ok- i know that saying... never use 4x4 on dry roads....

well i would like to know whats the difference in awd and 4x4 that allows awd to be used on dry roads and 4x4 cant....???

In a 4x4 the transfer case is "supposed" to be locked into a 50/50 torque split. On the BW 1354 transfer case this is true, but on the control trac 4405 it still allows some slippage when locked into 4x4.

The 4404 transfercase in the V8 explorers is not locked and can differentiate just like the front or the rear axle can. This is not good offroad though because if both of your front or both of your rear wheels leave the ground then you're stuck.

so are you saying the 4405 trac control 4x4 explorer can be driven on dry pavement without anthing getting hurt? is it basically an awd t-case that you can dis-engage?

Yes and No. The 4404 in the AWD Xs has a "viscous coupler" which allows the front axel to slip if it is turning faster or slower than the rear axel. In the Control Trac 4405 case on the V6s, there is an electric clutch as well as a low range.

When in 4wd Auto in control trac, the GEM senses front and rear axle speed and engages or disengages the clutch depending on whether the vehicle is turning or the wheels are slipping and 4wd is needed. The case can also be locked into 4hi and 4low, and wired to make 2wd. The AWD 4404 has no wires going to it, its strictly mechanical, while the 4405 has a shift motor as well as the clutch.

wait a sec, can someone tell me why having this 50/50 torque split is ad on dry roads?

because if your wheels can't slip and they're locked together, then something in the driveline has to give and break if the wheels start moving at different speeds. Wet roads or other situations give the wheels opportunity to slip and thus get rid of the stress on the driveline.

Originally posted by bates
wait a sec, can someone tell me why having this 50/50 torque split is ad on dry roads?

Okay, let me try. In 2WD, power goes through differential and out to the wheels. When you go around a corner, or experience slip, the diff allows the wheels to spin at different rates and take out any bind in your driveline.

In our part-time 4WD sytem, there is no center differential in the transfer case to allow the front and rear drivelines to differentiate. So in very basic terms, it means the front and rear are "locked" together.

Now lets talk about what happens when you use 4WD on dry or hard packed ground (high or moderate traction surface). When you drive in 4WD, the individual wheels can differentiate from one another, but the front and rear drivelines are spinning at different speeds and can't differentiate from eachother. What happens is that the system will build up bind. In short order this bind will need to release some how, and if it can't do it through wheel slippage (low traction surface), it will do so through breakage. If you drive around a city block with 4WD on, and then jack up the truck, you will see the wheel spin in recoil to release the bind.

Hope this helped.

--Sean

That's what I said, but much quicker ;)

ahh! i get it now, thanks!

Originally posted by Alec
That's what I said, but much quicker ;)

You post wasn't there when I started my novel. We only posted 2 minutes apart. What can I say, I am a writer, I like words. ;)

--Sean