Hard To Turn In 4wd?

[Ryloth]

This question doesn't really fall into any specific forum here on GM-Trucks so I'll ask in here.

 

Whenever 4WD is engaged, it struggles when taking tight, slow turns. I've noticed this on my 1500, my girlfriend's Xterra, and my ex-wife's Jeep Grand Cherokee.

 

Why is this? Is it bad for the vehicle to force it through a turn like that?

[KMGZ400]

yes...your not supposed to use 4wd on hard surfaces.. its called binding.

[Matt_]

x2

 

DO NOT use 4wd unless necessary.

 

4wd should not be used just because it is raining (its amazing how many customers i had that would use 4wd in the rain and bring their SUVs in to complain about hard turning in parking lots)

[Ryloth]

I keep it in 2WD.

 

This weekend was the first time I used 4WD towing my boat and pulling it up the ramp. The ramp was wet and had algae on it so 2WD was not working very well. When I pulled into a space, still in 4WD, is when it did it.

 

But if I remember correctly my ex's Jeep didn't have a 2WD option and was either 4WD or AWD (can't remember) all the time. So what makes that vehicle different in that it can run like that all the time?

[nickvrebel]

an all wheel drive transfer case is different, it will allow slippage between the speed of the front and rear driveshaft. your transfer case is hard linked by a chain, your front driveshaft and rear driveshaft MUST turn at the same speed, when in a turn your front and rear axles are trying to move at different speeds, it will bind and "chirp" the tires and make the steering difficult. if you were on pavement as soon as the slippery condition was clear you should have shifted back to 2wd.

[Ryloth]

Another question....

 

If it not supposed to be used on hard surfaces can I expect this binding issue in the snow?

[nickvrebel]

do you have the electronic transfer case, with "Auto", that would be the setting you should be using in these "maybe need it" situations and it is safe to use on dry pavement. There is more info on this in the owner's manual.

[Ryloth]

an all wheel drive transfer case is different, it will allow slippage between the speed of the front and rear driveshaft. your transfer case is hard linked by a chain, your front driveshaft and rear driveshaft MUST turn at the same speed, when in a turn your front and rear axles are trying to move at different speeds, it will bind and "chirp" the tires and make the steering difficult. if you were on pavement as soon as the slippery condition was clear you should have shifted back to 2wd.

 

Ah, good information.

 

I knew not to use it unless needed to but I didn't know the reason why.

 

This makes perfect sense.

 

do you have the electronic transfer case, with "Auto", that would be the setting you should be using in these "maybe need it" situations and it is safe to use on dry pavement. There is more info on this in the owner's manual.

 

I do so I'll be sure to check it out. Never seeing the "Auto" option on a 4WD vehicle before I honesty forgot about it.

 

Thanks for answering the noob questions!

[Matt_]

"IN" snow the tires will slip so you wont feel the binding.

 

i use 4x4 when pulling up a boat ramp too. once clear just hit the 2wd button since you can shift 4x4 to 2wd on the fly. it'll make parking the trailer easier.

 

your wifes jeep has an auto mode, its not quite the same thing as AWD.

4x4

auto 4x4

AWD

 

/\/\ each one is different

[Ryloth]

"IN" snow the tires will slip so you wont feel the binding.

 

i use 4x4 when pulling up a boat ramp too. once clear just hit the 2wd button since you can shift 4x4 to 2wd on the fly. it'll make parking the trailer easier.

 

your wifes jeep has an auto mode, its not quite the same thing as AWD.

4x4

auto 4x4

AWD

 

/\/\ each one is different

 

Thats what I figured would happen in snow, just wanted to know for sure so I can file it away.

 

I knew AWD and 4WD were different but I guess I didn't know what made them different in this particular issue.

[Matt_]

i hear ya.

 

for a GENERIC overview (because it get detailed based on which tcase and control system is being discussed):

 

basically 4x4 does not let the driveshafts spin at different speeds. when turning your front driveshaft needs to spin faster than the rear.

 

AWD lets the front and rear driveshafts spin at different speeds so nothing binds when turning.

 

auto 4wd only engages 4x4 when needed

[BadBowtie1]

Ya back in 98 the wife's old jeep grand cherokee all time 4wd never felt like it was in 4wd,when it turned kinda wierd but yet real nice when just driving on dry road's.

[leverlution]

No it shouldn't be used on hard surfaces, no it will not bind in snow. 4x4 is ONLY to be used in snow/mud/slick surfaces. Off road is okay, snow on asphalt is okay as long as it's DEEP ENOUGH that the tire is not making contact with asphalt. It's never to be used above 55mph.

 

I'm not going into it in depth, because I have to be at work, but when you engage 4x4, you are LOCKING the front and rear axles together. When you do that, the tires cannot spin at different rates. Think about it this way, when you make a turn normally, and the tires are wet, do you have 1 tire mark (That all drive the same exact place), 2 tire marks (Left side and right side tires drive the same exact place), or 4 tire marks (they all take different lines through the turn)? Each different tire mark is a little longer or shorter than the next. Kind of like how in racing "The inside of the corner is shorter than the outside." Because it travels a little farther, or a little shorter, the tires are spinning a little more/little less than each other. When you engage 4x4 on a dry surface and take a turn, the tires try to spin at these different rates, but cannot, because they are all locked together. Each tire is trying to force the transfer case/driveshafts/differentials etc to let it spin at a different rate. Thus, you get the "binding" which is REALLY bad for your drivetrain. If you try to take a real sharp turn on asphalt, sometimes you even get the tires hopping, trying to free themselves to spin. On slick surfaces, such as snow or mud, the tires can SPIN while turning(kind of like doing a burnout, but they only spin a little) due to the limited traction, and can free themselves from binding. This is all done automatically, nothing you are doing or can do, but that is why dry roads are really bad for 4x4. This includes rain too really. Like I said, if it is slick enough that a binding driveshaft can spin the tire with little effort, just from pressures in the drivetrain, it's safe to put it in 4x4. If it's too dry, you are going to be binding the drivetrain and damaging things.

[00Silverado4x4]

You can use 4x4 above 55mph depending on your truck. I have researched this many times for many varying years of Chevy & GMC trucks. My 2006 according to the orginal owners manual from GMC states that 4x4 (not just Auto) may be engaged on-the-fly & at any speed. There is no restriction. Of course "common sense" says if your in the need of 4x4 (snow, ice, sand) you probably shouldn't be going 55mph nor to say just because you have 4x4 that you now can go over 55mph.

[Wolverine350R]

So what makes the auto 4wd work? My 99 seems to bind the same in auto or 4-Hi. Maybe I have a bad sensor somewhere???