how fast in 4wd?

Well, it started spitting some snow yesterday morning and I realized I have never driven my jeep in 4wd on the road (only on rough unpaved mountain roads). Should the weather turn nasty this winter and I need to put it in 4wd to get to work, what is the top speed I should drive in 4H? I have a 62 mile round trip commute to work and back, 75% of it freeway driving. I can take back roads posted at 45mph or less if necessary. 1974 CJ5 with stock transmission and transfer case. I don't have an owner's manual....

 

Technically, you can drive as fast as you want in 4HI. However, remember that 4WD does nothing about the stopping distance needed at those speeds, nor does it change the lateral skid resistance around corners. It does change the way the engine power is transferred to the wheels, and how the car (Jeep) responds to the throttle. If you are trying to drive fast on a rough surface, it can help.

Despite this, I'd expect that if there's enough snow on the road to need 4WD for simple traction, you should be moving at way below highway speeds. Most cars will be off the highway, and braking and visibility will limit your speed.

 

Remember that just because you have it in 4-Hi doesn't mean you are invincible.

And that you want to drop out of 4-hi when you run on dry pavement.

Don't drive any faster than your brakes, whether in 4x4 or 2x4, and be ready for skids. Plan on extra time - leave earlier. Watch out for idiots, rain and snow really makes them come out of the woodwork!monkeys

And stay off of the sidewalks - That's where I drive!R)

 

I'd say that if the roads are bad enough to NEED 4WD, you'll be able to drive as fast as conditions allow. I never use 4WD on the street except on glare ice and in deep snow. If 2WD works, that's what I stay with.

Keep in mind that sometimes 4WD is worse than 2WD, thick smooth ice in high winds comes to mind. If you get all four wheels spinning, wind and momentum will push you right off the road. I've had it happen a couple times.

 

x2 on no 4WD on the highway. If you need it, stay in 2WD and drive slower. The purpose of the differential is to allow one wheel to go faster than the other on the same axle. There is no differential between the rear axle and the front axle. In 4WD with no loss of traction, the drive line will bind up and bad things can happen. Be very careful turning in 4WD.

Now in fresh snow, or icy roads, I'd use it buy I'd stay at a slow speed. As soon as I get on a road with any traction where 4WD is not needed, I'd shift to 2WD.

 

Do you just shift the transfer case lever or do you get out of the jeep and unlock the hubs each time?

The only other 4wd vehicle I have ever owned was a '93 Ranger and it just had a button on the dash to engage/disengage 4wd.

But yes, I've driven in the ice/snow numerous times, even in blizzard conditions. What I didn't know was if there was a certain speed I should not exceed while in 4H.

 

Naw, you can leave them locked when the weather is bad. Then just shift into 4hi when you need it. Once the weather clears then unlock them.

I have never driven even the speed limit when I have needed 4hi on the roads in my Jeep. I should say on 45mph or greater roads.

Yes, driving faster than your braking ability will be bad as well. That's why you see so many 4X4's in the ditch, or rearending people when the weather is bad. They all think because the GO pedal works so well that the WHOOA pedal will tooR)

High5

 

Just to reiterate, as Tim stated above, there's nothing mechanical that limits how fast you can drive in four wheel drive, the limits are all outside the vehicle.

 

Being from AK I've had some experience with this...

First, if there is going to be ice or snow pack, have your hubs in. Assuming you don't have a front locker, this shouldn't adversely affect handling. Your font axleshafts will turn, your mileage will dip slighty. You don't want to have to get out every time you put it in 4wheel.

With a vehicle this short, if there is frost/ice/snow on the road have it in 4wd. As noted above it will not help you stop. That's not the point though. It will help you not spin out every time you hit an expansion joint or try to steer. Stability is the trouble, not stopping distance.... stopping isn't really an option if it's really slick you'll need to steer; that's where the 4wd will help you.

Stay away from the brakes anyway - they will wreck you quicker than almost anything else. Leave lots of following distance. I've cruised at 65 in 4wd in a pickup on an open highway with ice pack and little traffic. Tearing up the 4wd isn't going to be the problem at that speed, keeping your short wheelbase rig off its lid will be, I would take those 45mph side roads.

