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all wheel drive safety concerns

Is all wheel drive car safer than a two-wheel drive one? No, it is not. All wheel drive is not a safety feature. All wheel drive is needed for better traction. Better traction means getting the car moved in difficult road conditions. All wheel drive can make your car faster, not safer.

All wheel drive lets you:

  • Accelerate faster on a slippery road.
  • Get out of a snowdrift.
  • Drive off-road (off-road capabilities depend on the vehicle).

All wheel drive does not let you:

  • Decelerate better.
  • Drive faster through a slippery curve (we are not talking about racing and rally-style snow drifting here).

When braking and turning, the same inertia, or centrifugal forces are applied to the vehicle, no matter if it is a four wheel drive or two wheel drive vehicle. Faster acceleration does not mean faster braking.

Besides, a vehicle with part-time all wheel drive system can be dangerous when driven in four-wheel drive mode. The vehicle heavily understeers (slides off the curve) and this can lead to an accident. Part-time all wheel drive is for off-road use only. When on the road, you must switch back to two-wheel drive.

In winter conditions, good winter tires are more important than all wheel drive. All wheel drive will not help you to stop or turn the vehicle on ice or snow.

Do not overestimate the capabilities of your all wheel drive vehicle.

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There are 4 comments
Ola Dahl
January 19, 2016 - 23:11

When it comes to active safety most awd systems does not improve handling and safety in itself. ESP does. (Electronic stability program) And the best ESP systems can actually work better in conjunction with AWD (i.e. BMW X-drive)
Some racecars improves braking (and sometimes high speed stability) by means of an actively controlled centre differential brake, but reducing drivetrain friction is just as important, therefore, awd is in most cases bad for high speed handling.

Joe
January 26, 2011 - 03:02
all wheel drive braking

I disagree that all wheel drive wont help you brake going down a hill if you place the transmission in a lower range ie 2nd or low the engine will be a brake because the trans will hold the vehickle back its an old myth that the trans wont slow you down if you place the transmission in a lower gear position the engine tach will show an increase in engine RPMs indicating the trans. is working in the lower gear position. no different that downshifting a manual trans. very few people realise this. transmissions have improved since the early60s when I test a automatic transmission for different clutch and band operation that is the method use the different selector positions. I held ASE certification in automatics for many yrs.Most owners manuals tell you to use a lower gear when decending a hill.

Reply to Joe
Bob
January 30, 2011 - 03:32
Re: all wheel drive braking

I agree with you Joe. Full time AWD (like Quattro etc) will be better than a 2WD when it comes to engine breaking as the breaking power is distributed to all four wheels thus will have better traction. (in my opinion going down hill (coasting) with engine braking is more stable that ABS.)

Reply to Joe
George
February 11, 2011 - 19:54

It depends if you have a center differential or not.
If you have a center differential, then yes you can get throttle braking to both axles simultaneously.

If you are using a PTO [power take off] system, then it is inadvisable to downshift, because most systems usually decouples on overrun [and all if the brakes are engaged].
So on a front drive system, you would only be braking the front axle, increasing understeer.
On a rear drive PTO system, you would only be braking the rear axle, potentially causing oversteer.

In a rigid coupling system [no center differential, no clutch] such as a pickup truck, you would be okay if you were going straight. The moment you had to turn, all stability is gone.

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