicle. . . .

4L Position
Four Wheel Drive Low Range — Locks the front and rear driveshafts together. Forces the front and rear wheels to rotate at the same speed. Additional traction and maximum pulling power for loose, slippery road surfaces only. Do not exceed 25 mph (40 km/h).

[Emphasis supplied.]

Note that the manual reads that one should not use 4H on dry pavement, whereas for 4L the manufacturer is more adamant, instructing that we do not exceed 25 mph in low range. Words have meaning and it must be presumed that the manufacturer intended a particular choice of words when it published it's comprehensive owners manual. Should not is advisory; do not is mandatory. That should tell us something about whether we need to go all Chicken Little about how dry the pavement needs to be if we are in 4WD high range.

By the way, here is the shifting procedure for 2H-4H-2H from the 2006 Jeep Wrangler Owner's Manual at page 197:

Shifting Procedure
2H to 4H or 4H to 2H
Shifting between 2H and 4H can be made with the vehicle stopped or in motion. If the vehicle is in motion, shifts can be made up to 55 mph (88 km/h). With the vehicle in motion, the transfer case will engage/ disengage faster if you momentarily release the accelerator pedal after completing the shift. Apply a constant force when shifting the transfer case lever.

The fact that the transfer case can freely be shifted from 2H to 4H and back at up to 55 mph further illustrates that our transfer cases are quite rugged and do not need to be babied.

Bottom line: Follow the procedures in the owner's manual whenever possible and use common sense.

 

[jjvw]

... and use common sense.

shifts into 4H, mid-burn out

 

[Mr. Bills]

Sticks head in hot oven to gauge temperature

 

[mrblaine]

@jjvw and @RubiconMike are both correct. The transfer cases in Jeep TJ's/LJ's are not fragile and need not be babied. 4WD high range should not be used on clean, dry pavement.

The 2006 Jeep Wrangler Owner's Manual reads, at pp. 196-197:

[Emphasis supplied.]

Note that the manual reads that one should not use 4H on dry pavement, whereas for 4L the manufacturer is more adamant, instructing that we do not exceed 25 mph in low range. Words have meaning and it must be presumed that the manufacturer intended a particular choice of words when it published it's comprehensive owners manual. Should not is advisory; do not is mandatory. That should tell us something about whether we need to go all Chicken Little about how dry the pavement needs to be if we are in 4WD high range.

By the way, here is the shifting procedure for 2H-4H-2H from the 2006 Jeep Wrangler Owner's Manual at page 197:



The fact that the transfer case can freely be shifted from 2H to 4H and back at up to 55 mph further illustrates that our transfer cases are quite rugged and do not need to be babied.

Bottom line: Follow the procedures in the owner's manual whenever possible and use common sense.

The problem with that is yet again, wheeling in Moab. It was described as 50 grit sandpaper and I think it is more like 24 grit. Not worn down ready to toss it 24 grit, but new get ready to remove some material with a purpose 24 grit. It is anything but the condition described in the blurb- loose, slippery road surfaces only with the emphasis on the key word that matters. If you use it as the manual describes, no one is going to Moab and doing any wheeling without a differential in the t-case.

That and you don't suppose the manufacturer is doing a little CYA with the 4 hi since there are a lot that won't understand the compromised handling when the traction is too high, do you?

 

[billiebob]

I was driving over loose dry snow and/or some slick ice on visible or semi-visible pavement

So in 4WD, the front and rear axles are locked to turn the same speed. In a straightline, with identical front rear axle ratios and tire sizes you can drive forever in a straightline, bare pavement or not in 4WD. There will be plenty of squirm in the tire tread to handle any gentle highway curves on the highway.

Turn into a parking lot tho and the 4WD will try to make the Jeep go straight. On dry pavement the tires will hop since the steering will work. On ice, snow, you might need to shift into 2WD to turn into a parking spot.

Turning on dry roads in 4WD really creates no more stress than turning while rock crawling in 4WD. It creates stress and is stupid to do so excessively but.... you forget to shift into 2WD and the Jeep jumps a few times is hardly an issue. If it were there would be a lot more rock crawlers breaking down.