On my truck when in 4-Lock, going around tight turns in parking lots, its causing a noticeable tire jarring. Is this caused by the 4WD being LOCKED, instead of allowing some slippage as some 4WD vehicles do? I thought the 4WD allowed the inner most tire to unlock as it must travel less than the outer tire.

 

That jarring is what it feels like to ruin a front end. "AWD" vehicles are fine on pavement, but our 4X4 systems are not designed to be run on dry pavement. (pp 273 of the owners manual)

 

Only problem is, it happens on snowy/wet pavement just as bad!

I've never had a 4wd that was this bad about it. I can do a U-turn in my Toyota buggy with lockers front and rear on DRY pavement and not have any of the same issues. "Ruin the front end"...it has less than 2k miles and did it since brand new! Unless it was ruined from the factory, it's just very poor engineering IMO.

 

On turns the outer tire on an axle has to make more turns than the inner so there is a differential to allow that to happen without protest.

Similarly, on turns the front axle has to make more turns than the rear axle, something about physics I think. If you lock the axles together (4-lock) they are forced to turn the same amount, and something has to give. More often than not a tire slips, but sometimes bang, a U-joint or transfer case chain lets go.

AWD systems allow the front and rear axles to turn at different rates (sometimes with some resistance).

I have a mega cab and have not noticed more binding and tire jarring than expected, nothing on dirt. No snow here yet . I think the mega cab has more spring in the frame than other CTDs, which allows the binding to build up a little more before being released via tire slip... perhaps giving you more of a jarring feeling. Like the shudder on backup, one truck is more susceptible than another.

Better tire traction will make for more 4-lock binding, those toyo's may be too good. Otherwise look for something loose, perhaps the transfer case mount.

 

My jeep has a locked (Detroit)44 in the front too, and it wasn't that bad on pavement- But the jeep weighs about half of what our trucks do. The front axle on our trucks is pretty stout, but you definitely want to avoid binding it up. Sooner or later, something will let go..

 

It was the same with the stock tires too. Doesn't matter if it's dry pavement, 6" of snow, ice, dirt, wet grass, etc...still binds really bad. Seems like the geometry/design of the front axle is just trash.

BTW - My 1st Gen doesn't have this problem at all.

 

Comparing the jarring of a 3,000lb jeep to a 8,000 lb ctd is Your jeep or yota whaever has no problem letting the tire slip while in 4 lock because there is less ground pressure. Whn you have 8k divided up over 4 wheels there is a huge increase in ground pressure making the tires not want to slip. The result is the tires don't slip and it binds the suspension up until a point where it finally lets go and gives you that 'jarring feeling' hence don't use 4 lock on dry or hard packed roads. Why would you need it anyways??

 

what you are feeling is not necessarily the tires, but the binding of the U-joints when you have the wheels turned sharp. They are fine at slight to mid turn, but when you turn sharp, they are being forced through a series or rotations that they do not really want to go through. The binding is not good for U-joints. also the tires do turn at different rates when turned, but all 4 tires are not locked together on our trucks, unless you actually have a locker in, a limited slip rear is not a locker. hence the title limited slip..

 

Bnold, if you notice, I also compared it to my 7000-8000lb 1st Gen. That kinda disproves your theory. I also mentioned it happens on VERY slippery surfaces like snow and ice...nothing to do with dry roads. I think it's pretty obvious why someone would want 4wd on a snow covered road.

The Jeeps and Toyotas have FULL LOCKERS front and rear and do not have ANY binding or jarring like this. I understand they weigh less, but you're comparing a fully locked 4wd system to a basic system with open diffs. There is no way the fully locked system should perform better when making tight turns...but it does! I'm guessing the Dodge/AAM engineers weren't so good in geometry class.



HappyGA, it's definitely the tires binding and not the U-joints. A U-joint doesn't last more than a second or two when bound up and torque is applied. Besides, the U-joints are rotating the same whether in 2wd or 4wd and the problem only occurs in 4wd.

 

In 4 lock, you have no center differential. An AWD vehicle has a center differential to allow the front and rear axles to turn at different speeds. With the front and rear driveshafts forced to turn at the same speed, something has to give in a corner. If you're lucky, it's tire slip.

Rusty

 

Wouldn't the rear tires be more likely to slip in this situation (much less weight over the rear)?

 

Well, it was snowing here but when I turned into a parking lot that is when I noticed the jarring.

I figure it is best to just switch the 4-Lock to 2-WD when in tight turns (backing,etc.) or parking lots. I think that it is much less wear & tear switching from 2WD to 4WD & then back, than to have it bind in 4WD in tight turns. Plus, I thought the U-Joints are CONSTANTLY turning even in 2WD, switching to 4WD just locks them?!???

My BFG TKO's have good grip so that probably doesn't help things.

HAS ANYONE LOST A U-JOINT DUE TO THE "BINDING"???

 

I've seen plenty of U-joints fail in the rocks, but never seen it happen on daily drivers (except for driveshaft ujoints)

 

If it binds in 4wd, -on pavement - Take it out of 4wd

Even in 6 inches of snow, I rarely use 4wd, and if I am in 4wd, im not trying to make a U-turn. If the front tires are biting enough while turning to cause binding rather than the tire slipping, I would say chances are the back tires have enough traction to make using 4wd unnecessary.

 

Not sure what the terrain is like where you are, but 1" of snow will make 2wd useless in many places around here. In a sloped parking lot 2wd will have you sliding into the cars next to you.

It still doesn't change the fact that most 4wd trucks don't have this problem.