Not sure if this is an actual problem, but it doesn't feel right.

I have used the 4WD HIGH very little as of yet, but when I have it engaged and turn hard left or right, it seems to jump a bit, like the tires are not spinning right in the turn and one is behind or ahead of it.

I haven't taken it to the dealership yet, but is it my imagination or is there a flaw here?

 

Here's a question... are you doing this on cement? (Seems like another silly question...) but some people may not realize that driving with 4 wheel drive engaged on dry pavement can damage drive line components.

 

If this is the case... It is because it's a part time transfer case that the JK has, so both front and rear axles are locked together in four wheel drive. In hard turn the axles and wheels on each axle will try to spin at different speeds. Of course being in four wheel drive prevents this and therefore it will hop on dry surfaces. It's not good for tires, drive line components as mentioned, and can also be dangerous. A full time transfer case doesn't have this problem, they do not lock the axles because they often use a fluid or some other method to transfer torque. Those can be left in four high indefinately.

 

Regarding the front axle, on a sharp turn in 4 wheel drive the tire on the inside of the turn will rotate more on then the tire on the outside of the turn. This is what is causing your jeep to jump while in 4wd during a sharp turn.

 

Actually thats not correct. The tire on the outside of the turn will rotate faster then the tire inside of the turn which leads to the problem of the outside tire skipping. The outside tire needs to travel a greater distance then the inside tire thus forcing it to move faster.

 

oops...what he said

 

Actually, I'd say you're both wrong... to a degree. The last sentence above is what is important. Both tires are actually trying to rotate at the same speed... and since the outside tire (as mentioned above) when turned in a hard turn actually (needs to) travels more distance, than logically it needs to spin slightly more than the inside tire in order not to 'jump'. Since it is being prevented (due to the 4wd being engaged) from doing so, you feel the inside tire grabbing and trying to turn you steering wheel closer to straight so that both wheels can again try and spin at similar rates.

Bottom line is... don't drive it on dry concrete in 4wd... it does wear on your drive components.

 

FYI

Here is why part time 4WD should not be used on pavement: http://www.4x4abc.com/4WD101/def_turnpart.html

Here is why part time 4WD should never be used on pavement (Part 2): http://www.4x4abc.com/4WD101/axle-wind-up.html

BTW, JK has 4WD - PART-TIME, not FULL-TIME.

 

Great Links... exactly what I was trying to put into words!

 

Actually, you're all three wrong The problem isn't with the front wheels trying to turn different speeds, or the rear wheels trying to turn different speeds. The differentials in your front and rear driveshafts take care of this (unless you're locked). All four wheels always spin at different speeds in any corner, that's what differentials are for. The driveshaft speed is always equal to an average of the tire speeds for each axle.

The problem is that the average of the speeds of the front tires is greater than the average of the speeds of the rear tires, and there is no differential in the transfer case to allow this to happen. Since the t-case always spins the front and rear drive-shafts at exactly the same speed, but the front tires need to go faster than the rear tires in a turn, they drag or scrub.

This is also the reason why the brake-lock differential technology on the JKs can cause a jerky ride off-road. When your computer senses a wheel start to spin, it applies the brakes to that wheel to try to control the wheel spin. If you have a situation where 3 tires have good traction and the fourth wheel is spinning, when the computer applies the brakes to that wheel, then the other wheel on that axle is trying to spin TWICE as fast for a moment. It can make for some jerky performance.

-E