Why Do NASCAR Stock Cars use Rear Wheel Drive (RWD)?


Why Do NASCAR Stock Cars use Rear Wheel Drive (RWD)

When you watch a NASCAR race, it’s hard not to be in awe of the machines on the racetrack; at their raw power and prowess. It leads those of us with a proclivity for all things automotive to wonder about both the powertrain and drivetrain of these cars: How big are the engines? How much horsepower do they have? But more fundamentally, how many wheels are really powering them on?

NASCAR Stock Cars use rear wheel drive trains in all their cars. AWD may provide better traction and acceleration from slow speeds, but the trade off with the additional weight, power and fuel requirements make this a diminishing return. Races are often at high speed and on banked tracks negating the benefits of AWD.

In today’s blog, we’re looking at NASCAR drivetrains and asking ourselves if the cars are AWD, 4WD, FWD, or RWD. At the same time, we want to help you better understand the differences between these different drivetrains, why NASCAR’s rules are as they are for their vehicles, and more. Let’s dive right in.

Are NASCARs AWD/4WD or 2WD?

The simple answer to this question is that NASCAR uses 2-wheel drive (2WD), and to be more precise they are rear-wheel drive (RWD). But why? We know that NASCAR tracks are only simple in form to the untrained eye.

The banking of the track and often difference in turning styles needed at each end of the oval on many tracks present many challenges. Therefore, wouldn’t AWD or 4WD be better to deliver more traction?

Why Are NASCAR Stock Cars RWD?

The reason NASCAR uses RWD drivetrains is because of their superiority when it comes to weight, cost, handling, and fuel use. A cutting-edge modern AWD system would add a great deal of weight to the car, which would change the entire dynamic of how it feels and drives on the track.

  • AWD systems also experience greater power loss compared to RWD vehicles. A vehicle with an AWD drivetrain might lose 20-25 percent of their power through the drivetrain, but a RWD car only 15 percent, and that difference makes the difference between winning and losing in a NASCAR race.
  • An important thing to remember here is that NASCAR is not a sport that prizes innovation in the same way that Formula 1 does. That’s not to say NASCAR enthusiasts are luddites, but rather that the sport has its traditions and standards and keeps them in place so as to allow all participants to participate in that same challenge that all NASCAR racers have gone through.
  • It is this same principle that kept NASCAR stock cars manual with just 4 gears.(although the new next gen has moved to 5 gears now) Adding a 6-gear transmission might seem like an interesting innovation, but it changes the entire way that the driver operates on the track. It would mean even the best drivers having to re-learn their sport, and there’s little justice in that.
  • RWD systems are simple, they last longer and need less repairs
  • The balance of cars is improved, which provides better handling overall. The weight is more equally spread along the car.

Will NASCAR Ever use AWD/FWD?

Although All Wheel drive provides excellent traction from slower speeds on more diversve road conditions this is rarely needed in a NASCAR race.

This coupled with the extra weight an AWD will bring to the car makes any minimal benefits (in this form of racing) not worth the trade off. this extra weight will increase fuel consumption, and require more power, again increasing fuel consumption.

If the engines are using more fuel that at worst will require more pitstops, and at best longer refueling times.

So the benefit of having a system that helps with slow speed acceleration is not relevant in most racing series including NASCAR, even Formula 1 who do slow down to 40-50 miles an hour, although experimenting with AWD have never taken it forward.

NASCAR Stock cars who before at high speeds on asphalt for most of their races and on have no need for this type of drive train.

Why Do NASCAR Stock Cars use Rear Wheel Drive (RWD)

Different Driving Dynamics Between AWD/4WD, FWD and RWD

Let’s add some context and clarity here by explaining the difference in driving dynamics between these various drivetrains, starting with all-wheel drive (AWD) and 4-wheel drive (4WD), arguably the most confusing of the set.

What is the difference between AWD/4WD?

The reason people get a bit mixed up over these 2 designations is mostly that OEMs tend to use them interchangeably and freely, without anyone agreeing on a real standard definition. The basic definition of both AWD and 4WD is that of a drivetrain system that sends torque to all 4 wheels while driving. The goal of doing this is to boost traction and control.

