Why have rear wheel drive?

Question

I'd like to know why there is rear wheel drive in more powerful cras. I know it's because they have the power to do it. But why even have such a things when front wheel drive works fine?

Answer 1

Front wheel drive is more prone to both understeer (a tendency to keep going straight when you're trying to turn) and torque steer (the tendency of the car to move left or right under acceleration due to uneven transfer of torque to the wheels).

Torque steer gets worse as the car gets more powerful, and most FWD cars over 250 or so horsepower over the years have had a problem with it, many to the point they're considered almost unmanageable, most (in)famously the Saab 9-3 Viggen. (edit: that is also the selling point of that car)

Understeer can get worse with more powerful engines assuming that that power is derived from the engine being larger. (This puts more weight at the front of the car, which is not balanced out by having the transmission in the middle and the differential at the back)

Under acceleration, the weight of the car shifts to the rear wheels, meaning that the FWD car will lose some traction, while a RWD car will gain it. Under braking it's the reverse, and the fact that the rear wheels are powered in a RWD car means that it is easier for a RWD car means there is the possibility of the rear wheels slipping if power is applied while the weight is still shifted forwards. This isn't a big concern, but it is possible. (Also the rear wheels of a FWD car can slip in cornering, due to the lighter rear end)

The CV joint on the drive axles of a FWD car are subjected to much greater stresses than those in a RWD car, because they not only have to deal with the angles imposed by the travel of the suspension, but with steering, as well. In light-duty applications this isn't a huge problem (it still neccesitates replacement 2 or 3 times as often in a RWD car, but once every 60-150,000 miles isn't bad), but a FWD performance car could easily wear out CV joints in a hurry.

A RWD car is easier to give a 50/50 weight distribution front/back, and so is easier to create more neutral cornering. (see understeer as a FWD disadvantage) Oversteer can be induced by using more power. (This can be a problem on slippery surfaces, particularly for inexperienced drivers).

Performance cars wear out things like clutches a lot, and RWD powertrains are much easier to work on.


Basically, for most performance applications, RWD is just vastly superior to FWD. The advantages of FWD are most apparent with small cars with little power. The advantages of RWD (and AWD) are apparent with everything else.

Answer 2

If you had the opportunity to stick any amount of power into a front wheel drive car the torque steer would be unbearable. The weight distribution in front wheel drive cars is biased to the front because the transmission output half shafts must align with the front wheels as perfectly as possible. All front wheel drive cars have a very dispassionate amount of nose weight and that means heavy loading on the front springs struts and wheels. In rain, snow when these cars are accelerating in turns they under steer like a bear. The driving force turns into a big surprise when traction disappears. 99% of the time when pushed FWD cars understear so bad it takes the fun out of driving.
If you look around very rarely will you see an excess of 300 horsepower in a typical FWD car van or small pickup. It would be an insane combination.
My pet peave is that there's no adjustment provision for caster and camber if adjustments are necessary the owner is required to buy camber plates that bolt on fabricated slots on the strut towers. The only adjustment is toe in or out.
Little front wheel drive cars are great but don't hint at handling or horsepower

Answer 3

Sometimes people have priority wishes in the car they drive.
The rear wheel drive car with driveshaft from a front engine probably costs less to build. The turn circle of a rear wheel drive car is less. Steering geometry is simpler in a rear wheel drive car. Rear wheel drive cars can have many more variations in final drive axle ratios. Rear wheel drive cars usually have fewer U-joints to worry about. Rear wheel drive cars often have Limited Slip axle options. The weight distribution front/to rear is more likely equal for better handling in sporty traction situations. Snow and ice covered roads yield to safer steering. While it is somewhat infrequent to see a rear wheel drive car with a rear engine, there have been many well known cars with such a layout, ie, Porsche, VW, Corvair, Ferrari, Maseratti, etc.

Answer 4

Because when you have more than 200-250 horsepower and front wheel drive, you can get massive under steer (the car doesn't steer that well when you push the gas)

With rear wheel drive you don't have that problem.

Answer 5

rear wheel drive was around first

Answer 6

its not a pheasable option in heavy duty vehicles. I would rather have rear wheel in anything. front wheel drive is just cheap crap.