4-Hi & Pavement - Why No Turning?

I have googled, searched & read - and still don't understand....why does the truck resist when you turn on pavement in 4 hi? (This came up when reading about driving in 4hi for 10 miles a month to lubricate).

I am somewhat new to 4x4 - but I understand what a locker is, and that the front & rear have lockers, the rear locker being optional and to be used ONLY when one wheel is slipping in 4-Lo.

Why does the front locker not have a button?

Thanks

 

Couple of things:

1.) Read this: http://www.4x4abc.com/4WD101/def_turnpart.html

2.) Tacoma's do not have front lockers.

 

Dude... The wheels all want to turn at the same speed in 4x4. When you're turning the outside wheel has to travel further than the others and at the same speed causes the wheels to chirp and resist. That's all I've got for you.

 

First of all we need to know more about your truck to help you out. If it is stock it doesn't have a locker on the front and if it's an off road or a modded truck it will/may have a locker in the rear. The issue with driving in 4hi on the pavement is your wheels on both axles have lots of traction. So the 4x4 system wants both of them to travel the same distance when your turning. But the thing is your wheels when turning actually go different distances. Kinda like when you run around a track in the inside lane vs the outside lane one distance is longer than the other. So when you try to force the wheels who mechanically want to go the same distance to go different ones it causes a great deal of stress to the drive line components and the wheel that is on the outside of the turn will skid and hop. So unless conditions are slippery and will allow on of the wheels to skip a little it can cause issues if you drive on dry pavement in 4x4.

 

This.

It's not a death sentence if you happen to do it but it puts a lot of strain on the drivetrain and if you keep it up, something's bound to break....or at the very least put more wear on the 4x components than they were meant to handle.

I turned over a concrete slab on a trail out in Cleghorn over summer in 4lo and the sounds my front end made weren't pretty.

 

Thanks scottclarkinco. Got it - that's what I needed. (Was misinformed/misunderstood r.e. the front locker).

I might still be misunderstanding - but in 4x4, the front & rear RPMs are locked together (the same way the rear locker locks rear left and rear right RPMs when engaged). Meaning - the tension you feel when turning in 4x4 is not from any left-right RPM issues, but simply front rear.

 

It would be left and right tension though wouldn't it? The inside tire when you're turning in 4x4 has a shorter distance to travel, both wheels have traction on pavement so they're both going to be getting power causing the tension. When you're on dirt lets say, it allows the other wheel to spin and release any tension that might be building up.

 

The way I understand it - in 4x4 the front left/right can turn at different speeds (it has a differential allowing this, but no locker) the same way the rear can (without locker locked). in 4x4 all wheels get power, but can turn at different speeds EXCEPT that the transfer case doesn't have a differential (center differential) so the front-rear differential is the problem.

 

Ah I see what you're saying, that makes sense. The center diff being what solves this issue for AWD vehicles.

 

Actually, it's both f/r and l/r. But mostly l/r. The rear wheels track differently from the fronts during a turn. But much like l/r the tighter the turn the worse it is. Its a horrible feeling when it starts to bind...

 

You're on the right track, but not quite on target.

The inside/outside difference is handled by the differential. No problem there.

Where the real problem comes in, is the fact that the REAR AXLE follows a smaller radius than the front, therefore actually travels a shorter distance around the curve.

Next time there is a light dusting of snow on the ground, find an empty patch of parking lot and drive in a tight circle, and observe after, that you have FOUR tire lines instead of TWO, because the back wheels don't follow in the exact path of the front.

 

^ He's actually more correct. I was messing with mine and had the locker engaged, exacerbating the problem.