awd understeer?

many poeple say awd has understeer... but y? doesnt it switch to rearwheel when 4wd is not needed?

all production automobiles understeer under normal conditions with the possible exception of a 911.

mmmmm 911 who wouldn't want one of thos. Drifting all day long, yay!

er.......... thats not the answer im looking for

more or less it's real similar to FWD since the rear wheels are not putting 100% power down! also weight distribution on an awd car effects the oversteer!

all wheel drive transfers power to the wheels with the best grip, could be front or rear depending on conditions. the actual design dictates its behavior and every manufacturer has their own idea of what works best.
Understeer is easier to control for the average driver, cars that oversteer tend to be widowmakers. In the case of 911 it has mild understeer that quickly turns into wicked oversteer if you exceed the available traction.

many poeple say awd has understeer... but y? doesnt it switch to rearwheel when 4wd is not needed?

This might be the information you are looking for:

http://autozine.kyul.net/technical_school/handling/tech_handling_4.htm#Neutral

Summary:

If you have three nearly identical cars with 50/50 weight distribution, all four tires are identical, and the power is equally distributed to each of the drive wheels. With the only difference being the drivetrain the result of acceleration while corning will be:

Understeer with FWD
Oversteer with RWD
Neutralsteer with AWD

However these condition describe the ideal case, and the real world is rarely ideal. So there many factors that can change the handling of a car regardless of its drivetrain type, many of which have already been covered in the previous posts.

Alastor

the camber of the wheels has soemthing to do with it as well as suspension stiffness. both of which can be manipulated to get the result you want.

Many all wheel drive systems can't transfer power that well, in some cases they split the power 25% to each of the wheels and using open differentials thay will transfer the power to the wheels that have least traction. Some use some sort of LSD that is braked, others use a system that can transfer the power between the wheels. Some of these systems are actually FWD (usually) or RWD cars in which the other axle will be connected when needed. Some also use a system which transfer the power to the wheels with the best tranction, but these systems are quite rare. Some systems transfer more power to the rear wheels but otherwise the AWD cars are much like a FWD car and tends to understeer.