i am trying to find out when i can and cannot use 4wheel high

i was told by the dealer that i can use 4 wheel drive high whenever i pull loads, am driving in the rain, or when in the mud or on dirt roads.

my transmission shop told me i should only use it when towing under 35 mph or i am off road.

which is the truth?

i have an 01 dodge ram 3500 4x4 auto with the cummins.

 

4 high can be used when the roads are slick on the highway or off road, I have used mine up to 65 mph with no problems.
I onle engage it when going like 10 mph, kick it out at any speed with no resistance on the gears.

Cheers, Kevin

 

i thought it would be ok up to around 60-65 but i could not find anything in writing on it. the dealer has been wrong before, i just wanted to be sure.

 

I've never had a problem at highway speeds in 4WH. I wouldn't run it on dry road in 4WH unless you don't care about replacing tires often. I shift mine at any speed.

 

4 wheel drive should not be run on a hard surface at any time. snow covered or icy roads it is ok. read your owners manual.

 

When in 4 WD, hi or low, the drive train is trying to force all 4 tires to rotate at the same road speed. This is not possible due to minute differences in tire diameter due to tread wear, tire pressure differences, going around a corner etc. OK, there is a device called a differential that to some degree will compensate for all this on the same axle only, but in reality one or two tires will be dragging slightly, specially between front and back. This is because our vehicles do not have a center differential. This is the main reason that the manufactures of 4WD vehicles advise that the vehicle only be driven on wet surfaces such as wet roads or snow. The wet surfaces to some extent allow for the dragging tire to slip a little and "catch up" to its buddies. Yes, you can drive in 4WD on a dry surface, at almost any speed, but you WILL see increased tire wear and not see the increased strain on the drive train components.
Hope this helps a little.

 

I usually don't put mine into 4WD unless I'm stuck or I need to start out fast and I'm on a slippery road. My thoughts are that if you get stuck with it in 4WD, then your only hope is to winch it out. Keep in mind that unless you have limited slip differentials (front and back), you only have two wheels with traction – not really a “4 wheel drive”. I swapped out my standard diff for a LSD after sitting on a city street with both right tires spinning on ice – my left tires were both on dry pavement. At least now I have a “3 wheel drive” rig…
Franklin

 

2WD HI - for streets and dirt all speeds.

4WD HI - for wet, snowy, icy... Plain all around bad stuff...Can be shifted at any speed in or out. Run at any speed.

4WD LO - For the serious stuff... Pulling logs, stuck fords, etc. Remember that LO is 3:1 reduction not the old 2:1 reduction. You must stop to make this shift. Don't pause in N! Top speed is around 30 MPH! It makes a 5 speed very short legged!

N - For those times you need to be towed or dragged out!

I hope this helps! My 02 cents!

 

Matt, my personal record for most continous miles in 4 HI is 250 done in an east coast snowstorm as I drove from Philly to my home in central MA. A lot of it was done on hard packed interstates and my speed was up near 50 at times. It ran great, but I recently had the entire front driveshaft replaced; badly worn U-joints. Whether that had something to do with the early failure or not, I don't know.

 

Doubt it... everything in the front spins at all times, engaged or not.

 

Funny when i lived in MT i would lock my hubs in October and unlock in April for all those years i never saw a noticable difference in wear nor any problems.

Then again the new trucks don't even have IAD so they are spinning all the time engage at anyspeed you will have no issues.

Towing or not is irrelavent. Except you will notice some drivetrian binding if you attempt to turn sharply with it locked. Wheel hop. otherwise dont worry.

Take it for what it worth in the winter in MT most of the year it is not as snowy or icy as one might think. Or you can take the advise of the dealership and owners manual what ever floats your boat or oils your chain.


You lost your front U-joints because you never greased them.

 

running with the hubs locked in is no big deal. all the trucks nowdays are locked due to design. the point is 4 wheel drive should not be locked in on hard a surface. any one who thinks that that is not a relevent fact is sadly mistaken.

 

I didnt realize that this was such a personal preference subject. First off you should know if your truck has the front axle vacumm disconnect system. You can see it on the passenger side of the front axle and you should be able to spin the front driveshaft by hand while parked. If you have this then you need to realize what is hapening when you are shifting into 4wd. The front driveshaft has to play catch up to the speed of the rear driveshaft so that the front axle vacumm disconnect system can lock up the front axle giving you 4wd. You shouldnt try to shift into 4wd at speeds over around 5-10 mph. Your manual should tell you the same. You can shift out of 4 hi at any speed but that doesnt apply to 4 lo. Driving around in 4wd on dry roads is hard on tires and does put pressure on the drive train but is it hard enough to cause damage? Not real sure but I would say probably not. You probably wouldn't like the feeling you get if you did it. The truck wont handle the same. Also people think 4wd means they can drive at any speed in any kind of weather. Bad move! You will find out fast that icey slick roads will be hard to drive on in 4wd since all tires are spinning at the same pace causing them to fight eachother. It isn't traction control, just power to the front and rear tires at the same time. Mud, dirt and snow need this but not ice. Your dealer told you to tow in 4wd? I dont know why. I dont see any reason this would benefit you in anyway. If anything it would put more stress on stuff because of the added weight. Yes I have heard of guys running in 4wd for long periods during winter. Sounds OK to me. Isnt that what its for? I dont see a sticker or anything saying "4wd is only for limited use". As for guys talking about locked in hubs. These trucks hubs are always locked in since there isnt a hub to lock out. The way this 4wd system disconnects is in the transfer case not the front axle. And for a little added fun fact, some guys drag racing these trucks with high HP/ torque numbers cant get the traction they need so they take off in 4wd, then down the track the they shift out. Never read about anyone saying how their 4wd broke. Thats strength.

 

Posted by KATOOM
"...some guys drag racing these trucks with high HP/ torque numbers cant get the traction they need so they take off in 4wd, then down the track the they shift out. Never read about anyone saying how their 4wd broke. Thats strength."
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Especially since the 4x4 won't disengage (at least on the 02) till you let off the throttle. That isn't happening till end of the 1/4 mile...and for some that's over 100 mph!
RJ

 

I think you guys are overlooking something. The above trucks are raced in a straight line and therefore theoretically the only difference in individual wheel speed would come from small differences in tire wear or pressures and consequently the extra load imposed on the drive train would be minimal.
When a vehicle is driven in 4WD hi or lo on the street (dry pavement) then the loads on the drive train increase a lot due to the fact that when turning, the inside wheels turn slower than the outside wheels. The differentials take care of this for EACH axle, but DO NOT compensate for the differences in these speeds for front and back axles. As I mentioned in my earlier post on this, you would need a center differential to compensate for the differences between the front and back axles.
The bottom line is that when driving in 4 WD on dry pavement there WILL be additional strain imposed on the entire drive train. How much this will reduce the life of the various components is another story. But why strain the mechanicals when you don't have to?
Driving in 4 WD hi or lo, on dry pavement WILL increase tire wear for the reason stated above. So if tire wear is increased, does it not follow that the drive train must be stressed somewhere, somehow?