But then why do we have 2 designations, AWD and 4WD? In principle, these 2 are the same, but the difference is in the way that they are applied. AWD has more of a focus in applying traction to on-road situations, and are sold either as a full- or part-time system.

Full-time AWD means that the AWD is on and working all the time. Part-time AWD means that you drive most of the time with 2WD, but the AWD kicks in at moments when sensors detect that additional traction is needed.

4WD, on the other hand, while also being about delivering torque to all 4 wheels, does so through a more intricate system of differentials, couplings, transfer cases and other hardware. A 4WD system is meant to be used on more rough and rugged terrain, like a muddy off-road trail, a rock-crawl or some other challenging terrain.

4WD is also often a feature manually engaged by the driver in “high range” or “low range,” using the former for slippery low-traction road conditions, and the latter for off-road conditions.

If you’ve always associated AWD and 4WD with SUVs and trucks, you’re not wrong to do so. While these systems are being applied to a wider range of vehicles in modern times, they were originally designed to help cars that handled rougher terrain and tougher driving conditions.

What is RWD?

It wasn’t just NASCAR that made RWD their default setting. For many years, RWD was the norm across the entire automotive industry. It was favored because it created a good balance for cars of all kinds, with the rear wheels handling the power and acceleration, and the front wheels handling the steering. This arrangement ensures smoother turns and less stress of the drive wheels.

There’s some advantage to having RWD if you’re planning on towing a trailer, too. The added weight of the trailer gives your rear drive wheels more traction, and keeps the front wheels from becoming overly burdened. The other benefit of RWD drivetrains pulling trailers is superior and more accurate maneuvering.

What is FWD?

So a FWD drivetrain is the opposite of a RWD one, with torque being sent to the front wheels as the main drive wheels. The main advantage that FWDs have over RWD cars is traction. The weight of the engine above the front wheels helps make FWD naturally more capable in slick road conditions after rain or snow. RWDs are more susceptible to loss of traction in those conditions.

There’s a comfort benefit to FWD cars, too, because they don’t have the large driveshaft running from engine to rear wheels.

This means that FWD cars can have flat floors in the rear and a more even layout free of protrusions. That makes things a lot more comfortable for passengers in the rear. Not something a stock car worries about too much.

Do Any Motorsports Use AWD/4WD?

While it may seem that all prominent motorsports use RWD or FWD cars, there are some exceptions to that rule, most notably rally cars in World Championship Rally series.

  • Not all rally cars use 4WD, though. Lower-class rally cars are usually FWD, and some RWD like the Lancia 037, for instance.
  • It’s Group N in the rally circuit that uses 4WD drivetrains, namely the Mitsubishi Lancer EVO, Subaru Impreza and similar R5 and WRC cars.
  • While there have been discussions about having 4WD/AWD in circuit racing, including Formula 1, it has never gotten off the ground. Only about 8 AWD Formula 1 car prototypes have ever been built.
  • Drag racing is still RWD, but there have been big impacts with AWD cars, especially is less ideal weather conditions
  • World Touring Cars are Front wheel drive
  • LMP ( Le Mans Prototype) are predominantly Rear wheel drive, however Nissan Built a Front wheel drive car in 2015.

Final Lap

It is not just NASCAR that favours rear wheel drive over other forms of drive in the motor racing world. The vast majority of racing series also either prefer or regulate RWD in their competitions. While there may be some debate about its use in these series, in NASCAR the reasons for RWD are clear.

  • Less weight
  • Less fuel and power needed
  • More power transference
  • Less requirements for acceleration from slow speeds
  • Less cost

and perhaps the most important reason, it’s almost impossible to do a burnout if you win in an all wheel drive car!

References

https://jalopnik.com/heres-how-modern-nascar-race-cars-compare-to-their-road-1827401884

https://www.reddit.com/r/NASCAR/comments/2j342p/quick_noob_question_can_nascars_now_have_4wheel/

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