Snow/Ice. FWD vs. AWD

**techy101** · 09-10-2005, 10:24 PM

So, I'd like some opinions, and the reasons for them. Not just "because" which is better in snow and ice. All Wheel Drive (Subaru) or a Front Wheel Drive vehicle?

**Rundell** · 09-10-2005, 10:34 PM

After having my Subaru AWD and driving it down and up hills with snow I can't imagine buying any other vehicle that does not have AWD, especially when I see other vehicles stuck on the side of the road!

Also, its great for me since I like going off roading and sling some mud and don't have to worry to much about getting stuck.

Edit: Just noticed your also a member at subaruforester.com , me too i'm grasshopper don't post much there tho

**RoyN** · 09-11-2005, 02:01 AM

I dont know technically what affects it really, but I've ridden in both AWD vehicles (audi and bmw - the former concentrates more acceleration in the rear though, I'm told... dunno exactly how that works tho), and I had a FWD A4 cabrio... the AWD is obviously more control... the FWD is funner in an empty lot tho!

**lgbr** · 09-11-2005, 02:13 AM

Pffffffffff.

RWD with 58% or more of the vehicle's weight in the back. Like it or not, you're going to get good at drifting.

**PatO** · 09-11-2005, 02:14 AM

I kind of like part time 4WD. You get all the joys of a RWD vehicle (whippin *****ties, better mileage) and you can pop it into 4WD in the snow.

There's nothing better than getting a good launch at a green light.... when there's a foot of snow and ice on the road!

**froop** · 09-11-2005, 08:21 AM

AWD is always going to be better that front wheel drive in snow/ice. Simply because you have all wheels driving instead of just two. But its always worth knowing how your centre differential works.

In a normal 2wd car (front or rear) all it takes is one wheel to lose traction, and you're not going anywhere. Eg, in a rear wheel drive with no LSD, jack up one of the drive wheels and if you start the car and put it in gear, the diff will cause the lifted wheel to turn and the one on the ground will stay still.

Getting a tyre onto ice has a similar effect to lifting it off the ground - no friction between it and the tarmac.

Same theory extends to AWD cars with the centre diff. If it is an open diff, just one wheel off the ground will cause an AWD car to turn into a zero wheel drive car. Fortunately, most AWD cars have at least some sort of limited slip in their centre diff, which means that you can lose traction on both rear wheels and still have drive in the front. Lose traction on the front and you still have drive on the back (but no steering!).

Slightly different story for four wheel drives (ie, Landrover, Landcruiser, Patrol, Jeep, etc) which usually have an open centre diff, but it is lockable. In these cars, the centre diff should stay open unless you're driving on a low traction surface like gravel or icey roads.

The best situation to be in is if your AWD has a limited slip centre diff and an LSD rear diff, and also uses the ABS hardware for traction control. Then if any of your wheels do start to slip the LSDs will help you out, plus the ABS locks the slipping wheels directing the torque in the drive shaft back to the wheels with traction. That way you need to lose traction on all four wheels before it all goes FUBAR.

Did that answer your question?

**HHdesign** · 09-11-2005, 02:58 PM

My cousions jeep is 4WD, That thing is amazing. I wish mine was. We've spun all tires at once, an amazing sight.

Get AWD, its fun. Then again, FWD is fun to fool around with.

**techy101** · 09-11-2005, 02:59 PM

On some of the Subaru forums I've been reading about a fuse that you can plug in to disengage the center diff. so the car turns into a FWD. I have to go hunting and see if my car is one of the ones what will do this. Best of both worlds if it does. (They say it's there in case you have to put a spart on that is the wrong size. that way you don't fubar everything up.)

**Rundell** · 09-11-2005, 06:10 PM

Originally Posted by techy101

On some of the Subaru forums I've been reading about a fuse that you can plug in to disengage the center diff. so the car turns into a FWD. I have to go hunting and see if my car is one of the ones what will do this. Best of both worlds if it does. (They say it's there in case you have to put a spart on that is the wrong size. that way you don't fubar everything up.)

Yeah my forester I can pull a fuse and have FWD. I did it once, has a light on the dash that says 'FWD'. I'm sure yours is the same even though its newer. My fuse was located in the fuse box in the engine compartment. The lid of the fuse box has a diagram and told me which one to pull to disable AWD.