AWD and use of Overdrive


#1

I have a 2006 Toyota Matrix xr that has AWD. It also has overdrive with an override button on the shift handle. When going down hill (i.e., foot off the gas) is the car “free-wheeling” (coasting) due to the OD, even though I have AWD? Should I push the override button in these instances so the car’s gears will give the car added stability? In short, what help is AWD when you are not accelerating?


#2

The AWD only works when slippage is happening at the front wheels and then power is applied to the rear. The benefit is fuel savings however the downfall is you get a front wheel drive car with a little kick in traction when needed and likely too late. The benefit is questionable at best in slowing down.

Other makes like Jeep and Subaru use a full time system with AWD always engaged. The AWD on these vehicles is helpful in slowing down in slippery stuff since you get engine braking to all four wheels and thus a more stable vehicle. The downfall of course is a slight fuel mileage penalty.


#3

“the downfall is you get a front wheel drive car with a little kick in traction when needed and likely too late.”

I might add that that extra kick is only going to help you get out of the ditch, but it will not help you keep from sliding into it.


#4

Don’t over think an awd. Just drive as you would a FWD and take it out of OD if you feel you need engine braking like anything else. Don’t expect the help as you could get with part time 4wd when locked in.


#5

“Overdrive” simply refers to a transmission gear ratio that is lower (numerically) than 1:1, like 0.8:1. This means the engine is turning more slowly than the driveshaft. Some transmissions have two overdrive gear ratios (these are mainly 6-speed manuals).It has nothing to do with freewheeling.

As stated by mconn, override overdrive for a little engine braking.


#6

…again, it certainly does give you increase steering control when the power is on in slippery going. We will perpetually disagree on this, but modern AWD shift power to rears when fronts slip allowing you to maintain steering, esp. valusble when going up hill and taking a corner; a very unusual circumstance I agree. But there are hills, snow and corners where I live.


#7

Just to confuse the issue of AWD www.autozine.org/technical_school/traction/tech_traction_4wd_2.htm - gives a brief discription of several syatems and how they work…tough to generalize how an awd behaves in different cars as manufacturers take different engineering approaches.


#8

I might add that that extra kick is only going to help you get out of the ditch, but it will not help you keep from sliding into it.

It most certainly does. AWD or 4wd will help a LOT in keeping the car on the straight and narrow path. I take it Joseph you don’t live in snow country and have never driven a 4wd or AWD vehicle???