What are some advantages/disadvantages of the following.....?

Question

Front wheel drive

Rear wheel drive

All wheel drive

4 wheel drive

and mid/rear engined automobiles

please explain in detail. im mechanically inclined, but i want to hear someone elses explanation/opinion

Answer 1

Front wheel drives have more interior space as there is no transmission tunnel and everything is packaged tightly at the front. This also makes them cheaper to manufacture and assemble, as the whole thing can be plonked right in. Apart from that the disadvantages are numerous: Most fwds (apart from the rare longitudinal engines like Audis) Torque steer with too much power therefore practical power is limited. Driving through the front wheels also ruins the "steering feel" and c***s up the steering ability of the car, which presents itself as understeer. As a result of every major component being at the front of the vehicle, they are always more front heavy than ideal therefore presents a challenge to be designed to handle well.  FWDs generally just aren't fun. however, for the same reason safer for inexperienced drivers as understeer is much more easibly controlled than oversteer. If you do manage to get your FWD in a rear end slide you can also stop it from spinning by FLOORING the throttle, which you can't in a rwd.

The advantages and disadvantages of a rwd are generally the opposite of what I wrote above, on top of that rwds are generally more robust and very often easier to service. Rwds have the potential to have a much better weight distribution as the components are spread out and designers have more freedom to place the heaviest components.(for example, the gearbox can mounted in front of the differntial if need be). In a similar fashion the tyres of a RWD car wear more evenly has the work load is distributed more evenly(front steers and does the majority of the braking, rear drives and brakes) In contrast, the rear tyres on a FWD are basically just there for the ride-they don't really do much at all. You can see that alot of older front drivers have tyres from 10-30 years ago, they still pass the MOT checks as the tread depth is mint, however the rubber is perished and disintergrating. The disadvantages are few but may not be trivial for some people: less potential for cabin space, may be less fuel efficient, generally more pricey and more prone to oversteer.

A good amount of oversteer in a rear wheel drive vehicle is hard to correct and requires some practice to be handled properly. Unless the vehicle the traveling at a low speed(in which case taking away the power will suffice) an oversteering RWD can't be "saved" by lifting off the throttle, increasing the throttle OR braking. In conjunction with countersteering, only two methods will bring the tail back(technically it's actually pushing the front out to counter the back's desire to spin round) either modulating the throttle delicately,(reducing just a little, slowly to holding to steady etc.) or braking hard with the left foot at the same time to lock the front wheels, thereby causing the front to slide and understeer. The rear wheels don't lock because the driver maintains throttle and the engine turns the wheel, preventing it from locking.  This method is highly unorthodox and isn't used commonly.

Mid/rear mounted engines are mostly made so for a better weight distribution while having a low angular intertia (by having the majority of the weight in the middle of the car) Angular inertia determines the rotational inertia of an object for a given rate of rotation. The yaw angular inertia tends to keep the direction the car is pointing changing at a constant rate. This makes it slower to swerve or go into a tight curve, and it also makes it slower to turn straight again. The car reacts very quickly, and this makes the car "twitchy" to drive. So according the driver must react fast or the car will be out of control. Mid/rear engined car typically have wieght distributions from 45/50 to 20/80, this rear bias puts more of the load that must be moved onto the rear tyres, which equals more grip to them in a straight line. However when turning, more weight=a higher force "pulling" that end car to the outside which translate to oversteer. This, combined with the low angular inertia, make these cars tricky to drive and an oversteer extremely difficult to save.

All wheel drive vehicles generally combine the best of both worlds, but the world is seldom so perfect. With so many spinning components the drivetrain efficiency will inherently be lowest, the driveline still takes up cabin space, and weight distribution isn't helped much in most cases as either the gearbox will be next to the transverse engine(most cars) or the the loongitudinal engine has to be mounted far up ahead as the gearbox has to be in front of the front wheels(audi quattros). all wheel drives are generally also prone to understeer. All wheel drives will usually have more cornering grip as the tyres are strained more equally. And obviously acceleration grip too, as double the number of tyres available to drive the car foward, this only applies however, if the car has a locked or good limited-slip differential, otherwise all the power will go to the wheel to spins the easiest and the advantage is nulled.

Probably abit much, but hey you said explain in detail, so enjoy your bedtime read.