 

I have a 74 renegade, and I don't trust it on hot dry pavement at over 55, so I would say in snow that requires all four wheels to turn, I would probably try around 30, but keep in mind to have enough speed to make it over hills (im in Tennessee we breed hills here) once you spin going up hill in the snow (especially on the north side), you get to enjoy sliding all the way back down the hill. I have learned that short wheel based 4x4s like jeeps and samurais like to spin like tops in the event of a "holy crap I should've taken that curve slower" situations. The good news as I see it is if you still have the 4 wheel eleven inch drums, its like ABS, because they won't lock up anyway...R)

 

The best suggestion is to avoid any situation or speed that may require panic stops. Common sense and good judgement go a long way. Allow A LOT of distance between you and the vehicle in front of you. As long as you have slipage not to put undue stress on the drivelines, the FWD sistem is safe. 40 MPH is about tops for me on rural roads. I've driven many miles coast to coast on icy snowy roads and highways in an 18 wheeler, accident free thank God, and the inability to stop (foot planted on the brakes and still moving foward) is a pucker factor + 5. A good set of snow studded tires may be a good investment. An old timer once told me when driving on ice and snow, to pretend you have an egg under the brake and throttle.

 

If you have lockers in the front turning will be harder and the jeep will want to plow/ understeer? guys if you do have a locker in the front maybe unlock 1hub for 3wd?is that right , I'm guessing here ,,,,snow is not an option in san diego.

 

Nope. Yep. Go as fast as you want to go.
Just tell the police we said it was OK !

 

A lot of people complain about this, but I've put a lot of miles on in snow packed canyons (maybe 100 yards of straight road at a time) with fully locked rigs without any real issues. You do have to change your driving style, but it's manageable as long as you remember your steering is very compromised. Again, slow down, feel the road, don't make any sudden changes, and you'll generally get where you're going. This is the reason ARB's are so great for snow, you can unlock the axles at the flick of a switch.

 

If you are in the spending mode on your Jeep, consider a good set of lockers. They make a world of difference. Also, if you are decelerating with the engine as opposed to the brakes, being in 4WD will help. The front wheels won't be free-wheeling.

 

oops never mind

 

Take it easy with the speed when driving on ice. If you get to skidding sideways, and hit something with the drivers or passengers side, there is virtually no protection for you or your passenger. You are only inches from the item, be it a telephone pole,tree or another car.

Frankly, I am always more concerned about other cars while driving here in Texas on ice. We don't have an abundance of experienced icy road drivers. And if they get into a problem, it can become your problem (real fast), if they are skidding towards you!!

I am especially alert at intersections and while meeting them coming at me in the other lane. I increase my "situational awareness" of other drivers and try to think of what could happen when driving on ice. And try to have a mental game plan in mind, should I need an out. Such as it would be better to run off the road and go through a barb wire fence than to hit some one head on.

Ok sorry, I know got to preaching about ice and your question was about using 4wd on ice. I use it when it is needed. If can make it without it, it stays in 2wd.

 

:iagree:

The 4WH will handle any speed you will likely be comfortable driving at in those conditions. So don't worry. Just make sure you go to 2H on clear roads.

Dallas/Ft Worth is bad enough on dry roads. When they ice you may as well stay home as every major road will be bumper to bumper because some people just should not have a license. I have seen people doing 60 as they approach a bridge, realize it is iced over and slam on the brakes just as they hit the ice. Makes for a lovely spin and acident. Not to mention every one around them reacts instictively and hits the brakes as well.

Take it slow and easy. Maintain momentum and don't ever panic break. It won't do any good anyway. Think ahead to intersections. The #1 thing ot keep in mind is how long will it take me to stop.

 

I have been driving my Jeep in various snow/ice conditions for over 15 years. Were I live we get a lot of snow and we often have days and days of snow packed roads. My opinion is to use 4 Wheel drive whenever there is ice or snow on the roads. I over the years have spun donuts through intersections as the wheelbase on these vehicles is so narrow. In 4 HI my jeep does not donut so easily. When you are moving at higher speeds if you get into the slush that builds up between the lanes it can pull you around so fast you will be spinning out of control before you have time to react. Being in Four wheel drive drastically reduces this effect. Lockers are not advisable in snow. I put a selectable locker in my for the very reason, the locker causes the jeep to pull sideways again pulling you into the Donut effect.