4x4 Behavior Question

leftover-salmon · #1 (**permalink**) 03-17-2002, 08:41 AM

Greetings,

Forgive me for the stupid question, but I've never owned a 4x4 until I purchased my used 2000 Tundra last November. Curious if this is "normal" behavior for a 4 wheel drive vehicle? I don't remember my truck doing this on the test drive.

When I'm driving around town in 2WD and I shift into 4WD Hi everything seems fine. The truck accelerates great and I don't hear any weird noises, etc.

I become concerned however, when I turn into a parking lot with 4WD Hi engaged. The only way I can describe this is that my Tundra begins "bucking" and "jerking" wildly when i cut my wheels to the left or the right sharply and apply the gas to ease into the space. I also find that I have to press the accelerator pedal a lot futher than one would normally to get the truck to move.

When I put the truck into reverse to back out of the parking space (4WD Hi is still engaged at this point) the truck seems to be very slow and "lethargic."

Again, I have to press the accelerator pedal a lot further down than one would normally to get the truck to move. As I cut my wheels to the left or the right, the truck continues to "jerk" and "buck." I can also hear the front and rear tires slipping.

Has anyone else noticed this? Is this normal?

Thanks!

Derrick
Redmond, WA

thunderhead · #2 (**permalink**) 03-17-2002, 08:56 AM

You are experiencing drive- train wind-up. It can be very damaging to your 4WD . Toyota 4WD is not designed to operate on dry pavement in tight turns. If you were on a slippery surface this would not happen. Basically it's caused by the difference is turning radius between the left and rt side arcs. When you reverse the DT is "unwinding". The wheel hop is relieving some of the torque that was in the system. The 4WD cannot disengage when it's in this state because the transfer case has so much stored energy(everything is in a bind!!!). As you back up the torque on the system returns to normal. On older manual 4WD systems many times you had to back up to get the transfer case out of 4WD.

Leathernuts · #3 (**permalink**) 03-17-2002, 09:59 AM

Thunderhead is absolutely right and no 4wd drive is designed to work on dry pavement.Even " All wheel drive " systems would do this ( bind ) if the system wasn't configured to disengage and compensate for this. Those systems tranfer the torque from one axle to another depending on where the "slippage" is occuring. But our trucks and all 4wd systems like ours are driving both axles simutaneously and when you turn, they tend to pull against( in different directions) eachother whereas in dirt or slippery surface, they can slip a little to compensate for this. Again, there is nothing wrong with your Tundra, this is normal on dry pavement ( although you should not drive in 4wd on dry pavement). Enjoy your new truck.